Rear end vibration after new leaf spring

Hey guys,
Brought my ‘95 4x4 in to the shop to get a broken leaf spring replaced to help with hauling. Only one spring, the damaged one on the driver side was replaced with a salvage part.

After I got it back it drove fine for a week around town (~150mi). But once I started taking it on the highway with medium loads in the back I’ve stared getting this awful vibration that began effecting normal around-town driving. Here’s what I’ve been able to narrow down:

>The vibration is not present when accelerating

>After accelerating to 30-50mph the vibration becomes apparent when decelerating and coasting.

>Vibration continues unchanged while coasting downhill with the trans in neutral as well as the transfer case

>The vibration is not affected by the brake pedals and is not transmitted through the wheel

>They vibration is reduced with engine braking or downshifting

After that I had it towed back to the shop because the vibration was so violent I didn’t wanna drive it on the highway. They took a good month to get back to me and now they’re trying to tell me that this vibration has got nothing to do with the salvage spring and that everting on the rear end is fine, they keep calling it a “headscratcher…” They’re trying to blame it on the tires somehow

Any thoughts on what changed in the rear to cause the vibration? Any thoughts on how to get my truck back in working order without just paying another shop? Been trying to get them to send me the measurements of the working angle but they just insist it’s “fine.”

 

The fact that they're not giving you actual measurements and just insisting that it's fine means they are not a reputable shop nor have any real clue what they're doing besides swapping parts. Home depot sells a digital angle finder for 30 bucks.

My guess is that some angle is out of whack especially since only one spring was changed. Traditionally leafs are a wear item and should be changed as a set. The vibration could also be a ujoint or center carrier bearing (if you don't a one piece driveshaft)

Honestly your best bet is to cut your losses and pay a better shop to actually diagnose the problem vs just scratching their heads

 

Dude, walk away from that shop. Sorry- run away from that shop.

Get yourself a new pair of springs. Springs aren't really a mix and match item. Especially on our trucks, there are left and right springs to compensate for the battery/driver/gas tank all being on the drivers side. Different brands might also have the center pin in slightly different locations- you just never know.

Generally speaking, when you add weight to the bed of the truck, drive line vibrations caused from incorrect drive line angles should go away- not increase.