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View Full Version : Curvy fork damping loss

85jas
07-03-15, 06:45 PM
Hi all,

I decided to take a look at my forks today as the front feels like it has gone markedly downhill recently - damping is reduced and there seems to be some sort of asymmetric wobble in the front end. Not good! The fork oil had done 10k so I started there...

I've got standard curvy forks with debrix emulators in, they've been in a couple of years now and all has been well.

Did the left fork just fine, all seemed well. When I was filling the right fork with oil I noticed that the rebound damping / resistance to me tugging on the stancion was markedly reduced, and there was an odd rattle when I quickly pumped it up and down. I took out the emulator and had a look, the check valve seemed to work just fine. Ah hah I thought, the damping rod is somehow loose. Nope, checked the damping rod bolt and it was tight as the proverbial, and there were no odd rattles when I shook the empty fork, apart from the rebound spring rattling about a bit. I refilled the fork and had another pump and noticiced that there was a whooshing of air being drawn in and out around the dust seal.

I don't have an impact driver to remove the damping rod bolt so can't properly strip the fork, however I need the bike for work on Monday so will have to sort it out tomorrow somehow - given the above has anyone got any idea what might be wrong with the fork? I'm gonna get cracking first thing tomorrow and was hoping someone had some pointers!
wideguy
07-03-15, 08:53 PM
Without the spring sitting on top of it, nothing holds the emulator in place, so when you were pumping it up and down and hearing a rattle, it was the emulator rattling around.
It sounds like you need new oils seals at the least, maybe dust seals too, then new oil. The damper rod doesn't need to come out for what you need to fix. If you don't have time, just fill with oil to the proper level and watch for leaks past the seal.
85jas
07-03-15, 08:59 PM
Cheers wideguy. Yeah I get that on the compression stroke all I'll be doing is lifting the emulator off it's seat - it's the madness on the rebound stroke that I can't get my head around. There aren't any oil leaks from the fork to the outside world so I figured the oil seal etc. is okay, but the oil seal atop the damping rod is hosed, hence no control of the oil flowing back to the bottom of the fork.
wideguy
07-03-15, 09:06 PM
Cheers wideguy. Yeah I get that on the compression stroke all I'll be doing is lifting the emulator off it's seat - it's the madness on the rebound stroke that I can't get my head around. There aren't any oil leaks from the fork to the outside world so I figured the oil seal etc. is okay, but the oil seal atop the damping rod is hosed, hence no control of the oil flowing back to the bottom of the fork.
Ah, the bushing is bad! Replace it soonest. The forks won't break off, but sloppy bushings will start to cause expensive damage. And you still don't need to take out the damper rods.
No, actually, I don't know what you're talking about. There isn't any oil seal atop the damping rod, just the emulator.
But if you mean the bushing is bad, change it. Inspect for damage as you do.
Bibio
07-03-15, 09:26 PM
could be the check valve is stuck.
85jas
07-03-15, 09:42 PM
Okay, I'll check out the bushings tomorrow - don't want any unnecessary wear and tear! I suppose that would accout for the air flowing past the dust seal, I suppose the oil seal there must be past its best too for the leakage to happen...

Bib, the check valve - this lives on the bottom of the stanchion right? It's been so long since I stripped down the forks that I've forgotton what's inside, and am working of the diagrams on the racetec website, aarg
Bibio
07-03-15, 09:53 PM
yup its on the bottom of the stanchion.
85jas
07-03-15, 10:17 PM
Great, thanks - Will get on that in the morning.

One of these days I'm gonna buy all of the beers, for all of the org, for all of the night...
carelesschucca
08-03-15, 12:05 AM
Oft! That sounds like someone's gonna have an expensive night at the AR!!!

Wait a minute come up to the GM it'll be way cheaper for ya :D
85jas
08-03-15, 12:03 PM
Be reet, I'll just budget to spend on drinks what I've saved through being on here. Must be a good couple of grand!

But OT now, effin' damping rod bolts. Effin' bolts. Basically, more of this...
http://forums.sv650.org/picture.php?albumid=948&pictureid=6177