Suspension gurus. Need advice on setup.

[AdRock]

Originally Posted By: BuickGN
Originally Posted By: AdRock
Personally I find it much easier to control oversteer than understeer. If you want some brakes that will not fade hardly at all throw some cryo treated rotors and some of the Hawk racing pads on when you switch to the wilwood setup.

As far as the tires go, I've got some friends that do road track days & autocross and they've been happy with the new Nitto NT01 that came out recently.

If you want something for daily driving I've talked to people that seem to like the NT05 street tire. I've been thinking about trying some of those out myself.


I looked at those Nittos and I'm so glad I did. Even the street version looks very aggressive and it looks like it would be fairly quiet too. I'm not one to consider looks at all when buying tires but those things are pretty. On top of that, they're cheap.

Besides the obvious wear, is there any problem with running the race tires as a daily tire such as heat buildup on freeway trips?

The car is handling awesome. I went one step firmer on the rear bar and there's a hint of understeer at the limit but it's not bad at all. I'm very impressed with the difference in handling with a minimal change in comfort. Now I'm trying to wear these BFGs out so I don't feel guilty for buying the Nittos with half the tread left on my old tires.


I wouldn't put the competition Nitto's on a daily driver. In the heat and dry they would be great on the road. However, for rain they can be a REAL handful and cause you to almost shat your pants if you're not careful. Also, on the competitions the treadwear isn't great. Driving them everyday would wear them out quick.

So, since you daily drive the car go with the street Nittos. They still have a 200 treadwear rating so they're on the soft end of a street tire. They'll last longer than the competitions but will be better for year round street use.

One other thing. Go take a look at the Nitto's and compare the width to the width of the BFG's you have now. I'n the Mustang world I'm in a lot of guys, including myself, are running 315035-17's on the back. Nittos run narrower than most other tires of the same size. Nobody seeems to know why, but they do. A BFG KDW 285/40/17 is just as wide as a Nitto 315/35/17. So if you do buy the Nitto's you might think about going up a notch or two in tire width to get the same contact patch you have with the BFG's now.

 

[BuickGN]

Originally Posted By: AdRock
Originally Posted By: BuickGN
Originally Posted By: AdRock
Personally I find it much easier to control oversteer than understeer. If you want some brakes that will not fade hardly at all throw some cryo treated rotors and some of the Hawk racing pads on when you switch to the wilwood setup.

As far as the tires go, I've got some friends that do road track days & autocross and they've been happy with the new Nitto NT01 that came out recently.

If you want something for daily driving I've talked to people that seem to like the NT05 street tire. I've been thinking about trying some of those out myself.


I looked at those Nittos and I'm so glad I did. Even the street version looks very aggressive and it looks like it would be fairly quiet too. I'm not one to consider looks at all when buying tires but those things are pretty. On top of that, they're cheap.

Besides the obvious wear, is there any problem with running the race tires as a daily tire such as heat buildup on freeway trips?

The car is handling awesome. I went one step firmer on the rear bar and there's a hint of understeer at the limit but it's not bad at all. I'm very impressed with the difference in handling with a minimal change in comfort. Now I'm trying to wear these BFGs out so I don't feel guilty for buying the Nittos with half the tread left on my old tires.


I wouldn't put the competition Nitto's on a daily driver. In the heat and dry they would be great on the road. However, for rain they can be a REAL handful and cause you to almost shat your pants if you're not careful. Also, on the competitions the treadwear isn't great. Driving them everyday would wear them out quick.

So, since you daily drive the car go with the street Nittos. They still have a 200 treadwear rating so they're on the soft end of a street tire. They'll last longer than the competitions but will be better for year round street use.

One other thing. Go take a look at the Nitto's and compare the width to the width of the BFG's you have now. I'n the Mustang world I'm in a lot of guys, including myself, are running 315035-17's on the back. Nittos run narrower than most other tires of the same size. Nobody seeems to know why, but they do. A BFG KDW 285/40/17 is just as wide as a Nitto 315/35/17. So if you do buy the Nitto's you might think about going up a notch or two in tire width to get the same contact patch you have with the BFG's now.


That's great info to know on tire ordering. I'm running 255/40/17 on stock rims. They're about 1/4" shorter than the stock 235/45 tires.

So is the overal width a little narrow or just the tread width? The reason I'm asking is because I'm already pusing the limits with a 255 on an 8" rim. I have no problem going with a 265/40, that would take me back to the original diameter.

 

[tdi-rick]

Is this thing FWD ? (we don't get Buick's here)

If so, the general rule of thumb for front wheel drive is as soft as you can on the front for front end bite and traction (run the front bar at full soft initially, a driven wheel in the air will not drive you forward

) and keep stiffening up the rear bar for balance.

At the track everything will feel different.
What can feel nice on the open road will feel like a wallowy, unresponsive pig at the track.

Anti-roll bars are load transfer devices, they transfer load laterally from the inside to the outside tyre, but also longitudinally, to the diagonally opposite tyre.

Also try some extra toe out at the front too when at the tack, it will help turn-in response.

As the dampers are rebound adjustable only, and Koni Yellows at that, maybe set both in the middle initially and adjust if necessary from there, maybe have the front set a little softer to full soft. You want the front end to roll into the corner and take a set early, particularly on a FWD car, but this holds true for almost any car.
The rebound on a Koni mainly affects the low speed circuit by closing the bleed (yes, it also pre-loads the rebound spring too) which affects the rate (speed) of roll (transient)
Where you may have to start increasing rebound is corner exit when you get on the throttle, increasing rebound may reduce corner exit understeer if it starts to become a problem by reducing the rate of lateral load transfer. By reducing the rate at which the load transfers to the rear you can help traction/drive at that critical point.

Damper adjusting is really only for the experienced at the track, and if this is your first time, you will experience sensory overload anyway, so adjustments to the car will be meaningless.
With fully adjustable shocks and a proper test day you start with bump and rebound at full soft and start adjusting bump until the car starts to hop (or goes slower) then back off a click or so, then start working on the rebound.

Basic rule of thumb is that bump controls the wheels (unsprung weight) rebound controls the chassis.

Confused yet

 

[BuickGN]

Originally Posted By: tdi-rick
Is this thing FWD ? (we don't get Buick's here)

If so, the general rule of thumb for front wheel drive is as soft as you can on the front for front end bite and traction (run the front bar at full soft initially, a driven wheel in the air will not drive you forward

) and keep stiffening up the rear bar for balance.

At the track everything will feel different.
What can feel nice on the open road will feel like a wallowy, unresponsive pig at the track.

Anti-roll bars are load transfer devices, they transfer load laterally from the inside to the outside tyre, but also longitudinally, to the diagonally opposite tyre.

Also try some extra toe out at the front too when at the tack, it will help turn-in response.

As the dampers are rebound adjustable only, and Koni Yellows at that, maybe set both in the middle initially and adjust if necessary from there, maybe have the front set a little softer to full soft. You want the front end to roll into the corner and take a set early, particularly on a FWD car, but this holds true for almost any car.
The rebound on a Koni mainly affects the low speed circuit by closing the bleed (yes, it also pre-loads the rebound spring too) which affects the rate (speed) of roll (transient)
Where you may have to start increasing rebound is corner exit when you get on the throttle, increasing rebound may reduce corner exit understeer if it starts to become a problem by reducing the rate of lateral load transfer. By reducing the rate at which the load transfers to the rear you can help traction/drive at that critical point.

Damper adjusting is really only for the experienced at the track, and if this is your first time, you will experience sensory overload anyway, so adjustments to the car will be meaningless.
With fully adjustable shocks and a proper test day you start with bump and rebound at full soft and start adjusting bump until the car starts to hop (or goes slower) then back off a click or so, then start working on the rebound.

Basic rule of thumb is that bump controls the wheels (unsprung weight) rebound controls the chassis.

Confused yet

Thanks! I had to read it 3 times but I think I've got an idea now. This is for my TL. The Buick was easy to setup but FWD is all new to me. I may have messed up getting the 28mm solid H&R bar up front. I may have been better off getting the TL-S 27mm solid bar for $200 less.

I've got everything in soft, going to start with stiffening the rear bar. I have a place where I can safely test the limits and you're right, what "feels" good on the street ends up being a very tail happy car at the limit.

 

[willix]

In a fwd body roll is your friend. It will enable you to slide the rear thru the center out of the turn. The rear suspension needs to be stiff across to allow this. The fwd cars are at a huge disadvantage because traction off the turn. The car is very controlable or steerable with the throttle. These cars are designed to push the front end driving over normal speeds. They work well in everyday traffic. On the track they tend to grip the rear tires to the point where it slows you down and you lose too much momentum out of the turn. Then you experience wheel spin on throttle out. Look at FWD as pulling a cart around. The anti-sway bars on a fwd street car are generally way too stiff and you are better off disconnecting it to get the front to roll more lifting weight off the rear giving you the rear slide. Its your friend on a front drive. In a tight turn enter at speed and lift the throttle and the rear slides out aiming the car for turnout add throttle to stick the rear and manage the wheel spin the best you can. Modifications can vastly improve turning performance. More rear antisway bar, springs & struts should be rated 25% more in front than the rear, a heavy sway bar in the rear, and little anti sway in the front if any.

 

[flacoman]

Set a little chalk mark on the tires' shoulders.
If the chalk gets scrubbed off, dial in more negative camber.

 

[tom slick]

Thread back from the dead!!

BuickGN did you ever go to Willow Springs?

 

[willix]

The chalk or wht. shoe polish is a handy tool should be more for determining tire psi(sidewall rollover) than camber angles. The camber needs to be predetermined for a given track before the engine cranks up. Tire shoulder marks work ok, better gaged by infrared temp gun or pyrometer across the tread. A temp gun can be had for about $30 nowadays and it has many uses for a car hot off the track, and elsewhere.

 

[carock]

I think you are going about this the wrong way....Springs, shocks, and sway bars will barely shave a second off your lap times. On road courses it is tires and brakes that cut your lap times (and of course POWER helps a lot!). Start with the best tires you can find in the size you are running. Upgrading the brakes will be a big improvement and allow you to keep your speed to the end of the straights. If you REALLY want to punish your car and cut your lap times you might try left foot braking in the tightest turns. This is really hard on the brakes but it should net you some good gains in a FWD sedan (works good in my Mini). I am fairly certain that you can't do left foot braking with traction control turned on, I am not sure about ABS though. Tuning your shock rates to adjust under/oversteer is probably not going to be successful in a sedan. In a lighter weight formula car it just barely works to adjust the under/oversteer on turn entry, on a heavier car the spring and sway bar rates are about all you can use effectively. Just set the shocks so that you don't pogo or skip in the bumps and have good ultimate grip in fast turns. Good luck chasing the Cayman, its about the most perfect track car ever made. Even a Bozo like me can go fast in a Cayman.