Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Centra Compensator falling apart.....

Thanks Red Three, more tools on order.
John.

How many miles have you done on the centra ? What's it's life span? My mog has arrived in the uk & is in storage till the factory opens on the 1st I believe.

I've done about 17 or 18000 miles on the Centa (assuming the factory didn't change them out when they changed the chassis about 8 or 9000 miles ago; they did change the clutch)
There seems to have been a bit of a rash of Centa rollers failing lately. Maybe internet self selection where people hear about it happening and so go and check only to find some deterioration visible, quite possibly just before or even long before any symptoms make themselves felt (this applies to me, the before bit anyway!) or maybe it's the additional power from the various Stage One kitted and other tuned engines or maybe its not the extra power and is more down to the smoother running of the tuned engines allowing people to run the engines at lower revs leading to larger torque transients getting to the Centa. It was the torque transients that led to a transmission shock absorber being necessary in the first place. It could be a combination of all three plus any other reason that might spring to mind. The rollers might just be consumables...

I wondered why I hadn't seen any photos form you red3, hopefully you'll be out and about soon.

It's a pity I hadn't read this thread earlier, I have an engine crane you could use and I must only be an hour or so away from you, if yours doesn't turn up and you want to borrow mine, ping me a note.

Thanks Calum for producing the very useful breakdown on tools required and also thanks must go to your inefficient crane delivery company for allowing you the time to write it up!

The Compensator is required to absorb the torsional vibration generated by the engine.

A big V twin in particular doesn't deliver it's torque evenly, but in unequally spaced peaks as each cylinder fires.

In most industrial applications the Centa type coupling, as used on the Morgan, is subject to continuous uni-directional loading. In these cases an element of backlash isn't of consequence. Obviously on a car this is not the case.

Any clearance or backlash in the coupling will result in increased shock loading as the load through the coupling is reversed i.e when the wheels drive the engine (Aero owners will be familiar with the "shunt" on such occasions)

This will result in increased wear rates on the rubber elements.

The coupling on the Morgan appears to be of a more basic Centa design and more suited to coupling electric motors to pumps etc.

Centa make more sophisticated models with zero backlash and elements that can be exchanged in situ.

In my opinion the Centa coupling fitted to the M3W is not suited to it's application.

Progress...
Had to work part of today then wait for the engine crane to turn up which it actually did late this afternoon. Spent a head scratching couple of hours assembling the thing something of a mismatch between the instructions, the steelwork and the supplied kit of bolts. The bolts were a strange mix of difficult to identify sizes, don't seem to be metric or UNF or UNC and are marked as a mix of grade 7.8 (new one on me...) and grade 4.7. The "that'll come in handy" bolt drawer in the tool chest was brought into play and everything finally went together. There's an old adage about tools; buy cheap, buy twice. I should have known better. It's allegedly rated for 750kg at the extension I'm using it at so I'm not overly worried about failure and at least I know it was cheap and made in China unlike many others that are more expensive and just as made in China.
Anyway, enough of the digressing, after a break for food it was back down into the lock-up and two hours later the engine is out and the Centa stripped down. All went smoothly and easily and it turns out that two rollers were completely gone and two were very much still functional albeit with some definite bites into the ends of the rollers. The old rollers are also a couple of millimetres shorter than the new ones. One of the rollers has clearly split length-ways pretty much in half. Might mean something, might not. Don't know.
Tomorrow I'm going to clean everything up and start re-assembling. Tonight I'm having a beer.

View on taking the cover and Centa centre piece off;


Seen better days;


Roller below ruler is new, above the roller is used;


"Bite marks" in ends of old rollers;


Phone photos, it's a damn sight more convenient than the big camera and lots more depth of field too.

Thanks ewn, appreciate the offer but am now sorted out. Just got to put things back together now...

Those Centa rubbers look just like rubber mallet heads...

Yup