Wolfmeat

I am currently running the Steeda Adjustable Suspension System on my 06 GT vert. The ride height is lowered 1.75 rear and 1.5 front. I am running 200 lbs/in springs in the front and rear. I also have Steeda's standard swaybar kit with billet mounts in the rear. The front swaybar was set to its softest setting. The ride and handling balance of the car was very good.

But now I have added a Wipple intercooled kit along with the extra 80 lbs or so of weight in the front of the vehicle. The front, although adjusted for ride height, now bottoms out occasionally where it did not before.

What would be a good spring rate to get the balance of the car back? Would a 250 lbs/in spring about right? I don't want to the front to get too stiff and encourage the dreaded Mustang understeer to return.

F1Fan

Hi Wolfmeat,

Steeda coilovers eh?How is it bottoming out, on the bumpstopsor are you getting into coilbind or some other mechanical interference? Are you on the medium 10" springs? Changing the front springs to250# springs sounds about right but with your front bar already as soft as possible you may want to buya Steeda Competition rear bar to regain the handling balance you used to have. The F250#/R200#spring rates and standard Steeda adjustable front bar and the Competition rear bar comboshould give you a nicely balanced car with the front A-R bar set to the center setting assuming you have the same size tires all around. Call Steeda and talk to Gus to confirm but you should have a sweet handlling car with the 250# springs and Comp rear bar.

HTH!

Wolfmeat

Thanks much. The bottoming was on city potholes and it is hitting the stock bump stops that were retained and reused from the old assembly.

The 250 sounded logical but I do not have the experience to know.

How much larger is Steeda's competition bar compared to their standard rear bar?

F1Fan

Hi Wolfmeat,

Withyour inital 200# spring rate all aroundyour S197GTwas probablya pretty smooth riding car and I would expect regular bottoming on rough roads with the car's ride height set at -1.5" from the stock height. If you liked thecar's balance and ridebefore the supercharger you may want toconsidera change to the Competition bar set full softand225# springsifyou are only bottoming out on potholes now and thenand willnot setyour ride height in front any lower. With a 250# spring you willvery rarelybottom out even through a pothole but the rateis starting tobe sort ofaggressive on a street car and ride may become an issue for you which is why I suggested keeping the 200# springs in back and instead using the Competition bar at the rear. The S197GTwith springs that are too close infrequencywilltend to produceunpleasantpitching ride motions andalarger differential in rates can reduce the pitching motionand you may get improvedride motion on the freeway especially at slower speeds. With a -1.75" drop in ride height at the rear I would expect your rear frame railsto be near the stock bump elastomers (unless you have installed Eibach's shorter firmer elastomers or modified the stockbump rubbers),while the car is static and the axle to be fully into the elastomer when moving and the rear D-Spec dampers set very firmly. This isO.K.with the 200# spring at -1.75"butthe car probably starts to getvery near bottoming out in the rear more than you know. You will know it when it happens,when you do actuallybottom out the S197GTwill snap oversteerhard enough to have to work at catching it if at speed.

HTH!

Wolfmeat

Hello F1Fan,

Thanks again for your response. You are an asset to this group with your knowledge.

The ride pre-whipple was very good. Due to the fact that I have the heavier vert w/whipple, comparing Steeda's Street/Comp Springs 225lb front, 185lb rear to my proposed 250lb front, 200lb rear. I should be right in the same ballpark.

I was able to get a great price on the Steeda Comp Rr SB with only new bushings to fit the billet Rr mounts that I already have.

I have also had the same concerns about the ride height. I am going to raise the height slightly to -0.75 Fr and -1.25 Rr. I may even be able to get the Rr to -1.0. This should get me more room for some suspension travel in the Rr. I've also installed the Steeda X5 ballpoints and bumpsteer kit. With their 0.75" correction this should put my roll-center right back on target. I have the bolt-on BMR LCA mounts to correct the Rr.

It is going to be a few weeks before I get to try this out. Unfortunately my Whipple developed an intercooler leak and had to be shipped back to Whipple for repair. Once I get it back on I'll let you know how it all works.

Thanks alot for your help. It helps keep my head on straight.

F1Fan

Hi Wolfmeat,

I try to help where I can. Wait a minute, your Whipple developed a intercooler leak inside the blower? Yikes! How did you figure that one out?

Cheers!

Wolfmeat

Disapearing intercooler coolant is a big clue. In approximately 100 miles I lost 8 oz of coolant. It was causing a Lean Burn condition and throwing trouble codes. I wasn't really certain 100% until I removed the blower/intercooler assembly. The waxy coating left in the intake manifold from the Redline Water Wetter is pretty telltale.

The unit was shipped back to Whipple and I'll hopefully have it back late next week.