The "clunk" questions.

Hey all. Got the old cobra clunk going but cant seem to narrow it down as to why. The irs has all FTBR bushings with all drilled and tapped grease fittings. Ford Racing diff cover with solid mount. FTBR diff mounts, stifflers trans mount. Few things i have noticed. The irs is solid, no play as far as i can see with a pry bar what i did come to figure tho is the pass side half shaft has slightly more play on the diff side then the other. Also seems to happen more when the car gets warmer and driven hard. Anything i can check for? I know this is a exhausted thing on here just have every part upgraded to avoid all this and here i am.

Thanks.


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Did you swap out the front cradle bolts?

slo984now said:

Did you swap out the front cradle bolts?

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This is going to sound noob like but. Were are the front cradle bolts. As in the irs? I do see the button head bolts for tire clearance if those are them.


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Its where the front of the cradle mounts to the car. It's the spot the lower control arms connect to on an SRA car. They need to be upgraded to a 12mm or 9/16" bolt.

slo984now said:

Its where the front of the cradle mounts to the car. It's the spot the lower control arms connect to on an SRA car. They need to be upgraded to a 12mm or 9/16" bolt.

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I did that with the Delrin diff bushings and the clunk is gone. Ftbr sells them.

slo984now said:

Its where the front of the cradle mounts to the car. It's the spot the lower control arms connect to on an SRA car. They need to be upgraded to a 12mm or 9/16" bolt.

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Stock is 12mm, they need to be upgrade to 14mm or 9/16. I went with 9/16ths because it’s SLIGHTLY larger than 14mm


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So looking under seems that the bolts were changes to Grade 8 already. Not sure if they are 14mm or 9/16 but getting it on the lift lter and do some looking around while the rear tires off the ground in 1st. Not sure were els to look being all bushings were done all the way around.


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There is plenty to read on the subject in here ----> Suspension

As long as you have the OE half-shafts, the clunk is not going away - the tripods bang around and make the noise. An upgrade to something like the GForce models, plus all the bushings and correct 14mm front cradle bolts completely did away with the noise.

My 03 has the clunk as well. Upgraded the cradle bolts, subframe bushings, IRS bushings, control arm bushings, etc in the hopes it would go away. It didn't. I may upgrade axle's over winter for piece of mind, hopefully that does it.

I had just redone my gears from a cooked pinion bearing.

this set of gears must be tight

Cause 1st thing I noticed was that clunky sound switching gears was gone

I just find it odd that it only does it once i warm it up or do some wot pulls. Just took it for a ride and it was very tight and wouldnt clunk when on and off the gas. But the other day pulling into the carshow it felt as if the clunk was super loud. This a rear end issue?


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roy_1031 said:

Stock is 12mm, they need to be upgrade to 14mm or 9/16. I went with 9/16ths because it’s SLIGHTLY larger than 14mm


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This, bye clunk.