47 AD Rear Cab Mount - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Gippetto · 04-10-2013, 03:01 PM

I hope I can get some insight on how and what to do to improve my existing rear cab mount. I understand GM went to a two trunion cab support in '49 because the single centered approach used in 47 & 48 was over stressing the cab sheetmetal where it is attached.
Does anyone have a picture of the original assembly viewed from inside the cab. In mine, the trunion is clearly visible because the sheet metal is torn off completely. There looks like there once was a box like assemby that enclosed it and kept the weather out. I am looking to re-enclose the trunion after I replace the bushings and beef up the attach point so it won't tear out in the future.
Anyone have pictures of a surviver that you can post.

Thanks for any help.

mknittle · 04-10-2013, 06:27 PM

Gm went from the center rear mount to a shackle set up. There is a rubber bushed shackle mounted parallel to the frame on each side The top mount bolts to the trunion
and the bottom to the frame. I think it would be pretty easy to adapt.

2ndGenRR · 04-10-2013, 07:56 PM

I'm building a '48 and it had the center mount...easily converted it to side mounts with the proper cab supports and mounts that are available through all the vendors. My understanding is that the side mounts were instituted to give a softer ride as they allow the back of the cab to flex a little.

As I recall, the center mount was a single captive bolt and I had to cut the sheetmetal in the cab to reach the captive bolt that had come loose. I cut a flap and bent it up and then simply welded it back down.

Hope that helps. Good luck!

mr48chev · 04-10-2013, 10:55 PM

I think that the original concept behind the triangle mounting setup was so the cab would move a bit when the frame flexed when the truck went over rough terrain but most of our trucks never see anything rougher than a driveway entrance.

I've got a later cab on mine because the original cab got tweaked in a wreck and I could never get it back square. It has the side shackles and they were pretty easy to set up.

One of us can trace the pattern for the bolts with exact measurements if you need them.

04-10-2013, 03:01 PM	#1
Gippetto Registered User Join Date: Aug 2009 Location: Woburn, MA Posts: 127	47 AD Rear Cab Mount I hope I can get some insight on how and what to do to improve my existing rear cab mount. I understand GM went to a two trunion cab support in '49 because the single centered approach used in 47 & 48 was over stressing the cab sheetmetal where it is attached. Does anyone have a picture of the original assembly viewed from inside the cab. In mine, the trunion is clearly visible because the sheet metal is torn off completely. There looks like there once was a box like assemby that enclosed it and kept the weather out. I am looking to re-enclose the trunion after I replace the bushings and beef up the attach point so it won't tear out in the future. Anyone have pictures of a surviver that you can post. Thanks for any help.

04-10-2013, 06:27 PM	#2
mknittle Registered User Join Date: Jul 2011 Location: Auburn ca. Posts: 2,886	Re: 47 AD Rear Cab Mount Gm went from the center rear mount to a shackle set up. There is a rubber bushed shackle mounted parallel to the frame on each side The top mount bolts to the trunion and the bottom to the frame. I think it would be pretty easy to adapt. __________________ Mark My GMC build. http://67-72chevytrucks.com/vboard/s...d.php?t=536602

04-10-2013, 07:56 PM	#3
2ndGenRR Registered User Join Date: May 2005 Location: Lowell, Michigan Posts: 159	Re: 47 AD Rear Cab Mount I'm building a '48 and it had the center mount...easily converted it to side mounts with the proper cab supports and mounts that are available through all the vendors. My understanding is that the side mounts were instituted to give a softer ride as they allow the back of the cab to flex a little. As I recall, the center mount was a single captive bolt and I had to cut the sheetmetal in the cab to reach the captive bolt that had come loose. I cut a flap and bent it up and then simply welded it back down. Hope that helps. Good luck! __________________ The Stable: 1952 GMC 1/2 ton, 5-window...Owned since age 16...that was awhile ago! Torn apart and waiting for my boys to get old enough to help me. 1990 Chevy K5, 5.3L, 4L60E, slowly going back together as my dune truck. 1951 Chevy 1/2 ton, 3-window...building to sell. Daily Drivers: 1998 3/4 ton Burb with a 6.5 Turbo Diesel and 1994 1/2 ton Silverado. I grew up in Flint, Michigan so I can't help but to bleed Chevy!

04-10-2013, 10:55 PM	#4
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,406	Re: 47 AD Rear Cab Mount I think that the original concept behind the triangle mounting setup was so the cab would move a bit when the frame flexed when the truck went over rough terrain but most of our trucks never see anything rougher than a driveway entrance. I've got a later cab on mine because the original cab got tweaked in a wreck and I could never get it back square. It has the side shackles and they were pretty easy to set up. One of us can trace the pattern for the bolts with exact measurements if you need them. __________________ Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around.



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