Rear Differential Bang 7AT OE LSD

Tractionless

At parking lot speeds when getting on the gas from a roll or upon slow speed manual downshifts followed by throttle application I will get a intermittent metallic bang that sounds like hitting the rear end with a sledge hammer. It has also happened when going from park to drive or park to reverse on occasion.

It sounds similar to the noise a LSD aftermarket mechanical differential can make when locking like my 2020 Silverado 1500 does.

While I understand a car can be put back to stock, when I bought it used in 2017 w/72k miles on it, tint wasn't even applied to the windows so it's doubtful the OE LSD was replaced with an aftermarket diff.

I only do spirited street driving, never drag raced, autox'd, etc. and currently have 102k miles. Pertinent mods are; OE subframe bushings with Z1 collars, diff. brace bolted to the subframe, and Whiteline poly diff bushings.

Would this noise be indicative of upcoming diff. failure or can it be attributed to sudden slack take up between the pinion and ring gears?

Thanks for any insight you can lend.

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Spooler

What diff bushing do you have and are your subframe bushings stock also?

Tractionless

Yes I realized later in the day after I posted these variables would help the diagnosis so I edited the OP with the info. below as well for the archives.

OE subframe bushings with Z1 collars, diff. brace bolted to the subframe, and Whiteline poly diff bushings.

As you've probably noticed I was doing a VR30 trans swap recently and checked the diff. bolts and brace bolts when under the car., all tight Additionally, the noise was present with both transmissions. Really sounds like a loud "ping" as if you hit the diff housing with a substantial hammer.

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Spooler

Yeah, I have had that sound too. Check your axle nuts. One of mine was loose but they are DSS axles with no Locks on the nuts. I have to check them from time to time. It turned out it was a U-joint in my driveshaft. I have a new DSS Carbon fiber driveshaft now.

Tractionless

Ok thanks for the input on your experience!

I'll get a look at the axle nuts as soon as I can and already have Kawi nuts in the toolbox waiting on install the next time I pulled the wheels.

The driveshaft is a new Godzilla for the VR30 swap that was at a driveshaft shop for rebalance and they blessed the assembly less than 500 miles ago. I'll definitely check the U-joints if the problem persists after replacing the axle nuts and update the thread on my findings for the archives.

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