Experience with JRZ RS suspension on a GT3
07-29-2010, 11:41 AM
#16
Rennlist Member
best springs rates are dark voodoo. i have investigated a lot prior to surrendering to my builder`s opinion. i think 600lbs/800lbs rule came from 993 days and is not very relevant for 997 cars, not to mention significant weight diff between, say, gt3 and c4s cars, for an example. 200lbs split is not a 'given' rule at all. my builder never uses split more than a 100lbs from front to rear.
I know TPC suggests using 900/900lbs springs for 997. cup cars go way over 1200lbs. go figure.
all i can say on this topic - 600/700lbs springs on my car that weights 3390lbs (me included) feels great on a street and is adjustable very well to be reasonably stiff.
I know TPC suggests using 900/900lbs springs for 997. cup cars go way over 1200lbs. go figure.
all i can say on this topic - 600/700lbs springs on my car that weights 3390lbs (me included) feels great on a street and is adjustable very well to be reasonably stiff.
even if I had a one, two or three way adjustable suspension system I am not sure that I have the understanding to set it up, or discern the impact of such changes ...
I guess this is why I like PASM since Porsche have done this for me! I do wonder about the Bilstein "damptronics" ...
07-29-2010, 11:54 AM
#17
Rennlist Member
that's part of the problem for me, the whole art of suspension tuning is a specialist "black art" matching the spring and shock rates to the car and the track requires an expert ...
even if I had a one, two or three way adjustable suspension system I am not sure that I have the understanding to set it up, or discern the impact of such changes ...
I guess this is why I like PASM since Porsche have done this for me! I do wonder about the Bilstein "damptronics" ...
even if I had a one, two or three way adjustable suspension system I am not sure that I have the understanding to set it up, or discern the impact of such changes ...
I guess this is why I like PASM since Porsche have done this for me! I do wonder about the Bilstein "damptronics" ...
i did not have PASM in my car. stock C2 suspension was way too soft for competitive driving, it was ruining my hoosiers. stock PASM is a bit better but not by far.
i have heard that putting GMG sways helps good deal for PASM cars in stiff setting.
problem with damptronics again is that they are street shocks and they come with softer than needed springs and you cannot simply replace their springs to 600/800lbs per se as internal valving in shocks is not matched so you need to ship them in for re-valving and WHEN you summ up all the costs to get those bilsteins rebuld, re-valved and ne springs ordered it is cheaper to get brand new JRZ RS - and that was exactly what I did.
07-29-2010, 11:57 AM
#18
Rennlist Member
well...
i did not have PASM in my car. stock C2 suspension was way too soft for competitive driving, it was ruining my hoosiers. stock PASM is a bit better but not by far.
i have heard that putting GMG sways helps good deal for PASM cars in stiff setting.
problem with damptronics again is that they are street shocks and they come with softer than needed springs and you cannot simply replace their springs to 600/800lbs per se as internal valving in shocks is not matched so you need to ship them in for re-valving and WHEN you summ up all the costs to get those bilsteins rebuld, re-valved and ne springs ordered it is cheaper to get brand new JRZ RS - and that was exactly what I did.
i did not have PASM in my car. stock C2 suspension was way too soft for competitive driving, it was ruining my hoosiers. stock PASM is a bit better but not by far.
i have heard that putting GMG sways helps good deal for PASM cars in stiff setting.
problem with damptronics again is that they are street shocks and they come with softer than needed springs and you cannot simply replace their springs to 600/800lbs per se as internal valving in shocks is not matched so you need to ship them in for re-valving and WHEN you summ up all the costs to get those bilsteins rebuld, re-valved and ne springs ordered it is cheaper to get brand new JRZ RS - and that was exactly what I did.
07-29-2010, 12:07 PM
#19
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07-29-2010, 04:55 PM
#20
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My plan is to have Orbit in West Palm Beach start experimenting with my spring rates while leaving the the stock PASM shocks in place. Springs are cheap, but installation, allignment, etc etc is going to drive up the cost a little. I would love to try the Bilstein B16 or whatever they are. Roger/Orbit stated that he would machine some hats and then we could just swap springs until we found the right combo.
07-29-2010, 05:39 PM
#21
Rennlist Member
My plan is to have Orbit in West Palm Beach start experimenting with my spring rates while leaving the the stock PASM shocks in place. Springs are cheap, but installation, allignment, etc etc is going to drive up the cost a little. I would love to try the Bilstein B16 or whatever they are. Roger/Orbit stated that he would machine some hats and then we could just swap springs until we found the right combo.
I dont even know if this is possible with PASM to adjust this over and above what the system does in the various modes ... I am a little "suspicious" that these guys have not mentioned this to you ...
07-29-2010, 05:45 PM
#22
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This might have been mentioned but you should decide on what tire you will run on. Each tire has its own effective spring rate (street, rcomp, slick). Picking spring rates without considering this is probably unwise. For example, CUP cars run very stiff as they are all on slicks.
07-29-2010, 05:48 PM
#23
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Utkinpol, I got notice that you replied to my post, but it's not here. Not sure if you deleted, or that there is something else happening.
Larry, I understand what you mean, but I think one of the main reasons why Roger want to try it is because of the progressive springs in the rear instead of linear. I think Rad has mentioned this before also. I know TPC also installs a different spring package on the stock shocks. As a side note, Roger is not happy having to do this with my preferred tires (RA1's) since the side walls are wayyy too soft in compared to Michelin slicks. So at one point, the tire is going to be limiting factor in the suspension, not because of grip, but because of the soft sidewalls
Larry, I understand what you mean, but I think one of the main reasons why Roger want to try it is because of the progressive springs in the rear instead of linear. I think Rad has mentioned this before also. I know TPC also installs a different spring package on the stock shocks. As a side note, Roger is not happy having to do this with my preferred tires (RA1's) since the side walls are wayyy too soft in compared to Michelin slicks. So at one point, the tire is going to be limiting factor in the suspension, not because of grip, but because of the soft sidewalls
07-29-2010, 05:51 PM
#25
Rennlist Member
Utkinpol, I got notice that you replied to my post, but it's not here. Not sure if you deleted, or that there is something else happening.
Larry, I understand what you mean, but I think one of the main reasons why Roger want to try it is because of the progressive springs in the rear instead of linear. I think Rad has mentioned this before also. I know TPC also installs a different spring package on the stock shocks. As a side note, Roger is not happy having to do this with my preferred tires (RA1's) since the side walls are wayyy too soft in compared to Michelin slicks. So at one point, the tire is going to be limiting factor in the suspension, not because of grip, but because of the soft sidewalls
Larry, I understand what you mean, but I think one of the main reasons why Roger want to try it is because of the progressive springs in the rear instead of linear. I think Rad has mentioned this before also. I know TPC also installs a different spring package on the stock shocks. As a side note, Roger is not happy having to do this with my preferred tires (RA1's) since the side walls are wayyy too soft in compared to Michelin slicks. So at one point, the tire is going to be limiting factor in the suspension, not because of grip, but because of the soft sidewalls
it might be worth starting with the .2 (RS) sways and springs?
07-29-2010, 05:52 PM
#26
Rennlist Member
p.s
I should probably point out that I dont (really) have a clue what I am talking about!
I should probably point out that I dont (really) have a clue what I am talking about!
07-29-2010, 06:27 PM
#28
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Larry that makes 2 of us.
Believe me, Roger had Peters (trakcar) car for week while he was "working" in europe this month and studied the suspension pickup points etc to see where they differ from the current cupcar and the rs1
Its a challenge for him to make the rs1 as fast as the 2
Believe me, Roger had Peters (trakcar) car for week while he was "working" in europe this month and studied the suspension pickup points etc to see where they differ from the current cupcar and the rs1
Its a challenge for him to make the rs1 as fast as the 2
07-29-2010, 06:27 PM
#29
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Larry that makes 2 of us.
Believe me, Roger had Peters (trakcar) car for week while he was "working" in europe this month and studied the suspension pickup points etc to see where they differ from the current cupcar and the rs1
Its a challenge for him to make the rs1 as fast as the 2
Believe me, Roger had Peters (trakcar) car for week while he was "working" in europe this month and studied the suspension pickup points etc to see where they differ from the current cupcar and the rs1
Its a challenge for him to make the rs1 as fast as the 2
07-29-2010, 06:40 PM
#30
Burning Brakes
I don't really agree that there is any black art to tuning suspension. I think it requires experience in the car and having your driving skill to a point where you can assess feedback from the car at it's limits without having to worry so much about keeping it on the track. Skilled and experienced drivers go through tracks on autopilot. I can only speak for myself, but I can't do that yet.
Once you have the ability to accurately 'report' results without scientific tools (shaker machine) it's easy to tune the car. First and foremost, get the ride height, corner balance, and alignment correct. There's a lot of information out there about good baseline setups. Contact the manufacturer of the tires you'll be running and get baselines for camber and pressure settings. Start there.
Unless you plan on changing springs on a regular basis, stick with something like Utkinpol suggested. Anything stiffer than your OEM springs will be good. Stiffer springs stick better on the track but let go more suddenly at the limit and are near impossible to live with on city streets.
Tuning sway bars would usually come next and because there are only three/four adjustments (some might argue you can mix and match but it's probably beyond the scope of this commentary). One hole at a time is good advice here. Look for a neutral mid corner feeling with a wee bit of understeer under power is what was suggested to me.
For adjusting the shocks, it's all about physics and your ability to observe them. Penske had a great 'How To' on tuning multi way adjustable units:
http://www.penskeshocks.co.uk/downlo...TechManual.pdf
Buy a pyrometer and use it religiously every time you put new tires on or change the setup.
Keep a notebook of your findings and settings.
Don't change too much at once. Small changes are best.
Don't become too overwhelmed with it all.
Buy a good book on the subject if you're okay with tech speak.
If you use a known good setup guy, I wouldn't worry too much about alignment settings unless your pyrometer sets off some red flags. Everybody needs to remember that a setup is only as good as it is matched to the driver. Different styles need different setups.
On the original topic, the JRZ RS is a great shock but if I owned a GT3 I'd probably opt for the true monotube shock. Truth be told, it costs big bucks to better the boys at the factory. I have a C2 and the JRZ was a huge upgrade from the OEM stuff but the GT3 will be hard to beat without getting into a true monotube.
Once you have the ability to accurately 'report' results without scientific tools (shaker machine) it's easy to tune the car. First and foremost, get the ride height, corner balance, and alignment correct. There's a lot of information out there about good baseline setups. Contact the manufacturer of the tires you'll be running and get baselines for camber and pressure settings. Start there.
Unless you plan on changing springs on a regular basis, stick with something like Utkinpol suggested. Anything stiffer than your OEM springs will be good. Stiffer springs stick better on the track but let go more suddenly at the limit and are near impossible to live with on city streets.
Tuning sway bars would usually come next and because there are only three/four adjustments (some might argue you can mix and match but it's probably beyond the scope of this commentary). One hole at a time is good advice here. Look for a neutral mid corner feeling with a wee bit of understeer under power is what was suggested to me.
For adjusting the shocks, it's all about physics and your ability to observe them. Penske had a great 'How To' on tuning multi way adjustable units:
http://www.penskeshocks.co.uk/downlo...TechManual.pdf
Buy a pyrometer and use it religiously every time you put new tires on or change the setup.
Keep a notebook of your findings and settings.
Don't change too much at once. Small changes are best.
Don't become too overwhelmed with it all.
Buy a good book on the subject if you're okay with tech speak.
If you use a known good setup guy, I wouldn't worry too much about alignment settings unless your pyrometer sets off some red flags. Everybody needs to remember that a setup is only as good as it is matched to the driver. Different styles need different setups.
On the original topic, the JRZ RS is a great shock but if I owned a GT3 I'd probably opt for the true monotube shock. Truth be told, it costs big bucks to better the boys at the factory. I have a C2 and the JRZ was a huge upgrade from the OEM stuff but the GT3 will be hard to beat without getting into a true monotube.