04 Cobra IRS "Swooshing" any Ideas??

TheOne2HotScott

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Hello Everyone...Newbie here, but not to the '04 Cobra. My first '04 Cobra I bought new off the showroom floor and she had the front bushing tsb done and the clutch "tube" tsb done at the same time just under 10k miles. Warranty work. Those are the only problems I ever had, other than that she was perfect and drove straight as an arrow.

Now, the 2nd was bought in '08 w/8k miles and flawless...I did notice the rear tires wore out, and the orig. owner said yeah I spun them. Who cares? right? So, I bought new rear tires and when I went to rotate them at 6k miles...they were wore out! I said no way! I don"t spin them enough for that! I got another set of rear tires and rotated them to the front and everything balanced and specifically asked the tech if anything was wrong with the rims...he said no. I've always noticed a vibration at 60-70 mph, especially on a incline, but goes away at 80+. 6k miles again, wore out...I just replaced the rear tires again last month. I had never driven the car in the rain in the nearly 3 years I've had it, but Friday my wife needed the daily driver and I drove the cobra...What I experienced! I almost,,,,,myself! The worst was at 65-68 mph, the best way I can describe it is-It felt like the rear had a mind of it's own, it felt like the tires were going right to left in a motion, but the car was still going straight, or felt like it. It felt like at any moment the rear was just going to throw the car right or left. I checked everything out today in the dry...drove her and it felt fine except around 63-68mph I could barely feel it, it must be more pronounced in the rain because I could only guess it is actually sliding back and forth. Now I know why my tires are wearing out.

I knew the warranty was out but called Ford Customer Service anyway...since I've had luck over the years w/other Manufactures fixing stuff they knew there was issues with, and with only 26k miles on her maybe I'd get lucky...Ford? O-NO once the Warranty is out they have no intention on fixing anything...

So. That's why I'm here. Anyone heard of this? If so I'd appreciate any and all responses...Thanx in advance
 

DSG2NV03

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If everything has been aligned correctly and you have no bent tie rods, my guess is that the rubber in the rear is allowing it to move around. These cars are no spring chickens and stuff wears out and wasnt good from the start. Also the front mounting points have the wrong bolts in them from the factory, so those need to be changed out. You can go with a Maximum Motorsports poly rearend or go with Full Tilt Boogie Racing Delrin rear, which I recommend. It is your choice though on how harsh or not you are willing to take your car. I am not saying the FTBR is harsh, but you will read alot on the forums the battle between the two. Me personally, I love how the FTBR feels. Others do not agree.

Alex
 
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nooner

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I replaced all my IRS bushings with the FTBR kit including aluminum diff bushings. I really only noticed a slightly harsher ride at low speed: 25 mph or slower. I agree with DSG2NV03, I love how the FTBR feels. The slightly harsher ride is a small price to pay for the reduced wheel hop and handling improvements. I actually think it feels more like a performance car should feel. If you want a nice smooth soft ride then you should be driving a GT, not a Cobra. IMO. :coolman:
 

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