Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Belt alignment on early M3Ws

Surely the compensator/Centa takes care of cush-drive duties?

Not sure why you should need a Cush drive on the back wheel when you have the compensator.

Hi
Well the compensator is upstream of the gearbox so doesnt damp any snatch between the bevel ox and the final pulley. I have noticed condsiderwble snatch when applying power after overrun at low speed. Generally I keep the revs up and am very gentle with the clutch but it is still a little annoying. Originally I thought it was backlash in the bevel drive but now I am sure it is belt snatch.

The rear sprocket on my car was replaced during the frame replacement. The original did not look bad for having 8k miles in it and I will hang onto it to do the neoprene tooth replacement if necessary. The thing I did notice was that it was drilled to accept an outer flange but did not have one on it. I would guess outer flanges were late in arriving and production moved on. I also got a new drive belt but the old one looked nearly unworn, also to become a spare. The belt was tightened to allow about a 50 to 60 degree twist (same as the old one) and there is no cush in the rear hub, the sprocket bolts directly to the wheel.

Roland in Arizona

I have a November 2013:
1. I think we should all avoid "snatch" at all cost. Never run the engine at a"lope" in fourth even if it feels good. Always keep the engine above 2500rpm (as has been said many times on TM).

2. I've had nothing but trouble with my belt rubbing on the side of the tire. I f the belt is adjusted properly to the center of the sprocket it will rub the tire. That is why there was no belt guard on the outside of the sprocket so the belt can be adjusted 3/8 inch off the sprocket to the near side. Which of course is WRONG.

3. There are two hubs available for the 3W. One is silver and one is black. My car had a silver hub and the later cars have a black hub. Its easy to check with a flashlight. The black hub places the sprocket about 1/4 to 3/8 inches out to the nearside and allows the belt to be run properly to the center of the sprocket where it belongs. It also allows for a belt guard on the nearside of the sprocket.

4. I just installed the black hub (pucker up it cost over $600.00 US) and so far it seems to have solved my belt problem (rubbing on tire) and I'll let you all know how it works.

5. I was hoping for some kind or "Retro" warrentee, but the dealer said Ha Ha.

Had the sprocket / hub assembly changed under warranty on my Oct 2012 car last year just as the warranty expired, although I think the dealer had trouble with head office but not sure of any details...

The wheel is now centred (which it wasn't before) and the belt runs in the sprocket with flanges each side and doesn't seem to rub the tyre.

All quiet and serene now (horrid racket before) but only 200 miles since the service due to winter wimpiness. Watching keenly for neoprene or steel hub developments.

Compensator and bevel box all original and working ok on my car at 4150 miles, and I don't religiously keep the revs about 2500 rpm. My car seems quite happy at 2100 - 2200 upwards although I don't use heavy throttles at lowish revs, and have always been mechanically sympathetic (my first car was a Hillman Imp!).

Worth pushing for the upgrade if you can under warranty, but I expect most warranties have expired for cars with the early hub fitting.

Exactly! Belt snatch causes both belt and pully wear - well I'm extrapolating from Chain and Sprocket experience.
Quite how MMC overlooked the need for a cush drive escapes me. Possibly because they are not bikers...

Clearly anyone with a very gentle use of throttle and clutch will have less of an issue than those with a lead foot, but it doesn't get over the problem that the rear drive is fundamentally compramised.

Unfortunately the solution isn't simple as to fit a cush drive will probably mean a new rear wheel as on all the bikes I owned one side of the cush drive was integral with the bike wheel hub, the other had the sprocket bolted to it.

The latest Guzzis do not use a wheel hub cush drive. There is an anti-snatch device that uses a stack of Belleville springs on the clutch shaft in the gearbox . I suspect the system used by Morgan is reasonably valid, it is probably just the combination of belt, bevel box, and gearbox, which inevitably has a bit of play in each component that, when added up, becomes excessive.

Pardon my ignorance (non-biker!) but can't say I really notice this belt snatch you mention. I find the drive take-up pretty good and the clutch to rear wheel feel is pretty good and (when the bevel box is quiet and the sprocket is quiet) it all works quite well.

What symptoms are there of belt snatch - is it just extra wear or is there something more unpleasant at work?

I've never experienced belt snatch in the various cars I've driven. And I still can't se the point of a Cush drive at the back wheel!