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Fork Springs

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Hi.  I have a 99 XR400.  The previous owner told me that he upgraded the fork springs and also gave me the stock springs when I bought the bike.  I've had it for several years and recently blew a fork seal.  So I'm in the process of replacing both fork seals.  I'm following the instructions in the shop manual and also using a couple of videos to help me with the process.  While I have the first tube taken apart, I measured the spring.  Manual says it should be 20.8" long.  It measures 19".  Strange...  I took one of the stock springs out of the box they have been sitting in for years and they measure 21".  So it looks like the upgraded springs are too short and there is no spacer in there to make up the difference.

 

Questions:

First of all, are there any markings on the springs that would indicate spring rate or designed length?

Should I just reinstall the upgraded springs as they were?

Should I switch back to the stock springs?

Should I make a spacer (PVC) for the upgraded springs?

 

I'm stuck here because I'm not sure the upgraded springs are worth it if they don't fit properly.  I have the stock springs so I'm tempted to swap back.  BUT everyone says the first thing to do on an XR is upgrade the fork springs...

 

What do you think?

Thanks,

Doug

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I use PVC in my ol xr250 I cut several different lengths until I found the length that gave me the preload that worked best. Oh ya my aftermarket springs were shorter than the stockers for wwhatever its worth

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If the springs were shorter with no spacer, there should have been no spring holding up bike for an inch. Was there a dead area?

My Eibach springs were shorter than stock. There was a piece of plastic tubing for me to cut for each fork tube. Also four washers. I cut the plastic spacer so the spring + washer + spacer = stock spring lenght. This way I could add a washer for some preload.

Racetech or Eibach should have installation instructions on their website.

Edited by Kev_XR

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I have no idea if there was dead area, or at least it never occurred to me to check.  There must have been because when I pulled the top bolt out of the tube, there was about 1" of space between the spring retainer and where it would set.  In the video I watched, the guy had to push the spring down a bit so that he could get two wrenches on and remove the top bolt from the damper rod.  I didn't need to push the spring down.  Plenty of room for two wrenches.  I made a quick drawing of what I found when I pulled to top bolt out of the fork tube.  I assume the spring retainer should have been pressed up against the stop bolt, but it wasn't.

 

 

Can you tell me about preload?  I assume the spring should be tight on the cartridge, not loose like mine was.

 

Thanks,

Doug

ForkSprings.jpg

Edited by Dougget

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Measure the stock spring and cut a spacer so your replacement springs plus spacer equal the same length. Eibach and Racetech springs are shorter so they can work in either the older 96-97 forks or the 1998 + forks. Same basic forks but the older ones were set up to run a shorter spring. Sounds like what you had in there was not set up and working correctly. That plus an oil change should make a world of difference for your bikes handling.

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RaceTech includes a piece of PVC for the installer to cut and make shorter springs fit properly. The end result should match the length shown in the manual or equal to the stock springs. There is no such thing as a "dead" area. 

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How is there not enough energy in a fork spring to shatter PVC when hitting big bumps and potholes and such? 

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How is there not enough energy in a fork spring to shatter PVC when hitting big bumps and potholes and such?

Because it's installed in such a way to act as a column between the spring and fork cap. The longitudinal load properties of a column are very strong. So PVC when placed as such works quite well.

I personally prefer to use the sch 40 stuff.

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RaceTech includes a piece of PVC for the installer to cut and make shorter springs fit properly. The end result should match the length shown in the manual or equal to the stock springs. There is no such thing as a "dead" area. 

My point was if the springs were almost 2 inches short without a spacer, the forks would drop that distance without springs holding them up.   I don't know what you would call that travel in the forks.   Other than improper installation.   With the front wheel off the ground, it would be possible to slide the forks up without springs resisting for almost 2".

 

http://www.thumpertalk.com/topic/38355-xr400-fork-springs-replacements/

Edited by Kev_XR

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Because it's installed in such a way to act as a column between the spring and fork cap. The longitudinal load properties of a column are very strong. So PVC when placed as such works quite well.

I personally prefer to use the sch 40 stuff.

Interesting. Thank you.  

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Bottom line is springs used in forks or on your shock NEED pre load to work correctly. If you have no pre,load and can't tell something is wrong you didn't need springs in the 1st place.l

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Bottom line is springs used in forks or on your shock NEED pre load to work correctly. If you have no pre,load and can't tell something is wrong you didn't need springs in the 1st place.l

I second that!

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Small side note we will not use race tec springs for the xr4.They are a fit all spring.Use Eibach or any other company.We use to get springs same size as stock.No more all are short now,so you need pvc spacer.Pre load very important to get good ride! BTR

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How is there not enough energy in a fork spring to shatter PVC when hitting big bumps and potholes and such? 

 

There is no impact - the spring is always in contact with the spacer.

 

I also used Eibach springs and used a washer+PVC spacer+washer to adjust the preload.  I set my bike up with about 3/4" of preload.  For the OP - that means when the fork is completely extended, the spring is compressed ~3/4".  I seem to remember the fork cap threading down about 1/2", so that means the spring would have to be compressed 1/4" when you put the cap onto the little tube.

 

Also - something that is incorrect in the manual (at least it was in '98).  Screw in the rebound adjusters out all the way, then turn them in the proper amount of clicks for the whole range of the bike (12 maybe?  Whatever is specified).  Then screw the caps onto the little tube lightly until it just seats, then tighten the lock nut.  Then turn out the clickers all the way and complete the installation.

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A quick trip to Lowes with the big washer from under the fork seal and the smaller one from the top of the spring and I was able to get some 1" sch 40 PVC for the spacers and some parts to make a fork seal driver.

 

I found a 2" to 2" PVC pipe joiner that fits inside the 2" PVC.  Matched up perfectly with the big washer and fits into the seal gap nicely.  Then I got a 2 foot piece of 2" PVC and an end cap.  Figured I can pound on the end cap with a rubber mallet to drive the seal home.

 

Not a bad deal for about $10.

 

Doug

 

SealDriverParts.JPG

SealDriverBuilt.JPG

SealDriverFit.JPG

SealDriverComplete.JPG

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A quick trip to Lowes with the big washer from under the fork seal and the smaller one from the top of the spring and I was able to get some 1" sch 40 PVC for the spacers and some parts to make a fork seal driver.

 

I found a 2" to 2" PVC pipe joiner that fits inside the 2" PVC.  Matched up perfectly with the big washer and fits into the seal gap nicely.  Then I got a 2 foot piece of 2" PVC and an end cap.  Figured I can pound on the end cap with a rubber mallet to drive the seal home.

 

Not a bad deal for about $10.

 

Doug

I did the same thing except i cut the joiner inhalf so its in two pieces like a actual seal driver

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I hope to try it tonight.  Will post some more pics of my progress with the PVC spacer too.  Can't wait to get the bike running again.  I'm sure it will be a pain to start since the gas has been sitting for so long.  Got the SeaFoam ready to go :thumbsup:.

Doug

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