Please help - car pulls right on acceleration and left at lift-off

[z6cyl]

New wheels and tires are on.. too much traffic right now to give it a shot.. will report back tonight

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[assclown]

What tire pressure are you running? I've found the car very sensitive to variances.

 

[z6cyl]

What tire pressure are you running? I've found the car very sensitive to variances.

Was at 32 on the 18”, Discount Tire mounted the 19”s at 40, I brought it down to 34 since they were hot

 

[z6cyl]

Still pulls left on lift off. So definitely not wheels/tires.

 

[GT Pony]

Still pulls left on lift off. So definitely not wheels/tires.

My suggestion is someone who knows what they are looking at and doing needs to look over all the suspension really good.

 

[WildHorse]

Hmmm.. hard to say but I'm betting a brake caliper is dragging.

 

[Shifting_Gears]

Check all the bushings, mounting locations and bolts on the rear subframe. My guess is you have a bad bushing, broken bolt or something to the effect that’s allowing the rear subframe to “walk” under load. It would explain the difference in direction under power versus off power. I don’t think you have a steering issue.

Alignment can be 100% spot on in a neutral setting on the rack, but the moment you’re on the road under load, it wouldn’t matter.

The car really needs to be inspected on a lift without the wheels/tires and with some pry-bars used on different mounting points to see if there’s any abnormal deflection when those spots are pryed on. You could also mount a GoPro or something under the car, different angles to try and visually see where the shift is happening.

 

[BluePonyGT]

Check all the bushings, mounting locations and bolts on the rear subframe. My guess is you have a bad bushing, broken bolt or something to the effect that’s allowing the rear subframe to “walk” under load. It would explain the difference in direction under power versus off power. I don’t think you have a steering issue.

Alignment can be 100% spot on in a neutral setting on the rack, but the moment you’re on the road under load, it wouldn’t matter.

The car really needs to be inspected on a lift without the wheels/tires and with some pry-bars used on different mounting points to see if there’s any abnormal deflection when those spots are pryed on. You could also mount a GoPro or something under the car, different angles to try and visually see where the shift is happening.

I was just thinking about this - specifically if there's some kind of toe deflection going on. Your toe links in the rear are basically welded together halves with a nut welded on one side, and a bushing on the other pressed into a welded housing. The bushing at the camber adjustment is better than the stock one pressed into the knuckle at the bottom - it's just a basic rubber bushing that isn't all that strong. Similarly in the front the lateral/tension links have standard bushings as well. If any of those are torn and allowing way too much movement then it might explain the car wanting to move in a particular direction if toe is out only on one side, but ONLY if you're accelerating.

 

[z6cyl]

Car is at a performance shop this week doing MGW shifter, clutch line, trans fluid, exhaust and checking the following:

In no specific order: toe link bushings, axle nuts, wheel bearings, IRS subframe/diff alignment, rear swaybar alignment, lower control arm bushings, ball joints, motor & transmission mounts. Anything in the suspension that could be bent/damaged from an impact. Any suspension bushings not mentioned above.

will report back

 

[Shifting_Gears]

Good luck - looking forward to hearing if any of us were right and more importantly for you to get your Stang driving in a straight line again, lol.

 

[z6cyl]

Shop reports they were unable to find anything wrong. Still waiting to hear back if they felt it on the test drive.

 

[SergioG]

Were they able to find the problem?

 

[RookieDDZ]

Just lurking and read this whole thing. I'm invested now and want to hear the end. Those upgrades should knock everything back into place.

 

[illadvised]

I had this exact same problem in my 2006 GT and I ended up finding out what the issue was.

It is a different rear end (solid axle), so its going to be a different part that is broken, but for me it was a bolt in the driver side rear lower control arm that worked its way out. The bolts/nuts used in the suspension for those cars are torque to yield and they are one time use only. So when I upgraded some suspension parts and reused the same bolts, it eventually worked its way off and fell out. So the left side of the axle wasn't connected to the control arm. Hard acceleration from the engine and the direction that the drive shaft rotates, literally turned and tilted the solid rear axle, like rear wheel steering. I could get out of the car and watch someone else drive it and on the driver side, the rear tire would move forward and back in the wheel well so the rear of the car would kick out on accel and kick back on decel

For anyone with this problem, put the car on jack stands climb under the rear with a flashlight and check all bolts and nuts, check all bushings. Look for anything loose or anything not tight. My nut fell off and the bolt was hanging half way out when I noticed.

 

[Bulldog9]

I'd have the shop check the thrust angle. I had a similar issue when I had the Steeda Springs installed. Car almost changed lanes. The Tech set alignment but didn't check the thrust angle of the rear suspension. I had to be a jerk and 3 visits to get it right.

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