First ride in several months yesterday and I noticed my forks were not performing well - a bit stiff. I checked the air and there was only 50psi in the main chamber (they are revelation dual air u turns). I let all of the air out of both chambers and tried to compress the forks but they only went down 2/3rds of the way then seemed to resist as if there was still air in them. I put my weight on the handlebars and the left stanchion seal unit blew out with a bang! I pushed it back in and pumped them up and they were working nicely again. Slightly worried though.. any ideas what was wrong? Perhaps air had migrated into the wrong part of the forks somehow? Do I need new seals?
Cheers
Dan
2010 fork? I think there was a problem with some u turn forks around this era and RS stopped making the ubturn soon after. Mine did exactly as you described, also my uturn stopped working. I tried a full service including new seals but this didn't work, so I sent them back under warranty. They came back with a new u turn assembly and have worked fine ever since.
They are the 2010 model - you have me worried now.. I Guess these will not be under warranty anymore!
Speak to loco.
Sounds like you have air passing between the chambers.
Normal use keeps the seals lub'd and soft.
I suspect that over time the air has passed the seal a service will have them working well again.
I don't think you have a uturn fault.
Is it a Team? I had very similiar issues, mine ended up needing half the air spring replaced as a part inside was a little damaged but Flotec who did the repair were surprised at that, they'd expected it to just need a full service and seals kit etc. It wasn't connected to the U-turn (which more or less sits on top of the air spring)
U-turn wasn't withdrawn from sale because of any reliability issues, it was just declared uncool as people find turning a dial 6 times too complicated. So they swapped to dual-position.
I had a very similar issue as what Northwind described.
Speaking to a few suspension workshops seems it is common for the O-rings to perish after a while and let air leak out of the spring and into the fork leg. The fork leg now becomes pressurised and will blow the seal if the fork is compressed.
Usually a full air spring service with new o-rings solves the problem. But in mine and Northwind's case it was a little more complicated and it needed a few more parts.
My dual air Rebas used to do it. Air was leaking from the negative air spring into the fork leg and when compressed the seal would pop out. An air spring service sorted them out.
Thanks for the help folks.. I have started pulling the forks apart and will order a set of seals and see how it goes!
So I have one more question if anyone can help. I am using the tech manual here:
On page 56 in the air service section it says "Revelation only: Skip to step 23." Do I take this to mean that the entire upper choke assembly does not get serviced or has no seals?
Also I have found various posts on here that mention adding oil to the air chamber. The manual does not mention this?
I am also being a bit dumb when it comes to working out how the thing works and how the fault I experienced could have occurred. There are large holes in the sides of the U turn mechanism.
http://www.flickr.com/photos/75567900@N07/13399991824/
A black metal sleeve fits over this and threads onto the U turn adjustment thread on the top of the air assembly. However it does not seem as if this would be air tight. i.e. air would pass through the plastic thread as it is only partially threaded. I am confused by this as this would mean that the fork lowers are pressurised?
The tech manual seem to refer to a different fork as in step 29. it asks you to test the air tightness by inflating the +ve chamber before reinstalling the air assembly. This is impossible in my case as the air will just exit the holes!
Cheers
Dan
My rev RLT Ti's did this. A (home) service fixed it. Probably a dodgy seal.