15 Base GT rear suspension upgrade suggestion

[MineralCobra]

Hello everyone,

Have a 2015 GT with a whipple and 6spd tranny.. making probably 800+ car is only raced on rolls 40mph etc never at 1/4 mile track or being launched ..

Car hooks greats but rear suspension feels way to soft.. car squats hard which is good for weight transfer but feels like almost hurts the shifts by how much travel " bounce" there is.

Suspension is 100% stock and rides great I do not want to lower the car or ruin the ride..

What is at the minimum that you guys would suggest upgrading in the rear suspension area. Looking to change out weak links.

Thanks

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[Norm Peterson]

Hello everyone,

Car hooks greats but rear suspension feels way to soft.. car squats hard which is good for weight transfer but feels like almost hurts the shifts by how much travel "bounce" there is.

If anything, a lot of squat does more to lessen the shock to the tires. At 800+, you might want to consider that more important than the aesthetics of squat.

Understand that squat does not create "weight transfer". Squat is only the visible evidence that weight transfer is happening and that the suspension is indeed not totally rigid or set up for 100% anti-squat.

"Weight" transfer (more accurately "load transfer" because none of the car's weight is actually moving rearward except for some fluid slosh and loose cargo/passengers) happens due to (1) your acceleration, (2) the car's CG height, and (3) the length of the car's wheelbase.

Suspension is 100% stock and rides great I do not want to lower the car or ruin the ride.

My first thought would be rear shocks with better low-speed bump damping (shock piston speed here, not car mph's). Next would be mildly firmer springs - BMR's SP088 springs at 800 lb/in and minimal lowering (about half an inch). Consider Steeda's spring spacers if you don't wish to lower the rear (you'd probably want their 1/4" spacers because 1/4" at the spring corresponds to about 1/2" at the tire).


IRS cars tend to squat more than their stick-axle predecessors because the tricks that people did to increase the side view anti-squat geometry with their stick axles isn't as readily available for most IRS designs. So to a large extent, you're stuck with it unless somebody figures an easy way to put more anti-squat in the geometry (I'm not exactly holding my breath on that). You might get a little improvement by replacing the integral links with links that use rod ends, but I wouldn't count on getting a whole lot of help like you could with relo bracket settings on an S197 or a Fox.

You're also getting a lot of nose rise, which is adding to the perception of squat since what you're seeing comes from more than just the tail squatting. Nose-up + tail-down gives the full picture of pitch, which is a side view angular change and shows up in any rear-facing camera view.


Norm

 

[NightmareMoon]

I’d guess that a fresh set of the bilstein or ford racing monotube shocks will help quite a bit. if you’ve never changed your stock shocks, I’d guess the stock ones are possibly shot from mileage as well.

Yes the base springs are very soft and can bottom out onto the bump stops so a mild spring increase may help too, even just to the PP1 shocks.

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