'11 GT500 pulls hard to the left under hard acceleration

[Glenn Manser]

As the title states, this is in at various speeds when heavy throttle is applied with full traction control on or Advanced Trac Sport Mode. Is this normal? I tried searching the forums for an answer but couldn't find anything specific to this.

I've noticed in from take-off and after downshifting two gears from 5th to 3rd at about 40 mph.
What happens is the car jerks the wheel to the left and as I let off the accelerator it straightens back out. It isn't confidence inspiring at all.

Any help would be greatly appreciated... I have nearly brand new Goodyear's that are the same as came with it from the factory with the Performance Package (staggered set directional, non-rotational tires). Only other modification is the JLT carbon-fiber airbox.

*I also had an alignment done when the new tires were put on. This was something I'd noticed before putting the tires on it. It has the 3.73 and LSD.

 

[Speedboosted]

Well you're about to get flamed for putting the Goodyear's back on...new lower control arms really helped the car track straight ahead when under power.

 

[SirShaun]

When you do a burnout, do you get 2 identical black marks?

 

[Speedboosted]

When you do a burnout, do you get 2 identical black marks?

Ooooo, didn't think about that. His carbon clutch disks could be worn out in the diff. Good thought

 

[SirShaun]

Anything in the rear, shouldn't be jerking the steering wheel to the left tho. I kind of over read that part.

Have someone rev the car while your looking at the engine. If it moves a lot, it could be a motor mount, moving the steering linkage when under power.

 

[SirShaun]

Also the 11+ cars have Power Assisted Steering.

I found a TSB in regards.

TSB 10-16-4

5.4L - STEERING SHUDDER/NIBBLE/PULL/DRIFT - BUILT ON OR BEFORE 8/2/2010
Publication Date: August 13, 2010
FORD:
2011 Mustang

ISSUE:

Some 2011 Mustang Shelby GT500 vehicles equipped with a 5.4L engine and built on or before 8/2/2010 may exhibit steering wheel shudder under heavy braking, steering wheel nibble, or a drift/pull condition.
ACTION:

Reprogram the Electric Power Assisted Steering (EPAS) Power Steering Control Module (PSCM) module to the latest calibration using IDS release 67.06 and higher. This new calibration is not included in the VCM 2010.5 DVD. Calibration files may also be obtained at www.motorcraft.com.

WARRANTY STATUS:

Eligible Under Provisions Of New Vehicle Limited Warranty Coverage
IMPORTANT: Warranty coverage limits/policies are not altered by a TSB. Warranty coverage limits are determined by the identified causal part.

 

[CLS64]

Sounds like friction clutched in the rear diff. Bu, if the car is breaking the tires loose and moving to one side check to see if the rearend is centered - can be off to one side if car has been lowered and an adjustable panard bar was not used. Good Luck.

 

[Glenn Manser]

thanks for the info. I will look into the TSB you suggested and if that doesn't fix it I will check on the rear diff or symmetry of the rear axle

 

[Catmonkey]

Are you actually experiencing the steering pulling or is the ass end wondering in one direction when it breaks traction? When you mentioned new tires, I would check my air pressure to make sure both back tires are inflated to the same pressure.

 

[99SSls1]

I was thinking the same thing.

 

[Cuda426]

Sounds like bump steer, but since you mentioned that the only mod it has is a JLT airbox, I would be looking at the alignment. Where did you have the alignment done? With electric power assist steering, I'm pretty sure they have to hook up the codelink module so when tow is adjusted that the computer knows where the steering wheel center is. Sounds like they may have skipped that step.

Is the car lowered? If so bump steer could be a factor.
Did you install new wheels with a different offset? If so then Scrub radius could be a factor