body mounts

[fire235]

How important is it to replace worn body mounts? The ones on my truck seem to be pretty dry/cracked, but the truck really needs nothing else and I don't want to start taking things apart for the sake of doing it. What real purpose do the mounts have? Do they just cushion the ride, help with sound, what? Thanks

[4x4Poet]

Besides cushioning the cab from the driveline vibrations transmitted thru the frame, they allow the frame to flex somewhat independently of the body which offers some forgiveness to the suspension movements. The body mounts also influence door alignment.

After 35+ years, much rust and dirt will be found in the body mount cavity that the bolts go thru. Expect the steel sleeves to be severely rusted, though probably intact. The bolts are also rusted and possibly weakened from the rusting.

A couple weeks ago, I used a lift to separate the body off the frame on my K10 burb (first time since factory install). All the body cushion cavities were full of dirt and rust. The four front, welded-in body bolts had some rust, but good threads. I POR15'd the threads down to where the nuts spin up. The six rear body mount bolts had rusted severely. The four rear carriage bolts has rusted so much they had lost much of their diameter, so they were weak, for sure. I wire-wheeled the captive bolts and all the mounting surfaces and painted them. Then I lowered the body on new mounts.

I picked up body mount cushions from GMC Pauls (ouch! a burb has too many, lol). They didn't come with hardware. I went to a 4x4 accesories shop and picked up free, thickwall tubing remnants which I cut down to use as sleeves (2b painted), I purchased new carriage bolts (4), hex head bolts (2), and nuts (6). I'm glad I did it since it's done right and I can now brag that I did a body-off resto.