I bought a set of 2010 Rockshox Revs 120-150mm Dual air black box forks a while back. As they were sticky I gave them a full service following the manual. Tricky as there are a lot of low-res b&w images and the instructions don't quite fit the forks.
After I'd cleaned them and changed the oil and grease - kept the seals as these looked fine - I put them back together and went for a short test ride. They felt much better but within a couple of minutes after hitting a tiny bump there was a sharp bang as the forks dropped from 150mm to 120mm.
The travel from 120mm to 150mm feels very under-sprung and my weight is enough to collapse them to 120mm. If I set the travel to 120mm they feel fine and behave how I'd expect so I'm reduced to 120mm travel.
I stripped the forks down three more times, but can't figure out why they're not extending to 150mm with full pressure. STW has reports of this happening - often to brand new forks - but I couldn't find any explanation or cure.
Can anyone point me in the right direction as it's becoming more than a little frustrating!
Thanks 🙂
Sound like a seal has 'blown' and you may have a had slight leak between chambers before the strip.
New set of seals/Full service or waranty inspection (if still under 12 months old) should sort the issues out 😀
Hi Simon, thanks for the advice.
It's a 2010 fork so out of warranty.
All the external seals look fine and the fork holds air at 120mm. The internal air-spring piston also seems well-sealed. Is there an internal seal between two chambers in addition to the four external seals? If so can I buy a replacement seal kit? I'd like to have a go at it myself.
Funny thing is the lower pressure between 120mm and 150mm when the forks are extended to 150mm doesn't seem to change after I pressurise the forks, and the higher 120mm pressure also holds. So it doesn't seem like any air is leaking inside the fork or to the outside?
When I took it apart I thought the 120-150mm travel worked purely by raising the top of the fork on an extender so allowing more travel on the same air piston. Could it be something to do with the way I assembled it - in terms of getting air in and keeping it fully extended whilst putting it together but I wondered if the piston had not been fully extended when I sealed the forks.
Does this make sense?
Cheers
John
I'm in the middle of the same thing at the mo, with my rev race 2010 forks. Your u-turn is shagged and you need a new upper assembely. There 70 odd quid 😥