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Higginsboat

GMC 6x6 some questions

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Hi all, pic of a Truck I found online, can you tell me what cab type this is? As I've looked at lots of pics and can't find another. And also  why on some front wheels are the center's like bake Bean cans sticking out and others not? Sorry if this is run of the mill.....

f1952_GMC_Korean_6x6_Military_Truck2_Garw_5b65a4d21d72e~2.jpg

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The upper cab may have been fitted as part of a snow plough or blower installation.  

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Looks like the type of cab fitted for civi use in Europe post war.

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Cheers guys, so post war, is there any where I can go to, or read from, to learn more about GMC different model types? I'm interested in different cabs and axle types?

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Well that is a standard open cab long wheelbase with Banjo axles and no winch, which is about all you'd be able to discover.  Some of the chassis numbers identified if it was originally a tipper, or a chassis cab, or whatever, but not mush more.

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Cheers Gordon M, this is where I don't understand and need to learn more, because when I look at the cab in the pick it looks like a closed in cab to me because it has a full door and a roof....

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30 minutes ago, Higginsboat said:

Cheers Gordon M, this is where I don't understand and need to learn more, because when I look at the cab in the pick it looks like a closed in cab to me because it has a full door and a roof....

It is not a GMC cab, could be grafted on from a piece of plant, like a grader maybe. There were some unique cab replacements on demobbed army trucks when they went into civvy use, especially those in France, Holland and Belgium

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Indeed, but if you look at a proper closed cab GMC everything is rounded and sloped, cab, roof, screen, rear.

Later in the war they made many, many more basic open cabs, easy to get out of when you are getting shot at, but post war when it was raining or snowing you really needed a basic square cab you could just replace the canvas of the open cab with - that's what you have in the picture

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16 minutes ago, Richard Farrant said:

It is not a GMC cab, could be grafted on from a piece of plant, like a grader maybe. There were some unique cab replacements on demobbed army trucks when they went into civvy use, especially those in France, Holland and Belgium

It's not a wartime production cab, no, and probably not from a GMC factory, but it looks like it was made for that specific job.  Somewhere in the US a small factory would have turned out modest quantities of these cabs, probably as quick assembly kits, just because there were so many open cab trucks that really wanted a roof.  May be military, or may not.  

This is a military arctic cab for the GMC open cab:

https://forums.g503.com/viewtopic.php?t=213119

 

... virtually identical except they kept the rounded lower door shape.

Edited by Gordon_M

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Thanks for the information guys, very interesting, I now understand about the cab. Thanks for the link,  great to look at. Any idea on the wheel hubs, I've noticed some stick out more than others? 

10-german-lorry~4.jpg

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GMCs were fitted with two types of axle, Either a Timkin split axle or a Chevrolet banjo type.

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Happy New year!

Thanks for the link G506, very interesting veriants on these GMC cabs. All good to see .

And thanks for the info John 1950, I thought it might be wheel spacers of some kind.  so is it that literal, the two different makes of axle have a different wheel hub that makes one stick out more then the other as I think from what I see, the distance between  the front wheels seems greater on one from the other? So would that mean say, the bango axle has a wider stance than the timkin?

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Posted (edited)

Overall width of the axles and road spring mounts would be the same dimentions. Rear split and banjo axles had the same brake cylinders and brake shoes, fronts had different wheel cylinders and brake shoes. Drive line viewed from above on a split axle vehicle is paralell with the chassis rails on a banjo vehicle the propshafts are off line. Engineering of the steering driveshaft constant velocity joint for split and banjo due to the position of the differential units will probably account for the different hub style.

Edited by john1950
spelling

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Well you know your stuff, thanks for your help, I've also noticed and it might just be an optical illusion, but in some pics the front wheels seem to be in line with the inner rear wheels, and in others in line with the outer rear wheels? Could this be do you think? And I'm sure I read somewhere they did a non driven front axle...

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Posted (edited)

6X4 and 6x6 GMC vehicles with the same chassis layout were supplied to the US army and lease lend contracts I think. Front wheels and tyres usually track the centre of the twin rears. In the interests of commonality the same wheel dishes were used all round. I have enclosed  pictures of a 352/353/DUKW banjo rear axle. DUKW axles have different oil reals to keep the water out of the diff.

SAM_1148.JPG

SAM_1147.JPG

SAM_1146.JPG

Edited by john1950
addition

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Hi John 1950, thanks for the pics great to see so clearly what you've described. Sorry to ask so many questions! Have you or anyone seen a front axle from a 6x4 as I'm wondering if it comes as a axle, ie as a cast item with a connected rod from one front wheel to the other, or two totally independent items only connected by steering linkage? Thanks for everyone's input : )

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Every day is a day at school, Questions are good, keeps the gray matter working Basicaly there is a centre beam section either split type or banjo, or in some cases bath tub with a differential that has steering /constant velocity joint housing, hub carrier bolted to each end. Then at the rear a track rod tying both housings together for the vehicle steering. These are basic drive axles with leaf springs suspension, not independant suspension design or walking beam. Axle torque is managed either by the design of the leaf springs or by the use of torque rods, mostly on the rear axles. Sorry I do not have a front drive axle to photograph. 

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1 hour ago, Higginsboat said:

 Have you or anyone seen a front axle from a 6x4 as I'm wondering if it comes as a axle, ie as a cast item with a connected rod from one front wheel to the other, or two totally independent items only connected by steering linkage? Thanks for everyone's input : )

The 6x4 has a forged steel beam axle which is straight with upturns outboard of the road springs. Check the following link, I know it is related to a model but the inset photo shows the real thing as well. Nothing out of the ordinary much like and other non driven axle on the front of a lorry.

https://www.ebay.com/itm/U-Models-1-35-GMC-CCKW-4x6-Front-Axle-/272690215631

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I forgot all about the dumb axle of the 6x4. I think the 6x4 had a higher gross weight than the 6x6 because it was not expected to do long distances or be used as much off road. In peace time it was the sought after truck for the burgeoning road transport industry.

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Well thanks John 1950 and Richard Farrant, from the link it looks very similar to modern forged I beam, that you see Even today, things don't really change that much! Would you know did the air potable GMC s come with 6x6 and or 6x4 as I imagine weight would be a issue, and have read that these vehicles split in half behind the cab???

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They were 6x6 and you are correct in that they did split behind the cab. The front part was supported by a jockey wheel to assist loading into aircraft, fishplates were used to connect the two halves.

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14 hours ago, john1950 said:

I forgot all about the dumb axle of the 6x4. I think the 6x4 had a higher gross weight than the 6x6 because it was not expected to do long distances or be used as much off road. In peace time it was the sought after truck for the burgeoning road transport industry.

IIRC the 6x6 was nominally rated at a 2.5 ton payload for off road, 5 tons on road while the 6x4 CCW was rated at 5 tons as it was not expected to be used off road.

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Thanks Degsy and radiomike? This is all good stuff ! I imagine there would be some references to a vehicle being air portable in the chassis number?.... But I wonder if there is a visible way to tell, even if you have to crawl underneath?

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