Vintage BMW Motorcycle Owners

Hi
The first of many dumb question I fear.

The "legs" that the brakes set in...facing up in this pic.



Do they face in towards the hub. Or face out away from hub. What forks do I actually have here? Which is LH and which is RH Note that one fork leg does not have the pinch clamp set up.
I cant see any R90S pics on line that show my setup. Thanks
Richard

The "legs" as I think you're saying are where the caliper resides...they point backwards when installed on the fork tubes. Not sure I understand what you mean by "facing in towards the hub".

All pictures I see online show that both fork sliders have pinch bolts. So, I'm not sure what the second one you have belongs to.

The brake calipers mount on the back of the forks, so the legs have to be positioned that way. Do you mean there is no pinch bolt on one leg because you have removed it and it is not in the picture or do you mean the fork leg does not have one at all? Both forks should have pinch bolts. By the way, LOL, don't over tighten them a friend did and it cost hime a new fork slider. St.

Richard,
You must have an (early?) '74 R90S. They came with the fork setup you have. Your bike also uses a smaller diameter 14mm axle rather than the 17mm one the later bikes use. And yes, only one slider has a pinch bolt. If I remember correctly, the one without the pinch bolt goes on the left side and the threaded end of the axle goes through it. There should also be some spacers/reducers that go through the bearings in the wheel hub to reduce the axle hole diameter to 14mm.

Hope that helps.
Chuck S.

Hi
Thanks to all.
Chuck S I think you have it....defiantly no pinch bolt set up on that one fork...not even drilled for it.

So that must mean that there is a spacer between the bottom of the LH fork leg and the LH side of the hub.

To stop you just winding down on the axle nut and dragging the bottom of the LH fork leg in to the hub.

None of this is on any of the parts diagrams I have seen that is why this has become such a chore.

Thanks
Richard

Well, I learned something new. I had a very early serial number 74 90S and it had both forks pinch bolted. Also, the last /6 bike I helped a friend rebuild the forks on had two pinch bolted legs.

Maybe I have been away from the 90S bikes to be giving help on them. St.

So, does this help any? #8 is needed as a spacer. Group #12 is the what deals with the axle diameter differences. This is for an early '74 R90S.

https://www.realoem.com/bmw/enUS/showpa ... Id=36_0154

Hi
Thanks Kurt it does.

It shows the 14mm axle as part #8 and the spacer #9

The spacer #9 is what is missing from the puzzle that is my bike/pile of bits.

Thanks guys it all make sense now.

Richard

Hi
Just to confirm the pic below is what I need to do. Thanks
Richard

FWIW, on my /7 with only the one caliper on the driver's left slider, the axle comes in from the driver's right and the spacer is as you show it between the slider and the wheel. The nut that secures the axle is on the driver's left. I would think that works for all front ends of this era, regardless if there is one or two calipers.