Will '83 R100CS rear drive fit '74 R90S? Easy?

[p2squared]

So, my rear drive's leaking, and I've got a '83 R100CS rear end that looks o.k.

My question, 'Easy/straight bolt-to-swing-arm swap?' That way I can keep riding
and deal with the leaky one at my leisure. And keep riding.

But I'm betting...nahh, it's never that simple or easy.

Thoughts?

And thanks.

p2

[ME 109]

Welcome to the nuthouse.

I don't think it will work, but someone who knows even less than me will be along shortly to help.
Different rear wheel, different brake etc.

[khittner1]

I certainly know less than ME109, but here's my swag---I think it might work. Both the 90S and the 100CS have rear drum brakes---that's part of what makes it a CS, rather than an S model. The wheels are different between the 90S and 100CS, but they take the same tire size: 4.00 x 18, so the geometry of wheel/tire/swingarm clearance and the location/placement of the wheels by the final drives must be the same/similar. The two bikes have different driveshafts---the OE R90S did not have the ramped coupler ("cush-drive") in the shaft, but my Haynes manual says that the cush-drive shafts, introduced in 1980, can be retrofitted into earlier /7 models, as well as to /6s and to long-wheelbase /5s. Checking the parts diagrams for the R90S and R100CS at Bike Bandit, they both use the same part-numbered seal between the driveshaft housing and the final drive assembly. If the driveshafts can be interchanged between all of these models, and the connecting seals are the same between the model years, the later final drive unit may well fit onto the earlier swingarm.

Of course, I'll defer to anyone's on-point experiences or research.

Konrad

[Deleted User 62]

I think that while it will bolt up and work in the short term, the difference in the brake shoe width (narrower) and spline length (shorter) on the later rear drive would make returning the bike to stock problematical, due to uneven wear on those parts.

[khittner1]

So maybe you'll need to find a rear snowflake, too.

[Garnet]

I know so much less then ME109 that I have no idea.

[ME 109]

I know so much less then ME109 that I have no idea.

Don't worry Garnet, I've only got one eyed deer.



Took this through my kitchen window coupla mornings ago.

[Deleted User 287]

I know so much less then ME109 that I have no idea.

Don't worry Garnet, I've only got one eyed deer.



Took this through my kitchen window coupla mornings ago.

It looks like his final drive is compatible with that follage.

Is that Windows 7 or Vista?

[p2squared]

Thanks guys. Suppose I could try it with the rear snow flake from the CS and see.

Probably just easier to fix the leak and be done with it.

Can't hurt to query, eh?

p2

[Deleted User 62]

Curious, where is it leaking?