1/ Reason for the project

2/ Liquid engineering

3/ layout

4/ bevel box

5/ Swing arm removal and refitting

6/ Machining the sprocket carriers

7/ Chain

8/ Alignment

9/ Mudguard

10/ first impressions

11/ parts and suppliers


Modifying the cush drive








the steering rod ends


the bonnet catches


the exhaust pipe and rectifier mounts


the pedal box


the timing belt cover



1/ Reason for the project:-

My 2013 Morgan threewheeler was purchased two years old with 635 miles on the clock. All the factory updates had been carried out at the expense of the first owner to whom I am greatly indebted. Brands hatch Morgans carried out all the work and delivered it to me like new. During the test drive I noted a bit of clunking as the belt jumped over the teeth of the pulley and they re tensioned it before delivery, all well and good

Subsequently the belt continued to jump teeth and had to be re tensioned almost every trip. After 7000 miles the rear sprocket was so badly worn that the threads of the side plate fixing bolts were visible and the belt stretched to the end of the adjusters. Those guide plates are another nonsense, they make so much noise when the belt rubs on them - and it does. Any belt, especially one which is no longer new, needs to be tracked under load, when the load comes off the belt will settle on a different part of the pulley and if we load it in the other direction it will move again. I return to the point that the vehicle puts too much stress on the drive system and so this problem becomes unbearable. I have read suggestions that one should continually apply washing up liquid to the belt to keep it quiet; what a lot of bollocks. My local dealer up here in Lancashire could not get a price for the elusive steel pulley and I was not sure that a steel replacement was the answer, after all the aluminium one was useless after only 635 miles. The only answer for me was to convert to chain drive. To quote one supplier " chains are for racing - belts are for holding your pants up" I could not agree more. While we may not be racing we are driving a vehicle weighing in at 500 Kg. the Harley Davidson, which I assume to be the source of inspiration here, only comes at weights between 250Kg. And 400Kg. and that for the fanciest of them. Research soon showed that there are numerous conversion kits available for the Harley Davidson machines, this speaks for itself. I resolved to put together a list of components and do the job myself.

Here you can see the state of the rear sprocket after only 7,000 miles

A further annoyance was the continued build up of dirt and dung in the rear compartment. The aluminium splash guard fitted to the rear wheel is so inadequate it defies my attempts to find enough adjectives to describe it. Did they get the tea boy to design it? That seems the likely reason why it so resembles an old tea tray cut up and screwed to the swinging arm. If this sorry excuse for a mudguard catches two percent of the road dirt from the back wheel I would be surprised and then, what little it does catch, it drops straight back in front of the wheel to be thrown up again. Surely someone must have known what effect water mixed with salt, grit, mud and small stones would have on a vehicle made largely of aluminium? Obviously not. This defect adds to the rapid deterioration of the final drive and so I resolved to address it at the same time.


2/ Liquid engineering

On dismantling some items on the threewheeler I have encountered huge difficulty due to the liberal application of " loctite" type assembly glues. The item which currently has me inflamed is the hugely over engineered fastening for the final drive sprocket on the bevel box output shaft; this nut would hold the airscrew on a Spitfire! The sprocket sits on a very well manufactured 28 tooth spline and should only need a retaining nut to stop it wandering back and forth; the clamping force of the nut Morgan have used would hold the sprocket without the spline and then they smear it with glue and use a tab locking device on the nut as well. These assembly adhesives, variously described down the decades as " liquid engineering" etc. are just quick fixes for situations that have arisen in the field, not as an alternative to proper engineering design and certainly not to be used on everything just because the designer wanted belt braces and suspenders! How do they think we used to cope without it? There is no substitute for using the right nuts and bolts and doing them up correctly. Using a nyloc nut, a spring washer and glue smells of panic. As to warming up components before dismantling - don't get the blow torch too near the petrol lines!

Back in the day I was taught to have respect for the next poor guy who had to dismantle a piece of equipment and I was encouraged to use a little tallow on precision fits and threads so that they came apart again easily and without damage. Mechanical locking devices such as tab washers, lock nuts and split pins keep things from coming undone perfectly well. These days I use copper slip or any other of the off the shelf anti seize compounds; a bit of grease or even, dare I suggest, tallow still works though.


3/ layout

The project started with checking out how the chain and sprockets will line up and the solution is not too difficult to see. Machining the front belt pulley to carry a sprocket on the outboard side and the rear pulley to accept one on the inboard side gets it all within a couple of millimetres and there is enough sideways adjustment in the swinging arm trunnions to cope with this. The original drive ratio is only just a fraction over 2:1 and so I chose to use 24 teeth on the front and 48 on the rear. Some basic calculations backed up with advice from suppliers pointed me towards a 5/8 pitch chain 3/8 wide or a 530 chain, in modern parlance.

4/ Bevel box

My bevel box was noisy. It was filled with a thick, black, presumably molybdenum disulphide based, lubricant. My inclination was to change this for a conventional gear oil and see what happened. Rumours had me think that the reason for this was that a normal lubricant would blow out of the breather / filler plug. This is backed up by the change of position of the breather to the top of the box on later models. Mine was in the back of the box centred on the output shaft. I erred on the side of caution and piped the breather up to a point beside the petrol filler pipe with the original breather plug inserted in the end of the rubber tube. I can now fill from here with a syringe or squeezy bottle. I refilled with straight 30 oil as a flushing medium and changed for a good gear oil after the first twenty miles.

I suspected that the rubber mountings on the bevel box allowed some movement which may have contributed to the belt problems. Having ridden BMW bikes with sidecars attached I had a good idea of the upward forces exerted at the front end of the drive shaft when accelerating ( the sidecar translates this in to sideways movement and it is quite scary till you get used to it ). I fitted up a video camera in the passenger seat and went for a drive with the prop shaft tunnel removed and a plywood trouser guard to stop me from getting wound up in the works! The rising movement of the input flange of the box when accelerating hard is negligible so, false alarm, no worries there.


5/ swinging arm removal.

Before removing the swinging arm I took some measurements to enable me to mock up the swinging arm and bevel box on the bench later.

After removing the rear wheel and its spindle complete with chain adjusters plus the three clips for brake hose and hand brake cable, comes the task of retracting the swing arm trunnions. These are locked in place by two rings requiring a "C" spanner to loosen them, a professional one at that. Mine covers the range of 1" to 2", made by Britool and is barely adequate I would recommend the 2" to 3" version. Do not assume that a cheap one cut from steel plate such as those supplied to adjust shock absorbers will do the trick, it will not. The nuts on my machine were incredibly tight and glued in place to boot. Screwing out the trunnions all the way ( more glue here!) allows the swing arm to drop out of the frame, I supported mine with a rope from the roll over bars, a friend to hold it up would have been even better. I should note, at this point, that the plastic plug which keeps the muck out and the grease in was missing on the drive side. It is not possible to remove the plug on this side with the bevel box in position nor to put it in if you forget to do so before replacing the bevel box. I conclude that mine was missing from the factory or forgotten when the bevel box was out for the rubber mounting mod. Anyway the upshot was that the drive side taper bearing was shot and in need of replacement.

Replacement of the swinging arm requires some caution as the bearings are back to back, which is normal for taper roller set ups but there is some flexibility in the front of the swinging arm fork and care must be taken not to over tighten the trunnions. After setting the swinging arm almost all the way over to the drive side in order to get the sprockets aligned, I just tightened until all play was eliminated and then half of one flat or a twelfth of a turn further, on one side only, to give some preload. Tightening the locking ring nuts was done with a 500mm long tube over the spanner handle and a pull of about 50kg on the end, not very scientific but with their tapered seatings I doubt if anyone would want to take on the maths for torque wrench figures. I guess this is why they use the locking compound but I still went for copper slip, old habits die hard!


6/ machining the sprocket carriers.

After struggling with the front pulley retaining nut ( see para. 2) I did a quick hardness test on the pulley with a file, only to find it is like glass! The whole thing is hardened but the teeth are slightly harder than the rest so operation 1 was to part off the teeth either side of the centre flange using a 9" angle grinder fitted with an ultra thin cutting disc. Followed by removing the remaining teeth one by one in the same manner.

The front side parted off with the disc cutter,
note the wet sack cloth to keep the grit off the lathe bed

This leaves you with a carrier flange which is still quite hard but can be machined all over using a CTC tip tool. I did this with the flange mounted on a mandrel in the lathe with a good shoulder for the centre boss to be tightened against. I left a 70 mm. Diameter spigot 3mm deep on the outboard side and just skimmed the rest to clean up and ensure it was all running true. Drilling for the sprocket bolts required a CTC tipped drill. I used hardened and ground shoulder bolts with a 10mm shoulder 16 mm long and an m8 thread. They were a good sliding fit in the drilled holes which is just as well as I do not think reaming the holes would have been possible. The front 24t sprocket was made by Cross Morse and has induction hardened teeth; this was bored out to 70mm. To match the carrier and then drilled, clamped in position, on the carrier using the same tip drill. I plan to use the hard carrier as a drill guide for any subsequent replacements whether for reasons of ratio change or just because the old one is worn out. Don't forget to check the plastic plug is in place over the swinging arm bearing housing before reinstalling the bevel box, you can't put it in later.

As can be seen from the raised area around the periphery of the job,
the teeth are very hard to cut and
had to be ground off one at a time

The rear pulley presents less of a challenge with the spokes being sawn through with a hacksaw and then, also mounted on a mandrel, I machined the tops of the spokes to give a couple of mm clearance in the recess in the sprocket; the sprocket is fitted recessed side to the carrier to get the chain alignment right.

Cutting through the spokes with a hacksaw.
this is just a pose for the camera,
the chain was removed from the bench before it got covered in aluminium filings!

The spokes turned and faced up ready to accept the sprocket.

I turned a 3 mm deep location spigot on the back, 112 mm in diameter to pick up the JTR 1871:48 Sprocket and drilled the fixing holes to match those in the sprocket. I chose to use the same hardened and ground shoulder bolts here too. The sprocket has 10.5 mm clearance holes and so the shoulders on the bolts were only a good precision fit in the aluminium of the old pulley but I think not being able to start twisting in the softer material is important and like the bike the sprocket was designed for, the clamping force of the bolts provides the drive.

The front carrier with sprocket fitted

The rear carrier with sprocket fitted


7/ chain Tsubaki sigma XRS TX4 -Ring steel 116 links.

I purchased 120 links and then cut it down to 116. (114 links will fit but does not allow for slackening the adjusters sufficiently to slip the chain off when removing the rear wheel). I riveted the chain joining link on the bench and slipped it over the swinging arm while it was removed from the machine. The chain is 530 size from Tsubaki which comes fitted with X ring seals. I would have liked to have completely enclosed the chain in an oil bath but there are too many odd shaped revolving bits to fit round and quite simply not enough room; as a result I have left the chain open but used ample mud flaps on the new mudguard ( in the style of " my other car is a Land Rover"). This will keep the rear compartment free of horse and cow dung as well as keeping the grit off the chain. I am also tempted to fit a floor in this area to further exclude the harsh elements from the workings but that will be at some later date. The subject of lubrication of open chain drives in harsh abrasive environments seems to cause much discussion but few conclusions are drawn. My thoughts are these:-

O or X ring chains seal in lubricant and exclude dirt but only from the pins and their mating bushes but not from the rollers.

Rollers must be lubricated from the outside, an oil bath is ideal but I have opted for regular manual application.

Oil, to be of use, must penetrate to the bearing surfaces inside the rollers and should therefore be of low viscosity.

Highly sticky, viscous oils will not penetrate well and help abrasive road dirt to stick in place on the rollers causing faster chain and sprocket wear.

I have chosen to clean the chain and lubricate with straight 30 oil from an oil can every thousand miles or so. If this does not give acceptable drive life I will try using no external lubrication which means less abrasive clinging to the teeth and rollers.

Many comments have been made about the danger of the chain smashing through the bulkhead in to the cockpit if it should break. There is no centrifugal force to make the chain flail outwards. The energy in the top run is purely linear. There is a great change of direction at the sprockets but due to the flexible nature of the chain this is not transmitted along the run. Sometimes, in machines with the final drive sprocket surrounded by the gearbox casings, the chain will bunch up between the sprocket and the casting and due to the throttle being wide open much damage ensues. This can not happen on the Morgan. Motorcycle chains are nearly always running just inside the riders ankle but we do not hear of accidents involving leg injuries due to chain failure. In my experience a broken chain just runs round the drive sprocket and lays itself on the road to follow you along like some high speed snake.


8/ alignment.

Sprocket alignment is of great importance for chain drives and so I did this before the chain was in place using a combination of straight edge, string line and good old line of sight. I have found no tolerances quoted by chain manufacturers for sprocket alignment. Having got the alignment as close as possible I then made a hardwood " feeler" gauge ( in my case 52mm long ) to fit between the front of the wheel rim and the inside face of the swinging arm at the front. The gauge can then be used to align the sprockets every time the wheel spindle is moved for whatever reason. Alignment of the wheel with the centre line of the vehicle is less important as any discrepancy is made up for in the centering of the steering wheel while driving. I doubt if any noticeable "crabbing" will ensue from the small deviation that might result from giving more attention to the alignment of the sprockets.


9/ the mudguard.

I purchased a fibre glass moulded custom bike mudguard and secured it to the aluminium factory item with 5 m5 nuts and bolts. On reflection I wish I had made something stronger but a regular check for cracks is not too onerous. I then cut and folded some stainless steel side mounts to pick up the lower suspension unit bolts ( see pictures) this has resulted in a tight fitting and quite rigid set up.

The mudguard prior to fitting with un trimmed mudflaps

The mudguard in place

The whole thing was assembled on the bench using 10mm packing all round the tyre, while drilling for the fixing bolts, to make sure the clearance was uniform all round. I fitted long rubber mud flaps which made the thing look like some Cromwellian helmet, these were only cut to length after it was all reassembled inside the rear compartment. The rubber probably touches the tyre due to slipstream effect but I foresee no problems or noise resulting from this. I did the first fitting with the swinging arm clamped level on the bench and the bevel box clamped in position using measurements taken before removing it from the vehicle.


10/ first impressions

The first outing was short and resulted in the rear chain needing to be tightened up quite a bit. This is due to the fairly hard lubricant in the chain which, once run in, softens and allows the links and pins to assume the one sided geometry which is the natural running state of the chain. Having tightened it to give approximately 10 mm up and down play in the middle of the top run with the bottom run tight, it has stayed that way. The bevel box output shaft is very close to being concentric with the swinging arm bearings so, a tighter chain than might be expected on a motorcycle with the drive sprocket in front of the swinging arm pivot is quite acceptable and welcome.

The end result of all this is quite remarkable. I now have a machine which is a joy to drive. The connection between the engine and the road is so much more positive and it took a while to get used to how much more easily the back end would break away, the machine does not take prisoners when traversing a patch of gravel for example.

There is still some whine from the bevel box but at a lower pitch. I think this is due to the noise of the air being expelled from the sprocket by the belt teeth no longer being present. The noise of the belt scrubbing on the side guide plates is, of course, history. There will be a bit of oil spray from the chain and the garage floor will show this up but I think this is better than all the aluminium and rubber dust emitted by the old drive.

As for longevity, only time will tell, watch this space.


With a few hundred miles now on the clock I am shocked to find that the initial problem still persists. With much higher loadings than previously, such as accelerating hard with a passenger on board and climbing a hill, the same jumping and banging in the drive train is evident. Some people commented that the problem was not the belt drive but that something else must be amiss - they were right. I have made the machine more pleasurable to drive, quieter, in need of less regular adjustment and all at a much reduced cost than the straightforward replacement of the original parts ( ignoring my labour, of course ). what I have not done is to eliminate the original reason for the project - my machine still bangs and jumps in a way that makes me fear that damage will result if it is not eliminated. My research continues.

Here are a few more general pictures.

Set up on the bench

The chain run

The mud flap keeps the muck off the chain

11/ parts and suppliers

Here follows a list of parts and suppliers, if anyone decides to have a go at this modification then please feel free to ask any questions; my contact details are at the bottom of the page.

The total price for parts was a little over £200:00 and it took about 60 hours to complete, including time spent researching suppliers and pouring over web resources.

I am indebted to a gentleman named Chas. from B&C Express in Lincolnshire who spent some time discussing options on the phone and even sent a set of drawings of all the sprockets he stocked, for me to choose from. You can find him on 01522791369 or via B&C From B&C Express came the rear sprocket part No. JTR1871.48 and the chain - Tsubaki Sigma XRS TX4 - ring steel you need 116 links, I bought 120 to be on the safe side.

The front sprocket is a 24 tooth plate wheel with pilot bore and induction hardened teeth to accept a 5/8 pitch x 3/8 wide chain,from Cross Morse 0121 360 0155 or cross-morse contact David Keatley.

The mudguard came from SGF Trikes, look in their E-bay shop

The shoulder bolts 10mm - m8 x 16 came from gwr-fasteners, E-bay again.


12/ Moving on to the cush drive or compensator.

Having replaced the final drive belt with a chain to good effect but without curing the problem of the banging in the transmission I decided to investigate the Cush drive. My machine is fitted with the Centa designed and built shock absorber. I believe that the design is based on the Centaflex RS coupling which the manufacturers claim copes with misalignment of the two shafts involved and provides progressive shock absorption by virtue of the four rubber rollers which provide low stiffness at low speeds. No arguments there, the idea seems sound and works well. It seems that the marine original has been modified to cope with reverse action due to engine braking which is minimal in the marine environment. The difference is that the cutouts in both inner and outer rotors are now near to being symmetrical which gives cushioning in both directions but on the down side, an increased range of movement and low stiffness at low speeds. This allows, in my opinion, too much slack at mid range. On removing the engine I found that the starter ring gear can be rotated back and forth 20 degrees total movement just with finger tip pressure. I believe this to be the source of the abominable clunking if one pulls away in too high a gear or if one is too light on the accelerator for any chosen gear. I have also targeted the Cush drive for the source of the banging under high acceleration. I theorise that the rollers allow the unit to " wind up" taking up the 20 degrees of slack and also as much as the rollers will allow in compression. If the rear wheel then looses traction, for only a moment, the Cush drive snaps back to the centre position causing the bang in the transmission. The loss of drive causes the rear wheel to regain its grip and the process starts over. Quite a theory and it has caused me much work.

In order to reduce or completely eliminate the slack in mid range I have removed the original rollers and made polyurethane blocks which completely fill the cavities between the inner and outer rotors.

Out with the old and in with the new

Hand fitting was the only way and it took several hours to get it right. I made a simple wooden template and then a set of blocks in wood. The wooden dummies allowed trial fitting as getting the shapes of inner and outer rotors relative to each other is very difficult. This difficulty is not encountered when using the original cylindrical rollers. I cut the final shapes from a single block of polyurethane at 70 Shore hardness which, with a simple bench test, seems to be about the same hardness as the original rollers. Cutting with the band saw and then shaping with a belt linisher taking impressions with engineers blue between each shaping and being sure to maintain the same thickness in the centre of each block as run out needs to be minimum, if not zero. The whole assembly in and out probably twenty five times! There is now no free play in the middle of the movement and the Centa drives shape still gives a progressive increase in resistance.

Wooden blocks in place

getting the blocks all identical

I put a little silicone grease on the blocks to aid final assembly and to allow them to settle in quickly with no damage.

Polyurethane blocks all nicely fitted

A lot of work but with, again, limited results. The clunking in too high a gear has gone. The machine is much nicer to drive and will pull away in third gear. It will go down to 1500 rpm in the first four gears with no problem accelerating from there, fith is not so forgiving but will go down to 2000 without too much alarming noise. On the down side the banging at high acceleration is still there!!! So much for my theory! Vibration when accelerating through 3000 rpm is worse than before and driving to avoid it is the only answer but not a nice one. So, what then is the cause of this?

Obviously my new Cush drive blocks are the cause of the change in vibration pattern but I wonder why it is there at such magnitude at all? One thing I noticed while the engine was out and the cush drive pulled apart was the unusual layout of the shaft which carries both the cush drive and the clutch. Normal engineering design practice is to place the supporting bearings at each end of a shaft and the load or loads, between them. Think of a plank, supported on a brick at each end - a bridge - you can walk over with confidence. now support the plank on one brick in the middle - a see saw - walk over with care because whatever you do at one end will cause an upset at the other! Overhanging loads at the ends of shafts are usually only found on shafts with well spaced out bearings. Morgan have chosen to put one roller bearing near the centre of the shaft and the loads at either end, this is at odds with everything I have ever been taught. At one extremity they have mounted the clutch, a mechanism, the normal operation of which needs good support to get it centered and balanced each time it is engaged. In the centre of the clutch is a support bearing for the gearbox input shaft, I believe that the support should be provided by the shaft on which the clutch is mounted and the gearbox shaft is the one supported, not the other way round. Normally the clutch is mounted on the end of the engine crankshaft, a solid shaft with good bearing support from the main bearings in the engine. At the other extremity of the shaft they have hung the centre rotor of the Cush drive, a mechanism which has no centring or supporting function at all and is, indeed, designed to be flexible. I assume that varying loads are brought to bear on the centre rotor due to the rubber rollers not all compressing in a uniform and precise manner; in laymans terms " it probably wobbles about all over the place". No criticism of Centa here by the way, that is just what it supposed to do. This revolving seesaw could result in early failure of the bearings which are under a variety of confusing influences although I have read no reports of this to date. I also think that it may be the source of some of the vibration.

My answer is a relatively quick fix compared to the proper answer which would require a new shaft with a longer nose and a redesigned outer rotor for the Centa drive which would house a plain bearing to support the longer shaft.

It should be noted that the Centa drive unit is designed to run between a marine prop shaft and the output shaft of the reduction box on the engine, both of which are well supported on properly spaced bearings. The barrel shape of the rubber rollers allowing for out of alignment due to the difficulty in accurately aligning the engine and the stern tube which are mounted far apart in the hull. Our Morgan's hopefully have no need of this.

I have made an aluminium bearing carrier, machined from a billet, and this fits accurately in to the recess in the back of the Centa drive outer rotor.

view showing the recess in the outer rotor

The bush mounted in its carrier, note the O ring groove

and again, viewed from the rear

The recess runs true with the splines of the hub ( .05mm total indicator reading which means no more than .025mm deviation from the axis - good enough for me! ) Modern CNC machining techniques produce items where everything runs true due to them being machined all over in one operation and barring a programme change, should also mean constant dimensions throughout the production run. My carrier is fixed in the back of this recess using socket head screws picking up the 6 M8 threaded holes which go right through to hold the alternator rotor. These holes are long enough to take fixings from both sides.

The carrier and bush in situ

The bearing it carries is an Oilite bush chosen because of the small amount of radial movement between the rotors. Small radial movements in rolling element bearings, especially when the movement is not enough to cause the rolling elements be they rollers, balls or needles, to turn through a full 360 degrees, will cause a phenomenon called false Brinelling and very early failure. Plain bushes are much better suited to this kind of duty as they present a much larger contact area and cope well with small angular movements. Oilite because it is damned nigh impossible to introduce grease externally and so I have filled the cavity around the crankshaft with oil and fitted an o ring in the bearing flange to keep it in, the Oilite sintered bronze should continually absorb this oil and hopefully have a long life. Fingers crossed as well, I have to say but I feel more confident in this set up which, if it fails will be easy and cheap to replace and will protect the bearings at the other end, failure of which could cause damage to the bell housing back plate and that would be a big repair bill.

A short steel stub shaft replaces the retaining washer for the centre rotor and is a light interference fit in the end of the rotor. This " nose" is supported in the Oilite bush.

the inner rotor showing the recess for the stub shaft

The stub shaft in place

The stub shaft is hollow and on assembly I fill it with oil, holding it in the vertical position and cap it off with a carefully cut disc of duct tape; on assembly the tape will be burst by the end of the crankshaft leaving the oil in the cavity. I do not see any harm coming from a bit of loose tape in there.

To make a little more space to allow maximum supported length for the stub shaft I have left out the front plate from the inner rotor and its fixing bolts. The face of my new bearing carrier will provide a sufficient end stop for the polyurethane blocks.

I now have a shaft with a decent spacing between its bearings which support the Centa drive between them and which provide better support for the clutch and gearbox shaft at the other end. Will this result in less vibration????

In removing the Centa drive rotor from the end of the crankshaft ( 3/4 Whitworth or 33mm. Socket ) I found that it was not as tight as expected and had, ( surprisingly! ) no locking glue to help hold it but a shake proof washer fitted on top of a very thin plain washer which was seriously distorted. Shake proof washers need to bite in to the nut and the thing being tightened on to, putting a plain washer underneath stops them from working. Why then are they so often fitted with a plain washer? I could rave on about proper apprenticeships but maybe elsewhere. Mine will be replaced with a thick machined washer, no shake proof washer and properly tightened. There is enough spare shaft thread for a nylock 7/8 x14 tpi UNF. nut if you prefer.

Pulling the outer rotor off was not too hard but needed a strongback in the form of a square steel bar with holes in to pick up two of the M8 holes in the face of the rotor (see picture below) and a central one for a jacking stud. I would suggest 25mm square.

Holding the rotor to tighten the crankshaft nut
can be achieved with help of a big spanner
and a couple of M8 bolts

I have taken my machine out for an initial trial run and am favourably impressed by the improvement in drive characteristics. The vibration is now less than it has ever been, one can feel the engine throbbing through the frame of the vehicle but pleasantly, without fear of resulting damage. There is negligible clunking when in too high a gear and a smoothness of take up when accelerating not previously experienced. On hard acceleration no banging, jumping, cogging, gunshot or whatever you like to call it. If one slams the throttle pedal to the floor, suddenly, from about 1500 rpm. a small jump is felt but this is minor compared to what was previously felt and can only be made to happen in this manner. Normal driving, however hard, does not result in any jump at all. To quote my late father " bloody good job - hooray!"

I believe that the origin of the problem is the wheel skipping on the road surface; a symptom of which is the jump and bang in the transmission. Having eliminated almost all of the slack in the system, I have also eliminated the noisy symptom. One might liken it to a blacksmith holding his hammer an inch or so above the anvil and then bringing his fist down hard on the hammer head, the hammer will move down sharply and bang against the anvil. If the hammer is then allowed to rest on the anvil, thus eliminating any possibility of movement, (no slack in the system) when the fist impacts the hammer head it will not move and there will be no bang.

So then, my conclusions - the banging is not caused by the toothed belt, it is not caused by the Centa cush drive unit, nor by any other part of the drive train, it is caused by the back tyre skipping on the road surface. The symptom, however - the banging - is definitely the result of too much free play in the drive train. this free play is mainly in the cush drive unit, also in the unstable cush drive shaft with its misplaced bearings and to some degree, in the toothed belt final drive and aluminium pulley which due to ingress of road dirt wear out prematurely and are seldom in prime condition. This has been a long journey but one with a most satisfying result. At last my five speeder behaves like a £ 35,000 vehicle and not like the " bag 'o nails" it was when I first bought it! My next expedition is to be a round trip to visit many old friends near Exeter, Paris, Dijon, Rotterdam and Sheffield, in that order; watch this space to see how the vehicle performs.



Having removed the engine a couple of times I thought it would be a good oportunity to write a guide for others who might want to take on the job.

You would be well advised to read through this a couple of times before you start

You are going to remove fuel pipes, have a fire extinguisher standing by.

The engine is heavy, you will need an engine crane or overhead gantry and somewhere to put it when it is out, maybe a sheet of plywood with some blocks of wood forming a cradle to stop the engine falling over.

You will need a 5/16 Whitworth socket spanner.

A hardwood stick about 25 x 50 x 500 will be useful as a drift and lever on some of the tighter bits and pieces; it will not damage the paintwork or the ends of threads when drifting out tight bolts. Take a felt tip pen and write the words " very useful stick" on the side of it and hang it up in the workshop - you won't regret it.

You will need new clips for the petrol pipes. The jubilee type of clip is not very good on small sizes due to the inflexible tightening device, you should look for the ones with a nut and bolt through the ends, they are numerous on e-bay and inexpensive.

You will need some cable ties to replace ones cut off when dismantling.

You would be well advised to have some new ( better quality ) mounting rubbers for exhaust pipes and rectifier mountings. I get mine here vibration-mounts

After removing the bonnet and disconnecting the battery earth lead ( when you re-connect there will be a slight sparking from the current draw of the electronikery be aware of any petrol fumes or leaks from the disconnected fuel pipes). I lifted the front of the vehicle and supported it on axle stands under the forward chassis members. Don't forget there is only one wheel at the back so the vehicle is quite unstable if you jack it in the centre at the front!

The next task is to remove the oil pipes and if you are ready for an oil change drain the oil out into an old container. The lower one is the feed and this is where most of the oil drains from. Don't get them the wrong way round when refitting. If not changing the oil put plugs (14 mm diameter wood with a taper at one end worked for me) in the ends of the pipes and tighten the clips.

Take out the two bolts holding the cooling fan and after un plugging the cable ( note which wire goes where, I am not sure if they are interchangeable) lift it off being careful not to loose the aluminium sleeves from the bolts or the bits of rubber hose which hold the fan housing away from the cylinder fins. You can now use the fixing bolts to hold some sort of lifting bracket of your own devising, I use a chain with the end links bolted down with big washers. The chain needs to be at least 600 mm long to avoid putting too much sideways force on the bolts, we don't want to be bending them. A rigid bar with a ring welded in the centre might be a stronger option but the chain works for me. Whatever you use make sure the bolts are tight and don't forget, this is a heavy engine.

Use a small chisel to flatten the locking tabs on the exhaust pipe flange nuts and remove the nuts. You will get one more go out of the locking tabs. It is now that you will discover the poor quality of the rubber mounts used for the exhaust pipes and for the rectifier heat sink. It would be best to have some better quality ones standing by. It is worth the effort of removing the pipes completely to get some space. Un plug and un clip the gas analyser cables first. I have replaced the flange studs and nuts with 5/16 18tpi UNC x 11/4 long socket cap screws in stainless; they make a neater job and there is not really enough clearance for the socket spanner to undo the hex nuts. Drill and wire them - no need for fancy tab washers then.

Next is the steering rack, remove the bolts through the rose joints from the front wheel steering arms and turn the wheels outwards. Remove the two bolts which hold the rack to the sloping support members. It is a good idea to check how easily they come out, especially if you have the retro fitted cross member which actually forces the supports on my machine further apart. I have drilled them a bit over size to make up for this, otherwise it can be almost impossible to get them back in. Take out the bolts and nuts from the upper and lower ends of the supports, you will need to take the top nut off the suspension unit bolts to get the bolts out. Then push the supports backwards at the bottom to get them off the chassis eyes. Juggle them out to the side and allow them to hang on the brake pipes. Remove the steering column clamp taking the bolt right out, as it goes through a groove in the rack input shaft as an added safety measure. When you replace the clamp you may want to set the steering wheel up with one spoke vertical at the top so that you can see the tachometer and fuel gauge. Now for the tricky bit, the rack will come out even with the retro fitted cross member in place; swivel the rack back(anticlockwise from the right hand end) till the input shaft is underneath pointing forward and slightly down, the rack can then be massaged out to the right (drive side) - persevere it will come out!

To the top of the engine now, remove the fuel pipes, marking them left and right for re fitting, you will need new clips. The jubilee type of clip is not very good on small sizes due to the inflexible tightening device, you should look for the ones with a nut and bolt through the ends, they are numerous on e-bay and inexpensive. The third, smaller, pipe has no clip, just pull it off and spit on it before pushing it back on later. No fuel will run out if you don't let the pipe ends fall down to the ground. For safety you might like to plug them off.

Remove all of the electrical plugs, they are numerous but with one exception, all different so it is not possible to get them wrong on re assembly but a photo might speed things up. Don't forget the ones on the alternator/rectifier and oil filter housing or the feed to the starter solenoid. Most of them have a security clip which has to be lifted with a thumb nail before pulling them out, don't use force! Pull the HT leads off the spark plugs. Remove the temperature sensor from behind the inlet manifold on the right cylinder, don't loose the thick seating washer behind it. The two wires on the fuel injectors have a wire clip which can be slid out with the tip of a screwdriver, don't launch them across the workshop never to be seen again and mark the plugs left and right. These ones can be fitted to the wrong side.

The throttle cable is a fiddle, take out the two screws holding the fixing bracket, leaving the outer cable wired in place. Use a length of string with a loop in the end to loop over the little knob on the disc and pull the throttle wide open, tie it in place. You can now feed the slack cable inner down far enough to twist and remove the nipple, note which hole it goes in, there are two.

Remove the earth strap from the top starter motor bolt but leave the starter in place. Strangely this bolt and those in the bell housing require a 5/16 Whitworth spanner. The live feed will be easier to remove when the engine is moved forward an inch.

Remove the rectifier and its mounting plates ( there must be a lighter way of fixing this thing to the vehicle ). The powder coating on mine, and also on the headlamp brackets is completely shot and I will have to repaint them. I have removed a bit of steel from the lower half of the intermediate plate to get some weight off. A better mod would be to make a new rectifier back plate in aluminium with the top fixing hole built in.

Remove the oval plastic sensor from the front bottom right of the crankcase and put a wad of paper in the hole to stop any dirt getting in.

Tie all the cables and pipes back out of the way with a length of string.

Take the weight of the engine on your engine crane or block and tackle being very careful not to lift the vehicle and dislodge the axle stands. Now remove the engine mounting bolts - three each side in the bell housing, two each side holding the engine to the mounting plates and two through the rubber mounts in the chassis. The plates will not come out at this stage but will fall out on their own when you lift the engine later, remember this when you come to reinstalling and be prepared for a struggle getting them in place.

The bell housing bolts come next, place a jack under the gear box just sufficiently to take the weight of the box and no more ( don't lift the whole vehicle off the axle stands) two socket cap screws are fitted from the front at the bottom. The rest are hex head bolts, 5/16 Whit. again. The long one goes in the top hole. To reach the one on the left side and the two on the right side I took a hole saw to the plastic body panel ( see picture ). The mechanics at Brands Hatch Morgans did it without resorting to this but it was beyond my ability with the tools available.

drill here with a30mm hole saw
to get the spanner on the bell housing bolts,
you need two holes on the right side.

If you do this be careful not to hit brake cables or fuel pipes as the saw breaks through. It also helps to unbolt the pedal box and move it to one side as best as you can and remove also the access panels above the foot wells. The heads of the hex bolts in the bell housing did not seem too clever and I will probably replace them with socket cap screws. It would have been thoughtful of the factory to have fitted a couple of access panels here.

I, later, took out the screws holding the two side panels and discovered how the dealer mechanic does the job. They remove the first two screws and then prise the panels back breaking them at the point where the very strong mastic seal commences; when the screws are replaced the break is almost invisible - good eh? If you look carefuly at the picture above you can just make out the cracks extending up from the bottom edge of the panel.

The engine can now be pulled forward and slightly lifted ( don't lift the whole vehicle off the axle stands). The two tubular dowels are quite tight and may require a bit of CAREFUL leverage. Don't loose them if they fall out. Remove the starter motor cable now.

If you are doing an oil change it is easier to change the filter while the engine is on the bench.

If you are to remove the clutch and the plate to expose the crankshaft shock absorber coupling this can be done by loosening the fixing bolts a bit at a time through the holes in the starter gear. There are three jacking screw holes in the flange to help pull the coupling rubbers out but I did it with my fingers.

Putting it all back together is just a reversal of these operations but be prepared for a bit of time wasted juggling the engine mounting plates, these need to be got in place before the engine is bolted back up to the gearbox bell housing. When replacing the engine swivel it a bit to allow the starter motor to go between the chassis members first. The steering rack with its support bars are also a faff. It helps to put the top bolt in LOOSELY to act as a guide when locating the tubular dowels.

Don't forget to fit the starter cable before the engine is all the way in.

Replace any cable ties which you may have cut off. Don't replace the battery earth lead till last and be sure there is no petrol about when you do it.

The clock will need to be reset but the mileage and trip meter readings are unchanged.

If you drilled holes in the bodywork a simple fix is to stick a bit of plywood over the holes with silicone sealer, hopefully you will not have to take it off again for a long time and when you do, a sharp flexible blade will do the trick.

When tightening the engine plate bolts leave the ones through the rubber mounts till last.

don't forget to tighten the top suspension unit bolt.



I wanted to carry luggage on my 5 speeder but did not like the look of the factory supplied rack, most especially the suction cup idea. I don't know why but it just does not seem to go with the machine.

Being a motorcyclist of long standing I have a penchant for pannier type cases and more to the point I had a pair in the garage. White - well they used to be - Golden Arrows from Craven. A little research and I found that they still make motorcycle luggage so I ordered a top box to make up the set. A coat of black paint, some new fittings and catches and all I needed was a rack to mount them on. I have to say that the latest equipment does not have the solid feel of the old stuff and the lock on the top box is a bit on the flimsy side so I have found some matching catches to augment the closure.

I do not possess a pipe bender these days ( not much call for one in flute making ) but I do have an eye for a bit of useful scrap and that eye fell on the old burnt out garden shredder - Ah Hah!

The Donor Shredder by Bosch

You will see that the supporting frame of the shredder is tubular steel and given a closer look the components for my luggage rack began to appear. An hour or two with hacksaw and welder gave me the frame. Add a short length of 25 x 25 box section and some 2mm plate cut to form the clamps and forks and I was in business I chose to mount the whole affair on the roll over bars. A quickly removable bolt holds the clamps in place at the top of the hoops and the bottom forks just rest against the tubes, the weight of the load holding it all down. I do not have any trouble with it lifting as I drive over bumps. The forks and clamps are lined with leather so as not to scratch the chrome.

More by luck than judgement the frame fits snugly in the luggage tray under the beetle back when not in use.

Snugly Packed Away

The bare rack is useful for carrying other things

I used Craven's rubber fittings for the top of the panniers and the back of the top box with some nice chrome toggle clamps, found on E-bay, to hold them all securely in place. An old steering lock from a Triumph motorcycle prevents the top box being stolen and while that is in position the panniers can not be lifted off.

I think it all looks OK

Side View

I do have to remove the top box to make filling with petrol easier but with care it can be done with everything in place. Not letting those last few drops from the nozzle go down Claire's neck is quite important!

The only down side to the set up is that one can not open the beetle back with the rack in position. Had I not been constrained by the dimensions of the old garden shredder stand, I would have positioned the top clamps at the apex of the roll bars so that the rack could be swung up and over the cockpit with the bolts still in place allowing the back to be lifted open. We just make sure that the only stuff carried under there is not needed till the luggage and rack have been removed. Visibility in the rear view mirrors is slightly reduced but one can live with it.

All in all I am pleased with the result, heavy loads can be carried, other items than the pannier set can be loaded and strapped to the rack and it is good to know that it is in the back, ready to be deployed, when you make that unexpected purchase.



The steering rack on my machine started to get very stiff last winter. Stiff enough to overcome the castor action on the way home one afternoon. I had parked outside a relatives house for three days over Christmas, in torrential rain and the steering rack had filled with water! The cure involved stripping out the rack to remove a fine coating of rust where the bushings run at the ends. Not something I want to do every time I go out in the rain.

It seems that there is a hole drilled near the centre of the rack by Quaife, the makers, the original hole is underneath towards the back. The purpose of the hole is to allow the use of a locating pin when setting up the tracking to get an even amount of lock left and right. The Morgan Three Wheeler has the rack passing through a cut out in the top of the cush drive bell housing making the hole inaccessible. Morgan's answer is to drill another hole in the top of the rack housing so that the pin can be inserted from above, all well and good. Their answer to rainproofing the hole is to stick a bit of aluminium tape over it and as one dealer mechanic told me " they sometimes forget"!

My solution was an easy one. Take a 2" length of 1 1/4" plastic plumber's waste pipe and slit it down one side. Open the slit to clip it in place over the rack housing at the non driver end and then push it along with a stick ( remember that very useful stick?) till it covers both the holes. The Quaife drilling is to the rear of the housing so make sure the slit in the plastic cover is at the bottom but slightly forward of vertical. Making a mark with a felt tip at the ideal top point on the cover will help to check when it is in place and the slit hidden by the bell housing. When it comes to tracking the steering the cover can easily be pushed to one side to allow the pin to be used. Quaife have confirmed that the hole is not left open as a breather and can be safely sealed off from the elements. I have had no more trouble.

The steering rack showing both holes

and the plastic cover waiting to be pushed along to cover them



The rose joints on the end of the steering rods need to be lubricated and they come with non return ball valve lube points. Finding something which will get oil or grease in through these things is a challenge and so I have drilled the rod ends, on top, to accept conventional grease nipples. Surprisingly enough, when I removed the rose joints I found no trace of lubricant at all inside them, I am obviously not the only one who has the problem - even the dealer didn't get anything in there when it was serviced.


The bonnet catches. The machine comes fitted with Dzus fasteners which, correctly applied, are a gem. They are unobtrusive, easy to use, don't rattle and I guess, would pass the Single Vehicle Approval requirements. They are designed with their little wire spring to hold hinged panels shut or panels which lift off completely. They do not work on panels which slide open, to make them work on sliding panels they have to be mounted on a little hinged plate. The Morgan bonnet is a sliding panel, as far as the fasteners are concerned, ie. the panel slides upwards to remove it. The boot lid is the same and the problem has been addressed by fitting little hinged plates, in the form of a leather strap ( which brings its own problems with damaged paintwork and stretching of the leather ).

The bonnet catches annoyed me greatly as it was always difficult to stretch the panel apart to line up the fastener bolt with its socket and generally involved walking round the vehicle twice. Old faithful, E-bay, provided me with some elegant chrome on brass, over centre catches which pull the panel down securely and can be closed, by reaching over, from one side of the car. They are also lockable with a tiny padlock should one be parked somewhere dodgy. Not that I carry a lot of expensive stuff under there but the scrap man would find the aluminium panel very tempting.

A certain amount of courage was needed to take the drill to the panel but holding the catches in place with double sided foam tape got them in the right place and I then drilled through and bolted them up leaving the ( black) foam for them to bed into. The final touch was to fit little plastic blanking plugs in the holes left by the Dzus fasteners

The rear catches are fastened down to the body with M5 stainless button heads screwed in to the ash frame, I drilled a 4mm hole in the wood and just screwed them in - sort of self tapping. the screws are 20mm long so they should hold well enough.

A similar solution for the boot closure eludes me at the moment but I am sure one is out there somewhere.



Whilst cruising down a quiet country village road in France on my recent trial run I was startled by a clattering from the road beside me only to see the right exhaust pipe dragging along the tarmac. I grabbed the thing up and coasted to a stop in a farm gateway, wired it back in place and continued on my way.

I noticed that the sheared faces of the rubber mounts did not line up by about 10 mm, the pipe being that much too far aft. I had already replaced the poor quality items which came from the factory with some better ones. The factory supplied ones have a bolt with a loose washer moulded in either end, they fail regularly. My replacements, from have a nicely turned solid stud with a flange which provides a better bond. Rubber components can be made cheaper by including fillers such as talc but this compromises the strength of the rubber and is suitable for pet toys and the like but not for holding components such as exhaust pipes on big throbbing V twins. So, why had my superior mounts sheared so suddenly? It seems that the pipe on the right side is too long by about 10 mm. I have had this confirmed by others. To date I had only replaced the pipes while they were detached from the cylinder heads. If one fixes the rubbers first and then bolts up the pipe to the head there is sufficient movement in the flexible section to allow the pipe to mate easily with its spherical seating. When one then tightens the bolts on the clamp flange the pipe assumes its position too far aft and one does not notice. My answer was to shorten the rear pipe with the angle grinder, not forgetting to extend the clamping slots to their original length. At the same time I shortened the bolt through the clamp so I did not skin my knuckles on the thing every time I washed the car. Best advice is to fix the pipe to the head before mounting the rubbers and then you will see immediately if the pipe is too long.

Rectifier mounting. The same cheap rubber mounts are used by the factory on the rectifier and I am unhappy about the fact that there is insufficient clearance for a hex nut on the fixing bolts. will also supply a rubber mount with female threads so that a socket cap screw can be used - much neater. A smaller mount will suffice as they are so much stronger. A replacement supplied by a Morgan dealer was not strong enough to take the turning force required to run the nylock nut down the bolt and sheared before it was even close to tightening.



"Plenty of people taller than you drive one" said the slick looking sales guy at the factory; I just nodded and said "hmmm". In my mind I was logging the first of the mods which I would undertake on this "project purchase". I challenge anyone taller than me to sit behind the wheel of this machine with knees up under the rim of the wheel and left foot held back from riding the clutch, for six hours and still be able to walk!

My short term answer has been to lift the pedal box at the front with some little male / female threaded pillars and then to push the whole thing forward, angling it to the right so as to miss the vertical frame tube with the master cylinder outlet banjo. I then, shamelessly, drilled and slotted the floor pan to accept bolts a good 150mm further forward than the original furthest position. This works well giving knee room below the wheel and allowing the left foot space to rest, off the pedal - just!

Longer term I would opt for moving the pedal box up above the under bonnet deck with pendant pedals. This would reverse the master cylinders putting the pedals in front of them. Loads more room and a rack to slide the box back and forth - lots of work but worth it. I can think of no more stupid arrangement than one which requires a return visit to the dealer when you want to change driver position and this is what the hand book recommends!


Thanks to members of Talk Morgan for pointing me towards this one. It would seem that heat is detrimental to the longevity of the timing belt so S&S have introduced slotted timing covers and spacers behind the fixing bolts to allow some air circulation.

I thought that a long cut edge through the chrome plating might be asking for trouble so I have drilled a row of holes which might do less to undermine the plating and I introduced some 2.5 mm. thick brass washers between the mating faces. Time will tell!



Nearly all applications for this type of prop shaft set up involve an offset between diff and gearbox flanges - sometimes two with intermediate bearing support. When it comes to greasing the hardy spicer units ( it is worth researching how to do this as a complete purge is recommended ) one has to revolve the shaft, till the grease nipple comes to the more open side of the joint, in order to get a grease gun on it. The M3W set up involves little or no offset and so there is no possibility of getting a grease gun on to the nipples and I can not find a slimline version which would make it possible. So what do the dealers do at service time? I'll bet they don't remove the propshaft from the machine in order to open up one side of the coupling and get some grease in. I will purchase some long series nipples for mine and change them over next time I do the job. This will introduce a bit of imbalance but I think the risk is worth it. I am also tempted to ask why a sliding spline and two hardy spicer joints are required in a system which does not involve movement up and down at one end? A couple of rubber doughnuts like the ones fitted to BMW cars would have been more sensible from a point of view of their shock absorbing qualities and being maintenance free.


Phil and Claire Bleazey
At The Old Furness Street Stables

Tel:- 0044 (0)1524 849085

Last Updated OCTOBER 2016