Front Sway Bars for ZO6 Autocross?
 

I'm wondering how many guys are running an aftermarket front sway bar on their ZO6 in SCCA Super Stock. The rules allow a front bar.

I'm running the stock OEM bar, and I've always thought this was good enough (and it works great for HPDEs, as an added benefit). But I'd like to have the rear end planted better on corner exit in autocrosses. I'd like to get on it a bit earlier.

I can fiddle with the alignment, and I'm going to have the alignment rechecked next week.

But does anyone think a thicker front sway bar is a good solution for this? What are folks using? OEM or aftermarket? And if aftermarket, which bar works for you?

Cheers.

Corner exit acceleration is always a compromise in autox. For best acceleration you want the tires at zero camber, zero toe. For best turning you want some negative camber and toe in (you pick the amounts). Plus, the LSD makes the rear end want to break loose while turning.

You can play with reducing the forward rake on the car (lower the rear in relation to the front), that will reduce oversteer at the cost of more understeer. YMMV

There, I've exhausted my knowledge. :ack: Perhaps Mr. Popp will join in and give you some real advice!

HTH, and have a good one,
Mike

Depends on the tires...

With the Kumho's we were running the stock bar. We tried poly bushings in the front and that resulted in steady state push...

Last weekend we put on Hoosiers and the car was loose everywhere...:eek: :willy: Put back in the poly front bushings for day 2 and it got more better (thanks for giving them back Al :thumbs: ), still a bit loose in transients :ack: , will try some more rear toe in and some more front shock to get ready for Kansas :ack: ... ACRACE tried a 32mm front bar with the Hoosiers and seemed pretty happy with that... :D It always takes a few weekends to get it totally dialed in if you aren't at a test and tune where you can run a lot...;)

Season to taste.... Your mileage may differ....If serious side effects occur see your doctor.... All the usual caveats apply.... :willy:

I think Danny will be busy with NASA Nationals this weekend, but TTT it on Monday and I bet he'll be around. :thumbs:

I think slightly stiffer might be valuable and the 32mm hollow seems to be a good size. It's the trade off between easier corner entry or a faster exit. My cars have always been fastest when you can exit hard, both in turns and transitions. This normally means a little more understeer entering slow corners, but it's worth it. I normally counter this with shock tuning to let the car enter the corner a little tail out, then let the bars/springs settle the car on the exit/power down. Rear toe in is also your friend here, 1/4" or more is not too much.

Take a look at new vendor www.pfadtracing.com and their adjustable bars. That may be the best of all worlds, and easy to adjust between high and low speed events.

Yes, I put on the 32 mm hollow bar, but the course was faster than your typical autocross, with only one semi-tight corner. There's a great variance between what the top guys run for bars - everything from the stock Z06 bar/bushing to the T1 bar. Seems that the fast guys are either stock, stock with the poly bushing, or the 32 mm hollow bar. As pointed out, your alignment, tires, shock selection, and driving style all are influencers.

Thanks for the responses.

As a stock 2004 ZO6 with OEM suspension running V710s, my car turns in beautifully and rotates great. What remains is just planting the rear end better. And I'm aware of the tradeoffs.

First thing I'm going to do is see what a more aggressive rear end alignment does for me. And take it from there.

You may also want to increase the amount of fuel in the car.

I've run the stock bar over the last two years, but have driven a car with the 32mm bar, also. There are so many variables to play with, given the great adjustability of the Z06 suspension, that I wouldn't say one is "better" than the other...it seems to be a matter of getting all the variables to work together to support the way you like to drive the car.

I would definitely play with rear toe and ride height to see if you can get where you want, prior to putting in a bigger front bar.

acrace is right, a larger fuel load helps putting down power out of the corners. Also I have found that getting the rear jounce stiffness right has a big effect on putting power down. In trying to reduce exit oversteer, the classic approach is to reduce rear jounce. Problem is, if you get too soft you loose a lot of the ability to put down power on corner exit.

That is a great, elegantly simple, suggestion. I'm used to running with a light fuel load, but it's just habbit at this point to save weight.

I should at least try a large fuel load in my next event and see what happens.

To me, running with the excess weight of fuel neccessary to change off corner bite is similar to adjusting tire pressures outside of the range of maximum grip to get the car to do what you want...in both cases, viable for a quick fix, when you don't have time to really solve the underlying problem, but not a long term solution...unless, like in a F-body you don't have the range of adjustment needed to really adress the problem...which is not the case with the Z06.

If you have truly adjustable shocks, that's another big variable you can play with, as has been said :thumbs: