Oil leaking out of Revelation U-Turn - Help!

[LazyTrailRider]

I recently bought a 2nd-hand 2009 RockShox Revelation U-turn (110-140mm) from a hubber, in almost-new condition.

Went for my first ride on Saturday, thoroughly enjoyed it, the fork was super smooth and controlled.

 

So I get home and decide to do my first bit of air pressure tweaking both front and rear. I also thought "let me drop the fork to its minimum 110mm for the next ride to get a feel for what's optimal".

 

Dropped it, went for a quick spin outside and then noticed a bit of a clunking in the first bit of the stroke. Almost like top-out, the first bit of travel is loose. So I think "maybe something to do with the negative air pressure"...

 

Screwed the shock pump on, registered 100psi (which is fine, positive is at 105psi as I only weigh 68kg). But then.... as I unscrew the pump, a crapload of oil comes spurting out the valve, flooding my poor brand-new pump in the process.

 

Help please! I'm new to fiddling with air forks, the Recon I had before this simply worked for two years, no attention required. What could be causing this?

[Johan Bornman]

It all depends on how much a "crapload" is. Air chambers have a little bit of oil inside and it is normal for some oil, a few drops in spray mode, to come out when you deflate.

 

If a fork doesn't do this, it means its float fluid (oil in the air chamber) is probably finished and it needs a service or top-up.

 

 Edit: The travel on that fork is completely independent of the the two air chambers. The air chambers are moved up and down via an screw mechanism, when you adust travel and it does nothing to the air chamber settings, pressure etc.

 

In other words, anything you did with the U-turn dial is irrelevant to the "problem".

 

Johan Bornman2010-05-26 14:38:37

[LazyTrailRider]

It all depends on how much a "crapload" is. Air chambers have a little bit of oil inside and it is normal for some oil' date=' a few drops in spray mode, to come out when you deflate. [/quote']

 

OK, thanks Johan. I guess my crapload is not necessarily your crapload, much like potatoes. Probably half a teaspoon, so 3ml or so? Enough to need me to spend a minute or two shaking and pumping the pump to get it all out... Yes, I did deflate the chamber a little bit to see what effect it would have.

 

I guess I'll just have to open it up and get my hands dirty when it's time for a service so I don't have to keep on wondering what goes on in there.

 

Inflated it again and all's fine. I suspect the knocking sound has always been there, I probably just haven't noticed it.

[Mecnic]

The clunk could becoming from the actual u turn mechanism

[Johan Bornman]

The clunk could becoming from the actual u turn mechanism

 

That's not my experience but perhaps you've seen something that I haven't.

 

The U-Turn mechanism is a robust nylon scew that works inside another nylon part and there is no play in there nor does any play seem to develop.

 

 

[Mecnic]

The clunk could becoming from the actual u turn mechanism

 

That's not my experience but perhaps you've seen something that I haven't.

 

The U-Turn mechanism is a robust nylon scew that works inside another nylon part and there is no play in there nor does any play seem to develop.

 

 

 

When I was down at cape cycles they showed me how to assemble the air u turn mechanism in a revelation,

 

He recommended filling the nylon threaded part with a good quality thick grease as at the extreme travel setting a small clunk could develop due to that little bit of play in the threads the grease just fills it up and help its not a loud clunk just enough t be annoying.

 

It could be many thing, rebound not working proper but it most probally something to do with the U turn mechanism it couldn't hurt to check it out and give it a good clean and grease, according to the tech manual available on the rock shox website.

 

The oil that came out the bottom chamber is oil from the + that just by passed the oring on the piston head as long as your not losing air it shouldn't be a problem.

[Johan Bornman]

Oh, I see. The clunk (if it is there), never bothered me but I'll remember the tip.

 

I agree with the oil story but still wonder just how much came out. If it all came out, the piston will leak air very soon.

 

 

[Mecnic]

Oh' date=' I see. The clunk (if it is there), never bothered me but I'll remember the tip.

 

I agree with the oil story but still wonder just how much came out. If it all came out, the piston will leak air very soon.

 

 

[/quote']

 

I agree if enough oil came out to fill the pump up the oring may be worn or damaged

[LazyTrailRider]

Sorry for the late response, and thanks for the feedback Johan and Mecnic.

Clunking: It's very slight, but quite annoying. Mecnic, your explanation sounds plausible. I don't think it's rebound damping related, as both the compression and rebound stroke is perfectly smooth and controlled, except for the little bit right at the top. It also clunks (or clicks, if that's a the less pronounced version) on both compression and rebound.

 

Oil: I sheepishly admit that my initial "crapload of oil" statement was a bit of a knee-jerk response to something unexpected. As I previously said, I reckon around half a teaspoon. I've inflated it twice afterwards and almost no oil came out.

MartinHattingh2010-05-28 10:39:33