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The Punk Hucker
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Discussion Starter · #1 ·
Ok my '08 Reba is seriously starting to piss the hell out of me. It started with a leaking + air because the upper left leg was bone dry. Easy fix, I was happy about it yet my fork felt easy to bottom out. I ramped up the + air and it seemed fine but squishy. Then my Floodgate knob starts leaking, I add some spacers to crush the o-ring and it seems to hold. I also unhooked the remote lockout spring in teh Moco while I was working of the fork and installed a manual lockout knob. I changed the oil while it was all open, reinstall everything and it looks good to go but I noticed it isn't as squishy or easy to bottom out as before I changed the oil, which seemed fine but I wanted to look after it, thinknig I put back too much oil.

So today I finally got the time to check out the oil level. I remove all + and - air first and notice the fork doesn't get all the way down. I'm surprised but it seems to fit with my "too much oil theory". So I loosen up the right upper cap. I expected to see the oil close to the top but it wasn't. I open the left upper top cap too and with both upers still open I tried to compress the fork. I can get full travel, but when I release the crown/lowers, it goes back down 1 extra inch.

I had a hydro lock last year and this doesn't look the same, I shouldn't get that last inch if it was a hydro lockout, right? So I'm wondering what the hell is going on with my fork this time. In a way it's not too bad as it really ramps up the last inch and prevents bottom it out but it's weird. I don't think the Reba has a bottom out bumper so maybe some kind of suction in the lowers is causing this? Dry o-rings maybe?

Any idea is welcome.

BTW, I'm planning on rebuilding everything and changing all the o-rings, just waiting for the order to arrive... For now I'll close everything back so I can race on sunday and I'm looking for a solution to do early next week.

Thanks folks and let me know if riding it may cause damage.
 

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The Punk Hucker
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Discussion Starter · #2 ·
I'm not sure if it makes sense but could it be that all is back to normal but that my "easy bottom out" of the past weeks was due to a lack of oil in the upper right leg?

Thx again.
 

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PissedOffCil said:
So today I finally got the time to check out the oil level. I remove all + and - air first and notice the fork doesn't get all the way down. I'm surprised but it seems to fit with my "too much oil theory". So I loosen up the right upper cap. I expected to see the oil close to the top but it wasn't. I open the left upper top cap too and with both upers still open I tried to compress the fork. I can get full travel, but when I release the crown/lowers, it goes back down 1 extra inch.
Are you getting full travel on the trail?

Some possibilities:

1. You have too much oil in the damper, and it was hydrolocking. When you removed the MoCo, it had the room it needed, and allowed the fork to compress.
2. If you release all the air in the + and -, you can generate a vacuum in the negative chamber when compressing the fork, which could make it feel like it's missing travel. This is most likely why the fork is extending again once you compress it all the way with the caps off.
 

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The Punk Hucker
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Discussion Starter · #4 ·
Yeah I can get full travel no problem but the last inch has a steep ramp up and when all air is removed from + and - the fork isn't all the way down in it's travel as it used to be. There is an extra inch of space left that I can compress by hand but it doesn't stay there, it goes back down when released.

Hydrolocking is a hard lock, isn't it?

Could it be there is a oil leak between + and - chambers so there is too much oil in the -? Since the + was all dry, I wonder where the oil went... That would be some sort of hydro lock I guess but I'm not sure why I'm still able to get the last inch of travel although it's very harsh. Since there isn't much oil in the lower left leg, maybe it just gets pushed around thus requiring more pressure?
 

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I would double check to make sure there isn't too much oil in the damper (right upper leg), and wouldn't bothering checking anything else before doing so.

Yes, you can definitely have a leak between + and - chambers, but that shouldn't make you lose travel.
 

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Your post is confusing as hell.

Probably not hydro lock but I don't know. Either I am have no reading comprehension right now or you are rambling.

It sounds like you have a bad/worn o-ring in the right(air) seal housing. They tend to go bad in the Reba and the fact that there was no lube in that side will greatly increase the chance that some +air leaked into the -air under the seal housing.
 

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The Punk Hucker
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Discussion Starter · #7 · (Edited)
boogenman said:
Your post is confusing as hell.

Probably not hydro lock but I don't know. Either I am have no reading comprehension right now or you are rambling.

It sounds like you have a bad/worn o-ring in the right(air) seal housing. They tend to go bad in the Reba and the fact that there was no lube in that side will greatly increase the chance that some +air leaked into the -air under the seal housing.
Confusing, possibly... I can assure you this issue is confusing me too.

Although there was an air leak in the past, it's not the case anymore as I have the problem with both upper caps removed and all air released. And BTW, the air leak problem leads to the fork not extending completely, I'm having the opposite problem.
 

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The Punk Hucker
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Discussion Starter · #8 · (Edited)
bad mechanic said:
I would double check to make sure there isn't too much oil in the damper (right upper leg), and wouldn't bothering checking anything else before doing so.

Yes, you can definitely have a leak between + and - chambers, but that shouldn't make you lose travel.
I did remove some and the problem was still there. I'm sure I could remove all the oil and still "lose" that last inch. If it was a too much oil problem, wouldn't the oil in the upper right leg be close to the top of the damper?
 

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The Punk Hucker
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Discussion Starter · #10 ·
Soft stop. I can even compress that last inch with some force but it "bumps" back into place when I release the lowers.
 

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I think it's vacuum in your negative chamber causing it. To test, put your shock pump on the negative chamber, force the fork to compress all the way, and then press the bleeder on the shock pump.
 

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If it is negative chamber, then what you're seeing at home is vacuum. The negative chamber is small volume, and when emptied can generate quite a bit of vacuum when the fork is compressed.

However, I don't think that problem is related to the harshness you're feeling in the last 1" of travel out on the trail, which I believe is caused by too much oil in the damper.
 

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The Punk Hucker
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Discussion Starter · #14 ·
I wouldn't say it's so noticable on the trail but it does ramp up which is to be expected on an air fork AFAIK. I really noticed it since the fork felt soft for the last weeks and I could bottom it easily.
 

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if i am understanding you correclty, this is perfectly normal. remove the valve cores from both air chambers, fully compress fork, and fork extends ~1.0" from full compression after compression force is removed. i was just working on my Reba last night and it behaved in the exact same manner.

think about what is going on here. you have two separate volumes of air being compressed as the fork compresses: one in the bottom of the fork lowers and one in top of the damper chamber due to volume displaced by the damper pushrod. the increased pressure in these small chambers causes the fork extend once the compression force is removed but it is not high enough to overcome friction in the bushings/seals and fully extend the fork.
 

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The Punk Hucker
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Discussion Starter · #16 ·
ktm520 said:
if i am understanding you correclty, this is perfectly normal. remove the valve cores from both air chambers, fully compress fork, and fork extends ~1.0" from full compression after compression force is removed. i was just working on my Reba last night and it behaved in the exact same manner.

think about what is going on here. you have two separate volumes of air being compressed as the fork compresses: one in the bottom of the fork lowers and one in top of the damper chamber due to volume displaced by the damper pushrod. the increased pressure in these small chambers causes the fork extend once the compression force is removed but it is not high enough to overcome friction in the bushings/seals and fully extend the fork.
Good to hear. It's funny that last week when I added oil in the upper left leg, it compressed all the way down when removing air from the + chamber.

Apart from this "unexpected behavior", the fork feels good. Would you say it's ridable?
 

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judging by what you have posted, yes. these forks are not very complicated.

when you say "unexpected behavior", have you compressed the fork before without any air it the spring and it stayed fully compressed??
 

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The Punk Hucker
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Discussion Starter · #18 ·
ktm520 said:
when you say "unexpected behavior", have you compressed the fork before without any air it the spring and it stayed fully compressed??
Absolutely, last week when I added oil to the upper left leg.

I rode the fork this evening and it behaves normally... I guess it's just a suction from the - as bad mec mentionned (although I didn't take the time to test it yet)
 

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i don't see how the neg chamber can generate a vacuum if the valve core is removed. did you have both valve cores removed when you checked the travel?

this is the first rockshox fork i have owned, and i haven't fully dissected it yet. i could be missing something here. i have changed the travel twice now and i'm pretty sure that when checking full travel each time it would rebound from full compression.
 

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ktm520 said:
i don't see how the neg chamber can generate a vacuum if the valve core is removed. did you have both valve cores removed when you checked the travel?
It won't if the core is removed, but he said he only emptied the chamber.
 
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