Ok so I'm thinking broken subframe bushings, but I want to make sure that's the issue.

So when I accelerate the rear of the car shifts the left. It's very notaceable. Soon as I let off the gas it goes back strait. It always pulls to the left.

Here's what I know is not the issue. Coil overs, dtss bushings, bearings. Sway bar.

I already have the subframe bushings, and I also have diff mounts, and rear control arm bushings.

 

Bad diff bushings shouldn't make your car pull one direction or the other but it should feel like a big clunk/thud when you accelerate. If you have the stock bushings you'll also notice the fluid leaking out if they've split/gone bad.

The last time I had a car that went off line when accelerating the coil overs where adjusted incorrectly. They were the cylinder length and spring length adj type and the previous owner had adj the springs on some and the length on others to set the ride height so some of the coil overs were longer than others which caused serious handling issues when accelerating. Under power the car went one way off power the other. Adj the coilovers and problem solved.

I would check your toe and camber alignment 1st. Also jack up the car and grap each wheel and see if there's any play at all. There shouldn't be any. If there is movement you probably have bad pillow ***** in the rear arms and possibly bad toe links as well. If they can be moved you can usually shake the wheel with one arm/hand and feel the movement in the pillow ball with your other hand.

 

Also, one thing that will cause this exact symptom is if one of your rear tires is low on pressure. May be something as simple as that you may have overlooked.

 

YEP never overlook the obvious

I was thinking he had a 3rd gen but I can't imagine the actual subframe itself having bushings so hopefully he's just worried about the bushings or ball joints in the arms and that is probably what is going on.

 

and sometimes things you do that are overlooked, like a LSD swap without changing the stub shafts from the appropriate differential will cause a similar symptom. such as say putting a clutch type LSD into an S5 while reusing the S5 viscous shafts, the reach on the shafts are different lengths and only one side will engage the differential so one wheel will try to push the car in circles.

 

I've checked all the obvious stuff. Yeah sorry it's an fc... Is a stock diff.

This problem started right before I pulled it all apart and put a bunch of new parts, suspension, bigger turbo, and fixed all the broken stuff. I have done everything except parts listed. Has new wheels. Pressures are correct.

There not so much bushings but mounts. I already have a set.

 

then break out the prybar and start checking your work.

could be the DTSS bushings just gave up, which happens, sometimes the bolts shear off them and give similar results.

 

have you gotten an alignment recently?

and what do you mean by shift, steers left? or the body tilts left?

it could be all kinds of stuff in the rear suspension. i'd just jack it up and start wiggling things. check your toe control links for play.

 

Are your tyres the same make / model?