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What direction do I go with my shim stack

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my son rides a 2018 gas gas xc 300 with almost stock suspension.  The springs have been changed to fit him.  He is an A rider in GNCC / Hare scrambles.   I'm wanting to get the best set up for him but not sure what direction to go from stock.  Should I change the shim stack and if so, does anyone have a stack they recommend.  

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What are the negative handling or suspension traits the rider feels need to be corrected or improved?

How much does he weigh and, what are the current spring rates?

Edited by mlatour
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fork spring 4.2, shock 46mm x 54n. he weighs 205 lbs.  We're looking for a more plush ride.  The current set up is ridable but he feels every rock, root and bump eastern us has to offer.  I've also noticed the shock bottoming on small jumps.  After a race, you can see where the rear tire has been hitting the fender.  We've played with clickers for the last year and ended about where we started, stock "race" settings.  Sag is at 103.  We've tried heavier springs and went back because the current felt better.  Also tried different oil levels. Now I'm questioning if a different shim stack is needed to get the feel he's looking for.

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The fork spring looks very soft

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I'm willing to try different set ups.  How heavy should I go with the spring?  I've tried to use the race tech calculator unfortunately they don't have this bike listed.  Do I leave internals alone?

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It uses the wp fork and it a bit heavier than a ktm ?

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I’ve had good results running stiffer low speed settings (damping/spring rates) and softer high speed settings. This has allowed a stable chassis which blows off harsher impacts. In the forks, I’ve found improvement in bottoming with this setup through high outer chamber oil levels which really ramp up the end of travel air spring resistance. You might want to experiment along these lines.

 

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KYB's mog.
It was a question , I was asking what fork and bike weight

Ah ok , the bike weight?

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2019 is claimed just over 100kg. 

I'm think the 18 is comparable. 

They run the older style AOS tubes, like the TM's, with a KYB shock out back as well.

 

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5 hours ago, ski-monkey said:

I'm willing to try different set ups.  How heavy should I go with the spring?  I've tried to use the race tech calculator unfortunately they don't have this bike listed.  Do I leave internals alone?

wHERE ARE THE CLICKERS?

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My charts for similar weight bikes say your just a tad soft on the springs 0.44 but 0.42 is s possibility


0.44 might be actually plusher with less damping

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A

3 hours ago, mog said:

My charts for similar weight bikes say your just a tad soft on the springs 0.44 but 0.42 is s possibility


0.44 might be actually plusher with less damping

Actual dry weight stock is 105 kg.  we've added an ims oversized fuel tank with dry break, aluminum rad guards, rear disc guard, skid plate and pipe guard. The 205 lbs is the rider weight without gear.  Would the added weight push it higher than .44 

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6 hours ago, motrock93b said:

I’ve had good results running stiffer low speed settings (damping/spring rates) and softer high speed settings. This has allowed a stable chassis which blows off harsher impacts. In the forks, I’ve found improvement in bottoming with this setup through high outer chamber oil levels which really ramp up the end of travel air spring resistance. You might want to experiment along these lines.

 

I've increased the oil level already from 350 to 365.  How much of an increase did you make in the forks?  Did you change low and high speed settings with clickers or shim stacks?

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I've increased the oil level already from 350 to 365.  How much of an increase did you make in the forks?  Did you change low and high speed settings with clickers or shim stacks?

My tuning was done on Showa 47 TC forks. I went from minimum oil height to maximum. I don’t have the exact numbers with me, but I went from about 315cc to about 410cc incrementally. I did this after revalving the forks and having a professional revalve the shock. I left the BV LS stock, and removed about five equally spaced HS shims, leaving the clamp stock. I believe a large part of the harshness was improved by MV alterations. I increased the float .05mm and softened the comp shim stack. Oil moves much faster through the MV than the BV, so it can experience rapidly increasing hydraulic drag as suspension velocity increases. As speed doubles drag quadruples, etc. So, square edge hits even at low motorcycle speed can create harshness and deflection. My preference (Not optimal for jumpy MX tracks) is suspension that doesn’t wallow (Firm LS), and blows off square edges, logs, rocks. etc. As my confidence improved with better suspension, my speed picked up. This lead to harder impacts and overjumping tabletops (bottoming). Raising the fork oil level helped s lot.

Your forks and shock are different than mine, but I believe the tuning logic should apply. Maybe someone with specific knowledge of your components can chime in.

Good luck!

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11 minutes ago, motrock93b said:


My tuning was done on Showa 47 TC forks. I went from minimum oil height to maximum. I don’t have the exact numbers with me, but I went from about 315cc to about 410cc incrementally. I did this after revalving the forks and having a professional revalve the shock. I left the BV LS stock, and removed about five equally spaced HS shims, leaving the clamp stock. I believe a large part of the harshness was improved by MV alterations. I increased the float .05mm and softened the comp shim stack. Oil moves much faster through the MV than the BV, so it can experience rapidly increasing hydraulic drag as suspension velocity increases. As speed doubles drag quadruples, etc. So, square edge hits even at low motorcycle speed can create harshness and deflection. My preference (Not optimal for jumpy MX tracks) is suspension that doesn’t wallow (Firm LS), and blows off square edges, logs, rocks. etc. As my confidence improved with better suspension, my speed picked up. This lead to harder impacts and overjumping tabletops (bottoming). Raising the fork oil level helped s lot.

Your forks and shock are different than mine, but I believe the tuning logic should apply. Maybe someone with specific knowledge of your components can chime in.

Good luck!

I'll get the new springs in Mog suggested first then after testing see where it needs to go.  Sounds like what you're suggesting might be what I'm after

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Had that bike dialed for EnduroCross in 2018 with 170lb rider without gear. We ran .46 fork springs with 5mm of pre-load. That should give you some direction.

 

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7 minutes ago, Suspenders said:

Had that bike dialed for EnduroCross in 2018 with 170lb rider without gear. We ran .46 fork springs with 5mm of pre-load. That should give you some direction.

 

Thanks

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