Cab Mount Replacement Procedure

[Caman96]

I searched through most cab mount related posts and if there’s a thread on replacement, I didn’t see it. I also checked YouTube and the videos I saw always seemed to skip over the jacking of cab. Most videos were a waste of time, with issues I don’t have. I kinda remember reading a few years back of someone replacing mounts and using a 4x4 timber when lifting cab or was that being used to tilt bed in a fuel pump replacement.
Anyway, who here has done it? I’m thinking with them all loosened up, what is best jacking procedure? I don’t want to just jack in one area and torque and twist the cab unnecessarily. For instance, do you jack the driver side and then say passenger side? Or, is it a rear cab to front jack. And that doesn’t even account for what’s happening to front of truck with the core support mounts.

 

[fancyTBI]

Here is how I’ve always done it:
1) break all the bolts
1) Remove all the bolts for the mounts on the side you are doing. Loosen the bolts on the side you are not currently doing. Core support, front of cab, rear of cab. You have to have enough lift without binding the sheet metal this is very difficult to achieve without undoing the core support mount.
2) use a 4x4 about the length of the underside of the cab and place it on the flat section of floor pan that is between the frame rail and inner rocker with the help of the floor jack
3) jack it up til you’ve got enough room to remove the mounts. Grab another piece of wood (I think I used a 2x4) and stick that between the frame and the cab floor. This is your “safety” board and won’t do much if the cab falls but it will make you feel better.
4) clean and inspect the mounting bracket. Wouldn’t be surprised if there were some pin holes. Good time to paint the frame.
5) replace mounts, anti-seize them, keep them loose because…
6) repeat on the opposite side
7) torque them all down to spec (remember to adjust for the anti-seize)

They are a pain even if it goes well.

 

[Supercharged111]

I did it on a lift. Used a long 2x4, forgot to loosen the core support, and didn't bend the floor. They came right out, no need to overthink this it's a pretty easy job.

 

[Caman96]

Here is how I’ve always done it:
1) break all the bolts
1) Remove all the bolts for the mounts on the side you are doing. Loosen the bolts on the side you are not currently doing. Core support, front of cab, rear of cab. You have to have enough lift without binding the sheet metal this is very difficult to achieve without undoing the core support mount.
2) use a 4x4 about the length of the underside of the cab and place it on the flat section of floor pan that is between the frame rail and inner rocker with the help of the floor jack
3) jack it up til you’ve got enough room to remove the mounts. Grab another piece of wood (I think I used a 2x4) and stick that between the frame and the cab floor. This is your “safety” board and won’t do much if the cab falls but it will make you feel better.
4) clean and inspect the mounting bracket. Wouldn’t be surprised if there were some pin holes. Good time to paint the frame.
5) replace mounts, anti-seize them, keep them loose because…
6) repeat on the opposite side
7) torque them all down to spec (remember to adjust for the anti-seize)

They are a pain even if it goes well.

Thanks, doesn’t hurt to ask. So when you jack up the cab, with jack under cab, it also lifts the front enough to get the core support mounts?

 

[fancyTBI]

I did it on a lift. Used a long 2x4, forgot to loosen the core support, and didn't bend the floor. They came right out, no need to overthink this it's a pretty easy job.

I can never get the fronts out without having the core support loose. Though I play it pretty safe I’ll admit.

Thanks, doesn’t hurt to ask. So when you jack up the cab, with jack under cab, it also lifts the front enough to get the core support mounts?

No, to do the core support you’ll want to jack up the core support while the other mounts are loose and it will lift/flex enough for you to get them out.

For what it’s worth, I was able to do the core mounts with the cab mounts tightened.

 

[Laredo]

Loosen one side at a time, raise the cab using a floor jack equipped with a cross beam, and place jack stands at the end of each rocker panel.

 

[Supercharged111]

I can never get the fronts out without having the core support loose. Though I play it pretty safe I’ll admit.

No, to do the core support you’ll want to jack up the core support while the other mounts are loose and it will lift/flex enough for you to get them out.

For what it’s worth, I was able to do the core mounts with the cab mounts tightened.

Thinking back I did reach a point where I had to loosen the core support, so it must have been for that front mount like you're saying. My fronts were pretty nasty and on a not rotten truck to boot. At the time I had poly on hand and tossed them in. I DO NOT recommend poly body mounts! You couldn't even have a drink in the dash holder, at least not for very long. I did the GMT900 rear mounts too, but whatever improvement they offered was far outweighed by how terrible the poly was for the ride. Some clean junkyard rubber core support mounts replaced those, but so much time had elapsed that I have no idea if the ride is better or worse. Oh, and I also did a 5+1 leaf pack in that round of maintenance as well.

 

[Caman96]

All bolts out on drivers side, zero issues. On core support, I used a floor jack with a 12” piece of 4x4. On top of 4x4, I used a 3/4” socket directly under
the upper core mount and jacked it up until it cleared. Got some shimming in there while I clean it, metal prep it and then Rustoleum Rust Reformer. So far, so good.

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Metal is solid, no pinholes.

 

[Supercharged111]

I'd do a few rounds with naval jelly or rust mort.

 

[Caman96]

Anyone know the torque # for the core, the front and the rear mounts?