Recently rebuilt my mates 140mm Travel Air U-turn 20mm axled Revelation 409's for him as they had been leaking oil from the U turn adjuster (as is par I understand, certainly most Air U-Turn rockshox I've seen on the trails have been leaking!). Anyway, he's ridden them once since I rebuilt them, was round his house today having a look at the bike, and funnily enough they're leaking oil again!
Now, I used new o-rings and the lot when I rebuilt the forks, I've no real experience of the air U-turn system though really, but have serviced a fair number of the fixed travel dual air revelations/rebas/pikes in the past though successfully. So what's the issue? How can I fix it?
Also, there seems to be a very annoying couple of mm of play in the forks (up and down) which results in a really rather annoying top out "clunk" when the forks extend fully. I've not come across this at all on any of the fixed travel dual air rockshox I've ridden. Is this normal? How is it fixed?
Cheers in advance for any info/feedback
Have you replaced the schrader valve on the top of the U-turn? That can cause a leak if is faulty or worn out. Dead cheap and easy to do. Worth a try anyway.
Grimey, you mean the valve core? Or the whole thing?
Sorry, yeah, the valve core.
Any more for any more?
yeah im interested in the 'top out clunk' ideas, mine and a few customers have said of this issue...interesting.
I have some 09' U-Turns that clunk sometimes. Apparently its play in the helix mechanism on the u-turn. It dissapears at the extents of the u-turn travel, so I leave mine on 140mm. By all accounts its never been properly resolved by RockShox. Apparently you cant swap the u-turn stack for a fixed spring stack either. I can live with it because the maxle version are great forks.
It dissapears at the extents of the u-turn travel, so I leave mine on 140mm
I tried it at both ends of the travel, and everywhere inbetween, and seemingly no difference. Leaving the forks extended at 140mm is not really an option anyway, his frame is designed for a 120mm fork so he leaves them at 120-125mm most of the time.
By all accounts its never been properly resolved by RockShox. Apparently you cant swap the u-turn stack for a fixed spring stack either.
Hmmmm... So there is no fix really then? Oh dear! And why could I not just replace the U-Turn air spring with either a fixed travel air spring, or even better, a coil U-Turn assembly? They're all the same fork except for the spring setup surely? At least that's what they look like to me...
Don't know about the top-out clink, but I spoke with tft a while back about the leaky u-turn adjuster. They acknowledged it was a problem, said the RS o-ring was slightly too small so they replace it with a slightly bigger one when servicing.
Mine have a very slight topout clunk, which I just ignore on the basis that bikes make noise. Never had the u-turn leak oil on any of my 3 or seen it happen on any other u-turn forks so I'm not sure what the issue is there but it's not normal.
I have this problem on my Rebas (Had Pikes and Revs and they were fine) and I find it annoying. Check out this thread form a while back...
http://www.singletrackworld.com/forum/topic/reba-29er-air-u-turn-clunking-help-please
Cheers guys, very informative
Anybody know if I can literally just take the U-Turn spring unit (along with adjuster) from a coil sprung Pike (as the chassis is essentially the same as these 08/09 140mm Revelations) and insert in these forks? Looks to me like it should be no problem, but obviously I don't want to spend any money on parts that might be of no use before I do it.
I have the 'clunk' except at the extremes of the travel that takisawa mentioned. Can't seem to sort it but I've got used to it and it doesn't seem to affect the fork performance.
I spoke to TFT about the clunk, their suggestion was to pack the top of the fork with grease, which does seem to help a little. Or live with it, but it does seem to get worse over time.