The Stovebolt Site Forums The Shop Area Interiors Cab Mount Access

As I sit here pondering the various projects I plan to undertake soon on my stored ‘54 3100 , it occurs to me that Job #1 may give me access to something that is further down the list ……

I have posted about gas fumes in the cab. I have decided to remove the rather new fuel tank and inspect the otherwise inaccessible lower seam for integrity/ leaks.
Here’s my inquiry:
Are the rear cab mount bolts under that fuel tank? My cab and box are not quite level to each other; I believe a slight shim lifting the rear driver’s corner of the cab would achieve alignment.

The truck is in a heated building with good access for the winter so I figure now is the time. I hope I’m not opening up a separate can of worms by bringing up shimming the cab; I’m tentatively allowing myself to think that it will be a simple process.

Input will be appreciated,
‘Ski

Ski, See the attached pic below taken from the FAM. Rear cab mount to floor bolts are accessed from underneath, although if those threads are rusty you will need to get to them them where they come through the floor under the gas tank with whatever product you may wish to use to help them become unstuck. Glad you have a nice indoor heated place to work in comfort during this time of year.

While we’re at it , can someone help me understand why a shackle was used in that application?

The cab mount shackles have rubber bushings, which provide some cushioning to the cab and let it stay stable as the frame flexes.

The bushings on yours are probably worn out, causing the cab to sag a bit at the rear. There are also shims used between the shackle and the cab floor to adjust the position of the cab on assembly. You can get replacement shackle bushings from the usual sources.

It’s been a couple years since that cab went back on the frame, I cannot say if those shackles were new at that time.

Lots of good reasons to go to the boat shed tomorrow and commence the winter truck work season!

I’ll report when able.

Seeing that you are dealing with a '54, most likely the bushings are pretty well shot. I replaced the ones on my '50 a couple of years ago, and I don't remember having to remove the bracket attached to the cab floor. I had some wooden wedges that I placed between the frame and the cab floor and then removed the shackle assembly. Once that was done, I drove out what was left of the bushings, put the new bushings in and replaced the shackle assembly. ( A little PB Blaster to persuade the nuts to come loose, and a little silicone spray on the bushings to persuade them to go in the brackets will make life a whole lot easier). Once the assembly was back together, I knocked the wedges out--Job done.

I just did that job with the tank in place and the nut plate is under the tank. It’s loose so if you remove both bolts you’ll have a hard time getting it back into position then reinserting the bolts. I was able to remove the mount by removing one bolt and inserting a stud then removing the second bolt. The stud enabled me to control the plate to reinsert the first bolt. I snugged the bolt, removed the stud, reinserted the second bolt, then tightened up both bolts.

Although this worked pretty well, I highly recommend removing the tank as it will be much easier.

The next tip I can give you is cut some blocks of wood the thickness of the clearance needed (I cut mine 13/16” thick and that will get you in the ballpark) and place them between the frame and floor then remount the rear cab mounts. That will get you really close.

Thanks for all that information guys.
Regarding the tank , remember that I intend to remove it in my continued efforts to find and eliminate the source of gas fumes. That will make access to that cab mount hardware easy.

TexasJim -

You used wedges instead of jacks?

Phak - I don’t believe I understand your last paragraph. Those dimensions are based on …?

THIS....

Alright - I understand that in normal assembly a shim of .76” is used the establish proper clearance between cab flop and frame. I don’t think such a shim is currently in place, but that will be easy to remedy.

Which brings me to my report of today–-
My rear cab mounts are like new. Bushings are good; I thought I had used replacements 2 1/2 years ago , now confirmed. Working with them will be easy.

When I got the seats out I was able to get a closer look at the interface hoses. The fill hose , although only a couple years old , had some separation, see image. (Note that the clamps were loosened just before the picture). I sniffed at those small splits - I think I found my vapor leak. I went ahead and removed the fuel tank anyway, to double check under the tank and the improve access for shimming the cab. However, I nullified the checking of the underside of the tank by snagging the fuel line fitting and wrenching it loose as I wrestled with the tank. A minor Exxon Valdez like incident occurred, eliminating any evidence of a leak under the tank , had there been any. I really don’t think there was a leak down there, but my mistake mandates a trip to a radiator/tank shop the get the fitting reseated , so it will be tested then anyway.

I made a mistake and a bit of a mess , but I have some projects started, and started very early in the New Year , so it wasn’t a bad day.

Rubber products just don't seem to last these days.

Looking at the photo , I do not think that the stock shim is there.

The shim is used to establish the .76” clearance between the frame and the bottom of the floor shown in red arrows in the photo. Using the block of wood I talked about helps get you determine the thickness of the shim.

Have you checked the front mounts? They also have an effect the rear mounts.

Haven’t checked the front mounts , they are a bit more difficult to access. The stance of my modified ’54 makes it very difficult to get past the running board on a creeper. I will be jacking up for clearance soon.

Good highlighting on that schematic, thanks.

Ski, I used the wood wedges due to the fact that I did not have a good jack available. My cab was sitting in good position (had not sagged) but I just wanted to go ahead and replace the bushings before they gave me problems.

Understood.