Tech ? on Trac Control for '01 Cobra

[Rlntlscbra505]

Just recently i've noticed something unusual whenever driving which I think has to do with the traction control.
When taking off from first or downshifting from 3rd I hear a knocking type sound coming from the passenger rear. Think that confuses me is that I lifted the car and had someone pop the clutch to see what or where it was but you CAN'T see or hear a dam thing, you can only hear it from the inside. I also noticed it doesn't do it as bad with the trac control off???

Any suggestions what might it be?? I'd greatly appreciate any help??

[JERK!]

It could be due to the traction control, but it's more than likely the IRS. The bolts that connect the IRS to the subframe in the front are a tad bit too small, which causes a knocking noise. The correct size bolts should be 14mm. You can research this as it is a common problem.

Welcome to the site BTW!

[Rlntlscbra505]

Thanks for you time. I haven't had the chance to pop off the tires to see the bolts your talking about. Would those bolts that your talking about that are located in the front, cause the knocking sound in the rear?? I noticed last time whenever I punched it whenever I smoked this one G35, It didn't do it as much or as loud. One thing i did notice was whenever I first started hearing it I popped off my rear tires and got someone to pop the clutch so I could listen and possibly see where it might be coming from, and NOTHING!!! Its something that I could only hear whenever i'm inside

[JERK!]

Originally Posted by Rlntlscbra505

Thanks for you time. I haven't had the chance to pop off the tires to see the bolts your talking about. Would those bolts that your talking about that are located in the front, cause the knocking sound in the rear?? I noticed last time whenever I punched it whenever I smoked this one G35, It didn't do it as much or as loud. One thing i did notice was whenever I first started hearing it I popped off my rear tires and got someone to pop the clutch so I could listen and possibly see where it might be coming from, and NOTHING!!! Its something that I could only hear whenever i'm inside

You will probably only hear it while the suspension and drivetrain are under load. I usually hear mine when putting the car in frist gear at a stop. It's the front (not the rear) IRS bolts that have 12MM bolts from the factory but are placed in a 14MM hole. I think Maximum Motorsports sells the correct replacement bolts.

Another common clunk noise is in the steering due to worn bushings.

EDIT: Upon doing a little research on this issue this may be an 03'-04' only issue regarding the 14MM bolts, not 100% sure though.

[OldSVTGuy]

You might check the differential bushings. They are very soft rubber and have a lot of give. I changed mine this summer and was amazed at how soft they are and allow the differential to move around a lot. The front ones are easy to change; the rear requires the pumpkin to be dropped but that's the one that allows so much movement.

I changed out the IRS bolts (fronts) to the correct size and replaced bushings with poly maybe 4 years ago that helped with the clunking. But, after I replaced the differential bushings with poly and added the Billet Flow IRS brace, I have no more rear end clunks.

Good luck....