gap measurment? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

55metalmonkey · 10-25-2010, 01:10 PM

Hi all,
I was wondering if anyone would have a measurement for the original gap/ space between the cab floor and the top of the frame for a 55 GMC ½ ton?
I just finished some fairly serious rust surgery on my cab floor and on the cab mounts and need to know the measurement off the frame that the cab should sit at, I want to be sure that in the process of fabricating and welding that I didn’t shift the dimension too much or at all.
When I took the cab off, the rubber was virtually gone and there was a shim or two on one of the mounts…..can’t be too sure how many because of rust expansion. So measuring before I took the cab off would have been pointless.

I might be wrong but I think that if I’m off slightly and don’t make adjustments when I put the cab back on that it might affect the gaps and alignment of the other panels later on and make more work later on to correct it or back track just to make a minor adjustment.

Thanks

OrrieG · 10-25-2010, 08:18 PM

If it is second series mine was about 3/8" but the assembly manual shows "shim" as required at the cab and radiator mounts. I raised mine 1/2" for clearance and expect to spend some quality time with alignment. Plan is to do the radiator and hood first to the cab, then hang the fenders to the hood and doors. Bed will be done last. When I set the cab I made sure the floor was parallel to the frame rails. there is also room for side to side movement so you need to make sure it is centered too.

dwcsr · 10-26-2010, 01:44 AM

On the front mounts all it is is shims and a thin piece of rubber. The back has a rubber mount about 3/4" thick.

55metalmonkey · 10-26-2010, 11:49 AM

Thanks for the info, it is a second series (TF) truck, do you know where I can get a hold of a copy of the assembly manual you have? I just hate getting into a situation where I have to back track due to lack of info and a manual would be helpful.
Several previous owners ago someone did a back-yard-hillbilly repair job and between the rust and good-enough repair it was hard to tell what should and shouldn’t be there, took some time to de-engineer what they thought was an acceptable repair, can’t criticize them too much though….at least they made the truck survive long enough for me to get my hands on it. I was wondering why I pulled out a thin piece of rubber, it looked like a couple of scrap pieces of mat that the guy just had lying around…. It almost seemed useless to have rubber that thin to dampen vibration to the cab… good thing I kept them for reference.
I guess I’ll be leaving room for adjustment to shim the cab and the rad support and finessing the alignment later.
Thanks again

OrrieG · 10-26-2010, 01:23 PM

Manuals are available online for around $20, I got mine thru amazon.com. Tons of good information and they show all the small parts that have been removed or fallen off over the years. Also show concealed body parts so you know what you are getting into during body work phase. Dave is right, front shims are solid to maintain fender/cab and hood alignment, back are rubber to give a little flex. Mine had two 3/16" metal at the front and "compressed" rubber at the back, hard to tell exact original depth. Parallel to the frame is the important element.

Spackle100 · 10-26-2010, 02:39 PM

Quote:

Originally Posted by OrrieG

Manuals are available online for around $20, I got mine thru amazon.com. Tons of good information and they show all the small parts that have been removed or fallen off over the years. Also show concealed body parts so you know what you are getting into during body work phase. Dave is right, front shims are solid to maintain fender/cab and hood alignment, back are rubber to give a little flex. Mine had two 3/16" metal at the front and "compressed" rubber at the back, hard to tell exact original depth. Parallel to the frame is the important element.

Orrie, is this the one you purchased?

Amazon.com: 1958 CHEVY PICKUP TRUCK Shop Service...

55metalmonkey · 10-26-2010, 03:32 PM

Thanks,
I'll have to pick one up

OrrieG · 10-26-2010, 03:59 PM

no, shop manuals are not the same. it is factory assembly manual, blue cover with truck on the cover.
Posted via Mobile Device

Spackle100 · 10-26-2010, 05:20 PM

Quote:

Originally Posted by OrrieG

no, shop manuals are not the same. it is factory assembly manual, blue cover with truck on the cover.
Posted via Mobile Device

Thanks, just bought one

10-25-2010, 01:10 PM	#1
55metalmonkey Registered User Join Date: Aug 2010 Location: West Kelowna, BC Posts: 488	gap measurment? Hi all, I was wondering if anyone would have a measurement for the original gap/ space between the cab floor and the top of the frame for a 55 GMC ½ ton? I just finished some fairly serious rust surgery on my cab floor and on the cab mounts and need to know the measurement off the frame that the cab should sit at, I want to be sure that in the process of fabricating and welding that I didn’t shift the dimension too much or at all. When I took the cab off, the rubber was virtually gone and there was a shim or two on one of the mounts…..can’t be too sure how many because of rust expansion. So measuring before I took the cab off would have been pointless. I might be wrong but I think that if I’m off slightly and don’t make adjustments when I put the cab back on that it might affect the gaps and alignment of the other panels later on and make more work later on to correct it or back track just to make a minor adjustment. Thanks

10-25-2010, 08:18 PM	#2
OrrieG Registered User Join Date: Jun 2006 Location: Idaho Posts: 8,800	Re: gap measurment? If it is second series mine was about 3/8" but the assembly manual shows "shim" as required at the cab and radiator mounts. I raised mine 1/2" for clearance and expect to spend some quality time with alignment. Plan is to do the radiator and hood first to the cab, then hang the fenders to the hood and doors. Bed will be done last. When I set the cab I made sure the floor was parallel to the frame rails. there is also room for side to side movement so you need to make sure it is centered too. __________________ 1959 Chevy Short Fleetside w/ 74 4WD drive train (current project) OrrieG Build Thread 1964 Chevelle Malibu w/ 355-350TH (daily driver) Helpful AD and TF Manual Site Old Car Manual Project

10-26-2010, 01:44 AM	#3
dwcsr Hollister Road Co. Join Date: Apr 2005 Location: Houston Posts: 6,131	Re: gap measurment? On the front mounts all it is is shims and a thin piece of rubber. The back has a rubber mount about 3/4" thick.

10-26-2010, 11:49 AM	#4
55metalmonkey Registered User Join Date: Aug 2010 Location: West Kelowna, BC Posts: 488	Re: gap measurment? Thanks for the info, it is a second series (TF) truck, do you know where I can get a hold of a copy of the assembly manual you have? I just hate getting into a situation where I have to back track due to lack of info and a manual would be helpful. Several previous owners ago someone did a back-yard-hillbilly repair job and between the rust and good-enough repair it was hard to tell what should and shouldn’t be there, took some time to de-engineer what they thought was an acceptable repair, can’t criticize them too much though….at least they made the truck survive long enough for me to get my hands on it. I was wondering why I pulled out a thin piece of rubber, it looked like a couple of scrap pieces of mat that the guy just had lying around…. It almost seemed useless to have rubber that thin to dampen vibration to the cab… good thing I kept them for reference. I guess I’ll be leaving room for adjustment to shim the cab and the rad support and finessing the alignment later. Thanks again

10-26-2010, 01:23 PM	#5
OrrieG Registered User Join Date: Jun 2006 Location: Idaho Posts: 8,800	Re: gap measurment? Manuals are available online for around $20, I got mine thru amazon.com. Tons of good information and they show all the small parts that have been removed or fallen off over the years. Also show concealed body parts so you know what you are getting into during body work phase. Dave is right, front shims are solid to maintain fender/cab and hood alignment, back are rubber to give a little flex. Mine had two 3/16" metal at the front and "compressed" rubber at the back, hard to tell exact original depth. Parallel to the frame is the important element. __________________ 1959 Chevy Short Fleetside w/ 74 4WD drive train (current project) OrrieG Build Thread 1964 Chevelle Malibu w/ 355-350TH (daily driver) Helpful AD and TF Manual Site Old Car Manual Project

10-26-2010, 03:32 PM	#7
55metalmonkey Registered User Join Date: Aug 2010 Location: West Kelowna, BC Posts: 488	Re: gap measurment? Thanks, I'll have to pick one up

10-26-2010, 03:59 PM	#8
OrrieG Registered User Join Date: Jun 2006 Location: Idaho Posts: 8,800	Re: gap measurment? no, shop manuals are not the same. it is factory assembly manual, blue cover with truck on the cover. Posted via Mobile Device __________________ 1959 Chevy Short Fleetside w/ 74 4WD drive train (current project) OrrieG Build Thread 1964 Chevelle Malibu w/ 355-350TH (daily driver) Helpful AD and TF Manual Site Old Car Manual Project



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