Removing cab mount bolts

[NJ C10 Guy]

I'm almost at my wit's end with these. My truck is in relatively good shape, with what I consider minimal rust for a 29 year old truck. I can not break the front cab mount bolts loose. I've tried a regular ratchet, breaker bar, and a cordless impact that puts out 133 ft/lb of torque. I've used a can of PB Blaster and I've been spraying it regularly. I even hit the bolt with a torch and hit it with a mini sledge to break up any rust on there. Still nothing. Oh, I am making sure I am backing it out and not tightening it. I don't know what else to do. I need to get this part of my build done, and it's driving me up a wall. Next up is to use an air impact. I really don't want to have to cut a hole in the floor, because I'm not a great welder and my floorboards are in great shape.

With the PB Blaster, I am spraying at the top of the cup where it meets the cab. Am I spraying the wrong thing? This is really killing me.

[bdiamond]

I drilled a small hole in the floor above the bolt and sprayed it thru there.

[NJ C10 Guy]

Originally Posted by bdiamond

I drilled a small hole in the floor above the bolt and sprayed it thru there.

That's actually not a bad idea. I wouldn't need to weld anything to close up a small hole like that. How did you measure or know where to drill the hole?

[chengny]

To locate it's position, you can:

1. Drill a series of small pilot holes (one by one) and look for it with a flashlight

2. Use a tape measure from underneath and then inside the cab

3. Use the pinch weld marks (and the dwgs below) on the cab floor as a guide:

[JAG123]

it took me two days to get mine out - (this past weekend actually)

I just went to Ace Hardware and bought a Propane Torch and heated those suckers up until they turned.. I also tapped on them to send vibration through the bolt while they were hot to help them lose their grip.

Hope you get them out - I feel your pain!

[NJ C10 Guy]

When I put torch on them, the rubber bushing started to melt and drop down. Did this happen to you too?

[bdiamond]

You can get pretty close with a tape measure and reference points on the floor.

[NJ C10 Guy]

Well, I think I broke the captive nut on the driver's side. The bolt spins, seems to be at an angle if that makes sense, and the upper rubber bushing ripped while I was loosening it, so I removed it. I snapped a pic for you guys. I think I may have to just cut a hole in the floor. The passenger's side I'm still working on. While I was turning it I heard a "bang" sound, like something was breaking free. Hopefully I didn't break that one as well. It has about 1/4 turn of travel in it before it gets difficult to turn, but that 1/4 turn moves pretty freely. I keep hitting it with PB Blaster and praying. Here is a pic of the driver's side. If you look at the bolt you can see it's at an angle. It hasn't loosened from the lower bushing at all.

[NJ C10 Guy]

Here's a thought, and I may be crazy...I heated the bolt with a propane torch. While doing so, the rubber started to melt and drip down. Is it possible that when the rubber cooled it bonded to the metal and that's why it's not breaking free? It just seems weird that after everything I have tried that the nut broke, plus some of those threads look pretty clean up top. I've tried looking through the holes I drilled in the floor pan but I can't see much.

[greg64]

I feel your pain. My cab mounts rusted completely away, and I had to replace them. That whole design is for assembly only, not disassembly. My 64 is much better because the head of the bolt is recessed into the floor a bit. So you can get at both the head and nut.

[FB85C10]

i sat and spraedy PB Blaster for bout 5mins. on each bolt spraying everywere i could get the spray into and came back bout 2 weeks cause i forgot that i sprayed them and i got my 1/2 rachtet and socket and a short breaker bar and pulled ever so slowly and it came loose like nothing its was awesome, came right out no issues!!

[mrolds88]

Well if it is spinning and not backing out, then you do have a problem. I would take some good measurements and cut a hole. Make it a nice square or round one. The nut is square if I remember right. A piece of square tube and a big wrench on top would work for you. Hit it good from the top with whatever you have for penetrating oil and have at it.

[albertgen]

What specific advantages do you notice after replacing all the mounts? Thanks, Al

[greg64]

Originally Posted by albertgen

What specific advantages do you notice after replacing all the mounts? Thanks, Al

My cab was actually attached to the chassis again, and it sat about 2" higher!

[NJ C10 Guy]

I finally said screw it, and cut holes in my floorpan. I used a 3.5" bi-metal hole saw. It worked really well, although when it catches it takes you on a bit of a ride. Turns out the one I previously posted pictures of (front driver's side) was backed out, but the bolt was rusted into the sleeve like another member suggested in another thread. It still took a lot of persuasion to get it out, but I got it. It wasn't really rusty, but the threads were caked up pretty good.

The passenger side mount was absolutely spinning, so I would have needed to cut the hole regardless. I just sprayed a liberal amount of PB Blaster on the nut. In order to back it out, should I weld the captive nut in place now, or is there another way to do it?

I'm going to just epoxy a couple pieces of thicker gauge steel over the holes. since they are in the floorpan, they should stay in place without any issues. They are also going to be covered by sound deadening panels, closed cell foam, mass loaded vinyl, then carpet. I think I'll be OK there.

I snapped a couple pics and also took video of the nut spinning. If anyone can tell me how to embed a video, I would appreciate it:

Here's the video
http://vid1192.photobucket.com/album...psmnonrbfm.mp4

[esbstuff]

Since you have that big of a hole there, I would weld the nut to the cab. That along with anti-seize should forever take care of the problem ever happening again.

[NJ C10 Guy]

Originally Posted by esbstuff

Since you have that big of a hole there, I would weld the nut to the cab. That along with anti-seize should forever take care of the problem ever happening again.

Well hopefully I never have to do this again. It's a weekend cruiser. I actually regret even doing this at all. They weren't in terrible shape but I figured I might as well do it before I put in all the sound deadener/carpet.

Now...On to the broken seat belt bolts!