Rear End Not Centered Under Car!

My 80k mile cobra IRS is off center towards the driver side at least 1/4" if not more. I am a huge fan of good stance so this really gets me. I have been trying to figure this problem out for awhile. When I measure from the quarter panel to the tire on both sides the driver side sticks out 1/2" to 3/4" more than the passenger side and it drives me nuts. I have had the rear end out and done FTBR bushings and it did not change. When I take a picture from directly behind the car it is noticeable. Car Fax says that it had minor driver side rear undercarriage damage at 30k miles but I can not seem to find any spots of damage or repair. At this point I am considering pulling the rear end and modifying the cradle to center it. Really looking for some advice and or someone else who has experienced this same thing.

that would drive me nuts as well. i hope this an easy fix.

welcome to owning a mustang.

I believe the solid axle guys can center it with a panhard bar, not sure how that works with the IRS cars

Mine is the same way.

This is a pretty common. I believe it is more often apparent when switching to wider rear wheels and tires. One side will rub on the IRS frame and the other side will not.

are you guys talking about rubbing inside or the fender? my tires seem to be pretty much the same and my IRS centerline holes line up with the center line of the car.

Makobra said:

are you guys talking about rubbing inside or the fender? my tires seem to be pretty much the same and my IRS centerline holes line up with the center line of the car.

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I never have any rubbing but I do notice it out of line easily by eye. I want to go lower and wider but I need my IRS centered first. Any chance you have a pic or can describe the holes location you say line up so I can check mine?

Rambro said:

Mine is the same way.

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To the driver side? Everyone else I have talked to says it goes to the passenger side. Makes me wonder if my car is damaged.

if you look at the IRS frame there are 2 holes that are dead center, one on the main big hoop in the back, and the other above the drive shaft. when i lined up my k member i found out that these holes lineup perfectly with the hood support bar in the front.

this is only really visible if the entire drivetrain is out of the car BUT you can get to the main hoop hole, drop a plumb bob from it, and then measure the distance to other plumb bobs if you really want to check.

it also could be that your alignment is off and giving the illusion of this (or that my alignment is off so it looks fine).

that's a lot of brain vomit but i hope it helps.

Mines same way. 5/16" spacer on driver, 1/2" on passenger. 18x10s

Maybe the camber just needs to be adjusted on the driver's side and that's why the top of the tire sticks out farther...?

TerminatoRS said:

Maybe the camber just needs to be adjusted on the driver's side and that's why the top of the tire sticks out farther...?

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I thought the same thing. I am going to check all possibilities before any major modification. I just assumed I would notice by eye the camber if it was that far out.

It's a mass produced car. I've seen somewhere that Ford's tolerance is something like a 1/2". The IRS in my 01 was centered. The one in my 04 is offset to the passenger side. I'm running a 1/4" spacer on the driver side to even things out.

My 01 is the same way. Towards driver I believe.

My car is same also. Drivers side sticks out farther. Thought it was alignment issue had it on the rack and everything was in spec. After going thru everything under the car just figured it was normal. I have FTBR as well.

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after doing some research and looking at my car I'm really glad this thread was posted because I think I would've been thinking I did something wrong with the install if my sn95 is the same way. its not off by much but the drivers side does indeed seem to stick out a bit more. that's pretty annoying but I'm too far down this road to turn back now

When we did the IRS swap on my 98 we measured where we would be installing it by looking at the 01 Cobra we had. Everything lined up correctly and measured perfectly. If you are concerned it may have a slight tweak in the rear of the vehicle I would take the car to a bodyshop and have the frame checked. If anything they should be able to straighten out what little bit they may find.

i measured the driver's side and sure enough its about 3/16" further out than the passenger side.
so weird. i'm going to have the car aligned then do measurements again after that.

Mine is not centered either. Not super noticeable on stock rims but have a set of 10.5"s I'm throwing on the back and figured I'd have to space out one side to correct.

This is a very common issue on the SRA mustangs.