Clunk when leaving a stop.

[PatDTN]

When I accelerate from a stop I feel and hear a clunk. Also while driving down the interstate I notice it is twitchy. Every now and then it will change trajectory slightly requiring a correction to keep going straight.

I was pretty confident that I had a bad bushing in the rear suspension that was moving around. A friend has a nice lift and we put the Tahoe up on it. All the various parts of the rear suspension are solid. There are no rub marks to indicate movement outside the norm and a pry bar applied at angles can't move anything.

We pushed and tugged on the rear wheels without finding any looseness. We checked the driveshaft just in case and can't find anything there.

My friend watched closely from outside and couldn't see anything going wrong.

This is a 2009 LTZ with 200k miles. I have no idea what else to check.

 

[HiHoeSilver]

When I accelerate from a stop I feel and hear a clunk. Also while driving down the interstate I notice it is twitchy. Every now and then it will change trajectory slightly requiring a correction to keep going straight.

I was pretty confident that I had a bad bushing in the rear suspension that was moving around. A friend has a nice lift and we put the Tahoe up on it. All the various parts of the rear suspension are solid. There are no rub marks to indicate movement outside the norm and a pry bar applied at angles can't move anything.

We pushed and tugged on the rear wheels without finding any looseness. We checked the driveshaft just in case and can't find anything there.

My friend watched closely from outside and couldn't see anything going wrong.

This is a 2009 LTZ with 200k miles. I have no idea what else to check.

Common for the u joint to do that. You didn't see any play there, huh?

 

[PatDTN]

Common for the u joint to do that. You didn't see any play there, huh?

No, my friend builds race cars and we both have lots of experience. No movement in the u-joints. Surprising with the high mileage.

 

[shreksbrother]

When I accelerate from a stop I feel and hear a clunk. Also while driving down the interstate I notice it is twitchy. Every now and then it will change trajectory slightly requiring a correction to keep going straight.

I was pretty confident that I had a bad bushing in the rear suspension that was moving around. A friend has a nice lift and we put the Tahoe up on it. All the various parts of the rear suspension are solid. There are no rub marks to indicate movement outside the norm and a pry bar applied at angles can't move anything.

We pushed and tugged on the rear wheels without finding any looseness. We checked the driveshaft just in case and can't find anything there.

My friend watched closely from outside and couldn't see anything going wrong.

This is a 2009 LTZ with 200k miles. I have no idea what else to check.

Hello, have you considered the motor mount?

Sent from my Galaxy Note9 using Tapatalk

 

[PatDTN]

Hello, have you considered the motor mount?

Sent from my Galaxy Note9 using Tapatalk

I read about those and I'm considering that. I need to get some more lift time with my buddy but he's always busy.

Thanks.

Pat in Tennessee

 

[shreksbrother]

I read about those and I'm considering that. I need to get some more lift time with my buddy but he's always busy.

Thanks.

Pat in Tennessee

No need for a lift to check that... Need to look under the hood while someone hits the gas in drive (obviously their other foot needs to be on the brake). Just watch for the motor to move a couple of inches with torque.

Replacement isn't really a job for a lift... You can do it with a couple of jacks and some basic hand tools.

Sent from my Galaxy Note9 using Tapatalk

 

[PatDTN]

No need for a lift to check that... Need to look under the hood while sometime his the gas in drive (obviously their other foot needs to be on the brake). Just watch for the motor to move a couple of inches with torque.

Replacement isn't really a job for a lift... You can do it with a couple of jacks and some basic hand tools.

Sent from my Galaxy Note9 using Tapatalk

I should be able to work that out. We'll see. Again, thanks.

Pat in Tennessee

 

[iamdub]

^^^ What Adam said. I had the hood up and, from the driver's seat, watched the motor (actually the beauty cover) through the gap between the back of the hood and cowl. Just do some light powerbraking and see if the motor jumps up and slams back down when you get off the throttle.

A bad motor mount will have nothing to do with the steering being twitchy. This is likely slack in the steering or front suspension. A worn steering rack is the least likely culprit. Worn inner and/or outer tie rod ends is a little more likely, but they'd have to be dangerously worn to have enough slack to cause sudden and drastic enough changes that you could feel. If the control arm bushings are badly worn, the arms can shift forward and backward when accelerating and braking. This can cause noise, looser steering feel (you may not notice this since you're "used to it"), and wandering due to the alignment constantly changing. With such a heavy vehicle, you may not be able to replicate the forces enough to see the slack. Idle backwards in reverse and jab the brake to come to a stop and continue to hold the brake firmly- you'll probably at least hear a clunk but that could just be a little slack in the brake calipers and not what you're trying to track down with this test. The point is to shift the front suspension forward to reveal slack. While still holding the brake firmly, shift to DRIVE and sharply jab the throttle while someone watches and listens from the front wheel arch. This will have to be someone that trusts you to not let off the brake and roll away. Have them closely watch the gaps between the control arm bushing(s) and frame mounts to see if the arms move backward when you try to jump forward. Continuously holding the brake after you reverse is important because you're using them to keep everything loaded in the opposite direction from normal driving. The cool thing with the control arms is that you replace the whole thing as one unit- arms, bushings and ball joints. They're a quick bolt-on repair so you can kill two birds and get stoned.

 

[iamdub]

I tried twice to edit my last post mentioning worn shocks also being a possible cause for noise when accelerating but was temporarily blocked from the forum. I'm not gonna type it all out again. But, yeah...

 

[PatDTN]

All great advice. I'm betting some part of that will pinpoint my issue. My buddy and I were convinced the noise was in back but we eliminated that so forward it is. Thanks. I will update with what I find when I find it.

Pat in Tennessee