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Discussion Starter · #1 · (Edited)
Trying to decide if this is a driveline shake I'm experiencing.

Replaced/Tried:
Center Support Bearing - Dmax Store
New Energy Suspension Cab Mounts
Added shims to support bearing

Truck does not seem to vibrate unloaded. Truck is stock motor/transmission. 197,000 miles.

If I have a trailer, it shakes bad enough I can't stand to drive about 60mph. Unloaded or loaded. I can see the bed of the truck moving/shimmying in the mirror

Leaning toward U joints, I have a 2-piece shaft with the carrier in the middle.

What U-joints do I need? Seems like the Rear end cap is 31mm and the cap on the center u-joint is 36~mm. Seems like all the joints on merchant or Dmax Store are 1.4"/36mm

Thanks in advance.
 

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At a certain tongue weight I have experienced a fast bounce on certain roads coming from the leaf pack making contact with bottom overload spring....
 

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Discussion Starter · #3 ·
At a certain tongue weight I have experienced a fast bounce on certain roads coming from the leaf pack making contact with bottom overload spring....
I'll take a look at that.

I've driven these roads before and not had this issue, though. I've either done something, or something has worn out recently that's caused this.

I may swap the tires/wheels over from my LB7 and see if it goes away or changes. Maybe its a tire.

Has the factory u-joints on it still, at 197,000 they're likely toast anyway. Truck has seen alot of bayboat pulling to the coast.
 

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Another that involves the leaf pack is the replacing the rubber pads on the ends between each leaf.
 

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Trying to decide if this is a driveline shake I'm experiencing.

Replaced/Tried:
Center Support Bearing - Dmax Store
New Energy Suspension Cab Mounts
Added shims to support bearing

Truck does not seem to vibrate unloaded. Truck is stock motor/transmission. 197,000 miles.

If I have a trailer, it shakes bad enough I can't stand to drive about 60mph. Unloaded or loaded. I can see the bed of the truck moving/shimmying in the mirror

Leaning toward U joints, I have a 2-piece shaft with the carrier in the middle.

What U-joints do I need? Seems like the Rear end cap is 31mm and the cap on the center u-joint is 36~mm. Seems like all the joints on merchant or Dmax Store are 1.4"/36mm

Thanks in advance.
To rule out tires/wheels I would rotate the tires (front/back, left/right) and give it another go. I wouldn't expect this to eliminate the vibration but it might change its "character," i.e., make it worse or better in different parts of the vehicle. If that occurs, you can be confident it's a tire or wheel issue.

Does applying the accelerator or brakes have any effect on the vibration? If so, suspension bushings might be the culprit.
 

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How 'bout your trailer?
I've had failing (separating tread casings) trailer tires on a TT, transfer the bounce/vibration back to the truck.
 
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Discussion Starter · #7 · (Edited)
To rule out tires/wheels I would rotate the tires (front/back, left/right) and give it another go. I wouldn't expect this to eliminate the vibration but it might change its "character," i.e., make it worse or better in different parts of the vehicle. If that occurs, you can be confident it's a tire or wheel issue.

Does applying the accelerator or brakes have any effect on the vibration? If so, suspension bushings might be the culprit.
It doesn't, it seems to be constant above 60 mph. Gets worse as speed increases. Seems to really pickup for a bit when the truck coasts down a hill, or accelerating up a hill, but even at cruising speed the shake is there.

Shake is not noticable below 55.

I have a 2002 LB7 I can swap the wheels and tires off of and see if it persists.

Truck has a whole new front end. All new Delco/Mevotech parts. New bilstein shocks. Brake job roughly 5000 miles ago. This issue has appeared within the last 1000 miles.
 

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Discussion Starter · #8 ·
How 'bout your trailer?
I've had failing (separating tread casings) trailer tires on a TT, transfer the bounce/vibration back to the truck.
This is a great point.

There's easy things I can test. I have 2 different trailers, Been using my longer one, I can pull a different trailer and see if it still does it.

Its possible I have a mismatched tire on one of the trailers, guess that could cause it.
 
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Not being able to see the trailer (tail gate hides it), I installed some 1" square tubing posts on each rear corner, so I reaffirm with a glance, that I've still got a trailer hooked on. :teehee

And for backing, I can see the trailer tracking from the rear view mirror. But they've also come in handy in identifying a bad tire problem, as I can see the post tops jumping from the rear view mirror. :howdy
 
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