Rear end Frame Knocking

jricher82 · #1 12-01-2012, 09:30 AM

I recently put the SRT on jack stands to remove the wheels and tires so I could plastidip them. I placed the stands where anyone else would, like I've done hundreds of times before.

After replaced all the wheels and taking the truck for a drive, I've noticed an audible knock coming from the rear from time to time when I hit a good enough bump or a dip in the road.

I've gotten underneath and can see something's making contact with the frame right near the brake hose bracket mount above the rear tires. Most of the time it comes from the passenger side but I've heard it from the driver side too.

One morning when it got cold and my tire pressure was low, it knocked more frequently. As the pressure rose in the tires when they get warm, it's not a frequent. (just out of curiosity, what PSI are you guys running your tires at, mine are usually between 3-35 PSI)

I've never had this problem before and it baffles me how lifting the truck temporarily would cause this problem. Anyone else experience anything like this? Any suggestions? Thanks

tonyl27 · #2 12-01-2012, 05:28 PM

make sure lugs are tightened. something easy to check. tq to 100 ft lbs.

jricher82 · #3 12-01-2012, 05:34 PM

Trust me, they're all tightened and torqued down to specs. That's not the Issue. Thanks tho, appreciate it

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tonyl27 · #4 12-01-2012, 07:28 PM

can you narrow it down by the speed your going relative to when you hear the sound?

tonyl27 · #5 12-01-2012, 07:34 PM

btw, I had a knocking sound from the front right before. i thought the worst of it, bearing or bent wheel. I started with checking the lugs, it was a tad loose but this isn't the case for you.

With that said, carefully examine from the inside of your wheel to see if any slight bends. Maybe take a picture of where you think contact is being made?

**nyjoed** · #6 12-01-2012, 08:06 PM

After market exhaust hitting the top of the rear diff housing??

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LASRT · #7 12-02-2012, 06:10 AM

I would say maybe exhaust but a picture sure would help.

**D VADER** · #8 12-02-2012, 07:45 AM

The fact that it started just after jacking up the Jeep would eliminate the exhaust unless he some how put pressure on the pipes when jacking?

**waumo** · #9 12-02-2012, 11:30 AM

I shoot for about 36-37 PSI at the ambient temperature.
So if it is 60F in garage and 30 outside, I set the pressure at about 38-39 PSI.

jricher82 · #10 12-02-2012, 01:08 PM

Think ill add a few lbs to the tires and see what that does. Never touched the exhaust.

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