JRZ adjustment advise
06-11-2005, 09:17 AM
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JRZ adjustment advise
After watching Norm & Ricks videos I am convinced my set up is way wrong. The car sticks fine. The only issue is the steering wheel, front tires bump steer through the corners, all corners. I have JRZ double adjustables with evo uprights. The front remotes are set on the first - position so I have 14 + remaining. I assumed that I needed to soften the front but - being less I thought I was as soft as it gets. Did I go in the wrong direction? The spring rates are only 600#.
2 years ago I had a issue with the car going into a 4 wheel drift in corners. The cold loaded shock pressure was 130. I dropped it to around 70 and the car sticks great.
What do you think? Just hang on?
Thanks for any advise.
2 years ago I had a issue with the car going into a 4 wheel drift in corners. The cold loaded shock pressure was 130. I dropped it to around 70 and the car sticks great.
What do you think? Just hang on?
Thanks for any advise.
06-11-2005, 02:34 PM
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I just got back from GT Performace who takes care of the car. They walked me through the operation of the two adjustment points and gave me a copy of the maunual. So if anyone, like me, had the shocks but no manual or clue let me know.
06-11-2005, 05:59 PM
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Sure Danny but from now on I wish to be referred to as Mr JRZ (unless I loose this operation manual)
Information provided are quotes:
The JRZ design allows the engineer (thats us I think) to vary the gas pressure from a low of 4 bar to a high of 20 bar...
8 bar is 116 PSI
10 bar is 145 PSI
what the manual does not tell you is to check your pressure with the car on the ground (not jacked) and cold. Immediately after a session I think some expansion will occur depending on the purity of the nitrgen. My "stick" works at 75 psi cold. Now that I have a work sheet to track all three settings I will find the right combo for old yeller. Suspension tune, who would have thought. I see a 2:03:99999 in my future (Watkins Glen next week! )
When I raced at Beaver Run their was a wicked fast BMW M3 that was killing me. He was constantly changing JRZ settings and checking pressure and filling out a log to track the right combo. My wife noticed this and asked me why I am not tweaking my JRZ settings....
Carrol Smith: "The pressure of the nitrogen in the gas chamber is transmitted to the hydraulic fluid in the working chamber as "nose pressure" and delays the start of cavitation. The higher the pressure, the further the beginning of cavitation is delayed. The situation is analogous to that of the pressure cap on the coolant water system- a 15 psi pressure cap will raise the boiling point further than a 7 psi cap."
Information provided are quotes:
The JRZ design allows the engineer (thats us I think) to vary the gas pressure from a low of 4 bar to a high of 20 bar...
8 bar is 116 PSI
10 bar is 145 PSI
what the manual does not tell you is to check your pressure with the car on the ground (not jacked) and cold. Immediately after a session I think some expansion will occur depending on the purity of the nitrgen. My "stick" works at 75 psi cold. Now that I have a work sheet to track all three settings I will find the right combo for old yeller. Suspension tune, who would have thought. I see a 2:03:99999 in my future (Watkins Glen next week! )
When I raced at Beaver Run their was a wicked fast BMW M3 that was killing me. He was constantly changing JRZ settings and checking pressure and filling out a log to track the right combo. My wife noticed this and asked me why I am not tweaking my JRZ settings....
Carrol Smith: "The pressure of the nitrogen in the gas chamber is transmitted to the hydraulic fluid in the working chamber as "nose pressure" and delays the start of cavitation. The higher the pressure, the further the beginning of cavitation is delayed. The situation is analogous to that of the pressure cap on the coolant water system- a 15 psi pressure cap will raise the boiling point further than a 7 psi cap."
06-11-2005, 09:06 PM
#7
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Hi Bill:
Good advice about checking gas pressures. They play a BIG role in how these (JRZ-Moton) shocks work.
Look at http://www.rennsportsystems.com/moton.html to see a chart and how that affects spring rates. Final shock settings are influenced by your gas pressures.
Good advice about checking gas pressures. They play a BIG role in how these (JRZ-Moton) shocks work.
Look at http://www.rennsportsystems.com/moton.html to see a chart and how that affects spring rates. Final shock settings are influenced by your gas pressures.
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06-11-2005, 09:17 PM
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Steve,
Thanks for your professional input as always but where in the hell have you been while us rookies are sliding & sawing our way around the track? ;-)
Your site has some great JRZ info Steve, thanks!
Thanks for your professional input as always but where in the hell have you been while us rookies are sliding & sawing our way around the track? ;-)
Your site has some great JRZ info Steve, thanks!
06-11-2005, 09:32 PM
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My pleasure, sir. 
We install, setup, (and sell) a LOT of Moton/JRZ packages as well as setup a lot of race cars here with comparable systems.
As you know, there are a LOT of variables involved here in configuring, installing, as well as the trackside adjustments to get the potential out of these suspension systems.
We install, setup, (and sell) a LOT of Moton/JRZ packages as well as setup a lot of race cars here with comparable systems.
As you know, there are a LOT of variables involved here in configuring, installing, as well as the trackside adjustments to get the potential out of these suspension systems.
06-11-2005, 09:52 PM
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Penske shocks also has a nice set up guide you can download. http://www.penskeshocks.com/Adjustab...h%20Manual.pdf Start at page 16 for the guide to tuning.
I would start my shocks more towards the middle of their settings. The first few settings have a much larger change than the last ones do. I think your springs rates are kind of low also but from the looks of your videos your car should not require the inputs you are giving her.
I would start my shocks more towards the middle of their settings. The first few settings have a much larger change than the last ones do. I think your springs rates are kind of low also but from the looks of your videos your car should not require the inputs you are giving her.
06-12-2005, 02:30 AM
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Mr JRZ thank you 
Steve thanks as well for the link. How did I miss it on your site? Strange.... One Q for you Sir,
It is correct to assume that varying the gas pressure from front to rear is something to do last or First? For example on an understeering car, after or before you exhausted the sway, shock adjustments, should one proceed to lower the gas pressure in the fronts in order to soften the car? If so in what increments should this be done?
Steve thanks as well for the link. How did I miss it on your site? Strange.... One Q for you Sir,
It is correct to assume that varying the gas pressure from front to rear is something to do last or First? For example on an understeering car, after or before you exhausted the sway, shock adjustments, should one proceed to lower the gas pressure in the fronts in order to soften the car? If so in what increments should this be done?
