Upshift Clunk

[LV99Cobra]

I have a cherry black ’99 Cobra with only 45k miles on it and I love this car (tho I may sell it and get a Harley).

However, I have this clunk that is driving my nutz. And it’s not the same “Cobra Clunk” described hear in another thread.

When I got the car back in June of ’05, I thought the clunk was my shifting technique as it had been many years since I had driven a stick (other than my old Harley). But, as time has gone by, it has become more pronounced and it is certainly not my driving technique.

Here’s what happens:

When shifting from 1st to 2nd I get a clunk from the rear of the car as if there is slack in the drive line. I can sometimes avoid it by really gently feathering the clutch, but that’s really hard to do.

I get the same thing from 2nd to 3rd. Same thing if I try to feather the clutch.

It’s the same thing all the way up thru 5th. But it is less pronounced as I go thru each higher gear and feathering is easier/more effective thru the higher gears. But the toe work is still difficult.

Oddly, as you back off the throttle, there does not seem to be any drive line slack.

I had a rear wheel bearing go out and had it fixed at a “responsible and respected” local drive line shop. They said my clunk could be easily fixed ($80) and showed me some pretty good drive line play (half to one inch) between the rear of the drive shaft and the front of the diff. They said I need to go to Ford and get a “Rear Diff Housing Bushing”.

Looking at the Service Manual CD I can’t find such a part.

I thought I’d get some feedback here. As good as the drive line shop is, they are still not Stang gurooz.

Any help would be appreciated.

[Samsstang]

Iam interested in an answer on this, cause i just bought a 01 Roush last month w/30k on it and has the same exact problem

[bassman97]

I think what they are refering to is the bushings that attach the differential to the IRS cradle. Being that they are rubber, they are probably worn out enough to not hold the diff snug. I suggest getting the Maximum Motorsports IRS package if you do decide to change the bushings.

[LV99Cobra]

Bass,

Are you talking about MMIRSB-45?

Urethane Complete IRS Differential Mount Kit, 1999-04 Cobra

[LV99Cobra]

Bass, Sam,

Yes, that's it. I printed out the info on the MMIRSB-45 and took it over to the drive line shop and got a "yep, that's what you need".

I'm going to order the kit and will report back after I get the install done.

Thanks for the help.

[LV99Cobra]

The MMIRSB-45 fixed the problem.