2007 YZ450F front end issue


6 replies to this topic
  • mch

Posted September 06, 2014 - 12:48 PM

#1

I bought the YZ over a year ago as a backup bike and have no idea what work was done to it prior to this.  I've put 35 hours on it so far, and I have no been able to fix this problem so I have just been dealing with it.

 

When getting the front end off the ground, it feels like there is movement in the steering stem.  If feels like the top triple clamp area moves like an 1/8th of an inch.  Before I even rode the YZ, I changed out the steering head races and bearings.  The problem continued and I did everything from over tightening it, to pulling everything apart and making sure the races were bottomed on the lip.  When all else failed, I bought a used/stock triple clamp assembly off of e-bay and bought new races/bearings.  That too didn't do anything, so I replaced wheel bearings just to be sure and have had the forks apart a few times and haven't noticed anything out of the ordinary.

 

After riding tomorrow, I'm taking it over to my friend's house (He's a garage mechanic type like me, but his kid raced AMA Pro and he has been a mechanic for other pro riders) and we are going to both take a look at it.  Maybe with two people pulling on the forks while it's on stand will tel us what the issue is.  He thinks it may actually be in the forks because "what else could it be."  The only thing else I could think of is that the steering head wasn't pushed in all the way so the inner diameter of the steering stem had some play on the bearing.  I remember that was a concern, so we had checked that like 2x.  If any of you can take a picture of the top nut of triple clamp, that would be awesome.  I'd like to see how much threads are showing above the nut, or if it is flush.

 

Anyone have a similar problem?



  • mikedabike

Posted September 06, 2014 - 08:46 PM

#2

Is this while riding or are you noticing when it is on the stand?  I know on the stand you can grab the front wheel and rock it back and forth. It feels like it is play in the steering but is actually play in the bushings between the upper and lower fork tubes.  Normal but a bit disconcerting if you are figuring it out for the first time.



  • mch

Posted September 06, 2014 - 08:59 PM

#3

Is this while riding or are you noticing when it is on the stand?  I know on the stand you can grab the front wheel and rock it back and forth. It feels like it is play in the steering but is actually play in the bushings between the upper and lower fork tubes.  Normal but a bit disconcerting if you are figuring it out for the first time.

 

No, this is while riding.  I changed out those bushings thinking that is what it was, but it's still doing it.  I'm kind of worried that something happened prior to me owning it, and the fork tubes are just worn.  Well, that is 1 of a few ideas I have.. I'm still not sure if it's coming from the forks or the steering stem.  I will probably figure it out once I have more than just me messing with it.



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  • mch

Posted May 21, 2015 - 07:16 AM

#4

Kind of an old topic, but I don't think I have rode the 07 YZ450F since I started this thread (my 12 WR450) is my primary bike.  In short, when you get the front wheel off the ground (and the forks fully extend), it feels like the forks have significant play in the last 1/2 inch of the stroke and there is a very noticeable feedback to the rider.  I thought it was side to side play which was either the steering head or the inner fork bushings (I eventually replaced both), while my friend said he thought it was the inner fork rod dropping down too much.  So, I spoke to him last night and he said the only thing he could find was the "bottom-out" spring seemed smashed.  This spring is located at the very bottom of the twin chamber assembly (NOT the small spring in the Twin Chamber Piston Assembly), where that bottom valve on the rod rests when fully extended.  I have never seen it, but he says you can get it out by putting a small screwdriver through the bottom hole and tapping it out.  He said it was completely stacked with no play, so he put it in a vice and stretched it back out a bit.  He says a test ride near his house showed it didn't have that play any longer, so I'm hoping that is the case.  That spring is not shown on any OEM schematic and I'd like to get new ones, so does anyone know the part number or a place I can order them from?  



  • grayracer513

Posted May 21, 2015 - 09:15 AM

#5

There is no "bottom out spring" in the SSS fork.  Bottoming is hydraulically controlled.  The spring in question is a "top out" spring.   Contact Suspension Direct. 



  • mch

Posted May 21, 2015 - 09:33 AM

#6

There is no "bottom out spring" in the SSS fork.  Bottoming is hydraulically controlled.  The spring in question is a "top out" spring.   Contact Suspension Direct. 

 

Doh, the "bottom" out would be your main springs / fork legs fully compressed.  I guess I may have some dyslexia.. :)



  • grayracer513

Posted May 21, 2015 - 09:57 AM

#7

No, the main springs never coil bind when installed properly.  The bottoming is managed by having the bottom end of the cartridge enter a short tube in the bottom of the fork called an oil lock collar that has a tapered inner diameter.  That forces the oil that is trapped under the cartridge to flow through a progressively reduced amount of space to get out from under the cartridge and acts as a hydraulic brake.







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