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Topic-icon 1984 R100 forks questions (re-assembly)

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2 weeks 6 days ago #5789 by 11731
Hello and good day. I am writing for assistance with my BMW wrenching; I have a fork question or two.

I’ve removed and disassembled the forks off my 1984 R100 (with approx. 67,000 miles on the clock). Photos of the stanchions and internals can be found here: photos.app.goo.gl/D4J8WjfvMswzaeWU9

I placed the forks on a big mirror (that had been laid flat on my workbench) and rolled them around against each other. I also employed a feeler gauge (between each other and between each one and the mirror) during this check to confirm that the forks were straight. All checked out true! However, my concerns were the major discoloration on the right-side damper rod and some longitudinal wear marks on the right-side fork stanchion. There were also some shiny spots within that tube's slider, that may correspond to the wear marks on the stanchion. Should I be concerned about the discoloration? What is probably causing the wear marks?

Aaannnd, what’s the trick to re-assembling these damper rods back into the stanchion tubes? How does one compress the springs on the damper rod enough to allow re-installation of the little snap-ring?

Thanks in advance,

John

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2 weeks 6 days ago - 1 week 4 days ago #5790 by Scott Ambler
Replied by Scott Ambler on topic 1984 R100 forks questions (re-assembly)
Hi John,
As to the rings, watch videos on Boxer2Valve and Brook's Airhead Garage. You can buy the "special tool" or you can use the alternate method shown. I cut up a milk jug and the piston went right in.

I too had some wear marks on my tubes, but put them together anyway and everything is working well. Best of luck!
Last edit: 1 week 4 days ago by Wobbly. Reason: Mods clarified text

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2 weeks 6 days ago - 2 weeks 6 days ago #5791 by Wobbly
Replied by Wobbly on topic 1984 R100 forks questions (re-assembly)

11731 wrote: However, my concerns were the major discoloration on the right-side damper rod and some longitudinal wear marks on the right-side fork stanchion. There were also some shiny spots within that tube's slider, that may correspond to the wear marks on the stanchion. Should I be concerned about the discoloration? What is probably causing the wear marks?

John -
The wear you are seeing is very normal. This particular bike may have missed a fork oil change, or may have been ridden low on fork oil. But that's all very normal for a bike of this age.

- The main thing is to clean the black sediment out of the bottom of the fork legs before re-assembly. You may need to buy a special brush to do this. In my experience it's not going to come out easily.

- Secondly, if the wear seems substantial, you can always re-assemble the forks with the stanchions rotated 180 degrees from their original position.

- Lastly, reduce future wear by installing 250cc (measured) of good, name brand motorcycle fork oil between 7W and 10W into each fork leg once they are back on the bike. Such an oil is Bel-Ray.

Hope this helps.

Don't hide 'em, Ride 'em !!
#15150
Last edit: 2 weeks 6 days ago by Wobbly.

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2 weeks 5 days ago #5792 by 11731
Replied by 11731 on topic 1984 R100 forks questions (re-assembly)
Thank you, Wobbly. That's good to know that those parts are simply showing their age. I will do a good job of cleaning the gunk out of the sliders over the weekend. I've got some brushes... may end-up gaff-taping one to a dowel or something, so I can get all the way to the bottom.

What's the trick or tool to use when re-installing the damper rod into the stanchion? How does one compress the springs on the damper rod enough to allow installation of the little snap-ring?

Thanks again,

John

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2 weeks 4 days ago #5794 by 8053
Replied by 8053 on topic 1984 R100 forks questions (re-assembly)
In my tool box, I have a home made ring squeezer. It consists of a piece of copper leaf the size of a playing card and a ribbon type hose clamp. I wrap the soft metal coupon around the little rings and tighten the clamp with some oil applied to the rings. I suspect that any soft metal would work.

James Strickland, IL. Airmarshal

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2 weeks 4 days ago #5795 by Wobbly
Replied by Wobbly on topic 1984 R100 forks questions (re-assembly)
My tool box is full of different size hose clamps. That's probably the way I would have gone, but I've never needed to take my forks apart.

Don't hide 'em, Ride 'em !!
#15150

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