LS6427

iTrader: (2)

So any time I'm moving at any speed say under about 50mph....just cruising steady.......if I hit the pedal to the floor and the rear end slightly drops down I hear like a "crunch" sound. Or maybe a very hard "rub" sound. Then the car just accelerates quietly and normally. Its only when I smash the pedal down. From a dig....its a longer "crunch" sound.....

Two days ago......a visual check of the entire rear-end was done by a power train shop as they were changing an axle seal for me. They saw nothing.

Maybe a shock as it compresses....?

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3 pedal SS

iTrader: (1)

My first guess would be tire rub. Check the tires and inner fenders for signs of it.

LS6427

iTrader: (2)

A member here did bang my inner wheel wells to fit the new wheels....18x10.5 rear with 315's. Maybe it needs a bit more in a spot......

Ill check tomorrow.

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leadfoot4

iTrader: (1)

With THAT big a tire, do you have an adjustable panhard bar?

joecar

Rear bump stops hitting and compressing...?

LS6427

iTrader: (2)

Yes....UMI adjustable panhard bar.........

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LS6427

iTrader: (2)

Bump stops have been removed....12 years ago.

Its like a "grrrrrrrrrr" sound.....like a grinding sound. Like a blender sound for just one second.....then it goes away as the car continues accelerating. Its very loud, very easy to hear.....but I cannot pick it up on my phone.....can't hear it on the playback.

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LS6427

iTrader: (2)

I can probably stick my fist on the inside of each tire and inner wheel well......theres that much room. On top of each tire to the wheel well roof...probably 4-5 inches. No rub marks anywhere.......

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LS6427

iTrader: (2)

Regarding my other thread about my sway bar being removed.....

******I removed my sway bar today because I lost the brackets while driving and I noticed it just hanging on the end-links.......

I was hoping that was the noise I'm hearing. So the sway bar and both end links are removed now.

Noise is the same........still there.....

........

LS6427

iTrader: (2)

How about a shock that has a problem like its binding up......? Could it make a grind noise on the initial WOT hit when the rear end drops and compresses the shocks......?

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JD_AMG

So does it only make this sound when you go WOT or when you hit a bump too?
If its only when you go WOT (or any throttle input) it is probably drive train related, maybe something in the rear end itself is going bad (bearings, clutches, gears etc.)
If you get the noise on bumps then get someone to push down on the back of the car while you are under there and see if you can find the noise then. Maybe the torque arm hitting the underbody? The rear end/torque arm/something hitting the exhaust?
Unbolt the shocks from the rear and push down on the rear and see if it makes the same noise. Watch to make sure the tires are not rubbing anywhere as the rear of the car gets pushed down, a little rub can make a big noise.
Try unbolting one side of the LCA's as well and move them around in your hand and see if they are making the noise.

LS6427

iTrader: (2)

I'll check all that when I get it on my friends lift in a couple days. Thanks....
I was thinking maybe a shock is bad.

To your questions:
It only happens when I stab the throttle and the car wants to take off.....mostly from any speed slow enough that the rear end drops down a little when I stab it. If I'm doing 80 mph and stab it I don't hear/feel that quick grind Because the rear end doesn't drop down.

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JD_AMG

Hmm, that really sounds like a rear end issue IMO.
Think about it, if it were something in the suspension making the noise wouldn't it make that noise when you hit a bump, or go over a dip or something that moves the suspension?
Sounds to me like the diff is struggling to put power to both axles when you hammer the throttle. Go to an area like a cul-de-sac and do a full steering lock u-turn and see if the rear makes noises while doing that.

LS6427

iTrader: (2)

You mean a donut, smoke the tires.....?

.....But if it is the rear end....then how can it be so perfectly silent and normal during every day normal driving.


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JD_AMG

Haha, you could do that. But im talking about a normal u-turn, the idea I have is the outer rear wheel will be spinning faster than the inner wheel, if the diff is messed up it may be making noise while trying to balance power to the wheels.

LS6427

iTrader: (2)

Oh....LOL......I'll try that big turn tomorrow slowly in a parking lot. The inner rear tire should spin a little during the tight turn.

If it doesnt then my posi is messed up....right...?

Am I looking for a certain type of noise/ticking...?

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joecar

A few more ideas:
Are the torque arm bolts/nuts at the axle case loose...?
Is the torque arm bushing at the transmission cracked/deteriorated/oilsoaked...?

alexcoreas

iTrader: (1)

I was about to suggest this, I'm new to cars and I'm having the same symptoms and kyle from bmr told me to check the torque arm bushing on the transmission.

I'm going to check mine today.

LS6427

iTrader: (2)

Well.....Im out here in the Middle East for 8 weeks now......got here 6 hours ago. I'll check everything when I get home.

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joecar

Keep safe.