So I have had several track days in my 302LS with some reasonable success....but not quite as quick as my other road car. In an attempt to bolster my ego and remain the quickest in my group of regulars I sent my car out to a local race shop for a complete suspension overhaul. I went with AST5200 double adjustable dampers, new springs, adjustable sway bars, camber plates, etc. etc. Also, I installed a new set of 18" BBS wheels in a square setup with a set of BFG Rivals. So, after all this work I ended up with an incredible result.....my car is now 4 seconds slower around the track than it was before I made the mods. I am not sure what the rates of the new springs are but the car is SOLID, zero nose dive on hard braking and no leaning on the turns. Has anybody experienced anything similar to this? My initial thoughts are that the spring rates are too high putting too much force on the tires which are not capable of allowing the car to setup in the corners. I am thinking a set of slicks might be the best starting point here....potentially softer springs????? Any comments would be greatly appreciated.

 

Defiantly get some hoosiers! Then come back! They make a word of difference!

Ever take the Scud on the track?

 

Yes, that's the problem. I am comparing everything to the Scud and that just isn't fair, it's basically a race car in a beautiful costume. I will try the Hoosiers and see what happens, definitely not the best feeling to be SLIDING around every corner.

 

with all the suspension work you did,
the car is now asking MORE from the tires
I have not tried the new RIVAL...I want to

I agree time for some race tires

 

Yup, bigger/better rubber should help...but it if your 4 sec slower it might not fix it. You don't want to be just as fast as you used to be after mods...you want to be faster. An R compound tire as a rule of thumb is typically a 2 sec upgrade...if your really using the tire to it's potential. That's only half of what your saying you lost so I don't think it's your silver bullet.

Seems to me like you have a few settings and or parts issues. Those 5200's are great shocks with a lot of adjustability, I have them on my STi and I am very satisfied. However, I know of other Boss guys that got rid of them in favor of Penske, JRi or Koni...even JRZ has some kick *** shocks out for the S197 chassis. I think that the ASTs low speed valving is perhaps not that well sorted for our cars. But it could be a spring problem too...or something else. Sometimes you go through parts to find the right combo...I know I did and still am.

My advice would be to try to tweak the settings to get the car as neutral as possible with the way it is now before buying tires. Maybe go to a few local Auto-X events as a cheaper way to test n tune. I don't know if the shop you went to has a lot of experience setting up S197's for the track or not. But the folks at Kenny Brown, Cortex racing or Steeda might have some insights they can share to help. But make sure you know everything about what was installed, spring rates, shock settings and alignment so they can better help you.

Just out of curiosity though...how big are the rivals? I know you can get up to a 335 in 18" in that tire and I also know that your car can get at least a 315 at each corner.

 

Your LS should have come with R-compound Corsa's. The Rivals are not an R-compound tire. That might be the difference.

 

Agree with this. I have heard the corsas don't hold up particularly well but they are R compound and should be quite sticky.

Have you tried your LS wheels/tires with the new suspension setup?

 

I would seriously look into a Cortex rear suspension setup. I have no experience with it whatsoever but have heard nothing but incredible things about what it does to Mustangs on the track.

It is very pricey so is do some research on it. But it's a torque arm/watts link setup that uses rear coilovers and it is bolt in. Those that I've read that hav used it says it allows them to accelerate with confidence starting at the apex no problem.

 

So my Corsa's with the original suspension setup lasted a total of 1,00o miles with 2 track uses. They are completely destroyed. I did however get a new piece of information that might be helpful. As I understand the stock spring rates for the are 137 lb/in Front and 191 lb/in Rear. The shop told me they installed 700 Front and 400 Rear. Is this even possible? I takes a hell of a lot of force to get any movement in a spring that stiff so I am guessing the wheels are taking up all that force. Maybe new slicks in combination with weaker springs will work.

 

I run 425 f, 200 rear on my AST setup. My guess is that your car may need some setup time.... because the parts you have on the list are good.

 

I too run the same set up 425/200 on the corsa tires and a Cortex watts link. 2.8 neg camber and 1/8"toe out. The car handles fine. I have found that 42 psi hot and soft settings on the shocks works better and you can run the curbs. The guys I know that have the R cars are running 600 front.

 

Thanks for the input guys, looks like my spring rates are way off, especially for the track I am running. Looks like I am swapping out springs ASAP.

 

Double check the factory shock rates, I believe there was some misinformation out there about front vs rear spring rates. I think the fronts are stiffer. But sounds like your car is very stiffly sprung regardless, little softer might be better?

 

2 words...Driver Mod



It takes a ton of experience in a certain chassis/vehicle to maximize the potential. I have autocrossed for years and people could not believe I was top 3 ALMOST every autocross with STOCK power and minor suspension mods. The other guys had tunes, exhaust, turbos(when I went to SM) etc and 100-200 more HP and were slower. When I switch to JRZ's I regularly made FTD. Make ONE change at a time and take your time to learn the changes. Track configuration, temp, etc, can change your times more than just a simple sway bar adjustment...


You changed a ton of components and I would expect your results. I would go back to more of the stock settings on your aftermaket suspension, back to the same tires you were running, and tweak from there. It takes a LOONG time to get the perfect "setup" and with so many changes the drive mod takes even longer. Good Luck and have fun perfecting that awesome build!

 

700/400 is WAY too stiff. Even our cars with full down force don't run nearly that high.

I would start in the 425/200 area and work from there. What size rear swaybar are you using? We try to run the smallest possible rear bar on all of our cars.

 

Why the small bar?

 

Thanks for the reply. Can you suggest a decent spring manufacturer as well as sizes I need to be concerned with as I haven't received that information from the original shop that did my work.

 

The competition Mustangs run a smaller or no bar in the rear to increase grip by allowing the back to be as soft as possible, plus with higher spring rates you're probably over stiffening the back with a bar.

Hypercoils seem to be a good name, have them on my dad's track car and they work well.

 

We always recommend Eibach first and foremost. We do have a couple of hypercoils in our stock, but they are emergency back up only.

 

Interesting, any reason or just because your preference is Eibach.