Need some help with 2012 GT shaking/shimmy 60mph+

[MisterFurious]

And we removed the washers off the studs before we put the 20s on?

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No washers

 

[MisterFurious]

I have always thought that a bent axle will produce a rear vibration, wobble or poor tracking (i.e., crab walk)... Not really a dash shaking, which is indicative of a front end issue... even a bad DS will produce vibration up through the transmission tunnel and into the cockpit, but he's only experiencing shake in the dash area?

Let's take the rear end issue out of the equitation... Put the rear up on jack stands and BLOCK/CHOCK the front tires so car does not roll away! Put the car in gear...Then watch from each side rear-to-forward along the body lines if the tire/rim assembly has any pronounced wobble. Being it's a manual gear box this might be a 2-person job, but you should be able to stick it in 1 or 2 and let it slow roll... You do NOT want to go up to 70MPH, only slow turning the rear tires to see if axle, wheel or housing is warped.

Dash definitely shakes, mirror shakes, windshield phone mount, steering wheel

 

[2011/5.0]

Would disconnecting the one piece shaft and rotate it half a turn, reconnect it and see if it gets worse or better help?

This....I had a 1 peice I had to clock 180° to get rid of a vibration.

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[yote0]

I had a dragging RF brake caliper causing similar issues. The worse the rotor warped due to the excessive heat, the worse the symptoms got.

 

[MisterFurious]

I have always thought that a bent axle will produce a rear vibration, wobble or poor tracking (i.e., crab walk)... Not really a dash shaking, which is indicative of a front end issue... even a bad DS will produce vibration up through the transmission tunnel and into the cockpit, but he's only experiencing shake in the dash area?

Let's take the rear end issue out of the equitation... Put the rear up on jack stands and BLOCK/CHOCK the front tires so car does not roll away! Put the car in gear...Then watch from each side rear-to-forward along the body lines if the tire/rim assembly has any pronounced wobble. Being it's a manual gear box this might be a 2-person job, but you should be able to stick it in 1 or 2 and let it slow roll... You do NOT want to go up to 70MPH, only slow turning the rear tires to see if axle, wheel or housing is warped.

I put it on jack stands this morning. I put sharpie marks on the bottom of the car in line with the tire treads and slow rolled it, no noticeable wiggle or oval. Pretty much right down the center all the way around. I looked at the side profile and no wiggle either.

 

[MisterFurious]

Your 2012 doesn't have band tpms sensors. What does the diff upper bushing look like? Has the pinion angle been checked? Bushings on lca's, what do they look like? Lots of stuff to check to make an accurate diagnosis.

I checked diff bushings, lower control arm bushings, all across everything looks very good. This car hasn't been beat on, or run with slicks/drag raced, so it's pretty fresh under there.

 

[JC SSP]

Hmmm didn’t think about sticking caliper. Since this will usually cause a pull while driving and/or braking but definitely need to be looked at.

After a short drive, touch the rim and/or brake caliper. If brakes are hanging up it will be HOT! If not, it will be warm.

Also, you can jack up the front of the car. Hand turn the rim/tire. If it won’t budge or you are struggling to turn the wheel then you might have a sticking caliper.

While your there check ball joints hands at 12-6 on the tire with a good tug back and forth. Also tie rods again hands 9-3 and same move of back and forth looking for any play/loose ends movement.

 

[JC SSP]

Yeah I didn’t think you had a rearend issue mostly because when they did an alignment and I am assuming it was at a reputable shop, they would have done a “thrust angle” alignment which uses the rearend as the centerline for the front wheels. If rearend would be significantly off-center it should have shown up then.

I continue to believ to have an issue up front but not really sure what it could be…

 

[MisterFurious]

Calipers were just rebuilt when the brakes were done, about 500 miles ago. I've checked both fronts and they spin freely, and the backs as well. ZERO play in front wheels also, ball joints were new as part of the new front control arms, and new tie rods, also about 500 miles ago. None of these changes affected the vibration whatsoever (unfortunately)

 

[MisterFurious]

It seriously feels like an slightly out of balance washer on spin is mounted to my hood

 

[JC SSP]

One option… Take it to a shop with a 4-post lift. Get in it and run up to 70 mph. Have tech inspect the undercarriage while its shimmy and shaking. True the suspension will not be under load but you will be able to have someone underneath while it’s at speed.

 

[JEWC_Motorsports]

If all in the suspension is good then you have 1 issue left to look at imo. The steering rack. They are known to fail and cause a vibration. You can search for boss 302r racks, a few have gone to them. I have one sitting in my garage waiting to install. My 2012 shakes when it wants and then will clear up and be shake free for months. If I was still drag racing I'd swap to a manual rack.

 

[MisterFurious]

Watched a few videos of people with EPAS issues... doesn't seem to be the same symptoms as mine has, mine is definitely rotational, not just a continuous shake-- and not effected by traction control either. Just to rule that out

 

[DieHarder]

What you're describing sounds like effects due to out of balance rotational masses. That makes the primary culprits wheels/tires; rotors; driveshaft; rear end. Understand you checked this but Might be beneficial to switch back to original tires after spinning them first. If still present rotate back to front. That will eliminate wheels/tires. Then I'd go after rotors. In my own case I found the washer used to keep the rotors on can create a severe shaking in the front. By chance can you check run out on the front wheels?

Agree, it'd be worthwhile to get it up on a lift and run it up to speed to check/ eliminate the driveshaft/rear end.

 

[MisterFurious]

What you're describing sounds like effects due to out of balance rotational masses. That makes the primary culprits wheels/tires; rotors; driveshaft; rear end. Understand you checked this but Might be beneficial to switch back to original tires after spinning them first. If still present rotate back to front. That will eliminate wheels/tires. Then I'd go after rotors. In my own case I found the washer used to keep the rotors on can create a severe shaking in the front. By chance can you check run out on the front wheels?

Agree, it'd be worthwhile to get it up on a lift and run it up to speed to check/ eliminate the driveshaft/rear end.

Unfortunately I don't have the original rims and tires, but the shimmy started when those were installed, and it did not go away or change at all when the rims were changed (or multiple sets of tires). Again, issue was unchanged after new power stop extreme brake kit was installed. Since it didn't make any change whatsoever with those changes, I'm about 99% sure we did eliminate those as a culprit..

trying to find a shop that wants to run my car up to 70 on a lift... know anyone in Raleigh? I haven't found a reliable one yet

 

[OX1]

Unfortunately I don't have the original rims and tires, but the shimmy started when those were installed, and it did not go away or change at all when the rims were changed (or multiple sets of tires). Again, issue was unchanged after new power stop extreme brake kit was installed. Since it didn't make any change whatsoever with those changes, I'm about 99% sure we did eliminate those as a culprit..

trying to find a shop that wants to run my car up to 70 on a lift... know anyone in Raleigh? I haven't found a reliable one yet

For the amount of money you spent so far, might be just worth buying a cheaper scissor lift and do it yourself, if no one else will.

https://www.ebay.com/itm/1656967263...IZd/Lw8CmwXM+X36pdiGY03B6RE=|tkp:BFBM9Oqj5qpi

 

[JEWC_Motorsports]

So stupid question time. Do you have the stock rotor retaining clips installed? They go on the wheel studs. If your new wheels do not have provisions for them it will cause a vibration.

not my pic but this is what im referring to.

 

[DieHarder]

Unfortunately I don't have the original rims and tires, but the shimmy started when those were installed, and it did not go away or change at all when the rims were changed (or multiple sets of tires). Again, issue was unchanged after new power stop extreme brake kit was installed. Since it didn't make any change whatsoever with those changes, I'm about 99% sure we did eliminate those as a culprit..

trying to find a shop that wants to run my car up to 70 on a lift... know anyone in Raleigh? I haven't found a reliable one yet

You say you added an extreme brake kit. Did that kit include rotors?

 

[MisterFurious]

You say you added an extreme brake kit. Did that kit include rotors?

Yes, new everything, and had the calipers rebuilt.

 

[MisterFurious]

So stupid question time. Do you have the stock rotor retaining clips installed? They go on the wheel studs. If your new wheels do not have provisions for them it will cause a vibration.

not my pic but this is what im referring to.

View attachment 88277

No washers or clips