944NA Street / AutoX suspension setup
10-05-2002, 12:14 AM
#1
Burning Brakes
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944NA Street / AutoX suspension setup
What's the final word on the optimal street/autoX suspension (and tire) setup for 944NA?
Pretty set on:
* Koni Sport Yellows front and rear
* Some of those new Yokohama AVS ES100 tire .. yes I'm sticking with 15", I like the nimbleness. I don't feel my NA is powerful enough to push 17's around regardless of how nice they look.
* Some sort of beefier swaybar?
* Strutbrace
* Don't think I want to touch the torsion bars.
The biggest question in my mind is ride height .. should I bother lowering it / going with 250# springs for just street/autox stuff, or is that overkill?
Ride comfort is not really an issue of concern for me. It's a Porsche.
Pretty set on:
* Koni Sport Yellows front and rear
* Some of those new Yokohama AVS ES100 tire .. yes I'm sticking with 15", I like the nimbleness. I don't feel my NA is powerful enough to push 17's around regardless of how nice they look.
* Some sort of beefier swaybar?
* Strutbrace
* Don't think I want to touch the torsion bars.
The biggest question in my mind is ride height .. should I bother lowering it / going with 250# springs for just street/autox stuff, or is that overkill?
Ride comfort is not really an issue of concern for me. It's a Porsche.
10-05-2002, 01:22 AM
#2
Race Director
Well How far/extreme do you want to go??
If you want to stay with stock t-bars then you will be limited to mild suspenstion and what you described is quite good. No experince with those tires although 225/50 R15 is ideal size.
I'd skip the strut brace. With 250lbs springs and Ax duty I don't think it will make difference. I have one on my race car, but I race and run 350 in the front and don't really know if it helps.
If you upgrade t-bars you have many more options.
Remember that 250lbs springs will generate understeer with stock rear tbars. Adjustable sway bars can help to reduce some understeer along with keeping a slightly butt high ride height.
Weight reduction (ie stripped interior) also has the effect of increasing spring rates as well.
Like I said how far do you want to go?
If you want to stay with stock t-bars then you will be limited to mild suspenstion and what you described is quite good. No experince with those tires although 225/50 R15 is ideal size.
I'd skip the strut brace. With 250lbs springs and Ax duty I don't think it will make difference. I have one on my race car, but I race and run 350 in the front and don't really know if it helps.
If you upgrade t-bars you have many more options.
Remember that 250lbs springs will generate understeer with stock rear tbars. Adjustable sway bars can help to reduce some understeer along with keeping a slightly butt high ride height.
Weight reduction (ie stripped interior) also has the effect of increasing spring rates as well.
Like I said how far do you want to go?
10-05-2002, 03:22 AM
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Burning Brakes
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I hear torsion bar stuff is a real PITA .. which is why I mentioned avoiding that for now.
What I'm is "Phase I" basically .. because currently I have lame tires and shocks that are truly worthless (they might even be the originals (!) ..)
Weight reduction and different torsion bars, etc. will come later. . Phase II perhaps.
As far as sway bars in this setup, do you recommend the Weltmeister, 968 M030, or ..?
I enjoy a very "responsive" sort of feel.
What I'm is "Phase I" basically .. because currently I have lame tires and shocks that are truly worthless (they might even be the originals (!) ..)
Weight reduction and different torsion bars, etc. will come later. . Phase II perhaps.
As far as sway bars in this setup, do you recommend the Weltmeister, 968 M030, or ..?
I enjoy a very "responsive" sort of feel.
10-05-2002, 11:18 AM
#4
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IMO -
Lowering the car will help, even if you just lower the rear to equal the stock front ride height.
Strut brace - I think your money can be better spent elsewhere. I highly doubt you will feel any difference or measure and reduction in times. Maybe the opposite, given where the weight of a strut brace is concentrated.
Your limits of your stock car's cornering are pretty much defined by understeer, particularly around the apex of tight autocross turns. Going with 250# springs without stiffening the rear will reduce body roll, but will greatly increase the understeer at the limit and you will probably be slower as a result. (That was certainly the case for my car on the track). Wait on the 250's until you're ready to change the torsion bars or install rear coilovers. And a stiff rear swaybar isn't a very good fix for overly stiff front springs.
Koni yellows will be a plus. Start with them adjusted full soft, they will probably be plenty stiff at that setting for stock springs/torsion bars. Adjusting them too stiff will hurt the handling.
I think good swaybars are the way to go, they'll make a big difference particularly if one or both is adjustable - contact Paragon about some Weltmeisters or the M030/968 (?) bars with the adjustable rear. I use the Welts (with a ton of other suspension mods) and they have worked out well, though a lot of folks like the factory bars.
'Course the very best place to put your money is in entry fees for driving events and toward the tires you'll use up there. There's almost always a whole lot more lap time advantage (and more fun) to be had from improving the driver than from improving the car -
Matt
Lowering the car will help, even if you just lower the rear to equal the stock front ride height.
Strut brace - I think your money can be better spent elsewhere. I highly doubt you will feel any difference or measure and reduction in times. Maybe the opposite, given where the weight of a strut brace is concentrated.
Your limits of your stock car's cornering are pretty much defined by understeer, particularly around the apex of tight autocross turns. Going with 250# springs without stiffening the rear will reduce body roll, but will greatly increase the understeer at the limit and you will probably be slower as a result. (That was certainly the case for my car on the track). Wait on the 250's until you're ready to change the torsion bars or install rear coilovers. And a stiff rear swaybar isn't a very good fix for overly stiff front springs.
Koni yellows will be a plus. Start with them adjusted full soft, they will probably be plenty stiff at that setting for stock springs/torsion bars. Adjusting them too stiff will hurt the handling.
I think good swaybars are the way to go, they'll make a big difference particularly if one or both is adjustable - contact Paragon about some Weltmeisters or the M030/968 (?) bars with the adjustable rear. I use the Welts (with a ton of other suspension mods) and they have worked out well, though a lot of folks like the factory bars.
'Course the very best place to put your money is in entry fees for driving events and toward the tires you'll use up there. There's almost always a whole lot more lap time advantage (and more fun) to be had from improving the driver than from improving the car -
Matt
10-05-2002, 01:06 PM
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Burning Brakes
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Definitely 
Regarding lowering the rear to match the front - how does one measure this?
I know it's done via an eccentric or something back there, but is there a certain measured amount to turn it that will make the front and back about even?
Regarding lowering the rear to match the front - how does one measure this?
I know it's done via an eccentric or something back there, but is there a certain measured amount to turn it that will make the front and back about even?
10-05-2002, 01:39 PM
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schlag,
Have a look at <a href="http://www.tech-session.com/Paragon/Tech/944_tbar_main.htm" target="_blank">this</a>. There is a section on rear ride height adjustment, and another section on ride height measurment.
Have a look at <a href="http://www.tech-session.com/Paragon/Tech/944_tbar_main.htm" target="_blank">this</a>. There is a section on rear ride height adjustment, and another section on ride height measurment.
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10-05-2002, 11:28 PM
#8
Race Director
As mentioned above, forget about the strut brace: it doesn't really help much, and gets in the way of working on the engine.
As far as sway bars go: I kept my front bar stock, and upgraded to the 968 M030 rear sway: 19mm 3-way adjustable. I started in the medium setting, now I'm full firm on it. Helps get the rear to step out a little.
If you upgrade your front sway to a thicker bar, it will increase your car's tendency to understeer, which won't help you around the cones!
Are you just starting out autocrossing? If so, then all the other suspension mods you suggest may be a little too much too early.
I suggest you do the following, if you have less then 3 years autocross experience:
1. Get the rear 968 M030 sway bar, set to medium, or full firm.
2. Have your camber adjusted to about -1 degree all around. It will help your cornering.
3. Crank up your tire pressures (I run 40psi front, 38psi rear COLD.)
I think some of your plans (different shocks, torsion bars, lowering your car) will knock you out of stock classes. Again, if you're just starting to get into autox, you may want to wait for that stuff, and continue to play in stock classes. Check with your local club.
Hope this helps,
-Zoltan.
As far as sway bars go: I kept my front bar stock, and upgraded to the 968 M030 rear sway: 19mm 3-way adjustable. I started in the medium setting, now I'm full firm on it. Helps get the rear to step out a little.
If you upgrade your front sway to a thicker bar, it will increase your car's tendency to understeer, which won't help you around the cones!
Are you just starting out autocrossing? If so, then all the other suspension mods you suggest may be a little too much too early.
I suggest you do the following, if you have less then 3 years autocross experience:
1. Get the rear 968 M030 sway bar, set to medium, or full firm.
2. Have your camber adjusted to about -1 degree all around. It will help your cornering.
3. Crank up your tire pressures (I run 40psi front, 38psi rear COLD.)
I think some of your plans (different shocks, torsion bars, lowering your car) will knock you out of stock classes. Again, if you're just starting to get into autox, you may want to wait for that stuff, and continue to play in stock classes. Check with your local club.
Hope this helps,
-Zoltan.
10-06-2002, 05:11 PM
#9
Burning Brakes
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Yep .. brand new to autox actually :>
I have a few questions though ..
1] Do you run 40 front/38 rear all the time or just for autox purposes?
2] What is the effect of having camber adjusted
-1?
As far as classification, I'll be playing up in the NNJR PCA region next season .. as far as I know for stock class they allow shock modification, bigger sways, but NOT tuffer springs. I'll wait on the springs, anyway.
I have a few questions though ..
1] Do you run 40 front/38 rear all the time or just for autox purposes?
2] What is the effect of having camber adjusted
-1?
As far as classification, I'll be playing up in the NNJR PCA region next season .. as far as I know for stock class they allow shock modification, bigger sways, but NOT tuffer springs. I'll wait on the springs, anyway.
10-06-2002, 11:03 PM
#10
Race Car
[quote]Originally posted by schlag:
<strong>Yep .. brand new to autox actually :>
I have a few questions though ..
1] Do you run 40 front/38 rear all the time or just for autox purposes?
2] What is the effect of having camber adjusted
-1?
As far as classification, I'll be playing up in the NNJR PCA region next season .. as far as I know for stock class they allow shock modification, bigger sways, but NOT tuffer springs. I'll wait on the springs, anyway.</strong><hr></blockquote>
Uh-Oh Zoltan, he's one of us! (I'll rant about the fact that only 4 NNJR members went to the Zone 1 AX later)
Schlag, You are correct on the rules. Here's my basic rule of thumb for starting out. "Run what you have". Until you have a few events under your belt the biggest variable is you, after a couple seasons the biggest variable will still be you but You will be able to put more of what the car has to good use. If your shocks are gone, replace them, get something decent (yellows are very decent) but don't worry about replacing parts just for the sake of what you might need down the road. As Matt said, spend the cash on the events, improving the driver is the best investment.
I'm pretty sure Z-man (like the rest of us) lowers his tire preasure at the end of the event, the turnpike isn't a good place for that much pressure and at highway speeds the tire will heat up increasing it further. I usually run ~36 psi at an event and 32 psi on the street, different tires react differently.
BTW, I ran my rookie season on fairly worn, stock rear shocks, stock struts, the stock (21mm ?) front bar and no rear bar. It didn't keep me from taking first for the season (points), and after that I rewarded myself with $100 worth of used 951 swaybars.
<strong>Yep .. brand new to autox actually :>
I have a few questions though ..
1] Do you run 40 front/38 rear all the time or just for autox purposes?
2] What is the effect of having camber adjusted
-1?
As far as classification, I'll be playing up in the NNJR PCA region next season .. as far as I know for stock class they allow shock modification, bigger sways, but NOT tuffer springs. I'll wait on the springs, anyway.</strong><hr></blockquote>
Uh-Oh Zoltan, he's one of us! (I'll rant about the fact that only 4 NNJR members went to the Zone 1 AX later)
Schlag, You are correct on the rules. Here's my basic rule of thumb for starting out. "Run what you have". Until you have a few events under your belt the biggest variable is you, after a couple seasons the biggest variable will still be you but You will be able to put more of what the car has to good use. If your shocks are gone, replace them, get something decent (yellows are very decent) but don't worry about replacing parts just for the sake of what you might need down the road. As Matt said, spend the cash on the events, improving the driver is the best investment.
I'm pretty sure Z-man (like the rest of us) lowers his tire preasure at the end of the event, the turnpike isn't a good place for that much pressure and at highway speeds the tire will heat up increasing it further. I usually run ~36 psi at an event and 32 psi on the street, different tires react differently.
BTW, I ran my rookie season on fairly worn, stock rear shocks, stock struts, the stock (21mm ?) front bar and no rear bar. It didn't keep me from taking first for the season (points), and after that I rewarded myself with $100 worth of used 951 swaybars.
10-07-2002, 02:48 AM
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Burning Brakes
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LOL .. the focus for sure is on the driver, and increasing his (my) abilities.
And you're right. Regarding the car, come next April (or whenever it starts next year), I'll run with whatever I have regardless of if it's optimal or not. Need some experience. Looking forward to it.
And you're right. Regarding the car, come next April (or whenever it starts next year), I'll run with whatever I have regardless of if it's optimal or not. Need some experience. Looking forward to it.
10-07-2002, 11:33 AM
#12
Race Director
[quote]Originally posted by Matt:
<strong>IMO -
Lowering the car will help, even if you just lower the rear to equal the stock front ride height.
[snip]
'Course the very best place to put your money is in entry fees for driving events and toward the tires you'll use up there. There's almost always a whole lot more lap time advantage (and more fun) to be had from improving the driver than from improving the car -
Matt</strong><hr></blockquote>
I agree about upgrading the driver first!!
For those considering modification however..
Don't lower the car too MUCH......
I have learned that you can adjust over/understeer balance by adjusting rear ride height. If you have a basic understeer set-up like 250lbs with stock rear bars you will want the back end just a bit higher this will induce just a bit of oversteer. Too low and it will push like a mother... Believe this comes from personal experinece. Currently I run 350# front & 28 mm rear (effective 254#) and it handles great... but the back end of my car higher than everyone else in 944-spec with a slight butt high stance. On the other hand my stock 944 turbo S has the rear spring plates lowered all the way... Its much lower than my race car and butt-down... It has too much understeer..
So what is the ideal rear ride height... Dunno...Depends on you set-up and driving perference..
Also
<strong>IMO -
Lowering the car will help, even if you just lower the rear to equal the stock front ride height.
[snip]
'Course the very best place to put your money is in entry fees for driving events and toward the tires you'll use up there. There's almost always a whole lot more lap time advantage (and more fun) to be had from improving the driver than from improving the car -
Matt</strong><hr></blockquote>
I agree about upgrading the driver first!!
For those considering modification however..
Don't lower the car too MUCH......
I have learned that you can adjust over/understeer balance by adjusting rear ride height. If you have a basic understeer set-up like 250lbs with stock rear bars you will want the back end just a bit higher this will induce just a bit of oversteer. Too low and it will push like a mother... Believe this comes from personal experinece. Currently I run 350# front & 28 mm rear (effective 254#) and it handles great... but the back end of my car higher than everyone else in 944-spec with a slight butt high stance. On the other hand my stock 944 turbo S has the rear spring plates lowered all the way... Its much lower than my race car and butt-down... It has too much understeer..
So what is the ideal rear ride height... Dunno...Depends on you set-up and driving perference..
Also
10-07-2002, 11:48 AM
#13
Race Director
[quote]Originally posted by schlag:
<strong>I hear torsion bar stuff is a real PITA .. which is why I mentioned avoiding that for now.
</strong><hr></blockquote>
OK... about Torsion bars.... They are a pain, but not that bad. The hardest part is proper indexing. All to often people don't know how to index these right (where to set-them) and then they have to do the entire job again. If you don't know what angle to set the bars at you will not do the job right and then need to use trial and error to get there. This where people don't do it right and then do the job 2 -3 times. It does not have to be that way.
Use Pargon's steps for removal & how to indexing (ie how to get it to a certain angle)
<a href="http://www.tech-session.com/Paragon/Tech/944_tbar_main.htm" target="_blank">Paragon Products- Tech Session - Torsion Bar Info</a>
There is PCA website/progam to calcuate the height (torsion bar angle) you need for any given 944 car weight and torsion bar size from and to and you can dial in any ride height change you may want. All you need is a tape measure, Microsoft Excel and some patience.
<a href="http://www.pca.org/az/tech/articles/upgrade_your_944_torsion_bar.htm" target="_blank">PCA Arizona Region - Tech Article for Proper T-bar Indexing</a>
DON'T BE AFRAID OF THE TORSION BARS!!!!!
<strong>I hear torsion bar stuff is a real PITA .. which is why I mentioned avoiding that for now.
</strong><hr></blockquote>
OK... about Torsion bars.... They are a pain, but not that bad. The hardest part is proper indexing. All to often people don't know how to index these right (where to set-them) and then they have to do the entire job again. If you don't know what angle to set the bars at you will not do the job right and then need to use trial and error to get there. This where people don't do it right and then do the job 2 -3 times. It does not have to be that way.
Use Pargon's steps for removal & how to indexing (ie how to get it to a certain angle)
<a href="http://www.tech-session.com/Paragon/Tech/944_tbar_main.htm" target="_blank">Paragon Products- Tech Session - Torsion Bar Info</a>
There is PCA website/progam to calcuate the height (torsion bar angle) you need for any given 944 car weight and torsion bar size from and to and you can dial in any ride height change you may want. All you need is a tape measure, Microsoft Excel and some patience.
<a href="http://www.pca.org/az/tech/articles/upgrade_your_944_torsion_bar.htm" target="_blank">PCA Arizona Region - Tech Article for Proper T-bar Indexing</a>
DON'T BE AFRAID OF THE TORSION BARS!!!!!
10-07-2002, 12:02 PM
#14
Race Director
[quote]Originally posted by schlag:
<strong>Yep .. brand new to autox actually :>
I have a few questions though ..
1] Do you run 40 front/38 rear all the time or just for autox purposes?
2] What is the effect of having camber adjusted
-1?
</strong><hr></blockquote>
Ok... Tire pressure.... you need to run high on street tires to make sure they don't roll over on you and to give firmer response. Honestly if you a are new don't worry to much. Ideal pressure change with car weight tire brand and track conditions,etc. Also tire pressure change during the day. Lower in the morning higher in the afternoon. It is big hassle, Those pressure are good enough for now.
Ahh, Negative camber.. What this does is leans the top the tire inward so that went the car leans in the corner it will tend to allow the tire to make full and even contact with the ground. On the Ax more negative is what you want in the front. I run 3.5 neg. Problem is that this really bad on the street since in a straight line you just running in the inside shoulder of the tire and therefore wear this down FAST. My car is track only so it does not matter, but it still happens even to me. (I think I am running too MUCH).
Basicly 1 negative is a good compromise for street and track/ax set-up. Too little and you'll be slower and wear down the outside of the tire. Too much and you kill the inside on the street. For the rear too much even on the track can cause the inside rear wheel to spin during power applicaton in a corner.
<strong>Yep .. brand new to autox actually :>
I have a few questions though ..
1] Do you run 40 front/38 rear all the time or just for autox purposes?
2] What is the effect of having camber adjusted
-1?
</strong><hr></blockquote>
Ok... Tire pressure.... you need to run high on street tires to make sure they don't roll over on you and to give firmer response. Honestly if you a are new don't worry to much. Ideal pressure change with car weight tire brand and track conditions,etc. Also tire pressure change during the day. Lower in the morning higher in the afternoon. It is big hassle, Those pressure are good enough for now.
Ahh, Negative camber.. What this does is leans the top the tire inward so that went the car leans in the corner it will tend to allow the tire to make full and even contact with the ground. On the Ax more negative is what you want in the front. I run 3.5 neg. Problem is that this really bad on the street since in a straight line you just running in the inside shoulder of the tire and therefore wear this down FAST. My car is track only so it does not matter, but it still happens even to me. (I think I am running too MUCH).
Basicly 1 negative is a good compromise for street and track/ax set-up. Too little and you'll be slower and wear down the outside of the tire. Too much and you kill the inside on the street. For the rear too much even on the track can cause the inside rear wheel to spin during power applicaton in a corner.