The Mustang Forum for Track & Racing Enthusiasts

Taking your Mustang to an open track/HPDE event for the first time? Do you race competitively? This forum is for you! Log in to remove most ads.

  • Welcome to the Ford Mustang forum built for owners of the Mustang GT350, BOSS 302, GT500, and all other S550, S197, SN95, Fox Body and older Mustangs set up for open track days, road racing, and/or autocross. Join our forum, interact with others, share your build, and help us strengthen this community!

My GT suspension mods - P springs and Boss shocks

Grant 302

basic and well known psychic
I only had a couple of hours to work on the car today...so I only got some of the mods done on the rear so far. It's a 2011 Brembo package GT, and previously had the '55D' 1/2" drop linear springs from Brembo50.com. The front is stock except for camber bolts. I put in the P springs, Boss shocks, and a J&M adjustable panhard bar.

I'm not a fan of leaving things half done, but I took it for a spin that way. So far, I'm really quite impressed. I put the Boss shocks on 5, since I was concerned that they wouldn't be stiff enough for the P springs...but so far it seems well matched for the street and I like the damping so far. I'll try them later at 3. The stock shocks with the '55D' springs seemed a little mismatched...shocks are probably too soft for a linear spring.

Good news is that it corners way flatter now. Off the cuff, I think it's flatter than the stock Boss even though the front is about 1/2" higher. Brake dive is much improved too. Seems better than the Boss with moderate braking, but not as good under heavy braking...at least until the nose settles. The results are surprising to me, but with a 1" drop in the rear and 1/2" up in front compared to the Boss, the CG should still be a net drop, right?

So I'm guessing that most of the benefit from lowering our cars is from the 4x4 reduction in the rear.
 
I'm a bit confused, did you only install the rear springs and shocks? if so I'm surprised by your results but wait until you get the front springs on.
 

Grant 302

basic and well known psychic
5 DOT 0 said:
I'm a bit confused, did you only install the rear springs and shocks? if so I'm surprised by your results but wait until you get the front springs on.

Yeah, just the rear springs, shocks and panhard today. Can't wait to get the fronts on. I should be doing the front in a day or two...along with the CoolTech front tow hook...pad and rotor swap...and another brake duct kit. Gonna be a long day.

Originally, the plan was to use the 55D rears and the Boss front springs, but I'm not sure if I want the drop from the P springs on the front too.
 

Grant 302

basic and well known psychic
Went with the P springs and Boss struts on the front yesterday...and this morning after *finally* figuring out how to tighten the strut top nut all the way...I finally got to take the car for a spin...

And it's like a whole new car! ;D ...or RCWALP... Seems like this should be the way that the LS cars should have been setup from the start. Reminds me of driving the FR500S without the harshness or the brake clunk.

Now it definitely handles better than the street Boss. There's a tendency to push, but that's expected for the staggered tires and a square suspension setup. Pitch and roll are all very well controlled at the limits of the Pirellis. Can't wait to try it with the R6s. I don't have the LCA anti-squat brackets and it is easier to break the rears loose in straight line acceleration.
 

TMO Supporting Vendors

Buy TMO Apparel

Buy TMO Apparel
Top