leaky fork bottom cap

[willyb]

I rebuilt the forks on my 76 R90/6 This past winter as one seal was leaking and i'm sure a rebuild was well past due. The internal bumpers were crumbling also I'm sure thry were original. Everything went together well and was pretty happy with the outcome. over the summer I noticed the copper crush washer for the bottom cap was leaking slightly so of course I snugged it up, no help so tighted it up a llittle more still no help. OK so now i'v flatened it and thats not good. I ordered new crush washers and was wondering if some one has some advice for doing this properly.
My plan is to remove the cap to dump the fluid does this make sense? Oh and I now have the proper size socket for the cap nut and can now tourqe it down properly was using a large cresent wrench and guessing on the 1st attempt bad technique I realize but hey thats all I had at the time.
Any suggestion on making this painless it greatly appreciated

 

[20774]

Brook has some good details and pics on a R75/5 front fork rebuild here:

https://brook.reams.me/bmw-motorcyc...755-rebuild-project/31-bmw-r755-fork-rebuild/

He might be along to help with the explanation.

 

[cseltz]

Same thing happened to me (‘76 R75/6). I ended up redoing the bottom seal with a new washer 2 or 3 times before I got it to stop leaking. Clean, clean, clean I think ended up being the answer.

 

[pglaves]

I would coat the new washer with a thin film of Three Bond or Permatex Ultra Gray sealant.

 

[willyb]

I would be honored to hear from brooks on this matter, I would love to do this just once.

 

[ccolwell]

I started using these on oil drain bolts for no good reason some years ago. They do crush and seal, or appear to, a lot better than solid crush washers.

https://www.belmetric.com/hollow-crush-washers-c-4_2121_2124/

 

[RPGR90s]

Listen to Paul

I would coat the new washer with a thin film of Three Bond or Permatex Ultra Gray sealant.

Per Mr. Glaves, I've rebuilt a few sets of Airhead forks and the copper crush washer needs help with some Permatex Ultra Grey. Never had a leak doing this trick.

Thank You Paul!

 

[willyb]

listening to Paul

OK, I'll try the sealer on the new washer before they are torqued, Sounds resonable, and Like I said I don't want to do this again. Does dumping the fluid by removing the caps make sense? I filled them with 7.5wt and they seemed a little soft so thinking of going with a 10wt when I refill the forks.
any opinions on this for fork oil ?

 

[chunk]

I was advised by Ted Porter who supplied my rebuild parts to seal the threads with Hylomar. I did, along with a new sealing washer and had no leaks.

 

[lkchris]

Don't reuse crush washers. You've experienced the consequences.

 

[willyb]

Success

Don't reuse crush washers. You've experienced the consequences.

I installed the new washers and lightly coated them with a perma tex non hardening thread sealer, I also put a thin layer on the bottom most theads on the bolt. Nice clean install and no leaks. I also switched to a Belray 10 Wt fork fluid and I think so far I like the ride better then with the 7.5 Wt I had installed after the fork rebuild this past winter, I also installed a new set of Ikon shocks this past winter. The bike rides and handles like new.
Thanks for all the suggestions I do appreciate the feed back I always get from the airhead forum here.

 

[chunk]

I installed the new washers and lightly coated them with a perma tex non hardening thread sealer, I also put a thin layer on the bottom most theads on the bolt. Nice clean install and no leaks. I also switched to a Belray 10 Wt fork fluid and I think so far I like the ride better then with the 7.5 Wt I had installed after the fork rebuild this past winter, I also installed a new set of Ikon shocks this past winter. The bike rides and handles like new.
Thanks for all the suggestions I do appreciate the feed back I always get from the airhead forum here.

I started with 5 Wt. and found it a bit too soft. I settled on 10 Wt. and liked the final result. Glad you got it sorted.