GS500F Fork Seals & Springs

[jbanst]

So my current project is replacing my fork seals and springs.  It was a major pain in the ass to get the damper rod out, but I finally figured it out.  There is no 'special tool' as I've heard from others online.  The Haynes service manual actually says to secure a broom handle on the open end of the rod, so that's what I did.  I had to file it down to a point and eventually hammer it in the rod for it to stay.  Then I used my cordless torque wrench with a long hex drive socket to get out the screw.  Here is a pic of the broom handle I filed down with my dremel tool:


I cut out a square at the end of the handle so I could secure it with a wrench.


Here's a pic of the opening of the damper rod in the newer GS500F models.  You'll notice that there are no grooves or anything for any piece to hold on to, so no 'suzuki specific' tool works on this thing.  The broom handle showed above is your best bet.



So my main question here is about the new sonic fork springs I'm going to install.  The stock spring is 13 1/2", the stock spacer is 8 1/8".  The sonic spring is 15" and there was a long plastic pipe included with the springs for the spacer.  Do I make the new spring and spacer the same total length as the stock spring and spacer?  So basically the total stock length is 21 5/8".  Do I cut the plastic spacer to 6 5/8" to meet with the stock length of the spring and spacer?  Here's a pic of the springs/spacers.  The top is the stock spring and spacer and the bottom is the sonic spring with the plastic pipe under that.

[xunedeinx]

I think mine was around 5 inches, but measure to be sure...

I think you want to measure from the top of the spring to the bottom of the threads for 0 preload, and add on for amount of preload.

If threads are 1 inch deep, and its 4 inches to the threads, than a 5 inch piece of pipe will give you 1 inch of preload.

[jbanst]

I think mine was around 5 inches, but measure to be sure...

I think you want to measure from the top of the spring to the bottom of the threads for 0 preload, and add on for amount of preload.

If threads are 1 inch deep, and its 4 inches to the threads, than a 5 inch piece of pipe will give you 1 inch of preload.

Okay I'm completely new to all this stuff so most of what you just said doesn't make complete sense to me...lol. 

Do you mean when everything is put back together and the new spring is in place, measure the distance from the top of the springs to the end of the fork?  How do I know how many inches of preload I want?

[xunedeinx]

Base measurement, without preload, is from the top of the spring to the bottom of the fork cap, which is the bottom most fork cap thread. Lets say, x inches.

You want y amount of preload, you add it to the x inches of base measurement.

If the distance ffrom the top of the spring to the bottom of the cap is 4 inches, and you want 1 inch of preload, you cut the spacer to 5 inches.

[slipperymongoose]

Can we do this in metric? I've wanted to know if I've done my spacer length correctly.

[bryan88]

Just my 2 cents worth but I would cut the plastic tube the same length as your current steel one. With the extra length of the new spring that should give you a bit of extra preload.

[adidasguy]

Some say cut to match length of top of fork tube, as screwing in the cap will add a little over an inch of preload (2.54 cm)
Some say go an inch above for more preload (2.54 cm).
I've opened up some that had a 1.25" aluminum spacer inserted for more preload (3.175 cm)
More preload simply means stiffer forks.

[jbanst]

Hey, thanks for all the help.  I'll probably go with the 1 inch of preload and see how that is.  If I need them stiffer, I'll just replace the spacer.

[jbanst]

Right fork completed!  New springs were added with a 1 1/4" preload.  Seals & dust covers were replaced as well.  One question on that, is the spring side of the fork seal supposed to be up or down?  I put it down, but hopefully it doesn't matter...   

Started doing the left fork and ran into the same freaking issue.  I can't get the god damn damper rod bolt to come loose.  I've been messing with it for an hour now.  I'm not sure what else to do.  Maybe I'll take it to a local shop and they can help me out.  With out that issue, I'd have to say that changing the fork oil & seals is a pretty easy job and I'm glad I attempted it myself.  If I could only get that MF'ing bolt out...   

[BaltimoreGS]

Spring down is correct, good job     That spring is what actually makes the fork seal work.  If the '04-up GS's are the same as an SV650, there is a special tool available.

-Jessie


Damper rod tool

[jbanst]

Spring down is correct, good job     That spring is what actually makes the fork seal work.  If the '04-up GS's are the same as an SV650, there is a special tool available.

Thanks.  Honestly your video on youtube is what got me through it all!  lol  Though I don't think that tool would work on my '05 GS.  There are no grooves or anything for that tool to catch on in the damper.  The manual says to use a broom handle (which I still can't freaking believe)  LOL. 

I figure I had an easier time with the other fork, because it was sitting without oil for a couple of weeks and it had time to 'dry' a little.  So this morning I turned the fork upside down and I'll let it sit for part of the day to drain as much as possible and try it later. 

[jbanst]

Finished!  I'd have to say an overall easy job (minus those god damn damper rod bolts).  I'm still surprised how much shops charge for this!  Well thanks for your help everyone! 

[Slack]

Preload adjusts the amount of force needed to start moving the spring.
If for example you were using a 100 in/lb spring your spring would move 1 inch if 100 lbs of pressure were applied, 2 inches under 200 lbs, etc.
But if you add 1 inch of preload then you could put up to 100 lbs of force on the spring and it wouldn't move at all.  Once you put over 100 lbs it begins to move; at 200lbs of pressure it has compressed 1 inch, at 300 lbs 2 inches.
If your getting the concept then you guessed what happens with 2 inches of preload: the spring can take up to 200 lbs without compressing and will then only compress 1 inch at 300lbs.
The amount of preload you want depends upon your weight, the spring rate in your front fork, the terrain you normally ride on, your riding style, personal preference, etc.  With that being said most people looking for a softer plusher ride are somewhere in the 10-15 mm, most folks are happier at 20-25 mm, and track stars often run 30-40 mm.
If you really want to tune your fork you can make a few different sized spacers and try out different preload settings.

[jbanst]

Preload adjusts the amount of force needed to start moving the spring.
If for example you were using a 100 in/lb spring your spring would move 1 inch if 100 lbs of pressure were applied, 2 inches under 200 lbs, etc.
But if you add 1 inch of preload then you could put up to 100 lbs of force on the spring and it wouldn't move at all.  Once you put over 100 lbs it begins to move; at 200lbs of pressure it has compressed 1 inch, at 300 lbs 2 inches.
If your getting the concept then you guessed what happens with 2 inches of preload: the spring can take up to 200 lbs without compressing and will then only compress 1 inch at 300lbs.
The amount of preload you want depends upon your weight, the spring rate in your front fork, the terrain you normally ride on, your riding style, personal preference, etc.  With that being said most people looking for a softer plusher ride are somewhere in the 10-15 mm, most folks are happier at 20-25 mm, and track stars often run 30-40 mm.
If you really want to tune your fork you can make a few different sized spacers and try out different preload settings.

hey thanks for the awesome preload definition!  I never really knew the what it all meant.  I figured that I'd start with a 1.25" preload and cut down from there if they were too stiff.  At about 250lbs, I think I'll be good though...lol.