BRZ stock suspension understeer... what to do?

[mtimney]

I'm new to auto-x and have had only had a little HP driver training. My understanding is that the stock BRZ is known to understeer slightly... and that's been my experience when I push the car.

I've upgraded my tires to Michelin Pilot Super Sports, but have done nothing else to the suspension other than Whiteline camber bolts... am running as much negative camber as I can, about 1.8-degrees. (I also put in the Whiteline rear, subframe bushings.)

What should be my next step toward improving handling if I'm NOT going to go to a full coilover setup at this time? (I'm in STX, but am not quite ready to pull the trigger on a full suspension system until I learn more.)

I read so much about what to add to the car to make it better, but then I also read about how 'good' the stock setup is. What do you all think?
Thanks,
Mark

[hushypushy]

Swap in the FR-S suspension. (Or rather, just the springs. I believe the only difference in the suspension is the spring rates. Not sure if the shocks are valved differently between the cars.)

[CSG Mike]

Besides more seat time (you can make the BRZ oversteer; it understeers if you crank the steering faster than the car wants to shift weight around), you can try a rear swaybar.

[agray56]

Play with your tire pressures. Either increase the rear or decrease the front.

[GTM_Challenge]

Rear toe out in a pinch?

[Miniata]

Originally Posted by agray56

Strano rear swaybar should correct the understeer, plus play with your tire pressures. Either increase the rear or decrease the front.

Strano's bar is a front sway bar, not rear. I was fighting oversteer more than understeer when I was autocrossing my BRZ and it was stock except for the crash bolts, lighter wheels and stickier tires (in stock sizes). I went with the Strano front bar, and it really improved my times and confidence on the autocross course.

[Sccabrz192]

You are overcooking corner entries. This car should not plow on as you state, even stock. I've autocrossed mine on Hoosier A6's and the stock primacies with zero modifications, not even an alignment and the car, just to make the point that the car does not have an understeer issue regardless the grip level of the tires. Sounds like you are coming into the corner too hot and likely using too much steering input.

As you stated you are a novice, I HIGHLY HIGHLY suggest spending your money on entry fees for more seat time rather than on parts. Parts will not correct driving deficiencies.

[Symmetrical]

I'd say a rear sway bar will do the trick, or better throttle management?

[agray56]

Originally Posted by Miniata

Strano's bar is a front sway bar, not rear. I was fighting oversteer more than understeer when I was autocrossing my BRZ and it was stock except for the crash bolts, lighter wheels and stickier tires (in stock sizes). I went with the Strano front bar, and it really improved my times and confidence on the autocross course.

My bad.

[GTB/ZR-1]

Originally Posted by Sccabrz192

You are overcooking corner entries. This car should not plow on as you state, even stock.

...I HIGHLY HIGHLY suggest spending your money on entry fees for more seat time rather than on parts. Parts will not correct driving deficiencies.

We have a winner

[feldy]

Originally Posted by mtimney

I'm new to auto-x and have had only had a little HP driver training. My understanding is that the stock BRZ is known to understeer slightly... and that's been my experience when I push the car.

I've upgraded my tires to Michelin Pilot Super Sports, but have done nothing else to the suspension other than Whiteline camber bolts... am running as much negative camber as I can, about 1.8-degrees. (I also put in the Whiteline rear, subframe bushings.)

What should be my next step toward improving handling if I'm NOT going to go to a full coilover setup at this time? (I'm in STX, but am not quite ready to pull the trigger on a full suspension system until I learn more.)

I read so much about what to add to the car to make it better, but then I also read about how 'good' the stock setup is. What do you all think?
Thanks,
Mark

Seat time. Your alignment is fine for stock ect. The problem is your overdriving the car. Remember your front tires only can only do 1 thing good at once. It can steer it can brake and on a fwd it can accerlate. But doesn't like doing two things at once. Always brake in a straight line. If you dive bomb the corners and are still in the brakes while turning you are going to push wide. If you are pushing you can lift off to help settle the car or you can throttle steer and get the car to rotate.

Remember in Autocross you have to go slow to go fast. Weird saying but it's true. Play with tire pressures a bit. If you are pushing bad try lowering the front pressures only until rollover. However if you are overdriving the car the rollover will seem more extreme then it really is. You can also up pressures in the rear to help the back end rotate more. What ever you do don't spend more money on parts you don't need yet. The car is very capable out of the box.

[mtimney]

I get what you all are saying about overdriving the car...and I do do that sometimes/frequently and have to work harder at not coming in to corners too hot. I also know I need way more seat time and will gain more by that then by any equipment change.

But I made a mistake when I wrote about understeer and used the word "push" in the same sentence. I don't think I meant 'push' in the way it's used by experienced drivers. ???

What I meant to describe was a turn where I've braked at the right time and have come off the brake appropriately, but still have the car a hair over the perfect speed. It's the front end that always looses traction first rather than both wheels losing grip at the same time. Or is this typical?

I've had more experienced drivers check my air pressure and check for rollover. I seem to be good there..... so....

And thanks all for helping a 'newb' learn!

[Suberman]

"Push" is NASCAR slang for understeer. Indy racers also use that word. Means the same thing. "Loose" is oversteer. On ovals this terminology makes sense.

For car control you want understeer at the limit which is the big difference between the FRS and the BRZ. Somewhere else on this site the actual spring rates are published. FRS is softer in the front and stiffer in the back than the BRZ. That may not make the FRS quicker.

Your description suggests you are not braking correctly despite your sense that you are. Generally speaking you should adapt to the car first and get the most out of it that is possible. Once you are driving your existing set up as quickly as it will go only then start worrying about the chassis setup. Only in that way can you truly understand what is the car and what is just you, before you spend the bucks. Buying parts will not make you a better driver. In fact, there's a hilarious short video on the Top Gear site showing the Stig driving a Honda ride on mower that has been somewhat modified ...or the video is speeded up. Some drivers can make anything go fast.

They say the most bang for your buck in getting better performance out of your car is to pay for instruction from someone who is already there. As many racers will tell you the most important part on any car is the nut holding the steering wheel.

[Sccabrz192]

Whether you are a hair over or a mile over if you are over on your entry speed, you will under steer or push. Slow in fast out is the mantra you need to start with to learn. 5 mph too slow on the entry is better than 0.5 mph over.

Reason is if you enter slow, you can get on the throttle earlier and make some of the lost time back. Earlier throttle can also induce throttle on oversteer and rotate the car. If you enter with too much speed, all you can do is sit there and wait. If you enter with too much speed, you will find the more steering angle you use will not provide any additional turning of the car until it has slowed appropriately... You use the scrubbing of the front tires to finish breaking.