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: https://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
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!
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.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
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
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.
former Airmarshal, IL.
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.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
I may have mis-understood the question.
To defeat the compression of the springs inside the fork tube, I just pull the top nuts out of the upper yoke.
former Airmarshal, IL.
Thanks for all the replies, Wobbly and 8053, though I remain confused. I may not have explained my issue well enough, so I took a photo and pasted it alongside the ones I linked to earlier. This is the direct link: https://photos.app.goo.gl/bKgrG2FRkDeefZ7M8.
I’m concerned about re-installing the damper rod and associated snap ring back into the bottom of the stanchions. That photo will probably explain it better than I can.
See if this answers your question.
See if this answers your question:
https://www.youtube.com/watch?v=y863W9-GB-c&t=653s
Advertisement
