How hard is it to change fork springs?


33 replies to this topic
  • ingramo

Posted April 04, 2007 - 06:50 PM

#1

How difficult is it to change the fork springs on an '07 Yz450? This coming from a guy who is mechanically inclined but has never tackled anything dealing with suspension. Can I do it? Thanks in advance

  • grayracer513

Posted April 04, 2007 - 06:54 PM

#2

Very simple, if that's all you're planning to do. Best practice would also be to change the inner chamber oil, and upgrade the fork seals at the same time, but even that's not as difficult as you'd think.

  • ingramo

Posted April 04, 2007 - 07:04 PM

#3

So is it as easy as just pulling the fork caps off and swapping the springs out?

  • grayracer513

Posted April 04, 2007 - 07:22 PM

#4

No, not that simple. But simple.

Remove the forks. Loosen the rebound adjuster at the bottom of the fork, and the Damper cartridge (cap) on the top of the fork. Remove the forks.

Unscrew the fork cap/damper cartridge, invert the fork and drain.

Stand each tube upside down, back the rebound clicker all the way out, unscrew the rebound adjuster, compress the fork, and disconnect the damper rod from the adjuster.

Remove the cartridge, swap the spring, and reinstall the rebound adjuster. Fill the outer chamber with the prescribed amount of oil. Finish the assembly.

  • ingramo

Posted April 04, 2007 - 07:24 PM

#5

Sounds like I can handle it. Thanks Gray!

  • tnl

Posted April 04, 2007 - 08:36 PM

#6

No, not that simple. But simple.

Remove the forks. Loosen the rebound adjuster at the bottom of the fork, and the Damper cartridge (cap) on the top of the fork. Remove the forks.

Unscrew the fork cap/damper cartridge, invert the fork and drain.

Stand each tube upside down, back the rebound clicker all the way out, unscrew the rebound adjuster, compress the fork, and disconnect the damper rod from the adjuster.

Remove the cartridge, swap the spring, and reinstall the rebound adjuster. Fill the outer chamber with the prescribed amount of oil. Finish the assembly.


Don't forget the $85 fork cap wrench and a good way to hold them suckers while you unscrew them. Yea you can use a big cresent wrench just don't scratch the hardware. That was the case with my 05 (twin chambers) before I decided to let the suspension shop do the front and back for $180. I feel a little defeated letting the shop do it though :bonk: Go for it if you think it's possible!

  • grayracer513

Posted April 04, 2007 - 09:35 PM

#7

In the first place, you only need to spend $20 for the fork cap wrench:

http://www.motionpro...ork_cap_wrench/

It lacks the little fork on one end that used to hold the rod up while you take the adjuster off (figure two on page 5-29 of the manual), but you can use anything for that, including a sturdy pair of needle nose pliers, as I do.

In the second place, the best "vise" to use for loosening or tightening the fork caps is the lower triple clamp. That's why I said to loosen them before you remove the forks (loosen the upper clamp before that, though). Use a round bar or the front axle inserted in the axle hole to hold the lower tube while working with the rebound adjuster.

This job is absolutely possible in a home shop. I've had five sets of them apart in mine.

If you want to service the cartridge, you'll need one more tool; a base valve wrench:

http://www.motionpro...e_removal_tool/

That, and a good seal driver, all for about what you'd spend on the Yamaha wrench, and you're completely set up.

  • tnl

Posted April 05, 2007 - 08:30 AM

#8

Good info! I'll do it myself next time. I thought I got a quote for $80 for the cap wrench with the fork tool on it? I'll try the needle nose pliers next time.

  • moochie

Posted April 05, 2007 - 10:43 AM

#9

In the first place, you only need to spend $20 for the fork cap wrench:

http://www.motionpro...ork_cap_wrench/

It lacks the little fork on one end that used to hold the rod up while you take the adjuster off (figure two on page 5-29 of the manual), but you can use anything for that, including a sturdy pair of needle nose pliers, as I do.

In the second place, the best "vise" to use for loosening or tightening the fork caps is the lower triple clamp. That's why I said to loosen them before you remove the forks (loosen the upper clamp before that, though). Use a round bar or the front axle inserted in the axle hole to hold the lower tube while working with the rebound adjuster.

This job is absolutely possible in a home shop. I've had five sets of them apart in mine.

If you want to service the cartridge, you'll need one more tool; a base valve wrench:

http://www.motionpro...e_removal_tool/

That, and a good seal driver, all for about what you'd spend on the Yamaha wrench, and you're completely set up.


Thanks for the link to the cartridge tool remover tool. I'm thinking the link for the fork cap wrench is the wrong size though. The 06 YZ's have a 49mm fork cap and the wrench in the link is for a 46-50 mm cap.

I was swapping out springs and figured I'd change the inner cartridge oil at the same time...that is until I realized I could not get the base valve seperated from the fork cap! For now, I fudged it and just changed the springs and outer fork oil and will go back and do the inner oil after getting the right tool for the base valve. I agree that the spring and outer oil is very easy to change.

  • grayracer513

Posted April 05, 2007 - 03:12 PM

#10

Thanks for the link to the cartridge tool remover tool. I'm thinking the link for the fork cap wrench is the wrong size though. The 06 YZ's have a 49mm fork cap and the wrench in the link is for a 46-50 mm cap.

Maybe, but that's the one I've used on 5 sets of forks, and it works just fine. .040" (1mm) out of 1.967" (50mm) isn't a huge difference.

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  • moochie

Posted April 05, 2007 - 08:18 PM

#11

This wrench is the hot setup for late model forks...one side is a 49mm for Kayaba, the other end is 50mm for Showa caps.

http://www.powerspor...ctCategoryCode=

  • grayracer513

Posted April 05, 2007 - 08:32 PM

#12

That would be better, alright. It doesn't show up on the MP web site, though. Maybe it's new.

  • ingramo

Posted April 06, 2007 - 03:19 PM

#13

I finished the fork springs last night and it was way easier than I thought. As for getting the rebound adjuster off, I just used a 15mm open end wrench, worked great. Thanks again Gray.

  • 700MX

Posted April 07, 2007 - 07:27 AM

#14

No, not that simple. But simple.

Remove the forks. Loosen the rebound adjuster at the bottom of the fork, and the Damper cartridge (cap) on the top of the fork. Remove the forks.

Unscrew the fork cap/damper cartridge, invert the fork and drain.

Stand each tube upside down, back the rebound clicker all the way out, unscrew the rebound adjuster, compress the fork, and disconnect the damper rod from the adjuster.

Remove the cartridge, swap the spring, and reinstall the rebound adjuster. Fill the outer chamber with the prescribed amount of oil. Finish the assembly.



Just curious, I have done mine several times now, and have never clicked my rebound clicker all the way out. does this make the manual's "base assy finger tight to dampener rod" gap measurement more accurate???

700

  • grayracer513

Posted April 07, 2007 - 03:49 PM

#15

Just curious, I have done mine several times now, and have never clicked my rebound clicker all the way out. does this make the manual's "base assy finger tight to dampener rod" gap measurement more accurate???

700

That's pretty much the point of it. Basically, the adjuster is supposed to bottom against the rod, then the nut gets tightened. If the clicker is too far in, the adjuster assembly will bottom against the clicker push rod instead, and you won't have the correct distance between the clicker screw and the rebound valve.

  • rexbond007

Posted April 08, 2007 - 08:33 AM

#16

If you want to service the cartridge, you'll need one more tool; a base valve wrench:

http://www.motionpro...e_removal_tool/

That, and a good seal driver, all for about what you'd spend on the Yamaha wrench, and you're completely set up.


it's not mentioned in the yamaha manual on servicing the cartridge that this wrench is needed? Is it hidden in another section?

  • grayracer513

Posted April 08, 2007 - 08:36 AM

#17

it's not mentioned in the yamaha manual on servicing the forks that this wrench is needed? Is it hidden in another section?

Top of page 5-90

Note:Should read: Page 5-30

  • rexbond007

Posted April 08, 2007 - 08:45 AM

#18

Top of page 5-90


5-90 doesn't exist. do you mean 5-39?

thanks gray..

  • moochie

Posted April 08, 2007 - 10:50 AM

#19

You'll definitely need a tool to remove the base valve while you hold the fork cap with a wrench. You can make one if you can find a large 36mm nut or bolt head.

  • grayracer513

Posted April 08, 2007 - 12:14 PM

#20

5-90 doesn't exist. do you mean 5-39?

thanks gray..

Sorry, typo. Page 5-30





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