shuddering forks

[gs1150]

hi folks

issues concerning forks. my dad had the forks re-done on his r100cs with new oil and seals a few months back along with a fork re-build. he now tells me that the forks and front wheel shudder whilst at 70 mph and gets worse the faster you go. he thinks that the oil he was told to put in is too thin and doesnt damped as required to. it never did this before and he had the work done as one of the fork seals was leaking.

any fork specialists who can shed light on this matter.

thanks

 

[ELIMINATOR]

Haynes manual says not to use ordinary fork oil, as the forks are designed to run with SAE3 oil as most fork oils are up 10 times thicker than this & will produce a very stiff ride.

This is the Haynes manual, someone will be along shortly who has actual practical experience on your forks.

Incidentally, you've posted this in the wrong section, it should be in the airhead section. You'll get a better response if you repost in there.

 

[davegs]

Forks

Oil wouldent do that sounds like warped discs or somethings loose have a good check up of all bolts etc ptu the bike on a stand and check for back and forth play in the forks this shold show something up the oil damps up and down but will no cause this effect. Also check the head bearings.
dave GS

 

[warmshed]

Hi, I think you may get a wider answer on the airhead threads. As you say its a R100CS I assume it would be around 1981. I believe the oil should be 5-10 grade. BMW 7.5wt or BelRay 5 is recommended by the Clymer manual. Worth checking for play in the bearings of the front wheel too. The air heads were prone to shaking their heads and need the head bearings to be adjusted properly. Dave.

 

[Kenny]

5 grade oil

first check your wheel bearings

then headstock bearings

if all OK then loosen fork leg bolts and wheel bolts just a smidgeon and bounce the bike up and down quite vigorously a few times, this settles the forks back in synchro. Nip all bolts up again. Finally just make sure the tyre is all OK and balanced/inflated properly

 

[Beemerboff]

81 forks would still have the flat plate top yoke, and are difficult to align properly, particularly if you are working single handed.

So you are probably going to end up with more stiction than you would want , and IMHO it is worth investing in the best synthetic suspension fluid you can find - Bel Ray 5 wt HVI? suspension fluid transformed the forks on my R75/7