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JRZ shock tuning advice please.....

 
Old 09-10-2011, 02:07 PM
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adfsouth
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Default JRZ shock tuning advice please.....

Cross post from GT3 forum

Any educated setup advice would be greatly appreciated.

Been enjoying DEs for about 6 years (10 to 12 events per year) and run advanced solo. Home track is Sebring which is a combo of smooth and bumpy. I like my car (07 GT3) to handle relatively neutral with an touch of understeer and I trail-brake). I installed JRZ RS Pro with 600/800 springs a couple of months ago and l'm in the process of adjusting things to my liking. There are 12 compression settings and 15 rebound settings. TPC suggested to start with a compression of 5 from soft all around with a front rebound of 7 and the rear at 9. Canister pressures are 200lbs all around. This felt ok but I've made a few changes since. I am currently running the setup detailed below. Please critique my settings and share your JRZ or Moton settings. Thanks.

Front:
Compression- 4
Rebound- 6
Sway - one from full stiff
Camber - neg 2.8 per side
Toe - 0

Rear:
Compression - 5
Rebound - 8
Rear Sway- Full Soft
Camber - neg 2.3 per side
Toe - 2mm in per side

Ride height about 20mm down from stock - tires are shaved RA1s
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Old 09-10-2011, 02:48 PM
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I've never been to Sebring but I have raced on many bumpy tracks with uneven surfaces. What you should be looking at is how the car's handling now with your current settings, and then asking for advise based on what you're trying to accomplish. Also remember that tires play a huge part of your car's performance so don't chase setup with bad tires.

I wills say that I think you have too much cannister pressure up front. I'd go 150 or less....
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Old 09-10-2011, 05:13 PM
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I completely agree that the RA1s are a limiting factor. I've used Hoosiers before and appreciate their grip, however from my experience they fall off considerably after roughly 12 to 15 heat cycles and its not wise to drive them to/from the track (which I do quite often). For DE with commute the RA1s are a pretty good tire and wear like iron.

That being said, the car feels ok....relatively neutral at speed with some understeer in the slow stuff.....it just doesn't seem to have the level enhanced grip that I thought it would. Yes, its flatter in the turns and doesn't have the nose dive during braking like before, however it still feels a bit twitchy on turn-in and under hard breaking. Granted, this might be partially solved with a guard LSD rebuild but for now the wallet needs the rest.

I will take your advise regarding canister pressure, however I guess I'm just looking to learn more from other people's experience and settings despite the fact that everyone has different driving styles. Also, would you leave the rear canister pressure at 200 or lower to maybe 175?

I know the new setup is a significant change from stock (especially the spring rates) and haven't had enough time to really explore the new limits but I just expected it to be more confidence inspiring out of the box.....I'm sure most of it is just in my head. In any event, Seth Thomas took my car for a spin at Road Atlanta on TPCs recommended compression and rebound settings and pulled a 136.5 on his 3rd lap so I know its capable. At that time I had the front sway on middle....he said stiffen it one hole and leave the rest alone. That felt good at Road Atlanta but Sebring is a different animal.

Again, any insight is appreciated.

Last edited by adfsouth; 09-10-2011 at 05:54 PM.
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Old 09-10-2011, 06:08 PM
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I agree with Seth regarding the front sway bar. Too often drivers setup their suspension for low speed mechanical grip when it's the high speed grip that you should be concentrating on. That where you'll find your speed and fastest laps. That's not to say that you want a car that understeers off the track, but you should be willing to give up a lttle speed in the tight, slow corners for a car that feels planted in the high speed sweepers. Of course all this will change if you put in Guard's LSD clutches. Then you'll really have to learn how to drive thru understeer . Again, you're really chasing the limitations of your tires. You're all set up correctly for some decent R-compounds, you'll just have to buy a second set of rims and get a friend to transport them for you. Oh and I'd leave the rear cannister pressures alone.....
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Old 09-10-2011, 06:21 PM
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Originally Posted by adfsouth View Post
In any event, Seth Thomas took my car for a spin at Road Atlanta on TPCs recommended compression and rebound settings and pulled a 136.5 on his 3rd lap so I know its capable. At that time I had the front sway on middle....he said stiffen it one hole and leave the rest alone. That felt good at Road Atlanta but Sebring is a different animal.
Yes it is. In deference to Seth Thomas, he obviously can drive a car with a lot of quickly changing levels of grip. You probably are not used to this coming from a stock suspension, and then onto a very rough track like Sebring. My suggestion is to soften the rebound 2 or even 3 clicks front and rear, and see if the grip and predictability return. If so, then learn to drive the car like that, and when you are more comfortable with it, you can work on tightening the rebound some.

Keep in mind that the same shock settings that may be great at Road Atlanta will not work at Sebring.
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Old 09-11-2011, 02:14 PM
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Thanks Larry....I'll give it a try.
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