C30 Chassis

[Charlie Down]

I'm trying to find out if the Chevrolet C30 chassis frame was the same as the 134" MCP chassis, as used on the 1533X2 LRDG truck. Any ideas? If there were any differences, what were they?
Many thanks

[Hanno Spoelstra]

Originally Posted by Charlie Down

I'm trying to find out if the Chevrolet C30 chassis frame was the same as the 134" MCP chassis, as used on the 1533X2 LRDG truck. Any ideas? If there were any differences, what were they?
Many thanks

I don't think so, but please check wanted: Chev CMP chassis views for reference info on the C30/C60S chassis.

[Grant Bowker]

My first guess would be "no" with the C30 being 4x4 and the LRDG 4x2.


I don't have a 1533x2 parts list to compare to the C30/C60s but by parallel and looking at 1542x2 and C60L parts books (both LWB), all frame rails and crossmembers have different part numbers from the corresponding part on the other truck. The differences may not have been great but there was something different to cause a different part number.

[David Herbert]

In general (not particularly in answer to this question) different part numbers can mean just a couple of extra holes in an identical pressing or even an identical part from a different supplier. Or a totally different part.

David

[Hanno Spoelstra]

Originally Posted by Grant Bowker

My first guess would be "no" with the C30 being 4x4 and the LRDG 4x2.

Agree. Look at the C8 4x4 and C15 4x2 chassis, they differ a lot.

I don't have a 1533x2 parts list to compare to the C30/C60s but by parallel and looking at 1542x2 and C60L parts books (both LWB), all frame rails and crossmembers have different part numbers from the corresponding part on the other truck. The differences may not have been great but there was something different to cause a different part number.

I presume you mean the 1543X2?

Charlie, that would be my starting point for modeling purposes. As far as I can tell the 1543X2 was the LWB version of the 1533X2.

[Grant Bowker]

My apologies, it is the 1542X1 and 1542X3 parts lists I was looking at.

[Hanno Spoelstra]

Originally Posted by Grant Bowker

My apologies, it is the 1542X1 and 1542X3 parts lists I was looking at.

Thanks Grant. What was the difference between a 1542 and 1543? Not familiar with the coding system.

I do know X1,X2,X3 etc are export destination codes - see http://www.mapleleafup.net/forums/sh...694#post147694

Edit - from the revised link I learned:

1542x3 3-ton 160" w.b.
1533x2 3-ton 134 1/2" w.b. with 9.00 x 16 wheels
1543x2 3-ton 160" w.b. with dual performance axle and 20x6 wheels and single rears

So the 1542 was a regular 3-ton 160" w.b. truck, while the 1543 was the same but with the Eaton 2-speed axle? If that what "dual performance axle" stands for, that is.

[Mike K]

Originally Posted by Hanno Spoelstra

Agree. Look at the C8 4x4 and C15 4x2 chassis, they differ a lot.

Not sure where this discussion is going but the C8A 4X4 chassis and the C8 4X2 chassis are virtually identical except for the middle crossmember , I've had both types and they clearly used the 4X2 chassis as the basis for the C8A

[Hanno Spoelstra]

Originally Posted by Mike Kelly

Not sure where this discussion is going but the C8A 4X4 chassis and the C8 4X2 chassis are virtually identical except for the middle crossmember , I've had both types and they clearly used the 4X2 chassis as the basis for the C8A

Maybe you are right. From my recollection when seeing them side-by-side there was quite some difference.

Anyway: do you know "if the Chevrolet C30 chassis frame was the same as the 134" MCP chassis, as used on the 1533X2 LRDG truck"?

[Charlie Down]

This is going down an interesting route.

I am intrigued that the 1542 and 1543 differences were a 'dual performance axle', which I assume is a 2-speed axle. Does that mean that the last '3' of 1533X2 also means a 2-speed axle and a '1532' truck would have a conventional axle? Would clear up some differences of opinion in the LRDG interest groups. I have been looking for evidence of this other than fuzzy photos for some time. The LRDG specification for the truck does not mention the 2-speed axle, which is a stumbling block for some to be convinced of the 2-speed fixing despite photos.

My original post was to determine whether it would be practical to use an IBG model C30A chassis (I know there are issues with the cab, but its not needed for my build, and the suspension components are a generation better than Tamiya parts.) to do an accurate 1533X2, rather than 'bodge' the 1972 Tamiya kit. Having done lots of research on the LRDG 1533X2 I can't not use it to build the model! Any build needs good and accurate foundations hence the chassis. Looking at numerous posts, On-line parts catalogues, and GM Heritage site for information I think my best bet is to do a scratch built chassis and cross kit various components. The C30A chassis, although related, is not the same as the 1533X2 chassis, but that was a conclusion based on your collective help, so thank you everyone.

[Charlie Down]

I have found drawings of both types of chassis from Maple Leaf up Forum and from the GM Heritage Centre website. I have grouped them together for comparison. The CMP chassis is a generic view and needs to be 33"s longer I think, between frames 3 and 4 to become a 134" chassis, but its the clearest view for comparisons sake. The most obvious difference is the angles at the front of the chassis with the MCP chassis having a more downward pointing end to the frame. This, I presume, is to accommodate the I beam axle for 2 wheel drive as opposed to the driven front axle on the C30 CMP chassis. There are other differences such as strengthening gussets on various cross members of the CMP chassis, as well as the lack of strengthening plates on the mid section of the CMP chassis. Despite my research I haven't found the width of the CMP chassis (more likely didn't notice it when looking for other details). I know the MCP chassis was 25-7/16" at the front and 36 at the rear and had a wheel base of 134-1/2". The MCP chassis diagram isn't great but ok for comparison. Ideally a better diagram would be helpful. I have attached another drawing to show the MCP strengthening plates on the mid section of the chassis. Hope that helps.

[Grant Bowker]

By coincidence we were walking around the CMPs in the field today and the width of the frame (outside of rails) is 34".

[Charlie Down]

I got some measurements for a chevy Blitz chassis courtesy of Allan Mazlin, from MCP Vehicles Australia. I've added the measurements to my comparison slide of the MCP chassis for clarity. The MCP Chassis is wider at the back and narrower at the front compared to the CMP chassis. I would have thought the CMP would be wider for military use to make it stronger and more stable. Surprising result. Also the spring hangers seem to be arranged differently. According to the GM Heritage site the MCP rear springs with auxiliary leaves were 46" or 1168mm long and 2-1/2" 63mm wide. It would be interesting to compare blitz rear springs to see if they have been modified (lengthened or shortened) with the rest of the CMP Chassis. I believe the MCP chassis had extensions to fit the Military front bumpers on, which made the chassis even longer.

[Hanno Spoelstra]

Good work Charlie.

See http://www.mapleleafup.net/vehicles/.../chevspec.html for spring specs

[Grant Bowker]

I'm not sure when it started (one source gives 1938) but I'm fairly certain that the 34" outside width of frame rails is a SAE standard, established to permit interchange of bodies between chassis of different manufacturers (to save body makers from having to make different bodies for Ford, Chevrolet, Dodge, etc.). In the same vein, the distances from back of cab to rear axle are also very close to standardized - for the same reason.
One reason that the lighter modern pickup trucks still have wider frames is that they are pretty much designed to have proprietary bodywork and single rear wheels rather than specialist manufacturer bodies and dual rear wheels.