front end clunk

[eriojas]

1979 r100rs, theres is a clunk on the front end when hitting a bump or pothole, like steering stem is loose, I adjusted steering head nut, it was ok, so doing a push with front brake engaged everything feels ok, so I did a fork oil change, but no change, I dont know if its something inside the forks, as I was doing the fork oil change, the top cap was directly on the springs, seeing diagrams there is a plastic guide that mine doesnt have, Max BMW diagram say the guides are from 09/80, , mine is a 79, so dont know if those guides are necessary

[barryh]

1979 r100rs, theres is a clunk on the front end when hitting a bump or pothole

One possibility for fork noise is from the damper valve body. I can't see from the picture you added which design of forks you have but if it's like the one shown below then you can see from the diagram that BMW did a modification to the damper valve body. They moved from the longer solid valve body #14 which could rattle to a shorter sprung valve body #19.

No guarantees that it's the cause of your clunk or that it will cure it but that change was made due to customer complaints of fork noise.

Screenshot 2025-04-09 193620.png (73.34 KiB) Viewed 417 times

[SteveD]

Try this.
Remove the large central nut at the steering stem.
Shim it with aluminium foil and refit.
If that helps, replace the nut as it's likely worn.
If no change, well, it hasn't cost anything.

The clunk isn't uncommon.

[dwerbil]

Try this.
Remove the large central nut at the steering stem.
Shim it with aluminium foil and refit.
If that helps, replace the nut as it's likely worn.
If no change, well, it hasn't cost anything.

The clunk isn't uncommon.

Sounds similar to .....Zen and the Art of Motorcycle Maintenance.

[Rob Frankham]

Jonah here...

While I agree with Steve, the wear is not necessarily all in the nut. It can just as easily be wear on the inside of the hole in the top yoke (triple tree) and more than likely both. Replacing the nut won't necessarily be a complete solution.

Rob

[SteveD]

The 'clunk" has been a repeat topic over the years. BMW came up with something from memory that may or not've worked.

Like many things, there's more than one contributing factor. The nut, the yoke, the fork guts...

[eriojas]

thks for your comments! will see the whole factors with more detail, good day!

[barryh]

Sounds similar to .....Zen and the Art of Motorcycle Maintenance.

I remember that. It was the handle bar clamps on his friends BMW and his friend was affronted at the suggestion of using a beer can to make the shim.

[Giles B]

Hi all. There is a some detailed info on 79 and post 81 forks on this links which are informative .
http://www.vintage-register.co.uk/libra ... 0Forks.pdf
I have a 1983 g/s which also clunks. I have done lots of research and and tried allsorts but never managed to stop it , ahhhh. I have also replaced the lower fork sliders in the past with ones which dont look as worn.I have been considering buying a cheap Telescopic Gauge ,Bore Micrometer Measurement Tool off ebay. I would have to heat and remove the lower circlip and disc off the slider to measure the lower bearing surface.Does anyone know of another way of accuratly mearing the bearing surfaces. Thanks .