View Full Version : IRS Wheel Bearing Faulare

Pauls 04
09-08-2006, 01:00 PM
Hi guys

I am a new member and a proud owner of a 2004 Cobra. I bought the Cobra off a Ford dealership and it was already built with a Wipple super charger running 16 lbs. of boost and long tube headers just to name a few. The dino sheet that came with the car was 549 RWHP and 510 RWFT. Last week I had to have the car into Ford for some warranty work on the IRS. The car had less then 7000 miles on it and the left rear wheel bearing failed. I have heard of other IRS losing their wheel bearings and have some questions about it.

Ford replaces the hub and wheel bearing as an assemble. Can you just replace the bearing if the hub is not damaged? Does the failed wheel bearing damage the hub as a rule of thumb? Is there a better wheel bearing replacement then the stock Ford one? I fore see more wheel bearing replacement in the future.
Could the failed wheel bearing be caused by excesses heat from the disk brakes? I want to install cooling ducks to both the front and rear brakes. Any input on how to install ducking to the rear brakes?
Can the failure be due the high HP of the motor? I do feel the body flex when I get on it hard and the first order of parts are the strut tower brace, shock tower brace and the extreme sub frame connectors. I have long tube headers so I will have to fabricate the lower brace. This should help keep the body ridged. Springs, strut, shock and new bushing will be installed later as money permits. What are the best bushings to get?
Looking at my car, the rear end seems to be shifted to the left side. It is also shifted on my 1989 Mustang. Is this from the torque, or did Ford set them up this way? I have run Mustangs most of my life and they all seem to have the rear end shifted to the left side. Anybody else notice this? Can this be corrected, or do I not worry about it?
I have always wanted an IRS and won’t give it up like other have done for a straight axle because it is the best for road racing there is, and it wouldn’t be a true Cobra without it. I know that there is always room for improvement over stock, all I need is information from people that have been there and done that. Any help or input will be greatly appreciated.

Speed is like hamburger, How much can you afford.


09-08-2006, 01:42 PM
you cannot replace just the bearing. I had the left rear fail at 20K Miles, replaced it, I'm at 60k+ and no problems.

09-08-2006, 01:57 PM
what happens that you notice that the rear bearings are no good

Pauls 04
09-08-2006, 02:09 PM
The car fish tailes when you get on it. It turns to the left when you give it a little gas, and turns to the right when you let off of the gas when going down the highway. I cannot believe you cannot replace the bearings. Can they make the hub and bearing as a unit? I have work in the automotive and aircraft fields and I have never seen a bearing that cannot be replaced. Getting the bearing is a different story.

Speed is like hamburger, how much can you afford.


09-25-2006, 06:29 AM
Just an opinion, I think that the hub carrier is made of aluminum and once the bearing goes it causes unrepairable damage to the inner race surface. Just replacing the bearing will not correct the problem unless the hub carrier is not effected. Since it is made of aluminum chances are it would have to be replaced anyway. If a bearing grenades it will even damage cast iron hubs but not score it as much as aluminum.

As far as the rear offset on my 04, the rear wheels seem to be centered in the car but there is a noticable difference in track width in the rear than in the front. A 10 inch rear wheel will correct that if it has the same back spacing as the factory wheel. The reason for the difference it track width is due to the larger brake calipers and rotor assembly up front. The calipers in the rear are relatively small in comparrison and would take up the same amount of space as a drum brake. This offset may look odd but once you place a wide width wheel on the rear problem solved. The 05 and up models do not appear to have any track width difference between front and rear and if you place a wide width wheel on the rear one of them it will stick out considerably.