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Discussion Starter · #1 ·
Been fighting this battle for sometime.

I purchased an LMM a while back for a good deal. When I test drove, I heard it make a few pops when backing out and turning right.

2008 2WD LMM CC

Rebuilt front end:

Torsion bar bushings
Moog Wheel Bearings
Delco Tie rods/Moog ends
New UCAs w/ balljoints ( new UCA pins/sliders/cams/bolts)
New LCAs w/ balljoints
New Bumpstops
Front brake job, new pads, turned rotors, cleaned calipers, greased slide pins.
New steering gear & pressure lines
New Pitman and Idler arms
New Delco Pro Sway bar links
RC Steering Stabilizer
Bilstein Yellows
New Intermediate Steering shaft( have clamp on steering column for now, but going to replace bearing soon)
New Body mounts - energy suspension, all 8.

Whats really confusing is the popping never stopped after I built the front end. Still pops when turning hard to the right, and then pops when moving back towards center.

I have some videos on youtube from under the truck. Looks like the torsion bar could be moving a little inside the new LCAs. Only happens on driver front side. Video is before the body mounts being replaced.


Fairly loud inside the cab, sometimes pops so hard I can feel it with my left foot in the floorboard.

Lived with it about 6 months. Kinda looking to fix it...took it to a tire/alignment shop. Aligns fine, they can't find any problems...so I'm turning to the internet!

Backing out of the parking lot at work turns some heads when it pops...it's occasionally that loud.

Any thoughts or suggestions?
 

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Try jacking each front wheel off the ground separately and see if the noise can be isolated to one side or the other. Here's more info from ALLDATADIY.


View attachment Suspension pop.pdf
Also check your jounce bumpers for nut tightness. Shocks also.
 

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Discussion Starter · #3 ·
Try jacking each front wheel off the ground separately and see if the noise can be isolated to one side or the other. Here's more info from ALLDATADIY.


View attachment 1044649
I've tried this. Tried to pickup on the suspension with the wheels off the ground. Cannot re-create it.

Only happens when the truck is on the ground and turning.

Thanks for the link. I've read through it, but I've already replaced all the body mounts with poly ones, and torqued to spec. I was convinced this was a body mount at one time...but after replacing all 8, and making 0 impact on the pop, I think I've ruled it out.
 

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My torsion bar mounts were worn out and I changed them but the noise from them wasn't that bad. Sounds kinda like leaf springs popping.
 

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Discussion Starter · #5 ·
My torsion bar mounts were worn out and I changed them but the noise from them wasn't that bad. Sounds kinda like leaf springs popping.
When I took the keys out of the crossmember, and took the crossmember bolts out, both torsion bar bushings fell out and fell apart. Hammered the rivets out and installed new aftermarket ones.

Didn't help the noise/popping sadly.

I had them bad on a 06 gasser 1/2 ton. The crossmember was actually smacking the frame or cab...sounds like a thump.
 

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I have experienced a popping noise backing, it was the brake caliper pins and rubber hardware getting thin. would shuck the caliper backing. Take your tires off grab the caliper and try to shake it.
 

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Might try checking the cross member bolts or rivets and or the body mounts.
 

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Discussion Starter · #9 ·
Might try checking the cross member bolts or rivets and or the body mounts.
Thanks for the reply

Replaced the body mounts. Had that in my post.

Also replaced the torsion bar mounts, hammered out old rivets and bolting new ones in.

Crossmember was torqued to spec, and a few extra ugg-duggas to make sure if wasn't loose.

I have experienced a popping noise backing, it was the brake caliper pins and rubber hardware getting thin. would shuck the caliper backing. Take your tires off grab the caliper and try to shake it.
Thanks for the reply.

You may be onto something here. I actually was thinking about it being the brake caliper during lunchtime. I didn't hardly use the brakes, just lightly to stop. Deliberately made low speed turns without pushing the brakes in, and couldn't reproduce it.

Pulled into a parking spot, pushed the brakes in pretty good when I came to a stop, and when I backed out it popped hard 3 different times before I pulled forward again...Maybe you're right, and the sliding part of the caliper is sticking? And then popping back when I turn because from the load of the truck turning. I had the calipers off last week checking something, and I didn't have any excessive brake wear...guess I'll pull it into the shop tonight and triple check the front driver caliper.
 

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Discussion Starter · #10 · (Edited)
I have experienced a popping noise backing, it was the brake caliper pins and rubber hardware getting thin. would shuck the caliper backing. Take your tires off grab the caliper and try to shake it.
So the caliper was a little wobbly, and it had some other issues, as in it was dragging a little bit with the wheels off the ground compared to the passenger. I replaced with a Delco Reman for 69$ last night.

I still have the popping noise. Think I've eliminated the brakes as a possible issue.

This has got to be Torsionbar/a-frame/crossmember related and I guess I'm not seeing it. Only thing I haven't replaced is the bar itself.

May try a better angle on some videos under the truck. Seems like the only way to 'see' whats going on. Had my brother look under the truck while I made it pop turning/backing up in the yard. No luck.
 

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I guess you've ruled out the leaf springs? Sounds travel funny on a vehicle.
 

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Discussion Starter · #12 ·
I guess you've ruled out the leaf springs? Sounds travel funny on a vehicle.
I haven't ruled them out. Honestly wasn't considering them a problem.

It definitely is easier to reproduce the sound if the truck is on uneven ground and the suspension flexes a little bit.
 

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Discussion Starter · #14 ·
Are your tires catching the mud guards?
Nope, looked into that Wednesday night. I had the truck flexing in a ditch at full lock while someone watched. Its not rubbing the fender liners.

I'm only running 265/75/16s ~ 32s
 

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I just know a guy that bought his truck new and ran stock tire size and it always did rub occasionally when he was backing up with the steering on a lock.
 

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Be sure to check to see if the front of the tire is catching the fender liner too. Is this truck leveled? If not, you could try leveling it and see what happens.
 

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Discussion Starter · #17 ·
Be sure to check to see if the front of the tire is catching the fender liner too. Is this truck leveled? If not, you could try leveling it and see what happens.
Tried the level kit. Road like shit.

I used lowering shackles on the rear end.

I've triple checked, its not hitting the fender liners. Its quite a thump in the floorboards. Right over the torsion bar.


EDIT:

For what its worth, I've tried a set of stock tires (245/75/16) and it still pops. Did it before the rear shackles too. Truck did this when I bought it, nothing I've done so far has changed anything.
 

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Does the thump happen just once when you put it into reverse or does it thump, thump, thump with the tire revolutions? Does it only do it with the steering on a lock? Have you checked the torsion bars and when the were under load for any play?
 

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Discussion Starter · #19 ·
Does the thump happen just once when you put it into reverse or does it thump, thump, thump with the tire revolutions? Does it only do it with the steering on a lock? Have you checked the torsion bars and when the were under load for any play?
It only happens while moving. Its not a shifting or transmission issue.

Its not a tire issue, as I've tried different tire and wheel sets.

Torsion bars don't have any play. They bind and pop around inside the A-frames, thats whats making the popping noise. I just don't know why. I can hang on the bar with the truck on the ground. It doesn't budge.
 

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Sounds like you are very sure it's the torsion bars making the noise. Now, what are you going to do to fix it?
 
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