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Is the rear drum hub on a Mototrans the same as an Italian rear drum hub ?

I have been looking for a rear wheel or just a bare drum hub for a yellow bike for a long time.
No luck so I'm looking elsewhere.

Regards
Graeme

The spoked wheel from a Mototrans bike will fit , but all the Mototrans spoked wheels and hubs come with the narrower ribs as used on the pre-1966 Italian Ducati singles.
In fact, the Spanish design of hub is more like the 1950s Italian hubs than the smoother Amadori hubs of the early 1960s Italian bikes.
It might look a bit odd on a late yellow widecase Italian machine.

Jon

Hello Graeme

All the Italian hubs are the same from the later 60's, so shouldn't be that rare. Cush drives and backplates do vary over the years, in that more reinforcing was added in the form of webs. They do show up on eBay in the US, a late narrowcase hub would do, but as I said the plate and cush differ slightly (in appearance) . I'm not sure if I have a spare rear hub (plenty of early fronts), I can have a look, but with shipping costs, you may be better finding one closer to home.

Regards Nigel

Thank you gentlemen
This side of the planet rear hubs are very hard to find.
I would have thought fronts were the ones that were damaged more in crashes but there are plenty of fronts about. Drums I mean. And disc fronts are available new.
A friend is looking at a possible rear from a parallel twin for me.
If that doesn’t happen I will ask again. Perhaps your possible rear might be my only option Nigel.?

Regards
Graeme

Hi Graeme

the reason for the rear hub shortage is the bearings come loose and they can collapse to .

i have two hubs laying around and both have the bearings loose in the housing . one is beyond repair the other one i can fix by shrinking a steel sleeve over it .

Eldert

if you dont care about original parts this is what i used on my RT . hub is from a Yamaha SR 250
it needed a lot a machining before the hub fitted and the chain lined up with the sprocket

Eldert

I managed to find a rear hub except for the spacer between the sprocket carrier and the swing arm and the axle nuts.
The 450 parts supplement shows only 1 of the 4 bearings as a C3.
Is that correct, or are they all C3 ?
(I will use 2RS bearings)

Graeme

Hi Graeme,

Others will doubtless disagree ; but I can do no better than quote you this from Simply Bearings:

"C3, C4 and C5 bearings are bearings that have an additional internal radial clearance to cope with high speed environments where excess heat is generated. <snip>

Applications like motorcycle wheels or bicycle wheels do not require C3 rated bearings.

Unless the bearing you are replacing specifically says C3 on it then you should not replace it with a C3 bearing. C3 Bearings are loose to the feel from new and often people complain at the quality of the bearing being poor and having more movement than the one they are replacing."

Can't see why even one would be C3 ...

I understand the difference
I thought C3 were used to allow for possible misalignment of several bearings as in a rear hub.??

Graeme

FWIW, here is my experience: bevel twin wheel bearings are C3 and so are the wheel bearings on modern Ducatis. Years ago I changed the wheels on my 900 bevel from cast to spokes with aluminium rims, and did not use C3 bearings; within 1000 miles the bearings failed. I replaced them with C3 and they have been in there ever since. My guess is that when wheel bearings are fitted, there is always some sideways loading, either from the bearings being up against the spacer, or if the spacer is slightly loose, when the wheel nut is tightened the bearings are squeezed in against the spacer; either way, sideways loading are created which ball bearings are not designed to cope with, but the greater clearance of a C3 bearing helps mitigate.

Something else that may be of relevance here is the interference fit of the bearing in the housing, which may close up the clearance and cause the balls to bind.......