White Brothers AT3 fork play & rebuild.

[eporter123]

So I just bought back an old Kona that I originally bought used in 2002 or so. I know I had the white brothers fork rebuilt around maybe 2007? I don’t think it has been touched since then. Fork seems to function fine, there’s minimal wear on the stanchions, and I think the bushings are still OK.

The first issue is that when you put just a little bit of downward force on the fork, it slides down about 10mm and stops with a loud “thunk”. Then it proceeds into the normal travel of the springs. You can hold the brake arch and the fork crown and pull up/push down through the 10mm range fairly easily. Is this an issue with a worn out rubber bumper somewhere, or a lack of preload, or something else?

I contacted MRP and they sent me a PDF service manual for the fork. The next step will be to tear down, and clean the fork components, and then try to figure out what to do with the cartridge as there are no instructions for that available. Does anyone know how to rebuild the cartridge in one of these?

 

[Magpiegifts]

Nice xtr spec on that kona. Hubs n V's
Great forks are white bros. I can't help but I'm sure someone can point you in the right direction

 

[Magpiegifts]

Does the fork compress anymore after the first clunk at 10mm?

 

[eporter123]

Does the fork compress anymore after the first clunk at 10mm?

Yes, I'll add that detail in. It compresses easily to the clunk, and it then works normally as you'd expect from the springs inside. Just real easy to get to the clunk, so would likely be topping out/clunking a bit on a rough section of trail.

 

[eporter123]

Nice xtr spec on that kona. Hubs n V's
Great forks are white bros. I can't help but I'm sure someone can point you in the right direction

When I bought this in 2002 just about the entire bike was XTR. Shifters/brakes/derailleurs/cranks/bb/hubs/qrs! The guy at a local shop said it was "Gucci-d out". The friend I sold it to "had to" put the deore cranks on as the XTR chainrings were worn and their shop didn't want to try to source things. I still have those parts, but I'm thinking about some kind of 1x setup now.

 

[Magpiegifts]

Did you try the fork straight after it was rebuilt? Or just now after all these years?

 

[eporter123]

Did you try the fork straight after it was rebuilt? Or just now after all these years?

Haha I wish! I should’ve mentioned I rode it for a few years after the 2007 rebuild and then it’s gone from friend to friend since then. I just bought it back from one that was upgrading to something more modern.

 

[Magpiegifts]

I'm no expert but it's sounds very similar to a problem I had with some forks last year.
Turned out there was a gap before the elastomers were being engaged. Missing spacer or whatever. I know you said you have springs.

 

[ishaw]

I had a set of these forks that had exactly the same thing. I asked around and don't recall finding a solution, though seemed a common enough problem. I seem to recall contacting white bros who at the time could still service them if I sent them back. Cost of export/import was a deal breaker. They seemed to work fine despite it, perhaps a perished bump stop or something?

 

[eporter123]

I had a set of these forks that had exactly the same thing. perhaps a perished bump stop or something?

I’ll have to take them apart and see if anything’s missing/dissolved. Per the owners manual “Zero preload means that at full extension of the fork, the fork caps just touch the top of the springs.” Seems like maybe the clunk is the fork upper sliding down to the point where the caps contact the top of the springs?