Stiff Fork, No Rebound?


3 replies to this topic
  • hvymtlfan

Posted July 27, 2012 - 05:25 PM

#1

Bump..... and Big Question regarding rebound (or lack thereof).

After VERY carefull study, finally replaced fork seals on my 2004 YZ450F
and changed the fork oil as well. Took plenty of time... over half day... flushing
w/ mineral spirits and replaced w/ Maxima 85-150 (5 Wt.).

Litterally did everything right... meas. down to 125mm, and rebound and
shocks were compressing as expected and everything "seamed" great.
Then mount tire, set brake, and walk bike around garage just jumping on brake.....
NOW, after about 10 times the forks are ROCK solid w/o any true rebound.

Lower clamp NOT overtight, and originally did feal great.
Pulled off @ 11 clicks in, then when orig. set at 6... bounced around garage
then clicked up to 8. Then after a couple times... noticed NO rebound so have
backed out dampening all the way, and even releived valve pressure.
Honestly at a lost... they "were" great.... and while first time performing task,
and dampening rod, spring, tubes look like new... so what the %#*& did I do
wrong now (any # of key points)?

Should I waste the time and ride to maybe work out... yet seams like would
damage at this point. Really appreciate any thoughts.

Thanks, in advance.

  • grayracer513

Posted July 28, 2012 - 03:59 PM

#2

If you suspect an alignment problem, or binding tube assemblies, you can check for it.

Lift the bike, get the bars out of the way, and unscrew the fork caps. Then try to raise the front wheel into the fork, compressing it. It's normally not to easy a thing to do, but you should be able to grab one end of the axle with one hand and the gas tank with the other and pull the wheel up without it binding someplace along the way. It should also return smoothly as you let it back down.

If it fails that check, then loosen the right side ("non-brake" side, opposite the axle nut) axle pinch bolts and repeat the process. You might have to wedge the fork lug open slightly by wedging a screwdriver into the slot. If it frees up, snug the axle pinch bolts back up. If it fails to free up with the right side loose, remove the wheel and check each tube separately to isolate the problem further.

What it sounds like you're saying is that your fork seemed alright at first, but after you worked it up and down a few times in the shop, they sort of seized up in that they couldn't be compressed and would not rebound on their own. Is that correct?

At what level did you set your oil height?

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  • marv02

Posted July 28, 2012 - 05:21 PM

#3

Did you buy the bike new or used are you sure the fork tubes are not bent.

I got my use the fork seals were leaking also when I took the forks apart and cycled them I notice the were binding up when I had them apart I noticed they were bent.

I asked the guy I got the bike from what did you run to he said he never did and never had them apart thats they way he got the bike 4 years before I got it.

The forks went about half way though there stroke before they would bind up.

I also replaced the Tripple trees just in case.

Remember the steering stem is Aluminum if been though a bad hit it could be cracked and a bad crash waiting to happen.

  • hvymtlfan

Posted August 01, 2012 - 08:06 AM

#4

GrayRacer,

Greatly appreciate reply & remarks.
Your Correct in the last statement.... excactly what happened.
Excuse delay.... working on house repaint project as well (rather ride).

Did purchase in 2010 used.. yet under 30 hr.'s all stock and very mint.
If anyone's bent the forks, it was me. Now around 60 hr.'s, and orig.
seals and oil, finally started to leak when compressed on trailer this spring...
and quick ride proved fact. Did hit a couple small jumps then trailered it up,
so Damn.. hope that's not the cause.

Actually did as you mentioned in first paragraph, had wife hold bike while
I pushed up on the forks from bottom (suggestion to push any air out).
Oil set at 122 mm ht. (manual 125 mm and range up to 115).
All hand compressions and return felt great, smooth, and returned
smoothly as mentioned (and pinch bolts set to torque).

All went smooth... yet should say.. once back on bike and walked
around garage forcing the front brake also "seamed" like the spring
was making noise... "binding" if you will in the tube.

Think I should take Marv02's advise... and tear down again and really
check the tubes. Didn't rotate in a block, yet they litterly look like new.
Maybe I did bend a tube... yet if so, nothing obvious. They look new,
W/O any issues till the leak began. Hope my quick pre-failed run didn't bend..

So, assume I'll need to purchase "another" set of seals ?
Also, and remarks on how "hard" the internal seals are to be driven down?
Purhased a M.P. driver, and Tusk seals first go-around, and "really"
studied the site to do this D.Y.I.

Sorry... new territory in this area yet bent on getting it done myself
and "right". Big realization that the forks are an area often overlooked...
Should have dropped and "at least" changed the oil when purchased.

Well, back to the house project for now.





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