2004 yz 450 forks


4 replies to this topic
  • delmas

Posted November 18, 2012 - 04:37 AM

#1

where can I download a service manual for a 2004 yz450f .How do the forks come apart.The bottom fork bolt will not unscrew

  • grayracer513

Posted November 19, 2012 - 10:13 AM

#2

The manuals are here: (see the Common Threads Sticky)

http://www.yamaha-mo...uals/index.aspx

http://www.yamahaown...ook.com.au/?r=0

The simplest way to separate the two main tubes for seal replacements is not to disturb the base valve ("bottom fork bolt") at all. Unscrew the cap, push the spring down to expose the lock nut, and separate the damper rod from the cap. Then pull down the dust seal, remove the seal retainer clip, and pull the tubes apart by extending them sharply and forcefully, as you would use a slide hammer, to pop them apart.

If when you say that the bottom bolt won't unscrew, do you mean that you've turned it, but it just keeps spinning?

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  • delmas

Posted November 19, 2012 - 12:36 PM

#3

The manuals are here: (see the Common Threads Sticky)

http://www.yamaha-mo...uals/index.aspx

http://www.yamahaown...ook.com.au/?r=0

The simplest way to separate the two main tubes for seal replacements is not to disturb the base valve ("bottom fork bolt") at all. Unscrew the cap, push the spring down to expose the lock nut, and separate the damper rod from the cap. Then pull down the dust seal, remove the seal retainer clip, and pull the tubes apart by extending them sharply and forcefully, as you would use a slide hammer, to pop them apart.

If when you say that the bottom bolt won't unscrew, do you mean that you've turned it, but it just keeps spinning?

yes that is correct

  • grayracer513

Posted November 19, 2012 - 02:54 PM

#4

OK, what's happening is that the bottom bolt you're turning with the big Allen wrench is actually the base valve body. Unless you are planning do do a very through cleanup/rebuild/revalve, you don't need to remove it.

The reason it spins is because it passes through the bottom of the lower fork lug and is threaded into the damper cartridge. Once it came loose, the cartridge started turning because it wasn't clamped anymore. There are two things you can do about this besides taking it to a shop.

First and most correct is to get a cartridge holding tool. You can buy one for around $20, or make your own from a piece of tubing such as PVC. The real tool is easier to use on the '04 and later fork, but you can get the home made piece going if you mess with it long enough.

The second is an old trick that usually works, but you need a good fast power impact wrench, preferably air, and a socket for that wrench with an Allen bit in it. With the springs and caps in place, turn the fork upside down and push down. It can be helpful to run a rod like the axle through the axle bore and have a second person bear down on it. The purpose is to use the pressure that the spring puts on the cartridge to hold it as you use the impact to spin it off. You can assemble it in the same way, but thread it by hand and be certain the threads are started straight, then give the wrench several short bursts until you feel it cinch up.

  • delmas

Posted November 19, 2012 - 03:49 PM

#5

OK, what's happening is that the bottom bolt you're turning with the big Allen wrench is actually the base valve body. Unless you are planning do do a very through cleanup/rebuild/revalve, you don't need to remove it.

The reason it spins is because it passes through the bottom of the lower fork lug and is threaded into the damper cartridge. Once it came loose, the cartridge started turning because it wasn't clamped anymore. There are two things you can do about this besides taking it to a shop.

First and most correct is to get a cartridge holding tool. You can buy one for around $20, or make your own from a piece of tubing such as PVC. The real tool is easier to use on the '04 and later fork, but you can get the home made piece going if you mess with it long enough.

The second is an old trick that usually works, but you need a good fast power impact wrench, preferably air, and a socket for that wrench with an Allen bit in it. With the springs and caps in place, turn the fork upside down and push down. It can be helpful to run a rod like the axle through the axle bore and have a second person bear down on it. The purpose is to use the pressure that the spring puts on the cartridge to hold it as you use the impact to spin it off. You can assemble it in the same way, but thread it by hand and be certain the threads are started straight, then give the wrench several short bursts until you feel it cinch up.

thank you Grey I knew you would have the answer.





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