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Fast with Class
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Discussion Starter · #1 ·
okay...here's the suspension setup on the car (aka BOOST ALMIGHTY's most current supra):

Suspension:
Tein Super Sport Coilovers
Cusco Rear Strut Bar

Suspension:
Tein Super Sport Coilovers
Cusco Rear Strut Bar

Wheels and Brakes:
CCW SP 500 19x10 front and 19x11 rear
ContiSport Tires 265/35/19 front 295/30/19 rear
Slotted and Drilled Rotors
Hawk Brake Pads


It seems like the car has a good bit of understeer to it in the twisties at only 75mph. I'd like to have it handle as well as possible. What do you guys recommend? Could the 19" rims with the small sidewalls be effecting handling that great? What about maybe putting wider wheels/tires on both front and rear of the car with maybe some better rubber like pirelli pzero's? As far as the coilovers, how close to the stiffest should they be adjusted? And is righty tighty lefty loosey being all the way to the right (tightest) the stiffest setting and all the way to the left (most loose) the softest and non stiff setup?

thanks for any advice! I love going fast in a straight line as much as the next guy...but if a car cant take a turn.....its not nearly as impressive. thanks!!

- Christian
 

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maximizing slip angles
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what are your alignment specs?

If you want a good starting point, start with the lance alignment on MKIV.com.

If you want to dial understeer out of the car, camber in the fronts a little more or get a stiffer rear sway bar...
 

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Also, treadwear aside, it seems like you could get a geat under/oversteer balance from the car by adding a degree of toe out to the rear, on top of the Lance spec.
 

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Old School
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Toe out in the rear for the average driver is not a good idea.
 

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OG
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For me starting with that same problem, what worked was a set of TMS sway bars. YMMV
 

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I'd run Lance's alignment specs, and have the car corner balanced. 19s aren't going to make it understeer any more or less, bu the additional unsprung weight will be noticeable in suspension transitions.

Toe out in the rear for the average driver is not a good idea.
:agreed: Toe out is not something I'd ever run on the street.
 

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For the dampers:

Pretty much all coilover dampers are going to be stiffer if you go clockwise (righty). As far as how stiff you want to make them, that's an art form. For super smooth, dry track on sticky tires you would want them fairly stiff. For wet or rougher roads on street tires, you'll want them a bit softer.

For my cars on the street, I generally start out on full soft and gradually increase the stiffness until I can drive through a crowned intersection at 35mph with the car coming down, then rising up to normal (with maybe a very, very slight 2nd oscillation on a more severe bump). Another test is to do hard braking and see whether the car oscillates when you come to a complete stop. I've found that most coilover owners have their dampers too stiff. They like the super responsive go-kart feeling of stiff dampers without realizing that they're giving up some grip in exchange. Drive smooth & deliberate and you won't miss that responsiveness...

As far as understeer/oversteer: Listen to the guys above on basic alignment starting points. But you can also make some fine adjustments to the balance with the dampers. In general, if you want one end of the car to grip more relative to the other, you soften those dampers. So if your car is still understeering after the alignment, you might back off the front dampers a click or two and see how that worked. Conversely you could stiffen the other end of the car...

You might also play around with tire pressure. Some tires like high pressures, others low -- try 2psi increments in the front and see where you end up. Then try 2 psi increments in the rear. If you're super anal, you could then try 1psi adjustments back on the front, then 1psi adjustments again at the rear...



Another quick note/misconception on understeer: If you drive too fast into a corner, even a well-balanced car will understeer. So try to make coarse handling adjustments under steady-state conditions (skidpad/freeway on-ramp/canyon sweeper). Once you get that dailed in, you can then work on the fine tuning like making the car handle better under specific situations.
 

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About where in PA are you? After you get it aligned/dialed in I'd like to see you bring your car to Pocono for a track day if you're not too far.
 

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I'm guessing stock sway bars? And what are the offsets on the wheels? Changing track widths relative to each other could bias the car in either the under or oversteer direction.

To really know what your problem is you need to be a little more specific. Is it happening mid turn, like you'll be able to turn in, but then the front end washes out? If it's that, it's a spring problem. Or is it at entry, when you go to turn in, the front washes out? Then it's a damper problem. If it's happening at entry, then are you on the brakes and turning or is it going from coasting to turning? Does it happen right away or when steer a certain amount? Or is it at turn exit when you get on the gas? Then it could also be a damper problem, but you would adjust a different end of the car. Or is it driver error, no offense meant, but sometimes it's the driver that's causing this kind of stuff to happen even if they don't realize it. Things that may have worked in another car, may not work in this one. So I would hesitate to make any suggestions on what to change, unless I knew a lot more about the situation.

And like everyone said above, alignment matters, tire pressure matter, etc. There's a lot of things happening at once and they all play a role.

Tim
 

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Or is it driver error, no offense meant, but sometimes it's the driver that's causing this kind of stuff to happen even if they don't realize it. Things that may have worked in another car, may not work in this one. So I would hesitate to make any suggestions on what to change, unless I knew a lot more about the situation.
+1


www.skipbarber.com
 

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Word to that. I think going to Skip Barber is going to be one of my CY08 goals.
If that happens, let me know if its worth the $$$$$$$$
 

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Fast with Class
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Discussion Starter · #13 ·
I've already attended, passed, and got my certification certificate that shows I successfully completed the Skip Barber Driving/Racing school at Lime Rock Park in Connecticut. I'm not the world's most perfect driver, but I dont think this is my error when driving. I'm not too sure of the offset on the rims, i know they came with the car and were already on there. Here's the wheels/tires/brakes setup that is on the car that i know:

Wheels and Brakes:
CCW SP 500 19x10 front and 19x11 rear
ContiSport Tires 265/35/19 front 295/30/19 rear
CCW Classic Drag Package 16x4 front 16x10.5 rear
Slotted and Drilled Rotors
Hawk Brake Pads

What's your recommendation on that setup? Good/bad/indifferent? Should there be a wider tire on both front and rear, if so..what exactly?

The understeer seems to occur as soon as entering the turn and through the turn. About half way through the turn it'll stop when you begin coming out of the turn back onto a straight. The coilovers are setup 4 clicks away from the stiffest setting on all 4 corners. Stock sways bars are still on the car as well. I'll have to get it to a good alignment shop to have that checked out as well...but from visually inspecting the car....looking at it from the rear the rear tires are bowed in a good noticeable bit.

Someone asked how far I am from the pocono's....I'm about an hour's or so drive away from there, and have been there before with other cars. It's an awesome time, total blast to rip around the infield and come back out onto the main stretch and haul ass into the banked turn:agreed:
 

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To be honest the wheels and tires don't concern me. It's the alignment that would concern me.

You can also stiffen the rear dampers relative to the fronts in an attempt to get the rear to rotate first under compression of the damper.
 

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maximizing slip angles
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What's your recommendation on that setup? Good/bad/indifferent? Should there be a wider tire on both front and rear, if so..what exactly?

The understeer seems to occur as soon as entering the turn and through the turn. About half way through the turn it'll stop when you begin coming out of the turn back onto a straight. The coilovers are setup 4 clicks away from the stiffest setting on all 4 corners. Stock sways bars are still on the car as well. I'll have to get it to a good alignment shop to have that checked out as well...but from visually inspecting the car....looking at it from the rear the rear tires are bowed in a good noticeable bit.
:
as quick said the suspension/ brakes/ tire set up sounds great.

i would seriously consider aligning the car. a small note on what you said about the rears being "bowed" in: if you want the car to be more neutral, the fronts have to be about just as much "bowed" in. Like the lance alignment says, I would have at LEAST -1 degree camber in the front.

most guys on here run 315'sR 285'sF on the track.
 

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more negative front camber.

lots more ;)
 

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www.ziptieracing.com
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As well intended as everyone is here, you're never going to get the car fine tuned over the internet. All the things listed above are great recommendations, but there are so many variables, its tough to say what will fix the problem without driving it.

In general, here are the things that will generally get you more oversteer tendancies. None of these can be set in stone rule as they all effect each other. Remember that more oversteer could either mean more front grip, or less rear grip. And oversteer isn't always slower.
1. more rear sway bar
2. less front sway bar
3. Stiffer rear spring/damping (softer front ones)
4. More front camber
5. less toe in the front (and sometimes rear)
6. larger front contact patch
7. more front down force
8. less weight in the trunk
9. more front track or less rear track
10. lower front ride hieght or higher rear
11. change your driving style. less corner entry speed, more throttle steer, drag your left foot on the brake to shift wieght...

plus a good number of others...
 
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