Panhard rod for 2nd gen. firebird?

[Aguila1]

So, I took the '79 Trans Am 455 to my first autocross event, SCCA Solo2, at the Michelin test facility and was thoroughly humbled. In mountain driving I always thought the car handled well, so this event was an eye opener. Granted I'm running 245-60/15 BF Goodrich Radial TAs, but somehow I thought that the car would fare better. I have Addco swaybars, poly mounted, Coil Spring Specialties drop coils, Flex-a-form composite leaf springs rear, KYB gas shocks, Comp. Eng. subframe connectors bolt-in style welded in. It felt fast and precise in the slalom, but in the curves it became a real tire-sliding handful.

Now, reading the instructions for Vette Brakes and Parts, the other guys that make composite leaf springs for f-bodies, I read this: "In racing or autocross applications, a pan hard rod is required for lateral strength." Hmmm.



With the Flex-a-form springs the car is jacked up, so that might contribute to the problem, but does anyone make a panhard rod to locate the rear axle, or is this something I need to fab up?

Any suggestions to make the car better for autocrossing is also greatly appreciated.

[Zee]

I think you will need to fabricate that one. From what I know, your mods would likely put you in a pretty aggressive class. If you are dead set on the stock wheels, you might want to consider going back to stock WS6 suspension stuff and competing in a different class. Nice looking TA BTW.

[MrQuick]

The leafs should be fine but adding a lateral device could/most likely cause a bind due to the different roll centers fighting each other. Adding a lateral device because a spring isn't doing its job seems redundant.

You have much going against you.

15" tires = sidewall flex
BFG's = super duper sidewall flex even at 50 psi

KYB's = too firm, tire hopping instead of suspension articulating


I'd look to different leafs, better adjustable shocks and a set of 17's with better tires. You might do better with changing the rims,tires and shocks alone.

Vince

[dcozzi]

+1

Lower profile tires and get rid of the KYBs for some Bilsteins or Konis.

[JRouche]

So, I took the '79 Trans Am 455 to my first autocross event.......


Granted I'm running 245-60/15 BF Goodrich Radial TAs, but somehow I thought that the car would fare better.



Any suggestions to make the car better for autocrossing is also greatly appreciated.

I know you were looking for some suspension info but.... IMO I think tossing the BFG T/As will get you alot of bang for the buck. Its been a few years since I have used some BFG T/As but when I had them they were a very hard tire. And they got worse with age. And Im not talking about racing. Just street tires. The TAs became rock hard after 6 months of road use and were like driving on 10 year old tires. They would break loose and skid across the road without any indication before hand. Even when warmed up. They were rock hard through and through. Maybe they have changed over the years, Im not sure. I wont use them again though. The TAs, not talking about any of their other tires. JR

[Skip Fix]

TIRES!! Even swapping on the 16x8 GTA wheels(light Classic repops them now) with BFG autocross compound DOTs made an enormous difference in my car. Of course cheap road race slicks are even better and really put a smile on your face. John Berget used to sell them. http://www.jbracingtires.net/

Shocks the next step. I've had good luck with Bilsteins.

My personal preference for handling about a 700lb/in front spring (Guldstrand or deisel S-10 truck). 1 1/4 front sway bar(should already be onm the car. Stock leafs and a 5/8" factory rear bar. For me larger rear bars would pick up the inside rear tire slightly and loose traction. As well as a softer front springs causing brake dive and unloading rear tires if braking and turning. And on the street even with solid bushings are not too rough.

Autocross buddy with a 4th gen Vette used to like to drive my car with the road race slicks on it.

[Lowend]

I'll echo... (this is gonna sound a little harsh, I'm really not trying to offend here)

Frankly, there is nothing you can do to go all that fast on those tires. The compound is just too hard, and the sidewalls are just too soft - for lack of a better way to put it.

Your money and time would be much better spent on a set of 17" wheels and decent tires. You can get a set of 17x8" front and 17x9.5" rears with tires for less than $2000. Even with cheap street tires (Sumitomo) you will feel a huge difference from the BFG's you have now.

The car really shouldn't need a pandhard rod, but I should also emphasize I am NOT a fan of composite springs in longitudinal applications in general... seen too many VBP springs split or splintered.
Those KYB shocks are junk; valving is all wrong for 2nd gen's. The composite springs have some very odd behavior and need a ton of rebound damping to control them. You are really looking at a custom valved shock to make them work right.

[Norm Peterson]

In addition to what's been mentioned (and repeated) so far, you need more seat time specifically at autocross. It's enough different from any street driving.

You're almost certainly well ahead of the autocross newbie who has never driven corners very hard, but the autocrosser who has lots of experience at it is in another league.

If your region provides instructor ride-alongs, do take advantage of them.


Norm