Rear End issues please help !!!

[2018_STINGER]

Quick rundown. 2020 RWD GT lowered had Megan Racing adjustable camber/toe/traction kit installed because I’m running 295’s on the back. I wanted it to look flush. Problem now is when put power to the wheels the rear end wants to go one way or another. Super sketchy. Can’t even enjoy it. I’ve had alignments done. Had the work of the install checked by 2 garages and still can’t find why it wants to do that. Everything is tight and the alignment is good. Please help

 

[nhcowboy28]

Stop running 100 psi in your tires.

 

[AusStinger]

Bottoming out on the bump stops ?
Control link bush gone ?

 

[StingertimeNC]

the wider you get the more you shorten your longitudinal contact patch. I'm running 275 Pilot sport 4s tires on the rear, RWD car and unless the tires are really warmed up, the rear steps out all the time. Of course I'm running JB4, map 7 with Meth, but still. the front to back contact patch is the most important thing for acceleration and breaking. The width is probably great for lateral stability (provided tires are warm and the surface is good.)

Edit, I assume you are talking about the rear sliding around under hard acceleration. If you want flush, use spacers and keep the car on 265's or 275's tops.

 

[2018_STINGER]

Bottoming out on the bump stops ?
Control link bush gone ?

Doesn’t bottom out. The bushings are brand new.

 

[2018_STINGER]

200 psi ?

Stop running 100 psi in your tires.

 

[2018_STINGER]

the wider you get the more you shorten your longitudinal contact patch. I'm running 275 Pilot sport 4s tires on the rear, RWD car and unless the tires are really warmed up, the rear steps out all the time. Of course I'm running JB4, map 7 with Meth, but still. the front to back contact patch is the most important thing for acceleration and breaking. The width is probably great for lateral stability (provided tires are warm and the surface is good.)

Edit, I assume you are talking about the rear sliding around under hard acceleration. If you want flush, use spacers and keep the car on 265's or 275's tops.

I’m thinking it’s the tires.

 

[AusStinger]

LSD failing ?

 

[2018_STINGER]

LSD (Limited Slip Differential) failing ?

I thought that too. No sounds coming from rear end. Smooth take offs ect. Only wants to act up when you put power down.

 

[BadTrainDriver]

Quick rundown. 2020 RWD GT lowered had Megan Racing adjustable camber/toe/traction kit installed because I’m running 295’s on the back. I wanted it to look flush. Problem now is when put power to the wheels the rear end wants to go one way or another. Super sketchy. Can’t even enjoy it. I’ve had alignments done. Had the work of the install checked by 2 garages and still can’t find why it wants to do that. Everything is tight and the alignment is good. Please help

Post alignment specs

 

[byebyeSTI]

sounds like a bad alignment for sure . i had the same thing happen under power the car would go into the other lane . kinda scary !

 

[StingertimeNC]

The car does allow for some slippage as long as the angle doesn’t get too crazy. Not sure if you have any power mods or not. People think if they just put wider tires on they will have more traction, for acceleration and that’s not usually the case, especially if you don’t improve the compound of the tire and can put substantial heat in the tire. At the track in mid 40 degree temps my summer tires initially had zero grip, so much so that pulling out of pit lane my rear end stepped out under the lightest acceleration. After two - four mile laps, pressure went from 31 psi to 38 psi, and I had all the grip I could ask for. As did all the other cars around me. We are talking taking 1g corners at 60-70 MPH in 45 degree weather.

 

[GT Elite]

I’m thinking it’s an alignment issue; specifically rear toe. If there is toe out the car will be all over the place and unpredictable. The other thing is how the after market pieces react to power. If there is some compliance, it could result in some toe out being induced under acceleration. In that case, the static toe in should be increased so that there is never a situation where there is toe out.

This explanation is a little more complicated. The wider tires may be part of the issue. If the centre of the tire contact patch is outbound from where the inclination angle of the suspension meets the ground there can be instability As the tires will tend to “pivot” around that point.This condition can be made worse with the user of spacers. You may want to temporality put narrower tires on to see if there is an improvement.

 

[oddball]

As said, primary suspect is alignment if this is new after the suspension change. Did they give you the alignment printout?

What rubber are you running? I'm running 285 nitto 555g2's, no problem.

When the LSD fails and you get one wheel peel then the rear end doesn't shimmy. Just the one tire spins, makes smoke and noise, and you sit there embarrassed.
When the LDS works, both wheels turn which lets the rear end dance.

Depending on what's going on, you may just finally be enjoying the car as it was meant to be enjoyed. Certainly this is how every teenager was in their muscle cars. And why so many got wrapped around trees.

 

[StingertimeNC]

That toe out thing may be the culprit. Im
Running 275’s, no issues per se, but definitely have lots of dancing going on. I have lighter rims as well so probably a bit easier to get them
Spinning. If the alignment really is good, I say welcome to a semi-powerful rear will drive. I also agree with possibly trying some skinner tires or even putting the stock wheels back in to just test the theory that narrower is better for straight line acceleration.

 

[GT Elite]

As said, primary suspect is alignment if this is new after the suspension change. Did they give you the alignment printout?

What rubber are you running? I'm running 285 nitto 555g2's, no problem.

When the LSD (Limited Slip Differential) fails and you get one wheel peel then the rear end doesn't shimmy. Just the one tire spins, makes smoke and noise, and you sit there embarrassed.
When the LDS works, both wheels turn which lets the rear end dance.

Depending on what's going on, you may just finally be enjoying the car as it was meant to be enjoyed. Certainly this is how every teenager was in their muscle cars. And why so many got wrapped around trees.

I had a clutch pack style LSD failure in a 4th gen Firebird Trans Am due to severe overheating from lapping days. With that failure, when going around corners the inside wheel would try to rotate backwards. The result was severe oversteer!

The problem was solved by going to a Torsen (geared) LSD.

 

[2018_STINGER]

As said, primary suspect is alignment if this is new after the suspension change. Did they give you the alignment printout?

What rubber are you running? I'm running 285 nitto 555g2's, no problem.

When the LSD (Limited Slip Differential) fails and you get one wheel peel then the rear end doesn't shimmy. Just the one tire spins, makes smoke and noise, and you sit there embarrassed.
When the LDS works, both wheels turn which lets the rear end dance.

Depending on what's going on, you may just finally be enjoying the car as it was meant to be enjoyed. Certainly this is how every teenager was in their muscle cars. And why so many got wrapped around trees.

295 Michelin Super Sports. Yes I’ve had 3 alignments from different places. My wheels in the rear are 19x11 with 55 offset. I’m thinking maybe just too wide of a tire or rims on my set up.

 

[2018_STINGER]

I’m thinking it’s an alignment issue; specifically rear toe. If there is toe out the car will be all over the place and unpredictable. The other thing is how the after market pieces react to power. If there is some compliance, it could result in some toe out being induced under acceleration. In that case, the static toe in should be increased so that there is never a situation where there is toe out.

This explanation is a little more complicated. The wider tires may be part of the issue. If the centre of the tire contact patch is outbound from where the inclination angle of the suspension meets the ground there can be instability As the tires will tend to “pivot” around that point.This condition can be made worse with the user of spacers. You may want to temporality put narrower tires on to see if there is an improvement.

Thank you. I will try the tires first then toe in if that doesn’t help.

 

[Stinger GT SS]

Are you still on OE Swaybars?

 

[GT Elite]

295 Michelin Super Sports. Yes I’ve had 3 alignments from different places. My wheels in the rear are 19x11 with 55 offset. I’m thinking maybe just too wide of a tire or rims on my set up.

Those are big tires and rims. I suspect the OEM alignment spec’s would not be appropriate for them. Which is to say you are going to have to come up with your own alignment spec’s.