So I was always of the opinion that it made more sense to do extensive cab repairs (floor panels, rockers, door pillars, cowl etc) ON the frame but seeing this video where the guy seems fairly strongly of the opinion that if 'done properly' it should be done off of the frame I am trying to understand why. i.e. what is the rationale/logic for doing it 'off frame'?
I have linked, below, directly to the relevant part of the video and you can see the driver's side front corner is pretty much rotted away.
1951 3100 5-window with a '55 235/floor mounted 3-speed Some of the story in ODSS Most of it in The Shops Area
I am new to this type of body work and with my first repair I learned very quickly you must take steps to protect/preserve fitment when you start replacing sheet metal. My first sheet metal repair was replacing the cowls. I got lucky in the fact I was able to make some adjustments after the fact and get a decent fit at the corner of the hood and fender. Since then I have watched a lot of YouTube. The detail the guy doesn't go into is what is involved in doing the repairs off frame. I feel doing the actual repairs off frame would be a lot easier in regards to access. The big "but" here is preparation. Just like everything else. Because a significant part of the structure is gone or compromised you would need to build supporting framework before pulling the cab from the frame. If you do that and have a rotisserie and the equipment to do it and the time, pull it off. for me, the back yard mechanic it is easier to do it on the frame.
I did just watch a cable vintage car restoration show last night and they were repairing some floor pan replacement work done by the owner of a 1951 3100. It was a nice looking truck but when the owner cut out the front floor pans and rockers he did not support the door opening. He did not realize the cab slightly collapsed at the bottom closing the distance between the door opening at the bottom of the door. After he welded his new pans and rockers back in his doors would not close. He brought it to this shop to repair his repairs.
Access, as said, would be the only reason to remove. Otherwise it's sitting on a nice "work table" and "jig", saving space. Bolted or not. Maintaining structural integrity and dimensional stability are normal procedures, off or on frame. This would include door and windshield openings, cab width, straightness, parallelisms, flatness, warpage. I think I would prefer to leave cab bolted to frame.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
Make sure that you start with new rubber bushings in the rear shackle cab mounts and set the cab height at the rear with shims if necessary. If you don't, you might as well do all of your cab repairs on the lumpy back yard. Carl
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
Good point. The rear shackles weren't high in my mind until I went out to the workshop last night to look at why the cab was leaning down on the passenger's side. I suspect the collapsed passenger front mount has caused the rear of the cab to lean as the rear mounts allow it to swing from wide to side. I ended up putting a piece of 2x6 under the rear between the bottom of the cab and the top of the frame to keep it level.
However, this made me realize that if I had simply started cutting metal from the front, the cab would then dip on that side anyway as the rear mounts wouldn't 'hold' it.
I just hadn't realized there was a need to brace the cab level to prevent a lean, my bad.
Paul
1951 3100 5-window with a '55 235/floor mounted 3-speed Some of the story in ODSS Most of it in The Shops Area
Paul, you have illustrated how the rear shackles are designed to articulate with frame flex. By having a collapsed front cab support on one side, even a rebuilt rear cab shackle mount will allow the rear cab corner to raise. Once you restore the bad front cab mount bracket, the rear of the cab will level out.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
Last evening had me scratching my head a little. I raised the passenger front corner (the rear is leaning into the driver's side) and it made no difference at all at the back. After putting the truck up in the air on the lift and trying various things I have come to the conclusion that the cab has collapsed onto the floor in such a way that the only way to raise that side of the body is by the door opening. lifting on the floor simply causes the floor to rise but not the cab.
s'gonna be a challenge but strangely one I am looking forward to. I must be nuts...
1951 3100 5-window with a '55 235/floor mounted 3-speed Some of the story in ODSS Most of it in The Shops Area
I am adapting rear cab shackles to my 48 which had a center mount design. Does anyone know what the spacing should be between the cab floor and the chassis top? The pictures I've seen look like the shackle is at 45 degrees. I need to know these things to drill the mtg holes in the right place. Joel1948
The Factory Assembly Manual says the cab floor to top of frame is 3/4 inch.
I have my cab off the frame and could measure the bolt hole locations for you sometime tomorrow, assuming I remember to do that.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Here's the dimensions for the cab support shackle holes in the frame. My frame is in camouflage right now. It still needs to visit the sandblaster.
There MIGHT be holes in the cab floor reinforcement shown in the photo you posted, but if not, let me know and I can measure those for you also. I haven't seen a '48 floor, which I imagine would have reinforcement in the center where the single mount is. Just a single thickness of sheet metal in that neighborhood on the later cabs.
Last edited by klhansen; 02/02/20199:17 PM.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
