forks knocking on rebound


8 replies to this topic
  • centermass

Posted June 08, 2007 - 04:14 PM

#1

just had my suspension done by race tech and they did a great job. theres just one problem. i had heavier fork springs put in and now they knock when they rebound. so much so that it feels like the bars are coming loose i know thats not it but nevertheless it's an uneasy feeling. it happens especially through rough chop or the whoops. i should mention that it did this before i had it serviced but just slightly. i assume it's due to the heavier springs, and slowing the rebound is probably the answer but has anyone had this issue. by the way it's an 06 yz450f and i started with stock springs.any feedback would be appreciated

  • 2012 450 xc-w

Posted June 08, 2007 - 04:37 PM

#2

I got my '06 December '05 and noticed this right away. Don't pay much attention to it anymore. Just Fuggedabowdit and rail.

  • tnl

Posted June 08, 2007 - 09:32 PM

#3

My 05 has what the shop called negative rebound. When the forks rebound they have more travel than they should. When I had one of the stock forks in my hand and quickly shook it in a upward motion while holding the bottom tube it clicked at the top of the rebound travel like it went past it limit? The shop installed something similar to a shim/washer to eliminate the excess play. Dunno how or if is the same situation? Good luck!

  • mxracer206

Posted June 09, 2007 - 04:47 AM

#4

I know on the 05 forks the fork springs had no preload. They were actually too short resulting in a negative preload on the spring. This could be heard and felt in the forks when they were topped out however I thought they had fixed this problem for 06. This does not sound like anything I have heard about with this fork and I would probably check it out a little further.

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  • 2012 450 xc-w

Posted June 13, 2007 - 09:08 AM

#5

I mentioned this to my suspension guy several times when I first noticed it and he thought it was not a problem. Forks have been revalved and resprung and still ahve this noise occasionally. No signs of damage or anything else at this point and have over 100 hrs. on the bike.

  • motobeck

Posted June 13, 2007 - 10:13 AM

#6

My 06 does the same thing, most noticable in whoops. I've read several posts where others have had the same noise. I just don't pay attention to it anymore.

  • 2012 450 xc-w

Posted June 13, 2007 - 04:54 PM

#7

Yeah, mostly whoops when I hear this. I pretty much ignore now.

  • Nitroused383

Posted June 13, 2007 - 09:02 PM

#8

If you read the manual it says something about a knocking sound if the amount of oil in your forks is incorrect or too low. In the outer chambers I had 320cc of oil in my forks and my forks made a knocking sound. I added 15cc to each fork and the sound went away and the forks feel much better now. This is for a 06 yz250, same forks. Hope this helps.

  • grayracer513

Posted June 14, 2007 - 09:06 AM

#9

The base amount of outer tube oil is 355cc. However, the manual does list 300-380cc as the range through which the oil level can be adjusted. Interesting in light of what you found with yours regarding the knock.

MXA found that the fork is somewhat sensitive to oil level, as they were attempting to address a harsh feel by lowering the oil level 10cc a side. They were surprised to find that that small change had mead the fork too soft, and ended up adding 5cc back.





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