Revelation (Motion Control) not getting full travel

[Koos Likkewaan]

Hi,

 

Some help needed please.

 

I have a 2016 Rockshox Revelation, 120mm travel with motion control damper.

 

Over the weekend is saw that I am only getting +- 60mm travel when riding. When locking the fork, I can hear the different sound ( Bypass ?) but travel stays the same.

 

Not sure what happened, but was working fine a week ago.

 

Had a full/major service not long ago. 

 

Normally I do all work on my bike myself, but have always send the forks and shocks to the experts.

 

Any idea what I can do myself to find the reason for this ? Heard about hydraulic lock and oil bypassing in the damper, but have never attempted to work on the fork.

 

Thanks.

[droo]

If the full 120mm of stanchion is showing, let all the air out and see how far the fork compresses. If you can't get full travel out of it, there's too much oil somewhere, either in the lowers or in the damper. It's most likely a seal in the lower damper seal head that's failed.

[Koos Likkewaan]

If the full 120mm of stanchion is showing, let all the air out and see how far the fork compresses. If you can't get full travel out of it, there's too much oil somewhere, either in the lowers or in the damper. It's most likely a seal in the lower damper seal head that's failed.

Thanks Droo.

 

Will try this tonight.

[Koos Likkewaan]

If the full 120mm of stanchion is showing, let all the air out and see how far the fork compresses. If you can't get full travel out of it, there's too much oil somewhere, either in the lowers or in the damper. It's most likely a seal in the lower damper seal head that's failed.

 

Released the air and, as expected, still same travel ( +- 60mm ).

 

Where to start ? Remove the damper and measure oil level ? Or do I have to remove the lowers and rebound shaft ?

 

Thanks for the help so far.

[droo]

Remove lowers, see how much oil comes out. If there's more in one side than the other (which is my guess) then you'll need to replace the U cup seal in the lower seal head, which basically means you'll need a rebuild kit cos that's the only place you'll find the seal.

 

If it's not that, keep looking. MoCo dampers aren't rocket science, any problems should be reasonably easy to spot.

[Koos Likkewaan]

Remove lowers, see how much oil comes out. If there's more in one side than the other (which is my guess) then you'll need to replace the U cup seal in the lower seal head, which basically means you'll need a rebuild kit cos that's the only place you'll find the seal.

 

If it's not that, keep looking. MoCo dampers aren't rocket science, any problems should be reasonably easy to spot.

 

Thank you Sir,

 

I you were not so far, I would have just brought it to you :-)

[Koos Likkewaan]

Update on my travel problem.

 

Took out the damper. Found oil level way too high. Removed some oil. Bottom of damper is +- 15mm into the oil.

 

Assembled. Corrected air pressure. Tested. All working as it should. Full travel etc ...

 

Now the question. Where did this oil come from ? +- 20ml.

 

Or has it been over filled at the service and I did not notice it before ?

[droo]

Did you drop lowers?

[droo]

Did you drop lowers?

[Koos Likkewaan]

Did you drop lowers?

Did not take it out completely. Took rebound knob of. Loosened bolts, knocked shafts loose. Little bit of oil came out , which I put back. Assembled and took out damper. Wanted to see which side had a lot of oil.

[droo]

If the same amount came out of both sides, the damper was most likely overfilled at service. If less came out of the damper leg the damper may have ingested some of the oil from the lowers, which isn't good for stanchions and bushings. I'd recommend draining all the oil from the lowers and replacing it, also so that if the issue happens again you know why.

[Koos Likkewaan]

If the same amount came out of both sides, the damper was most likely overfilled at service. If less came out of the damper leg the damper may have ingested some of the oil from the lowers, which isn't good for stanchions and bushings. I'd recommend draining all the oil from the lowers and replacing it, also so that if the issue happens again you know why.

Thanks Droo. Will do that and test. Appreciate the help.

Was about the same amount.

Edited February 8, 2020 by Koos Likkewaan