Odd thump sound past 20mph

[cory9oh4]

Hey everyone. Haven't been around in a while. Hopefully everyone is doing well.

Vehicle:
2008 H3
115,000 Miles
3.7l

Issue:
When I'd drive over 20 mph I start hearing and feeling a thump that cycles in revolutions. As I go faster the sound is more frequent. It seems to be coming from the front. I feel it in my gas pedal and on the passenger side front. It started after having to get on the brakes really hard due to an idiot pulling out right in front of me and almost getting T-boned.

What I've done:
My first though was it must be something with the front passenger side brakes. The wheel was pulled off and the pads, rotors, calipers, and caliper pistons seemed to be in good shape. So then I considered the wheel bearing. The truck got jacked up, and I did the 6 o'clock and 12 o'clock rock to check for vertical play. There was a decent bit. So I went ahead and replaced the wheel bearing and hub assembly. Unfortunately the thump is still here.

Does anyone have any ideas what to start checking and looking for next? Fortunately my grandfather is letting me use his truck until I can fix mine.

Thank you everyone,
Cory

TL;DR Odd thumping past 20mph on the front end. check brakes, they were fine. replaced wheel bearing and hub, thump is still present.

 

[giovannihdzretir]

Wish I knew

Sent from my Z981 using Tapatalk

 

[Happy Hummer]

Hey everyone. Haven't been around in a while. Hopefully everyone is doing well. Vehicle:2008 H3115,000 Miles3.7lIssue:When I'd drive over 20 mph I start hearing and feeling a thump that cycles in revolutions. As I go faster the sound is more frequent. It seems to be coming from the front. I feel it in my gas pedal and on the passenger side front. It started after having to get on the brakes really hard due to an idiot pulling out right in front of me and almost getting T-boned. What I've done:My first though was it must be something with the front passenger side brakes. The wheel was pulled off and the pads, rotors, calipers, and caliper pistons seemed to be in good shape. So then I considered the wheel bearing. The truck got jacked up, and I did the 6 o'clock and 12 o'clock rock to check for vertical play. There was a decent bit. So I went ahead and replaced the wheel bearing and hub assembly. Unfortunately the thump is still here. Does anyone have any ideas what to start checking and looking for next? Fortunately my grandfather is letting me use his truck until I can fix mine.Thank you everyone,CoryTL;DR Odd thumping past 20mph on the front end. check brakes, they were fine. replaced wheel bearing and hub, thump is still present.

I'm going to suggest the following in no particular order....* front rotors replace* Front pads replace* Front CV one or both* Front drive shaft (prop if your a GM'er)* Front bushings for the steering rack* Front differential bushings* Front Diff undercarriage mount bushings* Engine mounts* Trans, Transfer case bushings etc.Start here....Let us know what you find pls...I'd check all of these items thoroughly...

 

[08H3]

Sounds like a U Joint to me. Sometimes the vibration is hard to figure out which one. I thought it was a front but ended up being on the rear. Check them all. Outside of that, not sure.

 

[cory9oh4]

Sounds like a U Joint to me. Sometimes the vibration is hard to figure out which one. I thought it was a front but ended up being on the rear. Check them all. Outside of that, not sure.

I just finished changing the front u- joint. I'll try the rear one next. It almost sounds like the sound is coming directly from under the radio area but slightly more towards the passenger side than drive.

 

[cory9oh4]

bump

 

[Bigunit]

Check your front diff mount bushing. Better yet, crawl under your rig and take and post a pic of the bushing - top and bottom.

 

[DJinCO]

My standard answer for odd sounds is this.

Maybe it's a Prius stuck under there.

I know, I'm being a smart aleck. :gaah:

 

[f5moab]

Go back to basics, swap the front tires to the rear and see if the thumb goes with the tires.

 

[650Hawk]

Yeah, that /\

Did you lock up the tires during your emergency stop? Maybe a flat spot on a tire?

 

[cory9oh4]

Yeah, that /\

Did you lock up the tires during your emergency stop? Maybe a flat spot on a tire?

It wasn't a lock up but I got on the brakes really hard.

 

[cory9oh4]

Go back to basics, swap the front tires to the rear and see if the thumb goes with the tires.

Will be trying this in the morning. Good advice. I feel like I should have tried this first.

 

[cory9oh4]

Check your front diff mount bushing. Better yet, crawl under your rig and take and post a pic of the bushing - top and bottom.

I'll check them while I have it jacked up tomorrow to swap tires arojnd. Thank you.

 

[SuperBuickGuy]

I agree Bigunit.... the bushing that holds the differential to the front crossmember is notorious for failing and causing that noise. You have two choices of aftermarket replacement. Just choose one, don't ask opinions here.... they both work fine but there are strong supporters of either solution.

 

[cory9oh4]

Huge thank you to everyone's responses and help. The problem has been fixed. It turned out to be my front driver wheel bearing assembly.