NickD

So last time I was at the track when I would get on the brakes after the main straight, ~125mph there were two things I started experiencing. First the car started to pull left after a few laps, I am guessing air in right caliper, even though I bled them the day before. The other thing is a feeling of instability. I've recently managed to do some heavy braking from similiar speeds and noticed that the car just doesn't seem very settled when I brake hard from around 100+. This could just be me, but prior to my Cobalt I had a BMW e46 328i that I used to take to the track and I didn't get this sensation. Any thoughts on this and if it's not just me, how to improve it? My car is a stock '09 SS Sedan.

RoadconeTuning

i believe these cars are still a little too rear brake biased... i know at low speeds in parkinglots i can lock up the rears when i've got new brake pads back there well before the fronts do.

68nova200

iTrader: (2)

Rear sway bar will help this dramatically. When i switch between summer and winter setups i notice the difference.

NickD

I was actually just posting in another thread about getting a rear sway bar. I definitely can see how it can help on the track. I didn't consider this for braking. Do you remove your aftermarket rear sway bar for winter driving with winter tires?

68nova200

iTrader: (2)

Yes i remove the sway bar for winter and put on snow tires. Hard braking above 70 i can feel the rear end loosen up. It has happened a few times when avoiding morons driving in the snow on highways.

NickD

What real advantage does removing it for the winter give you or are you just trying to keep wear and tear down on the bar?

68nova200

iTrader: (2)

Cutting down on wear and tear, yes. But mostly because i dont feel like drifting like ken block every time i let off mid corner with snow on the roads.

Cobalt_Daddy

my car did this to me once too. not sure why it did it. i was doing about 120+mph though.

Wangspeed

iTrader: (2)

There are a few things that contribute to this. You probably have the stock squishy rear CABs, or torn ones. The Powell spherical versions will help. The other is the struts and shocks. Konis tend to control this a little better, but realize that any threshold braking in a FWD car will always result in a light rear. You may need to correct as you brake. Also, try not to jump on the brakes. You need the weight to transfer smoothly up to the front. If you get on the brakes too quickly, you won't give this a chance to happen, and it'll upset the car. The upcoming springs from Powell will also help. Right now, there's a very good chance you are bouncing off the bump stops, and this is where the Konis help. They sort of hide this issue a bit. A rear swaybar has absolutely nothing to do with this.

All that said, I have no problems going deep into a brake zone in this car

Powell Race Parts

iTrader: (3)

^^^ this, the rear koni's sure do help and make the ride on the highwaybetter, there is noticeably less body movement with rear konis, but its 268.00 at least for Koni rears, compared to 99 dollars for FE5 + shipping.

rear twisting beam bushings help as well, but at the end of the day Dynamic Rear Brake Proportioning is in there doing its stuff as well. Heinricy wanted it turned off. Regrettably the really good racing abs calibrations developed by GM engineer Zelinka aare only good for the 05-07 Cobalts. And there are few if any out there, and dont even think of asking if they will make more.
The Z06 abs calibrations that Zelinka did, are fantastic as well, I purchased three sets in 2007 for customers at a cost of $1500. Each...YSad to say its hard to appreciate how good these calibrations are, and the tons of track time money and work that went in to making them that way...

so bottom line use the Wangspeed driver mod its less money and easier to develop. Sad that GM shelved the GMPD and all those brilliant engineers are doing electric cars or sumthin'.