[joeduquette]

Hey guys, anyone have problems holding power after upgrades? I have FBO, MHD stage 2+ tune, dinan springs and a 235/265 MPS4S setup. The cars feels amazing except when really punching it. The back end gets squirrelly under load, the wheels don’t spin out but it doesn’t feel planted at all. Actually feels dangerous but still kinda fun lol. I’ve ordered powerflex rear diff and subframe bushing inserts to see if that helps, if it does I’ll eventually change out the bushings to stiffen everything even more. I’ve checked my tire pressures and they were all good. Has anyone else had this problem? Thanks!

[dradernh]

Originally Posted by joeduquette

...when really punching it. The back end gets squirrelly under load, the wheels don’t spin out but it doesn’t feel planted at all.

Do you have a limited slip differential installed?

[joeduquette]

Originally Posted by dradernh

Do you have a limited slip differential installed?

No LSD wasn’t sure if that would help the problem, I’ve read mixed reviews. How have your subframe bushings been?

[dradernh]

Originally Posted by joeduquette

No LSD wasn’t sure if that would help the problem, I’ve read mixed reviews. How have your subframe bushings been?

From a performance perspective, the base car needs an LSD. You will definitely improve the car's ability to get and stay hooked-up by installing one.

My solid Al subframe bushings have had no discernable downsides over the last 9K miles of street driving. I considered them and the LSD as a pair to be installed at the same time, and that's what I did.

I'm in the 'burbs outside Cincinnati, and the roads here are so-so. They're better than where I used to live in New England. Still, between raised manhole covers and things like surface imperfections and the rare minor pothole, I do get the chance to see how the coilovers, front swaybar, and rear subframe bushings react to less-than-perfect roadways.

The difference I perceive is that the front's a little noisier than stock, and that's pretty much it. I'm getting nothing from the rear to tell me that I made a change, much less that it was a change for the worse. FWIW, I had the LSD and rear subframe bushings installed at 2K, and those miles were pretty much all highway miles at 65-70 MPH; so, not much to compare to.

What I will say is that the rear of this car hooks-up very well. I might not be able to say that if I only used the car on the street (where I don't drive particularly aggressively), but it was true on the track as well, where a lot more was asked of the car when exiting corners.

Cost aside, I recommend stiffer bushings to go with an LSD.

[joeduquette]

Originally Posted by dradernh

From a performance perspective, the base car needs an LSD. You will definitely improve the car's ability to get and stay hooked-up by installing one.

My solid Al subframe bushings have had no discernable downsides over the last 9K miles of street driving. I considered them and the LSD as a pair to be installed at the same time, and that's what I did.

I'm in the 'burbs outside Cincinnati, and the roads here are so-so. They're better than where I used to live in New England. Still, between raised manhole covers and things like surface imperfections and the rare minor pothole, I do get the chance to see how the coilovers, front swaybar, and rear subframe bushings react to less-than-perfect roadways.

The difference I perceive is that the front's a little noisier than stock, and that's pretty much it. I'm getting nothing from the rear to tell me that I made a change, much less that it was a change for the worse. FWIW, I had the LSD and rear subframe bushings installed at 2K, and those miles were pretty much all highway miles at 65-70 MPH; so, not much to compare to.

What I will say is that the rear of this car hooks-up very well. I might not be able to say that if I only used the car on the street (where I don't drive particularly aggressively), but it was true on the track as well, where a lot more was asked of the car when exiting corners.

Cost aside, I recommend stiffer bushings to go with an LSD.

Thanks for the write up! I’m hoping these bushings help and guess I’ll have to look into the LSD now. Glad to hear the ride isn’t affected that much on the street tho.

[HP Autosport]

Originally Posted by joeduquette

Hey guys, anyone have problems holding power after upgrades? I have FBO, MHD stage 2+ tune, dinan springs and a 235/265 MPS4S setup. The cars feels amazing except when really punching it. The back end gets squirrelly under load, the wheels don’t spin out but it doesn’t feel planted at all. Actually feels dangerous but still kinda fun lol. I’ve ordered powerflex rear diff and subframe bushing inserts to see if that helps, if it does I’ll eventually change out the bushings to stiffen everything even more. I’ve checked my tire pressures and they were all good. Has anyone else had this problem? Thanks!

Subframe bushing flex can cause what you are describing and so can toe changed. Look into a set of adjustable toe arms as well to take away toe changes under acceleration. You may want to consider solid vs urethane bushings.

[joeduquette]

Originally Posted by HP Autosport

Subframe bushing flex can cause what you are describing and so can toe changed. Look into a set of adjustable toe arms as well to take away toe changes under acceleration. You may want to consider solid vs urethane bushings.

Thanks for the response! Installed power flex bushing and it did make a noticeable difference. Much more planted on the rear and can smoothly put the power down

[HP Autosport]

Originally Posted by joeduquette

Thanks for the response! Installed power flex bushing and it did make a noticeable difference. Much more planted on the rear and can smoothly put the power down