Monolever fork stiction

[pxc433]

Hi Guys

My bike is a 1988 R100RS, so a monolever, with the factory fitted fork brace. The forks are completely standard.

I have issues with stiction in the following circumstances:

- Putting the front wheel in place, then tightening the side axle bolt to the specified toque setting, then tightening the pinch bolts.

I have no issues with stiction if I:

- Remove or losen the fork brace OR
- Bounce the forks up and down, then tighten the pinch bolts, and then the axle side bolt.

From the above, it feels like I need to shim the front wheel into place. The act of tightening the side axle bolt is pulling the fork sliders to a position they don't want to be. The difference isn't big, but it's enough to make a difference.

What's your take on this? Does anyone else shim these wheels into place, and if so where do you get the shims from?

Thanks a lot, Andy

[Bamboo812]

The bouncing before tightening the pinch bolts is BMWs recommended method of ensuring the axle is centered. Tighten the axle nut first, then bounce. It helps if the axle is rust free and greased. If it ain't broke...

[Major Softie]

The bouncing before tightening the pinch bolts is BMWs recommended method of ensuring the axle is centered. Tighten the axle nut first, then bounce. It helps if the axle is rust free and greased. If it ain't broke...

His point is that it only avoids stiction if he does NOT tighten the axle first, thus tightening the axle first is drawing the ends of the forks together.

'88 has the top triple clamps, right? So none of Duane's alignment procedures apply? If you have a (even slightly) bent tube, this could happen. Turning the tube in the clamps would at least quickly identify if this was the case.

[SteveD]

I have issues with stiction in the following circumstances:

- Putting the front wheel in place, then tightening the side axle bolt to the specified toque setting, then tightening the pinch bolts.

I have no issues with stiction if I:

- Remove or losen the fork brace OR
- Bounce the forks up and down, then tighten the pinch bolts, and then the axle side bolt.

I know nothing about the monolever except what applies to the twin shock models.
However you have identified the way to do it that works for your bike in your second description. So my ignorant question is, does it matter which way if you get it right anyhow?

[Major Softie]

I know nothing about the monolever except what applies to the twin shock models.
However you have identified the way to do it that works for your bike in your second description. So my ignorant question is, does it matter which way if you get it right anyhow?

I'm not him, but yes, it matters. The front wheel would be floating back and forth on the axle. It results in no stiction, but not in a safe setup to ride.

His question about shimming would result in a safe situation, but it would be a band aid covering some problem. Better to discover what that problem is. If it's that the upper and lower clamps aren't truly aligned, then I could see shimming the front wheel as a reasonable solution. Any other problem creating this solution needs to be addressed at the source.

[pxc433]

Hi and thanks for the replies.

Major Softie is quite right.

I have a choice at the moment that I find unpleasant.

- A wheel sitting on an axle with no endfloat, but fork stiction.
- A wheel with endfloat (not much, but some) and no stiction.

I've read Duanes pages carefully, but looking at the arrangement I have I'm not sure that it applies to me. However, I don't think there is a triple clamp on top. The arrangement is there is a pathetic top yolk made from a flat piece of metal, and a more substantial lower yolk. Then there is a substantial fork brace, then the sliders/axle etc.

I think the issue lies in the arrangement of the fork brace. If I remove the brace, which puts me into the same position as a twin shock, then it is all fine, I can put the wheel on, tighten it properly starting with the side axle bolt, and all it well.

It has crossed my mind to remove the brace. BUT I try to keep the bike stock, and there may be insurance issues with a mod like that in the UK, I'm not sure. Also it look a bit crap, and the enhanced handling was what caused me to trade my twin shock R100RS for the monolever.

Just to add to the variables, I got some great advice on this board about two years ago. I had knocking from the forks when hitting bumps, it turned out I had a worn out central top nut - replacement of this nut fixed this. Now I wonder if I should have replaced the top clamp at the same time, as I wonder if it was worn out as well.

So should I be looking at doing something like:

- Loosen the stanchion bolts on the top
- Loosen the lower yolk bolts
- Loosen the axle and pinch bolts
- Bounce the forks a bit
- Tighten the axle and pinch bolts correctly
- Bounce the forks a bit more
- Tighten the upper nuts
- Tighten the lower yolk nuts?

Andy

[Gibson]

The last thing you want to tighten is the lower fork bolts that clamp the end of the axle without a flange. Or if it is easier, just tighten everything then loosen bottom axle clamp bolts as you have been doing. Tightening the axle after these clamp bolts will always pull the fork out of alignment on any make cycle...

[Major Softie]

Ah, pxc, if you have the flat top plate, then yes indeed the instructions on Duane's site apply, and your problem is being caused by the fact that your forks are not properly aligned.

[ME 109]

Ah, pxc, if you have the flat top plate, then yes indeed the instructions on Duane's site apply, and your problem is being caused by the fact that your forks are not properly aligned.

I thought mono's had a heavier top brace and not the 4mm thick top plate like my 81?
If pxc has a 4mm plate, he doesn't have an 88, or someone has changed things, or I haven't a clue what I'm talking about.

There is nothing wrong with a 4mm top plate btw. There are however other mechanical situations that fail to support the 4mm top plate.

[Major Softie]

I thought mono's had a heavier top brace and not the 4mm thick top plate like my 81?

So did I. That's why my first comment was that Duane's site probably didn't apply. But, he says that's what he has.

Maybe we need some pictures....


What am I saying, we ALWAYS need pictures!