S2000 STR prep resource
Joined: May 2004
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From: Tucson
Originally Posted by TheNick,Feb 9 2010, 01:06 PM
Do yourself a favor and do two step shim stacks. One shim stack for low speed - then a spacer - then your smaller stack for mid-high speed damping. DO NOT USE ANY PRELOAD. Try it out and see what happens.
You don't need a whole lot of rebound, but I would try the double digressive piston if I were you - you need SOME low speed rebound and right now you don't have any at all with the linear rebound. When you added more rear rebound - you added a ton of high speed damping that will cause the inside tire to skip over the surface. This can cause some goofy handling characteristics.
Your rebound adjuster only touches the bleed through a jet in the shaft. You can replace the jet to get different low speed characteristics as well. I don't think you can mess with the 8100 canister much - you'll just need to put thicker shims on the compression side.
You don't need a whole lot of rebound, but I would try the double digressive piston if I were you - you need SOME low speed rebound and right now you don't have any at all with the linear rebound. When you added more rear rebound - you added a ton of high speed damping that will cause the inside tire to skip over the surface. This can cause some goofy handling characteristics.
Your rebound adjuster only touches the bleed through a jet in the shaft. You can replace the jet to get different low speed characteristics as well. I don't think you can mess with the 8100 canister much - you'll just need to put thicker shims on the compression side.
I've got way more rebound than the Konis which is my baseline for comparison. Apparently it's enough to jack down the suspension and cause handling issues on the rear. I'll post some dyno plots eventually.
For anyone wondering what TheNick is talking about here's a couple images of a "crossover" shim stack. See second from right. This image is from the Shimrestackor web page, see link below. The second image is one I found some where along the way doing research.
This web page provides some interesting info and software for calculating shim stacks -> Shimrestacker
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Joined: Jul 2007
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From: Twin Cities
Originally Posted by TheNick,Feb 9 2010, 11:10 PM
Its just after the downward slope of the cam - as in - when the intake valve is closing.
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Joined: Jun 2008
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Thats on the low RPM cam.
You can feel it when you rub your nail over it, but its very very slight and I was actually able to scrape some "black crap" off it. I don't know if that was dirt under my fingernail or if it was actually part of the cam surface. It still looks exactly the same.
What is interesting to me is how its only in the middle of the cam - the roller rocker runs over the entire surface width, so this isn't an impact thing. Especially considering its the low rpm cam - there is no reason why it would float a valve there.
I think its a casting flaw.
You can feel it when you rub your nail over it, but its very very slight and I was actually able to scrape some "black crap" off it. I don't know if that was dirt under my fingernail or if it was actually part of the cam surface. It still looks exactly the same.
What is interesting to me is how its only in the middle of the cam - the roller rocker runs over the entire surface width, so this isn't an impact thing. Especially considering its the low rpm cam - there is no reason why it would float a valve there.
I think its a casting flaw.
Joined: Nov 2003
Posts: 2,246
Likes: 1
From: Atlanta
Do you have a helms manual? I wouldn't do the job without one.
1. Remove the head cover
2. Losen the rocker arm adjusting screws
3. Remove the camshaft holders and camshafts. Unscrew the holder bolts 2 turns at a time to prevent damage to the shaft.
4. Remove cam gear and CMP pulse plate.
5. Reassemble.
1. Remove the head cover
2. Losen the rocker arm adjusting screws
3. Remove the camshaft holders and camshafts. Unscrew the holder bolts 2 turns at a time to prevent damage to the shaft.
4. Remove cam gear and CMP pulse plate.
5. Reassemble.
