Went back and done some reading on the Time Attack Cobalt. In the suspension setup, the took off the front swaybar and added stiffer springs to the front and rear. What did taking the front sway bar off do for handling? Does anyone know what spring rates the went to?

 

The deduction of the front anti-roll bar will decrease the roll stiffness of the front end of the vehicle, hence increasing the front end load transfer when subjected to a lateral force. This will increase the front end traction at turn entry, but at a cost of slower steering response. In addition, under steady state cornering and accelerating out to the exit of a turn, due to the FF layout of the car, the increased front end traction will help counter the degradation of traction of the drive wheels during corning.

The deduction of the the front anti-roll bar is "a" way of proportioning the amount of loading between the front and rear end of a vehicle, conversely one can simply increase the rear roll stiffness. The fact that they have to resort to removing the front anti-roll bar means they cannot increase the rear end roll stiffness further more, probably due to the nature of the weight distribution of an FF vehicle and their particular set up.

The spring rate used for their car is matched to their particular vehicle's suspension set up, damping, sprung weight and weight distribution, to achieve a certain ride frequency for a particular application. Simply plugging that number into any other car will not work.

 

The Time Attack and first season race Cobalts(Grand Am Cup, now Koni Challenge) didnt use any fron sway bar. It had to do with the facts that rocket mentioned, also because the race cars were capable of ripping the front sway bar clamps out of the frame(later remedied by a switch to a full bolt on clamp, as opposed to the '05 design with a bolt and a tab) Many of the decisions made on the TA Cobalt were based on John Heinricy's personal preferences as well. The TA and GAC/KC Cobalts use a MASSIVE rear anti-roll bar. The Koni/GAC cars use a stock style bar which is welded into the rear axle assembly, its something on the order of 1.5" OD or more, with varying wall thicknesses(stock is 7/8"). The TA car(though you wont likely see many/any pics) uses a different style bar, it however was never given approval by Grand Am, so they continue to run the original style bar to this day.

The fact that the race cars use coilover type racing dampers and racing springs is also another reason they ca get away without a front sway bar. They can get the proper roll stiffness just from springs. I'd expect that youd find several hundred pound springs in the front and probably 100-300lb heavier springs in the rear, all depending on the track, conditions and driver preferences.

You arent going to be able to get spring rates to match the race cars on your stock suspension, even if you got someone to make dropin springs in race weights, it would be a nightmare on the street with OEM dampers.

Koni Challenge rear axle


Koni challenge anti-roll bar(rear)


Pics Courtesy of Powell Motorsports, builders of the TA Cobalt and 15 Cobalt GAC/Koni Challenger chassis.

 

Good answer guys, good pic of the cool roll bar too.

 

That's some cool info Mav.

I would assume given the choice they would rather run an ARB rather then not, because without one they will have to compromise the spring rate since now the springs will have to do double duty.

 

Damn I think my IQ goes up 30 points everytime Maven touches the keyboard

 

Great info guys! That is a lot of excellent info on suspension setups.

 

All the cars do run sway bars now(other than perhaps in the rain) For 2006 production a fully bolted ARB clamp was introduced and since then the race cars have been using a full production front sway bar setup with the exception that they use adjustable endlinks(which are commercially available and super sweet. Power Grid Links)

 

This is probably a stupid question, but what would the adj sway bar links help you out with. I am assuming you can't preload the swaybar or anything.

 

click...

 

Thats exactly what they allow you to do.

Setting up a preloaded sway bar system properly requires corner(wheel) scales, and track time. Preload of the swaybar is very heavily track dependant and since it changes the way the car turns one way in relation to the way it turns the other,and since weight moves around a lot in street cars(passengers/cargo) and we arent running on a circuit with the same progression of turns its not a street friendly setup

 

Ok... makes sense now... had it in my mind for some reason you couldn't preload it. This might be something that would be good to go with a coilover kit if I end up going that direction.

 

On the street you would just set both links to zero preload.

Yes they would be great on a coilover setup since many(all?) coilover kits for our cars cant use stock links.

 

Not to mention they are using Ohlins that cost 6K a pair with gas reservoirs on the grand am cars!

 

The Koni Challangee cars use....get this......KONIs