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Brand New S550 owner, car pulls right under accel?

Racin4ds

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Hi ladies and gents, long time Mustang owner (4 foxes, 3 SN95's) but finally got my dream car last week, a 2015 GT PP1 it was a copart auction car, got it really cheap but have to put the a new front bumper and headlights on it. Anyway, during a test drive, I noticed it wants to veer to the right under heavy acceleration. Drives perfectly fine otherwise even at highway speeds. Any ideas where I need to look?
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Look up BMR alignment specs. And go get it aligned. 👍
 

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Could need a alignment. These irs cars tend to go to the right under hard acceleration or wheel spin, that's just something I have noticed on my car
 
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Racin4ds

Racin4ds

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Good to know, thanks!
 

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Hi ladies and gents, long time Mustang owner (4 foxes, 3 SN95's) but finally got my dream car last week, a 2015 GT PP1 it was a copart auction car, got it really cheap but have to put the a new front bumper and headlights on it. Anyway, during a test drive, I noticed it wants to veer to the right under heavy acceleration. Drives perfectly fine otherwise even at highway speeds. Any ideas where I need to look?
My car (bought new) did the same thing, after lots of research I ended up doing the steada irs brace and alignment kit. There is a considerable amount of play between the chasis and unibody on the s550's. Mine used to pull hard to the right on launches at the strip (almost put me in the wall in drag mode), but after the steeda irs brace and alignment it launches straight as an arrow. I love the body, motor and trans but the suspension needs a lot of work in these s550's to get them right.
 

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ORRadtech

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These irs cars tend to go to the right under hard acceleration or wheel spin, that's just something I have noticed on my car
Right? Just watch Mustangs leaving cars-n-coffee videos for confirmation...

Sorry, it was too hard to resist...
 

sms2022

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Might be slightly bent from whatever accident was in. Just get it aligned.

my car sidesteps to the left (pushing front right) on a hard shift. Not really a big deal though. I imagine it will be no issue with better tires holding the car down
 

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If you are looking for some Steeda upgrades to upfit it with, we do have our Valentine's Day Sale going on - www.steeda.com

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MexicanFiestaST

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Since you bought it used, one easy thing to rule out is whether or not the rear tires have worn identically. From personal experience, I can tell you that unevenly worn tires will cause the car to pull one direction or the other.

After 25k miles, I had developed a flat in one of the rear tires. Not wanting to have the dealer touch my car, I removed the flat tire/wheel myself, brought it to the dealer(QuickLane) to repair, and they instead replaced it, free of charge. Yay, but after I took it home and installed it, I immediately noticed the pull on heavy accels, and realized I now had two rear tires that were no longer the same diameter. To confirm this, I switched rear tires from side to side. Sure enough, the car now pulled the other direction. Doofus.

Bummed, I took the non-flat, but worn tire back to buy a new one so that I would have a matching pair. I expected to pay full price, since this one was not flat, but to my surprise, the dealer replaced that one free also. I realized that if I had brought the car in(and not just one tire), the dealer would have insisted I replace both tires at once, still without charging me. Installed the second new rear tire, and the car stopped pulling. Yay.

OCD comment: this was 25k vehicle miles. Elsewhere, I have posted that I drive the car year 'round, and install winter tires for almost 6 months out of the year, so the actual road mileage on my summer tires(one of which developed the flat) was far less than 25k miles. Still, I was amazed how noticeable the pull was, requiring significant steering wheel correction.
 

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Oakley

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the alignments on these cars are bad from the factory a lot more than ya think.
ford was doing really well over the last couple decades but in the last few years they've really started to phone in a lot of the quality.
 
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Racin4ds

Racin4ds

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Since you bought it used, one easy thing to rule out is whether or not the rear tires have worn identically. From personal experience, I can tell you that unevenly worn tires will cause the car to pull one direction or the other.

After 25k miles, I had developed a flat in one of the rear tires. Not wanting to have the dealer touch my car, I removed the flat tire/wheel myself, brought it to the dealer(QuickLane) to repair, and they instead replaced it, free of charge. Yay, but after I took it home and installed it, I immediately noticed the pull on heavy accels, and realized I now had two rear tires that were no longer the same diameter. To confirm this, I switched rear tires from side to side. Sure enough, the car now pulled the other direction. Doofus.

Bummed, I took the non-flat, but worn tire back to buy a new one so that I would have a matching pair. I expected to pay full price, since this one was not flat, but to my surprise, the dealer replaced that one free also. I realized that if I had brought the car in(and not just one tire), the dealer would have insisted I replace both tires at once, still without charging me. Installed the second new rear tire, and the car stopped pulling. Yay.

OCD comment: this was 25k vehicle miles. Elsewhere, I have posted that I drive the car year 'round, and install winter tires for almost 6 months out of the year, so the actual road mileage on my summer tires(one of which developed the flat) was far less than 25k miles. Still, I was amazed how noticeable the pull was, requiring significant steering wheel correction.
Good to know! I'll certainly check this evening and see what I have for rear tires. I know the car came with mismatched tires, rear tires are fairly new looking Continentals and fronts are Michelin Pilots.
 

Cobra Jet

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Since it is a CoPart S550, I’d suspect there may be other underlying damages you have not found yet.

I would definitely check the rear diff bushing mount locations. These are very well known weak spots on the S550 for the securing bolts to break within the mount. If this has happened, upon acceleration and torque of the rear, the car can and will go either left or right instead of a hard straight line.
 

ORRadtech

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Since you bought it used, one easy thing to rule out is whether or not the rear tires have worn identically. From personal experience, I can tell you that unevenly worn tires will cause the car to pull one direction or the other.

After 25k miles, I had developed a flat in one of the rear tires. Not wanting to have the dealer touch my car, I removed the flat tire/wheel myself, brought it to the dealer(QuickLane) to repair, and they instead replaced it, free of charge. Yay, but after I took it home and installed it, I immediately noticed the pull on heavy accels, and realized I now had two rear tires that were no longer the same diameter. To confirm this, I switched rear tires from side to side. Sure enough, the car now pulled the other direction. Doofus.

Bummed, I took the non-flat, but worn tire back to buy a new one so that I would have a matching pair. I expected to pay full price, since this one was not flat, but to my surprise, the dealer replaced that one free also. I realized that if I had brought the car in(and not just one tire), the dealer would have insisted I replace both tires at once, still without charging me. Installed the second new rear tire, and the car stopped pulling. Yay.

OCD comment: this was 25k vehicle miles. Elsewhere, I have posted that I drive the car year 'round, and install winter tires for almost 6 months out of the year, so the actual road mileage on my summer tires(one of which developed the flat) was far less than 25k miles. Still, I was amazed how noticeable the pull was, requiring significant steering wheel correction.
On a similar note, the front tires need to be the same size (I have seen front tires mismatched on used cars before) and of similar wear.
Not doing this can result in the electric steering rack failing.
My daughter learned this the hard way on her Focus. The subframe had to be dropped to replace the rack. Took my son and I about 6 hours on jack stands...
 
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Racin4ds

Racin4ds

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Since it is a CoPart S550, I’d suspect there may be other underlying damages you have not found yet.

I would definitely check the rear diff bushing mount locations. These are very well known weak spots on the S550 for the securing bolts to break within the mount. If this has happened, upon acceleration and torque of the rear, the car can and will go either left or right instead of a hard straight line.
Ahhh OK makes perfect sense, thank you! I have no issues with repairing it, I've turned wrenches for a very long time, just very new to this IRS setup.
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