Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Chain drive conversion for five speeder

I can't seem to find anything on the web anywhere so do we know of anyone doing ( or who has done ) a conversion to chain final drive? I would like to compare notes or share ideas.

Please don't bog the subject down with opinions as to wether this is a good idea; after 7000 miles of adjusting the thing "bar tight" before every run to stop it jumping the teeth and now needing to replace both belt and rear pulley I see no alternative for owners who drive hard and long distances. I quote a recently read Harley dealer website " chains are for racing, belts are for holding your pants up" enough said.

Something doesn't sound right to me . I always drove mine hard , often for long distances , when I sold it with a little over 15000 miles I had never adjusted the belt apart from when the tyres or sprockets were replaced .

Yeah...there's a problem there for sure. Of course, a quote from one Harley dealer does make one ponder!

There was a member some time ago who was investigating the swapping in a GoldWing shaft drive setup. Nothing came of it as more gearing had to added to match the drive shafts to the Wing input without losing seat space.
There is certainly adequate room for sprockets and a chain and the rear sprocket would be the easier of the two to set up. You would need a spacer to align the sprocket and then just bolt it in where the belt drive sprocket currently lives. I have not looked at the bevel box side of things to have an opinion as to the ease or difficulty of changing out the sprocket for a chain sprocket, probably a custom part would be needed.
As an aside, we have a bit over 17,000 miles on the original belt and it looks fine. We are on sprocket number two and I will put on a Super Max sprocket at the next tire change. I have never had to adjust the belt other than tire changes and have never experienced jumping a tooth. I run the belt on the loose side (45 to 60 degree twist in the center).

I'm not at this stage yet but will follow any developments here with interest (and admittedly low expectations I'm afraid). I just adjusted my belt slightly. Without a DIY garage (is that an essential for M3W ownership?) I did it with the wheel on the ground and adjusted both sides in turn to keep the geometry in check until the top belt just deflected 1cm. In the test run I was delighted with the new sound (much deeper exhaust - how that comes from the belt I've no idea) BUT it still skipped 2 teeth accelerating onto a roundabout... dang!.

PS: was reading about the Bugati 100 (airplane). They used an offset and offcentre drivetrain (actually engine to gearbox, or rather engines to gearbox). Would reduce the passenger space to get to a shaft drive but that would have to be the ultimate solution?

Nice drawings PaulV, thanks. If I left the belt slack enough to twist 45 deg it wouldn't pull me off the drive. Anyway, thanks for your comments, it seems I am to be a pioneer in this adventure; watch this space for photos of the project and a report on the results - coming soon to a forum near you!

Just as an after thought, it jumped the sprocket when I took it out for a test drive with only 625 miles on the clock. The dealer said that he would get it adjusted before I took delivery - which he did. Which goes to show that it is not a problem onset by worn components.

Just musing here, but I remember years ago (like back in the '70s) on bikes there was a well-known problem with bikes on soft suspension where the centre line of the swinging arm pivot was a long way in front of the centre axis of the gearbox sprocket.

This led to large changes in tension under suspension movement, leading to unpredictable power delivery. Some frame manufacturers, I think Moto Martin was one of them, went to great lengths to design the swing arm so that its pivot was co-axial with the sprocket. Others (like British bikes and Ducatis) just had rock-hard suspension instead.

Could it be, I'm wondering, that the reason that some people suffer belt jumping whilst others don't, is down to differences in tyre pressures, damping and rates maybe? If the swingarm is moving more in some cases than others, then the belt tension may not be consistent, leading to tooth skipping.

The swing arm pivot and front sprocket if not actually on the same axis are very close to it so there is very little tension change with suspension travel.
If the belt is going slack within a short distance, the culprit will be inadequate tightening of the wheel spindle. The adjusters are simply that; they adjust the position and alignment of the wheel spindle, the only thing that stops the wheel spindle wandering off from its set position is the friction created when the spindle is tightened. If you set the alignment and belt tension perfectly but don't tighten the spindle enough the adjusters are quite happy to deform and allow the belt to slacken and the alignment to wander off. Cue the belt jumping teeth and the wheel bearings taking a pounding.
Good luck with the chain conversion but please keep it aligned, tensioned and well oiled, there isn't much to stop a snapped chain from visiting the inside of the cockpit.

The spindle did not slip back, it just kept needing to be moved till there was no adjustment left. Some of this undoubtably accounted for by loss of metal on the rear pulley but mostly and there can be no other answer, this is down to belt stretch. Maybe I should just wear a lighter boot on my right foot?

I would have liked to have videoed the belt while driving, to see if it tracked differently under differing load conditions. We can, after all, only adjust the tracking while the vehicle is stationary. My experience of belt conveyors makes me think that the tracking would be all over the place as the load changed. Different animals I know but I often heard the belt squeaking against the side plates but not consistently, which made me think that it moved as the load changed. For a while I used to try to track the belt to eliminate side contact and squeaking at all times but sadly life is too short.