Rate my suspension setup!

[shogun32]

Divorced Spring location is 0.5ish. And shock is 0.75ish. Putting a 750 at the shock is wildly high

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[TeeLew]

strange. What phase of the corner would you say its oversteering? FWIW my car would oversteer more with the lower front spring rate (350# DR fronts) and the konis than it does with better shocks and the 500# or 650# front coilovers. I wonder how much alignment is affecting things too.

It's massive. I prefer to set the ride/roll rates where I want them and get balance with alignment/rides/damping. Make the front spring stiff enough to support brake dive and turn-in support The rear spring needs to be as soft as you can for traction, but as stiff as you need to keep the total rear travel window within reason. The big squat is great for traction, but it takes a lot of patience to drive correctly. Many people won't care for it.

I run the front bar as big as I can, specifically because it helps exit traction. The rear I add for balance until it hurts traction. My go-to bar right now is off of a V6 and it measures 20mm. Keep in mind, at times, adding rear bar will improve traction because you will have arrived to the apex having done more total turning and with a better angle. If your hands are straighter, the rear can hook up better, even if it's taking more of the roll couple. A lot of times it's not how the statics of the equation work out in a steady-state scenario, but how all of the items work together through the transients.

The easiest way to improve the balance of a nose-heavy, understeering car is to get weight off the nose. Shifting the battery to the trunk is a no-brainer. Anything you can do to shift the weight distribution to the rear will be a benefit and you don't have to compromise any springs/bars/alignment. Don't sleep on this tool.

 

[lo-fi]

What your describing is why I went with a Steeda front/rear adjustable sway bar combo. I wanted a much stiffer bar up front. I've completed most all the chassis rigidity and drivetrain slop removal I care to (i don't want excessive NVH) via all the Steeda front/rear bracing and stop the hop stuff which really made the stock suspension feel quite good on the street. It will be interesting being on the stock GT suspension with the bigger bars. I'm going to drive that a while simply to see what it feels like, then go to the Bilstein B6s and Steeda minimum drop spring setup. Drive that for a while, and see what I think. The Steeda springs are only a 35lb increase on the front (200) and 22lb increase in the rear (750). I want to stay soft in the springs and more aggressive on the sway bars. If it sucks, I'll rip it out, and start over.

 

[bnightstar]

corner spring rate * M.R.^2 = wheel rate

750*0.77*0.77= 445 #/in

I think that's supposed to be the rear damper motion ratio, not the rear spring. I believe the rear spring is more like 0.53 or something really low.

750 * 0.53 * 0.53 = 210 #/in

This rate seems in the ball park.

rear MR in oem position is 0.47 even.

 

[NightmareMoon]

Keep in mind, at times, adding rear bar will improve traction because you will have arrived to the apex having done more total turning and with a better angle. If your hands are straighter, the rear can hook up better, even if it's taking more of the roll couple.

this is why ita hard to discuss oversteer on exit with people. With 400+ hp, if you’re getting ln the gas aggressively at the right spot, I would hope you’re balancing the car on the edge of oversteer. At higher speed in taller gears, maybe less so.

Just like you said, theres so much technique involved in what position you get to and how well you match up what your hands are doing (hopefully unwinding the wheel) and what your foot is doing. Someone says their car is loose on exit and I’m wondering what their line is like, whats the orientation of their car and what driver inputs look like.

having learned to drive a car setup to oversteer, setup to understeer, and setup neutrally, and once you get the right feel for attacking (where you can) with some amount of slip angle, IDK, there are advantages to a car that will rotate well in response to the right inputs.

 

[TeeLew]

My problem with oversteer isn't that it's scary or even inherently a bad thing. When you're balancing the car on throttle at corner exit, you're spending time going laterally across the track, not longitudinally down it. If driven right, an understeer car is just plain faster.

As a rule of thumb, zero throttle to full throttle should take about 1 second in an "average" corner. If it's taking longer, you have to ask why? If pure understeer, then you initiated throttle too early. If only oversteer, then you need more rear grip. An understeer to oversteer snap means you weren't able to carry the brake far enough into the corner to get the car rotated appropriately early. That might be an unstable entry or pure understeer (the former is more common and more difficult to feel).

The driver can do more to load the front with his feet that anyone can do with springs/bars. The trick is to supply enough stability so they can do what they need to do and do it with enough rotation in the car that the timing of everything happens at the right time.

 

[TeeLew]

I really like this video clip. It shows how hard you need to chase full-throttle. This was a Cup car almost 20 years ago, so we are talking about an arcane car, but he is driving it exactly like you need to drive a big, nose-heavy beast with a ton of power and not much tire. This is how he drives all GT cars and it's a great example to learn to apply. You do everything you can in a straight line, because that's the only thing these do right. He's braking hard, but not burying the car into every corner. He's being very careful not to over-charge the entries and then get the car turned early. If you show up to the corner with flames pouring off the front tires, you can't expect them to turn.

On throttle, he's using a 2-step application. The initial roll to the throttle will determine how the car reacts in terms of balance. If the initial roll is abrupt, you'll be more likely to get the car to turn on throttle, but you'll also be more apt to break the rears loose and have to chase it. If you roll to throttle soft, then you'll shift weight off the nose and to the tail in a more gradual manner and this is likely to create understeer. Boris is creating a mild understeer with his initial application and then as soon as he gets pointed to the exit, he stomps. If he had an understeering car, he'd do a quicker initial application to get it to turn, pause at about 30-50% for a moment, then stomp. The only difference is this hurts the tires, so he would only do it enough to degrade the rear tires a little and help the balance. If you drive like this excessively, you'll burn the rears up, and then you're back to the soft application to create understeer. Count in your head the time between when he initiates throttle and when he stomps. It's very close to a, "One-Mississippi." almost every time.

 

[Biggsy]

I know it wasn’t the topic of the thread but thanks for all the good info. Suspension is always a lot to take in and can be very subjective based on driver and car. The trial and error aspect of it can be exhausting but well worth it in the end.

 

[NightmareMoon]

I really like this video clip. It shows how hard you need to chase full-throttle. This was a Cup car almost 20 years ago, so we are talking about an arcane car, but he is driving it exactly like you need to drive a big, nose-heavy beast with a ton of power and not much tire. This is how he drives all GT cars and it's a great example to learn to apply. You do everything you can in a straight line, because that's the only thing these do right. He's braking hard, but not burying the car into every corner. He's being very careful not to over-charge the entries and then get the car turned early. If you show up to the corner with flames pouring off the front tires, you can't expect them to turn.

On throttle, he's using a 2-step application. The initial roll to the throttle will determine how the car reacts in terms of balance. If the initial roll is abrupt, you'll be more likely to get the car to turn on throttle, but you'll also be more apt to break the rears loose and have to chase it. If you roll to throttle soft, then you'll shift weight off the nose and to the tail in a more gradual manner and this is likely to create understeer. Boris is creating a mild understeer with his initial application and then as soon as he gets pointed to the exit, he stomps. If he had an understeering car, he'd do a quicker initial application to get it to turn, pause at about 30-50% for a moment, then stomp. The only difference is this hurts the tires, so he would only do it enough to degrade the rear tires a little and help the balance. If you drive like this excessively, you'll burn the rears up, and then you're back to the soft application to create understeer. Count in your head the time between when he initiates throttle and when he stomps. It's very close to a, "One-Mississippi." almost every time.

Would love to see his hands. That kind of snapping the throttle down is commendable if you know you’re past a point unwinding the wheel and you know you’re rear tires have the grip margin. I try to remind myself to hit it to the floor on autocross courses where possible instead of babying the throttle needlessly. Its easy to forget when the courses are designed to keep you transitioning and turning…. The more power you’ve got (versus your overall lateral grip) the more you want to straighten/flatten the exit so you can flat foot it, for sure. You can learn what angle of steering allows that kind of go pedal application (depends on the gear). Higher gears = lower torque so in faster corners I expect to see him floor it sooner.

But dont try this at home kids, do that too early in 2nd gear corner before the cornering loads back off a bit and its suddenly another cars and coffee video

The 180 hairpin he was the slowest to add throttle back. Slowest corner on track and possibly the lowest gear (highest torque) so it took a little longer to feed power back in and spiral out before it opened up enough to hit it. Ive driven that track in a VR sim so that was fun to watch.

 

[TeeLew]

Would love to see his hands. That kind of snapping the throttle down is commendable if you know you’re past a point unwinding the wheel and you know you’re rear tires have the grip margin. I try to remind myself to hit it to the floor on autocross courses where possible instead of babying the throttle needlessly. "

I can guarantee his hands are unwinding on the tip-in portion and straight or getting straight on the stomp.

But dont try this at home kids, do that too early in 2nd gear corner before the cornering loads back off a bit and its suddenly another cars and coffee video

This speaks to how much rear grip they have tuned into that car. Everything is trying to get the rear better stuck. My opinion is that the stock Mustang is loose as hell from the factory. Even if it has final understeer in a steady-state, the transients are not stable at all.

The 180 hairpin he was the slowest to add throttle back. Slowest corner on track and possibly the lowest gear (highest torque) so it took a little longer to feed power back in and spiral out before it opened up enough to hit it. Ive driven that track in a VR sim so that was fun to watch.

I think he was short-shifting to second there as well. Again, he's *trying* to make understeer by the slow roll-in. Those guys are fighting to get to full throttle all the time and to do that means the car *has* to have some excess rear grip. What's really impressive is the magnitude of understeer these guys need to go fast.

 

[shogun32]

I wonder how the pedal stomp is modulated by the use of cv carbs. Or are these pumper carbs. Vs direct injection

 

[TeeLew]

I wonder how the pedal stomp is modulated by the use of cv carbs. Or are these pumper carbs. Vs direct injection

The carbs were based on a Holley double-pumper. Throttle response was _very_ good. The only thing EFI really improved was fuel consumption. I've seen Boris' footwork 'other places.' It's exactly the same in a GT car with EFI.

 

[shogun32]

I've seen Boris' footwork 'other places.

I'm gonna catch a ticket if I keep trying this 1 Mississippi and mashing the go stick doing the loops around here...

 

[TeeLew]

I'm gonna catch a ticket if I keep trying this 1 Mississippi and mashing the go stick doing the loops around here...

Ya, it's not so effective on a 270 degree on-ramp.

 

[BVLCK_S550]

Well after long hours of debating and research, parts are starting to arrive as are more questions! Can someone please point me in the right direction of how long the adjustable sway bar end links need to be? These will be paired with the steeda sport progressive springs. Photo for reference!

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