Fork not reaching full travel

My 2012 Rebas aren’t reaching full travel and I don’t have a cue why not.

I’ve just serviced the damper with new o-rings and new oil to see if it’s that but it isn’t. The damper (lowers removed) definitely ramps up through the stroke for some reason. There is the right amount of oil in there. I put in 106ml as the Rockshox chart tells me to and it was measured with syringes.

I am utterly bamboozled now! It’s definitely something in the damper, that’s for sure as I can feel it ramp up when I push the damper rod. What could be the problem?

Just to check – when fully assembled – you let all the air out of both sides : you still cant compress them fully?

yep and when the forks are apart I can’t fully compress the damper rod due to it ramping up so I’m certain that the damper is the cause.

The damper will ‘ramp up’. It’s a sealed system and the damper rod takes up space as it enters the upper leg, so the air in there gets compressed, so it’s effectively a spring too.

Can you get full travel with the fork assembled, but no pressure in the spring side?

Someone more knowledgeable than me will be along in a minute.

In the mean time – some more diagnosis:
– Have they done it from new?
– when you added the fluid are you sure there was none leftover below the piston thing.
– With the damper out you should be able to see a doofer inside the assembly moving when you turn the lockout lever.

Nope, I still can’t get full travel then 🙁 They always stop about an inch shy of full travel, even with about 20 PSI in the positive and negative.

I am honestly at loss at what to try next 😥

In that case there must be too much oil in the damper.

– Have they done it from new?
– when you added the fluid are you sure there was none leftover below the piston thing.
– With the damper out you should be able to see a doofer inside the assembly moving when you turn the lockout lever.

No, they didn’t do it from new. They started playing up when I followed Peterpoddy’s guide to making them crown mounted lockout.

There was definitely no leftover fluid in there as I stripped the whole thing down and took everything out of the stanchion when I did the service.

Yes, I can see the little silver thing moving when I turn the low speed compression adjuster.

In that case there must be too much oil in the damper.

I can’t see how though, I put in the 106ml of 5wt oil that Rockshox say to use here:
http://www.sram.com/sites/default/files/techdocs/gen.0000000003511_front_fork_oil_chart_2012_0.pdf

I’ve got the 2012 Reba RLTs, so I’m looking in the right place.

Peterpoddy’s guide to making them crown mounted lockout

That’s probably related then 😉

Do you have a link to the guide? I probably wont be able to help much more – just interested.

Here it is:
https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0B1AoGIWBz4H1YWNhYWRkODYtNzRiNi00YTA1LTlmMjctNmQzOWQwMDdiZGFl&hl=en_US

Sounds like you have a lot of air above the oil.

Remove all air from fork, undo the top cap damper side and pull it out a little bit, fully compress fork with the top cap slightly pulled out, soak up excess oil that comes out from under the top cap. You can do this with a syringe too. Then, with the fork still fully compressed, do up the damper side top cap again.

GB

gee- That’s worth a try I suppose but won’t they not fully extend, then?

That’s probably related then

I’ll take that back – I dont see how that guide would affect things.

peter can tell you what to do but he can’t help it if you have hands like a numpty 😀

proper comment: to much oil i reckon.

I might as well try what Gee said and ty taking some oil out too.

If it’s too much oil then I don’t know what Rockshox are on.

If there is air above the oil when you seal the system, ie if you seal the system with the fork extended, the air above the oil acts as a secondary spring. What I suggested above helps to counteract that.

Is there a lot of oil above the piston on the air side? If there is more than a couple of cc’s this acts to reduce the air volume of the spring and cause ramping up too.

GB

I haven’t touched the air side and I’m sure that the problem is caused by the damper.

I suppose I’ve got nothing to lose, giving what you said a try, Gee.

OK, I tried to do what Gee said but I still couldn’t depress the forks all the way with the top cap removed so it can’t be too much oil if it was too much oil it would have just came out the top. So it’s got to be an internal problem, I think?

So, shhould I try removing some oil next?

Let all the air out of the + and – springs, then remove both top caps and try to fully compress the fork again. If you have massively overfilled the fork oil will come out under the cap. You should be able to remove the air spring top cap completely and the damper side top cap a little bit.

If you can’t compress the fork with both caps removed there is an internal problem.

GB

Both top caps were removed and I compressed the forks, suddenly the wiper seal on the damper side popped out. The air side was unaffected. I’m now incredibly confused!

Let all of the air out, negative first.Then with the fork compressed see if you can eek more from the negative.

Both top caps were removed and I compressed the forks, suddenly the wiper seal on the damper side popped out. The air side was unaffected. I’m now incredibly confused!

How much oil did you put in the lower legs?

Let all of the air out, negative first.Then with the fork compressed see if you can eek more from the negative.

How would that help with the problem of pressure build up in the damper/ damper side lower leg.

5ml went in each lower leg.

Unless some suspension genius comes up with a brilliant idea it looks like I’m just going to ride them until monday next week when I’ll have the time to give it another crack.

In the meantime anymore ideas are very welcome.

Because if you set the negative first it won’t get full travel anyway.

I always set the positive chamber first anyway, as you should

To much oil in the damper – just remove some and try it – it only needs a few ml too much to cause issues.

I had the same problem with my revs. I turned the bike upside-down, let all the air out of the + &- then loosened the bolts holding on the lowers then compressed the fork by hand. The last 15mm of travel squeezed oil out around the bolt hole on the damper side. Solved the problem….I must have somehow put more than 5ml in the lowers. Could be the same thing?

my guess is 10ml in one leg and none in the other

It’s worth a try, I suppose. Well, just about anything is worth a try! 😆

I’ve now tried everything mntioned and I’ve given up trying. Luckily for me, my mate is an insider in the industry and mext time he’s runnning an event with SRAM he can get the tech guys to have a look inside for me.

did you try removing some oil from the damper?

I have had exactly this with a pair of similar forks and that was the reason – Only took 5 0r 10 ml out

BUMP with more relevant thread title…

Where did my attempted service of my Reba SL 29ers go wrong?

I followed the rock shox tech document instructions Here

I replaced the all the O rings, foam rings and topped up the oil with the recommended weights and volumes, and pumped up the air chambers to the recommended weight.

Having put the forks back together again, the original fault appears to be fixed – there is no horrible clunking, bottoming-out noise, and I’m definitely getting more travel. I’m still not getting 80mm – there is now only about 65mm of stanchion showing above the tops of the lowers, and going by the O ring I put on the stanchion I’m only getting about 55-60mm of travel out of the 80mm I’d expect.

Any ideas as to what I’ve done wrong and how to put it right if have to open ’em up again?

The fact there’s only 65mm showing suggests too much negative air. With the negative air chamber empty, and some pressure in the positive chamber, can you see 80mm of stanchion then?

For the second problem (not getting all the travel) – follow the instructions as above. Either you’ve got too much positive pressure (let it out and try and compress the forks fully) or they’re hydraulically locking because you’ve put too much fluid in the damper side. I’m not sure I fully trust RockShox’s damper fluid amounts. I’ve measured it exactly and had hydraulic locking, let a bit out and all is fine.

Silly maybe, but does the syringe you used have a pointed plunger? Most of them do. Have you perhaps filled the syringe to the point, rather than the edge of the plunger seal?
Another silly one, but is there possibly a spacer in the fork, to reduce the travel? EG a 20mm spacer fitted in a 120mm fork would only allow 100mm travel…….