I just changed the transmission mounts on my truck it's an automatic, and now i have tons of vibration in the cab when the truck sits at idle, it stops as soon as the rpms go above 600. When I installed them I tightened them down till the metal sleeve that slides in them was sandwiched in between the crossmember and transmission. By doing that it compressed the mounts, does anybody know if this is the way to do it or should I loosen them up a bit, or if I have a whole other problem to deal with.

 

my 75 had the same issue, basically i just turned up the idle, before it would vibrate the cab apart, but nice and smooth now, but i have a manual, i'm not sure how many rpm's the auto will let you get away with but thats where i would start,

do you have cummins powered 77 PW? if so lets see thoes pics!!!

 

Ya thats what I was thinking of doing, was just wondering what could be causing this as it didn't do it before i changed the mounts. The old ones were pretty spongey and the new ones are solid of course. Because it's an auto I don't really want to have to bump up the idle to much. And the trucks actually an 89w250 with the metal of a 77 swapped on, here's a couple pics hopefully they work their the only 2 i could find on the computer

 

the only other option there is, pull the mounts apart, and find some material (pipe ect.) the same specs, or close to the bushungs and cut them just a bit longer, so there isnt quite as much squeez on them

the truck looks awsome!!! i love the looks of the 78 style grille, i have been thinking about switching mine back, if i can find one, here is mine

 

I'm gonna try and loosen them up in the morning so that the mounts are just getting squeezed a tiny bit and see if that helps. Good looking truck you got there, mine was almost as clean as yours when I bought it but being a daily driver for the last 3 years has taken a bit of toll on it, espescially these canadian winters it gets put through. What size lift and tires you running on yours.

 

loosening them might work too, just make sure you have lock nuts or double nut them, the tires are 33x13.50x18 but were supposed to be 35's the jack*** that i ordered from required a deposit, and ordered the wrong set, so i got stuck with the problem, the lift has somewhere around 8-10" up front and a custom 4-link i built for the rear

 

It's got the lock nuts on them made sure of that. That lift looks awesome. I'm running some BFG's right now 37x12.50 17's now with 4" suspension and 3" body lift, I had a set of Pro Comp Xterrains 325/80 16's on it till I had a little bit of a blow out. Even with the 7" lift the tires have done some damage up front to the fenders. Will let you know how loosening them up works.

 

tried to put pictures up with last post, had to remove the other pics

 

oh ya, i forgot there is also a 2" body lift on it too(i did that to clear the 5" exhaust)

 

having the mounts just snug got rid of the vibration, but now i have to tighten everything in the cab to get rid of the rattles