CSG and RCE tag-team suspension Q&A thread! Ask us anything!

[7thgear]

Originally Posted by Calum

If that were true rock climbers would make the best tarmac race cars ever

when i read this, i thought of rock climbers as in people who climb mountains

and i laughed, because it was a funny analogy

then i realized you meant rock climbing cars... cuz that's a thing

[Dimman]

Originally Posted by Calum

Anti roll bars prevent the suspension from articulating independently, so the more they can move away from bars, the better the suspension will be able to conform to the road surface. The Mclaren MP4-12C come with no sway bars for this reason, didn't it? But the Mclaren has other ways to manage roll resistance and still maintain decent ride comfort and keep the tire in contact with pavement.

The subject of roll resistance keeps coming up, and guys like me keep getting told in some form or another that it doesn't matter, only conforming to the road surface matters. If that were true rock climbers would make the best tarmac race cars ever, with their 20 odd inchs of wheel travel and rolling like an old Corvette in a storm. Maybe I'm too old, or have read too many 'yo dogz my car iz stiff as nuts dog, coiloverrrzzzz!!' on the forums, but I can't get away from the idea that roll stiffness is still a large factor here. We need to prevent the weight from transferring around too much so the outside tires don't get overloaded and so the car can react to direction changes quickly. What am I missing?

The no anti roll bars has been a MacLaren 'thing', since the F1. The rather significant advantage they have is being much more in control of their geometry due to the single purpose of their car.

It's just that while everyone goes on about roll, pitch (dive and squat) is important as well, and, too me, a degree of separation makes sense. Pitch is what you are playing with, when you're steering with the throttle, and comes into effect with front to back weight transfer leading up to entering a corner, then exiting.

In low downforce formula cars they have managed to completely isolate pitch and roll resistance using center mounted coilover monoshocks with bellville washer stacks on the sides. So I'm curious why conventional tuning has gone the opposite way, relying principally on springs and fixing pitch and roll more together.

[Racecomp Engineering]

Originally Posted by Dimman

Like @7thgear mentioned before, why aren't people emulating the rally setups that seem perfect for non perfect roads?

It's arguable that the good european coilovers ARE sort of tarmac rally inspired. Decent bump AND droop travel due to being single height adjustable with helper springs and not double like all the asian shocks. Usually fairly digressive on compression. Not insane on spring rate.

It's a great way to appraoch a street set-up because you have to be fast and be able to soak up real world bumps. It's why we primarily stick with european brands...it works.

A real tarmac rally coilover of course will have an assload of compression damping for ultra-quick reactions and fast transitions without super stiff springs. Also tons of travel. But you can use those same ideas on your street car.

- Andy

[Racecomp Engineering]

Originally Posted by cdrazic93

it could be that the suspension is tuned so specifically, or to the very limit that they would need a rebuild after each run and cost a bazillion moneys to make, making any ordinary coilover budget a laughable excuse for a setup...I'm shooting in the dark now, I should stop before I hurt myself lol

It is true to that real race (whether it's tarmac rally, gravel, circuit, whatever) coilovers are not designed to last 5 years on the street without rebuilds. They're expensive and need to be serviced often. So you do end up with compromises with everything.

- Andy

[Racecomp Engineering]

Originally Posted by 7thgear

when i read this, i thought of rock climbers as in people who climb mountains

and i laughed, because it was a funny analogy

then i realized you meant rock climbing cars... cuz that's a thing

Totally did the same thing at first.

- Andy

[Racecomp Engineering]

Originally Posted by Calum

Anti roll bars prevent the suspension from articulating independently, so the more they can move away from bars, the better the suspension will be able to conform to the road surface. The Mclaren MP4-12C come with no sway bars for this reason, didn't it? But the Mclaren has other ways to manage roll resistance and still maintain decent ride comfort and keep the tire in contact with pavement.

The subject of roll resistance keeps coming up, and guys like me keep getting told in some form or another that it doesn't matter, only conforming to the road surface matters. If that were true rock climbers would make the best tarmac race cars ever, with their 20 odd inchs of wheel travel and rolling like an old Corvette in a storm. Maybe I'm too old, or have read too many 'yo dogz my car iz stiff as nuts dog, coiloverrrzzzz!!' on the forums, but I can't get away from the idea that roll stiffness is still a large factor here. We need to prevent the weight from transferring around too much so the outside tires don't get overloaded and so the car can react to direction changes quickly. What am I missing?

I always hesitate to compare a normal street car to a supercar or formula car. Electronically controlled swaybars, high dampers, separate dampers for pitch, ride, roll, bump,...it's not always something you can compare.

Remember that "magic" suspension frequency often cited? 2.4 Hz or whatever? Why do so many go sooo much stiffer than that? Well that number is for ride. Not roll. And on our cars, we have 4 springs that affect ride. With swaybars we can increase our roll resistance beyond that without affecting ride motions so we can have that magic* suspension frequency and still have more roll resistance if needed. There is an effect on single wheel bumps and that's one reason why instead of big ass swaybars you'll see stiffer springs.

If you read through the optimum G articles, they talk about having separate dampers for ride, roll, and pitch. Ideally you have 10 dampers. Obviously no one does that but for complete control that's what you do. If you can't due to rules or compromises like packaging and money, you use 4 and to try to control everything that way.

I'll write more after lunch.

- Andy

*there's no such thing as magic

[Wepeel]

Originally Posted by Racecomp Engineering

I always hesitate to compare a normal street car to a supercar or formula car. Electronically controlled swaybars, high dampers, separate dampers for pitch, ride, roll, bump,...it's not always something you can compare.

Remember that "magic" suspension frequency often cited? 2.4 Hz or whatever? Why do so many go sooo much stiffer than that? Well that number is for ride. Not roll. And on our cars, we have 4 springs that affect ride. With swaybars we can increase our roll resistance beyond that without affecting ride motions so we can have that magic* suspension frequency and still have more roll resistance if needed. There is an effect on single wheel bumps and that's why instead of big ass swaybars you'll see stiffer springs.

If you read through the optimum G articles, they talk about having separate dampers for ride, roll, and pitch. Ideally you have 10 dampers. Obviously no one does that but for complete control that's what you do. If you can't due to rules or compromises like packaging and money, you use 4 and to try to control everything that way.

I'll write more after lunch.

- Andy

*there's no such thing as magic

Yeah, that 2-2.5Hz thing with the rear being about 10% higher in frequency than the front (recommended for low downforce cars)... well there are a lot of successful autocross setups that reach well into the 3+ Hz range (and downforce isn't much of a factor at autocross speeds).

There's that old Chapman quote, something along the lines of "any car suspension will work if you don't let it"...

OptimumG and anything written by Mark Ortiz is some great reading.

[7thgear]

autocross is autocross

the speeds are so low and the tire rules so constrained that it is a big game of compromises to simply cut down the time. Having a FWD car that can rotate on a whim and hammer down the moment you've got it pointed right will be awfully dangerous in an offcamber sweeper at 180kph +.

I can't imagine this like car, for instance, being able to tackle any sort of highspeed racetrack without the potential for a serious accident

[ame="https://www.youtube.com/watch?v=x4qRVfioR2g"]Mini Autocross - YouTube[/ame]

[digital_assassin]

My car is lowered on KWv3's about 2". Thinking about getting the Buddy Club Ball Joints that are supposed to correct roll center. Any thoughts on those?

[Dimman]

Originally Posted by Wepeel

Yeah, that 2-2.5Hz thing with the rear being about 10% higher in frequency than the front (recommended for low downforce cars)... well there are a lot of successful autocross setups that reach well into the 3+ Hz range (and downforce isn't much of a factor at autocross speeds).

There's that old Chapman quote, something along the lines of "any car suspension will work if you don't let it"...

OptimumG and anything written by Mark Ortiz is some great reading.

I've read somewhere that some British rules require the suspension to move, because people would just lock it down and rely on the tires.

I've never seen 2-2.5Hz described as magic, just as the recommended start for low downforce cars on certain quality surfaces. As much as people adjust damping for smooth/rough tracks, it should be the base frequency that is adjusted first. But budgets...

The other problem seems to be the continuous evolution of tires, which seems to exceed the dissemination of general tuning knowledge. I noticed that Hoosier supplies a good deal of information on theirs, such as their effective spring rate at 'x' psi.

And the full coefficient of friction curves for load, temp, camber, etc... would be helpful to more grassroots tuners, but seem to be rather guarded information.

[7thgear]

Originally Posted by Dimman

The other problem seems to be the continuous evolution of tires, which seems to exceed the dissemination of general tuning knowledge. I noticed that Hoosier supplies a good deal of information on theirs, such as their effective spring rate at 'x' psi.

right on

if you have so much grip from the tires for a given vehicle power and weight that you don't lose traction, then you might as well not care about any of this and lock up the suspension

if you're approaching a corner at 50kph because that's all you could accelerate at out of the box, and the tires can let you take the corner at that speed, then all this science is moot.

and old buddy of mind commented on the old Group B racers.. that ALL the cars were so capable that the actual road became the limiting factor to their speeds

[Calum]

Originally Posted by 7thgear

when i read this, i thought of rock climbers as in people who climb mountains

and i laughed, because it was a funny analogy

then i realized you meant rock climbing cars... cuz that's a thing

I was worried about the reference to the old ships, I never even considered the rock climber being obscure.

[Racecomp Engineering]

Originally Posted by digital_assassin

My car is lowered on KWv3's about 2". Thinking about getting the Buddy Club Ball Joints that are supposed to correct roll center. Any thoughts on those?

Do they come with a solution for bumpsteer (tie rod ends)?

- Andy

[gramicci101]

Originally Posted by 7thgear

and old buddy of mind commented on the old Group B racers.. that ALL the cars were so capable that the actual road became the limiting factor to their speeds

I'm pretty sure that in my case, the driver will always be the limiting factor.