F/R antiroll bar size for best track handling

Track day is coming!!!!

So, here is the situation, QA-1s 400 lb front and 350 rear, Saner Bars, (25.4 MM front and 22 mm rear), 225/40 front and 255/35 rear goodyear F-1 dsg3 tires, close to stock alignment and the car has a lot of power on understeer and almost no trailing throttle oversteer.

I tightened up the rear bar one notch last track session and the car basically behaves the same.

Micrometer tread depth measurements seem to indicate that the pressure and camber is using the tires close to even with a bit more inside use.

I also have 22 mm front bar, so i am thinking of trying the front at full soft and backing the rear bar off to full soft as well. If the car has too much trailing oversteer, i can tightenup the front bar one notch,( that is all the adjustment there is).

What do you guys think of this approach??? What i'd feel most comfortable with is a bit of full throttle understeer, (not much) and some manageable, (meaning i can catch it with throttle and easing off on the steering) oversteer.

Is this likely achievable. I am still in the novice group but will be moving to intermediate at thunderhill, (hopeing to not be run over by faster drivers/i don't want to be a moving road block). I'm having a hell of a time staying ahead of the 10 cyl bmw and the 550's

What's an old Phad Phugger to do
chris
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Hi Marcel,

It has QA-1 shocks and, yes, it is mostly street driven. Generally, the end of the car with the greatest roll resistance takes more of the lateral weight transfer in turns which makes it easier for the other end to stick. So, to reduce understeer, increase the roll resistance of the rear bar or reduce the front bar size.

I will try going to -2 on the front camber, (the tread ware is currently a bit more on the outside).

The Saner bars i am using are 1 inch front,(25.4mm) and 7/8 rear, (22mm).

If my math is correct, the relative stiffness goes up roughly 44% with a 1/8th inch diameter increase, (D4).

Looking for suggestions,
chris

 

Hi Paul,

At this point, i cannot afford track dedicated wheels and tires, so am using the Goodyears. I ahve run a few auto x cars with slicks and yes, it is really really fun, but you still have to truck all the stuff to the track and do the change, i am jsut a bit more laid back in my old age.

What size wheels and tires for the track???

So, how would you describe the handlling with the 22 mm f&r. How much trailing throttle oversteer or push under power???

I gotsta know,
thanks,
chris

 

So, Pit Bulll,

What did you do to get the extra fork length, weld on longer bolts??? Or just make new forks??? We have already established that you can be "bought", so how much is this magic going to cost me ????

IIRC, i am at about -1 now and could maybe go to -2. I am also trying not to burn off the inside of the street tires - I know you can't have it both ways, but i am a cheap bastar#.

thanks for the advice,
chris

 

Hi Doug,

I am having big hesitations even on the straights, so am going to be looking at the accelerator pump circuit and maybe revisiting the float height.

stumbling along,
chris

 

Hi Sean,

I didn't mean to imply that i had achieved -2 with stock bolts only that i was going to give it a try. So, I guess I need to go with the longer bolts. What length do you suggest???

thanks,
chris

 

Hi Paul,

I'm running 225/40 and 255/35 Goodyear dsg3s and may go to Extreme performance tires, (I need to get a bit ou touring mileage out of my tires and i do not want to go through trailering orhaving someone else haul race tires/wheels to the track for me, nor frankly, the expense. I'll just run what i brung. I know it isn't the fastest way but it is what i am comfortable doing.

So, how does it handle with the stiffer bars and springs with street tires.

I have the baffle kit, but havn't had the time to install it - hopefully before the 4-15 thunderhill event

On a side note, what dou you track rats think about the stock rear hubs/failure???

thanks,
chris