A synopsis of the work to cure the perceived faults in my vehicle
why the cures were needed and how they work

Since May 2016 I have been working to rectify problems in the transmission / drive train of the new Morgan three wheeler. The subject of my research has been a 2013 model, purchased by me in 2015. The machine had been fitted with the Centa flexible coupling and the NVH ( Noise, Vibration and Harshness) kit from the factory.

The problems were, from the start, an inability to pull away at engine speeds below 2,700 rpm. without lurching and banging from the transmission and an inability to pull away in any gear but 1st. Later, a loud bang and jerk developed when accelerating hard, especially when carrying a passenger. Throughout, the machine has vibrated excessively, most noticeably when accelerating through 3,000 rpm.

The result of my work is a vehicle which will pull away in any of the first three gears, without an excessive rise in engine speed and without any jerking or banging noises. The loud banging on acceleration has stopped completely. The vibration is much reduced and there is no need to avoid certain engine speeds to maintain a comfortable ride. The high torque developed by the engine which was the cause of much of the trouble is now available for use and the true character of the V twin engine is now evident when driving.

The bevel box mounting kit

This kit will restrain the front of the bevel box from lifting, thus eliminating the fierce vibrations felt when accelerating hard through 3,000 rpm especially in high gears. It will also eliminate the sudden bang and jerk on hard acceleration which is currently controlled by over tightening of the final drive belt. You will be able to run the final drive belt at the correct tension which will reduce stress on wheel bearings, belt and sprockets, swinging arm trunnion bearings and the output shaft bearings of the bevel box.

If you do not have the factory NVH ( Noise, Vibration and Harshness) kit fitted you will not derive any benefit from my bevel box mounting kit.

The kit consists of a complete set of bevel box mountings. There are three of them which satisfactorily secure the bevel box in all of the twelve planes / axes of movement. The bevel box mounts are clamped to the chassis to enable fitting without the need for welding and they avoid the need to grind away the residue of the old, original, rigid bevel box mounts. Neither welding nor grinding are desirable in close proximity to petrol pipes! The mountings for the bevel box are isolated from the chassis with polyurethane linings in all of the fixing clamps to reduce the transmission of bevel box noise to the chassis. If you are replacing the factory NVH kit then the components you remove will weigh 9.3 Kg and the new mounts weigh in at 3.0Kg a net saving of 6.3Kg.

DO NOT be tempted to fit the top mounting in conjunction with the NVH kit. The three mountings in my kit must all be fitted together and the NVH kit fully removed.

The bevel box mountings are best fitted before the cush drive upgrade which can be fitted at a later date.

More details of the kits, the reasons for fitting them and instructions on how to do it can be found here :-

Morgan 3 wheeler workshop

Please subscribe to my channel and go to playlists where you will find the videos categorised.

The cush drive upgrade kit

This component is often referred to as the compensator - my kit is applied to the crankshaft shock absorber made by Centa UK.

The kit consists of one set of high temperature polyurethane inserts - An aluminium carrier plate with sintered bronze support bearing and alloy steel stub shaft - A splined replacement hub in alloy steel with taper pins for fixing - A new crankshaft oil seal and O ring - All fasteners and tools for changing the inserts. To achieve maximum benefit the quick change modifications will also be required, please read on for a description of this.

The kit is available to purchase for you to fit. You can also buy the kit on a service exchange basis whereby you send the inner and outer rotors to me and I return them with the machining work carried out for the quick changing of inserts - the replacement alloy steel hub shrink fitted and the intermediate bearing/shaft in place - all ready for you to reinstall. You will still have to cut the hole in the bell housing but this can be done by hand if no milling machine is available or you can bring the bell housing to me - I do not recommend posting as it will be a very difficult item to replace if it is lost! You can also bring your machine to me and I will cary out the upgrade for you and if you wish you can stay here and work with me, thereby learning much about your machine and its future maintenance and servicing.

This kit will reduce the bouncing action of the coupling thereby making pulling away at lower engine speeds possible without the jerking and clanking normally experienced - driving in traffic is much more pleasant. Vibration will also be reduced especially in conjunction with my bevel box mounting kit.

The support bearing restrains the sideways forces on the single bearing intermediate shaft which occur when the inserts start to fail - one of the inserts always fails first leaving the remaining, opposite insert to wedge the shaft sideways with enormous force. Many vehicles arriving at my workshops are down to the last one! These sideways forces can cause irreparable damage to the rear bearing and its housing which will be expensive to replace.

Reversing the assembly of the central rotor in the Centa cush drive along with cutting an access hole in the bell housing makes inspecting and changing a set of inserts possible without removing the engine.

The alloy steel, inserted hub safeguards your crankshaft from damage which can result from failure of the splines in the original hub - this is becoming more common as machines get older. The splines in the new hub are fitted on both major and minor diameters as well as to the flanks. I will not reassemble the unit without this modification, should you choose to do so I accept no responsibility for later failures. The new hub has the correct diameter shaft, with the correct finish, for the oil seal ( the originals are often almost a millimetre undersize) and it incorporates an O ring for the internal seal instead of the silicone mastic originally employed. I do not think it is good practise to use a silicone type sealant in an area of such mechanical importance. Correct assembly of the hub on to the crankshaft makes for a much stronger unit, giving good support to the intermediate shaft. Fitting the splined insert requires machining of the Centa coupling to remove the soft splined area and to make a shrink fit for the new insert. This will be carried out for you if you choose the service exchange option.

The P.G.Bleazey drive train upgrade kit uses inserts, in the Centa coupling, of modified shape to reduce the bouncing action which is the cause of much of the shunting and banging on pulling away. The shock absorption is achieved by combined distortion and rolling action of the inserts, not by rolling alone . The ones used in my kits are high temperature resistant and are true prisms and do not allow for misalignment, this function is not needed in the Morgan three wheeler application. The inserts incorporate a tab for ease of removal through the hole cut in the bell housing.

The upgrade kit contains an extension for the shaft which supports the inner rotor of the Centa coupling, this extension runs in a plain bearing. The bearing is mounted in a carrier which fits within the Centa coupling outer rotor. The intermediate shaft is thus supported at both ends which creates a much more rigid, true running, unit. Please do not fit my design of inserts without the support bearing. In any case I recommend fitting a support bearing at the earliest opportunity.

Please be aware that the inserts in a Centa coupling are consumable - like tyres and brake pads- they have to be replaced at regular intervals. My non rolling inserts are designed with longevity in mind and I hope they will outlast any other alternative but in common with all the available alternatives, they are not immortal.

With the original set up, when the inserts come to the end of their life it is necessary to remove the engine in order to replace them - at least 12 hours work for a mechanic. If you make my quick change modifications You will be able to inspect the inserts - or replace them before a long trip, in half an hour. This can also be carried out at the roadside in the event of failure - if you can lift the vehicle safely.

More details of the kits, the reasons for fitting them and instructions on how to do it can be found here :-

Morgan 3 wheeler workshop

Please subscribe to my channel and go to playlists where you will find the videos categorised.

Fitting the new hub.

Start by pulling the Centa rotor off the crankshaft. The m8 tapped holes round the periphery of the aluminium casting can be used with a bridging bar and fine threaded jacking screw. Have your work bench clear and free of all ferrous scraps, tools, swarf etc. the magnets in the rotor will grab them all and will be difficult to clean. Do not strike the rotor or drop it as the magnets are glued in place and are fragile. Remove the six screws holding the alternator rotor to the Centa casting and put the rotor in a stout plastic bag, keep it there to avoid all the swarf in the workshop from collecting on it. Before fitting the insert it is best to try it on the crankshaft using engineers blue to establish if there are any tight spots which need to be filed out. The insert must be a light drive fit on the shaft and no more than light blows with a hide mallet should be needed to get it to go on. Do not forget you will need a puller to get it off ready for insertion in the Centa rotor.

To fit the new hub you will have to machine the old rotor out to accept the new hub following the drawing. Great importance should be given to the bore which must be an interference fit on the new hub and must be parallel, and concentric. When the machining is done the Centa rotor should be fitted with an 8mm / M8 guide pin fitted to one of the bolt holes for alignment and heated with a gas torch or in an oven till the bore expands to 60.20 or bigger. The new hub and the bore of the rotor must be clean, smooth, free of burrs and have a small lead in chamfer to aid assembly. The new hub must be cold. Slide the new hub over the guide pin and in to the bored out rotor. This must be done quickly and precisely. Should the hub catch and not slide in freely it must be pushed home quickly before heat transfer takes place and jams the whole thing up, it is, therefore, good practice to have the assembly ready to be pushed in by a drill press mandrel or maybe to do the assembly in the lathe using the tail stock as a guide and press. DO NOT USE A HAMMER. Once the hub is all the way in apply a little pressure to hold it home while the rotor cools. The hub must go all the way in, first time and quickly before the rotor has time to cool - if you get it stuck half way press it out and start again do not press it all the way home after the rotor has "grabbed" the hub. It is vital to make this shrink fit and not to press the hub in cold - a shrink fit has three times the resistance to slippage as a pressed fit of the same interference. Three tapered pins should then be inserted through the flange for extra security. The heads of the pins must be below or flush with the surface, I like to skim the face in the lathe to make sure.

Once the hub is in place remove the guide pin and bolt the alternator rotor back in place tightening the bolts fully and using loctite. I like to replace the countersunk screws with socket cap head screws with a countersink machined on the underside of the head; these are much easier to tighten and also to remove later should the need arise. Use Loctite - you do not want these coming loose. This brings the heads close to the windings of the stator and I always check to see that there is enough clearance just in case a stator winding is unusually high. If you feel competent to carry this work out yourself or if you have a trusted machine shop who can do it for you I can supply just the insert with drawings for the machining.

Quick change coupling insert modifications explained

The inner rotor of the Centa coupling and the bell housing are modified in such a way as to make future replacement of the inserts a job lasting less than an hour and a task that could also be carried out at the roadside, if you have the ability to raise the vehicle safely.

The modifications consist of an enlargement of the grease gun access hole in the bottom of the bell housing, where such a hole exists or machining the access hole from scratch. This is best done on a milling machine but can be carried out by hand The inner rotor is then re machined so that the insert retaining plate can be fitted to the rear end such that it can be removed to give access to remove the inserts.

For those who choose to have this mod done locally or if you want to do it yourself, I have made drawing and instructions available please click on the link at the top of the page. Having done the mods fix the plate to the rotor with four M8 socket head screws 16mm long NO LOCTITE. four more socket head screws 16mm long should be inserted and loctited in to the four holes in the aluminium outer rotor - these are used to turn the engine over while removing the securing plate and the inserts.

To remove the bell housing you must strike the heads of the four fixing screws two or three times using a brass drift, to break the loctite, you may also need to heat the crankcase around the threads. The screws are imperial and you will need a long series 1/4 inch allen wrench driven by your socket set tommy bar. It is essential to re fit them with loctite and torque them down to 30ft lbs. or 40 newton metres. these are the bolts that hold the primary chaincase on to the crankcase in motorcycle installations. they are very small for the Morgan set up and need to be tightened correctly.

I do not think it necessary to cover this hole as I have seen no signs of damage from water or road dirt and there may be some advantage from the extra cooling air flow.

How to change a set of inserts

At the first sign of any deterioration of the inserts ie. excessive vibration and bits of polyurethane coming out of the hole under the bell housing, or as a preventative measure before a long run, or just as part of your routine maintenance schedule, you should inspect or change the inserts.

Start by jacking up the vehicle and supporting it on some good axle stands. Alternatively run the vehicle on to a pair of ramps. Either way, high enough to work through the access hole under the bell housing. Remove both sparking plugs and cover the holes with a rag to safeguard against any foreign matter falling in.

Using the 1/4 inch drive hexagon bit driver with a 6 mm bit inserted and a 1/4 inch hex extension handle in place - these were supplied with your kit - loosen the first accessible cap screw holding the retaining plate in position, a good blow with the side of your fist on the extension handle should do the trick - re tighten them in the same manner. With two fingers or finger and thumb if your hands are small enough remove the screw and place it somewhere clean - it is important not to get any contaminants such as grit or grease on the threads - this makes the job of removal much harder especially if the contaminant is transferred to the female threads in the rotor. Then, using the same tool inserted in one of the four dummy cap head screws in the outer rim of the aluminium rotor, turn the engine clockwise ( viewed from the rear of the vehicle ) till you can reach and loosen the next retaining plate screw - continue till all four screws have been removed.

Slide the retaining plate back till it registers on the rearmost, larger diameter, part of the shaft. The insert at the bottom can now be removed using a thin screwdriver or something similar in the hole in the extraction lug and inspected for wear or cracking - replacing if necessary. Move on to each insert in turn - do not take them all out at once or you will have difficulty in re aligning the rotors.

When you are happy with the condition of the inserts - inspected and replaced or changed for new, slide the retaining plate back in to position and ( this is the tricky bit ) line up the lowest bolt hole with a threaded hole in the rotor. An Allen key can be used to poke in the hole and jiggle it all about till they line up. Now, again with two fingers, enter one of the cap screws and screw no more than finger tight. Move around till all four are just finger tight and the go round again tightening each screw in turn with a blow to the extension handle with the side of your hand - this is tight enough - they do not come undone on their own and you will want to be able to undo them again next time without too much force. If more force is needed to loosen a screw then jack the rear wheel off the ground (to prevent the possibility of your driving the vehicle of the axle stands! ), apply the hand brake and engage a gear - this will give you some resistance to your loosening effort.

Finally, drop the vehicle back to the ground and check the workshop clock - less than an hours work compared to an engine out exercise on an unmodified vehicle - well done!

More details of the kits, the reasons for fitting them and instructions on how to do it can be found here :-

Morgan 3 wheeler workshop

Please subscribe to my channel and go to playlists where you will find the videos categorised.

The chain drive conversion kit

The kit contains:
An alloy steel front sprocket to directly replace the belt pulley
A hardened steel rear sprocket
A carrier for the rear sprocket which directly replaces the rear belt pulley, fitted with studs and nuts for the sprocket
A sealed chain with rivet link for joining ( this will require a riveting tool to install )

While the original belt system will probably out last a chain several times there are good reasons for converting to chain:-

The rear steel belt pulley weighs in at 8Kg - an enormous unsprung load: the chain sprocket weighs just over 1 Kg.
If you have the original aluminium rear belt pulley then, when the time comes to replace it (probably less than 10,000 miles), a chain conversion will cost about half of the price of the steel rear pulley and its installation.
A toothed belt needs to run on precisely aligned pulleys like the ones in the timing chest or it needs to have adjustable pulleys at both ends for alignment. It should be noted that adjusting the pulley at one end moves the belt on the pulley at the other end. The system on the M3W has a wide pulley at the front to allow for alignment of the rear wheel but no adjustment at the front to align the belt on the rear pulley which, being narrow, has side plates to prevent run off - the inevitable result is squealing from the belt when it runs against those retaining plates. A chain allows for some misalignment and runs very quietly.
A chain can be replaced in minutes at any motorcycle shop anywhere in the world.
A chain is marginally more efficient than a belt.
I can supply front sprockets with 23, 24 or 25 teeth to facilitate overall gearing changes. 24 teeth will give the same overall gearing as the original belt drive.
None of my upgrade work is irreversible and to this end your original belt and pulleys will be returned to you.

If you choose to have the kit fitted by or with me then the following work will also be carried out:-
Removal of bevel box and swinging arm
Service swinging arm bearings: I insist on this as the factory fitting usually involves no grease other than the protective coating in which the bearings are supplied and often the plastic dust/water shield is missing on the drive side
On earlier models with no security fasteners on the swinging arm trunnions I will lock wire them to the chassis.
Install front and rear sprockets
Re align rear wheel and drive components
Fit and rivet sealed chain

While in my workshop you may choose to have the swinging arm rust proofed. The swinging arm is the worst affected component when it comes to dirt and salt contamination and I see many vehicles with rust in their area.
The rust proofing excercise must be left overnight for sealants to cure before re assembly so reckon on being here till the afternoon of day two.

More details of the kits, the reasons for fitting them and instructions on how to do it can be found here :-

Morgan 3 wheeler workshop

Please subscribe to my channel and go to playlists where you will find the videos categorised.


When removing the swinging arm there is danger of the trunnion shafts seizing up in the chassis - a hugely expensive failure - While I work carefully to avoid such problems I will accept no responsibility for such failures - they are due to poor selection of materials at the design stage and therefore beyond my control.


Why not go for the ultimate M3W upgrade experience? Bring your car to my workshops in Lancaster and work together with me to install your upgrade. Take your car home with a fully upgraded drive train, road tested and ready to "go like the wind ".

My fully equipped workshops will cope with any problems which we might encounter and I have, in stock, spare parts for your drive train such as a refurbished clutch, seals and bearings should they need to be replaced.

We will work together and I will explain every step of the operation giving you a good understanding of how everything works. I will also (within the limits of my knowledge) give guidance on future servicing work which you may wish to undertake at home and answer any questions you may have about your vehicle

Why not stay as a guest in Claire's Little Crooked House? you can see it here :- Little Crooked House

Take your meals with us and generally be part of the family for the duration of the installation.


Lugging the motor , an expression used by S&S and something to be avoided. The reason for this is not too clear without some research but I can give the following advice. Loading the engine up at low Revs. causes the pistons to be pushed to one side of the bore, this may be due to short piston skirt length. The result is over consumption of oil and all the problems which accompany this. In a recent 1500 mile road test I utilised the ability to accelerate hard at low revs. - very satisfying it is too - nothing quite as satisfying as hearing the rear tyre break away at every firing stroke! However - the cost was 2.5 litres of oil lost in 1,000 miles which will bring disaster if one continues driving in this fashion. The P.G.Bleazey drive train upgrade kit will allow you to do this but it is imperative that if you use low rpm, for example, in dense traffic, you only employ small throttle openings till the revs. rise above 2,500 rpm. Alternatively just change down a gear to get the revs up but DON'T just push the pedal to the floor at low engine speeds!

The internal splines of the Centa coupling outer rotor are made of soft steel. They run on a hardened, alloy steel, splined crankshaft. The fit is only on the driving faces of the splines making this a very vulnerable area. Lugging the motor may also result in the soft internal splines being hammered and distorted to the point that they will become loose on the crankshaft. To repair this is expensive. My machine has an alloy steel insert in the outer rotor, fitted on the drive faces and on both major and minor diameters, to avoid any recurrence of this failure.

On all of the machines I have examined I have noticed another likely cause of trouble. The bearing behind the clutch is not secured to the shaft other than by the interference fit. There is a circlip groove but it is about 3 mm away from the bearing inner race and has no clip fitted which could allow the shaft to move. The only retaining force would then be contact with the gearbox shaft within the spigot bearing.

I will not accept responsibility for such failures - they are caused by inadequate design and are not under my control.


A full installation manual is available on other pages within this site, just click the links at the top of this page. I am happy for the installation manual to be printed off and for it to be passed to your garage mechanic if you are not doing the work yourself. Please feel free to study it before deciding to purchase a kit. I am also available, within the limits of my daily life, to give advice via e-mail or telephone to anyone with installation problems. To the best of my ability I promise to provide technical backup to customers.

With the exception of the quick change modifications ,the kit does not require any alteration of the vehicle components and can be removed and replaced by the original equipment, not that I can foresee anyone wanting to do this but it may bring peace of mind to the sceptical.

The P.G.Bleazey drive train upgrade kit can be described for insurance purposes as not being performance enhancing but merely comfort enhancing.

This button will take you to the Pay Pal site which will enable you to pay securely with your credit/debit card even if you do not have a Pay Pal account

Please contact me to check on availability before doing so.

I reserve the right to charge for alterations to the components in the kit if your machine is different from the standard model which has been the basis for my work

To register your interest in a kit, with no obligation, please click on the E-mail link below and e-mail your name, country of residence and the year of manufacture of your vehicle. Any comments or questions will be most welcome at the same time.

My work has been published and I have no objection to individuals learning from my work in order to enhance their own knowledge or to make modifications to their own machines. Please, however, be warned that protection has been put in place to safeguard the intellectual property stemming from the research and development of the P.G.Bleazey drive train kits. It is a criminal offence to copy a registered design. Any person or organisation found to be copying or using my work for commercial gain will be pursued strenuously till they cease this activity and where appropriate, for compensation.

Phil and Claire Bleazey
At The Old Furness Street Stables

Tel:- 0044 (0)1524 849085

Last Updated January 2021

Morgan three wheeler drive train Morgan three wheeler compensator Morgan three wheeler drive quality Morgan three wheeler bevel box P.G.Bleazey drive train upgrade kit