I recently picked up a 1940 Ford ex-RCAF crash tender. It is a Marmon Herrington 6X6 conversion to a 6 ton tandem axle. I don't claim to be an expert on these trucks, I just know I think that the "tonners" were a gorgeous truck. I have tried to contact MH to obtain the PDF files that others say they have for their trucks but have not had any luck. I will need info on axles, brakes, wiring and door interiors(don't ask). Hopefully I will be able to return the favor if I learn enough.

Was ticked off about missing out on a late 30's 2 ton Diamond T so when a cousin told me about a late 30s ford I had to take a look.




Tandem axles. Double the trouble... or more.




What a driveline! transmission with pto, transfer case, full time 6 wheel drive, 3 axles, tandem rear end with double 4 link setup.




Didn't notice it at the time but one side of the truck has 18's on it and the other has 20's. Doh!






21870 miles

 

Needed to get all the rims to a standard size but keep the 37" tire height of the 20's. Couldn't find anybody who could supply 5 on 8 budd style rims for less than a second mortgage so I recentered the middle of two of the 20 budds that were already on the truck. Trued up and powder coated, they will do for the front two rims. 255/70R22.5 tires in drive tread will do. I can't mix and match sizes on this project as it is full time 6 wheel drive and will rip itself apart if anything doesn't match.

 

Nice job on the 22.5". If I'm correct your original 18s were shallow dished and specific to your single wheel configuration, i.e. can't be used in a DRW set up. As for the Maintence and Parts Manual, as well as for M-H specific parts and service, your gonna want to get to know Chuck Mantiglia of Chuck's Trucks in CT. He should have and be willing to copy the manual.

Chucks Trucks LLC., Chuck's Trucks, Chucks Trucks

Your axles look similar to this Truckstell unit, except with Timkens. Stu

 

Can anyone identify what type of transfer case this is? I am currently unable to get at it to do anything other than take these pictures. My plan is to change the whole gear ratio in the transfer case to solve the hyway speed issue.

 

Thank-you. Too bad I don't have more of the Budd style with proper centres capable of building with proper offset. I plan on stepping the back out a few more inches so I built a CAD file to cut new centers which will be welded into 22.5 o

CNC cut center for 5 on 8 budd look rim cut from 3/8" plate.


pen rims. They are not identical but should give the truck the right feel.

 

In several other threads you have mentioned the desire to gear your truck up for higher speed. Installing an auxiliary transmission was mentioned as one option. Here are my thoughts about changing your truck for higher speed.

First, is it really a good idea? You have a lot of truck with a lot of drive line. The amount of inertia in all the moving parts of your truck is not small. Getting all that stuff moving with 85 (maybe 100) horsepower is asking a lot. With low gears your engine is happy to move your truck around at low speed. With higher gears the stress on your motor goes up a lot. If you will only run higher speeds when empty, then modification is probably ok. If you plan on hauling antique tractors or big hit-and-miss engines to shows then you won't have enough power to move very fast anyway. I am assuming that you will get all six of your brake sets working properly so stopping is still acceptable, but still you will have a lot of truck to stop too.

The first option for faster gearing may be simply using what Ford made available when the truck was new, higher speed gears for the axles. It looks like you have three stock Timken axles as used by Ford in the 1 1/2 ton and 2 ton trucks. Most likely you have the 5.83 or 6.67 gears in your axles. The highest speed option was 5.14, which can typically be found under F-4 trucks in the 48-52 era. Re-gearing three axles might not sound like fun, but it is probably the most practical option. Borrowing some calculations I did for another thread, here are speed calculations for the different axles.
Doing a bit of math your speed with 34 inch diameter wheels at 2700 rpm with the different gears is:

gear _______ speed in direct drive ____ speed in 15% overdrive
5.14 __________ 53 m.p.h. _______________ 62 m.p.h.
5.83 __________ 47 m.p.h. _______________ 55 m.p.h.
6.67 __________ 41 m.p.h. _______________ 48 m.p.h.

You can see what a difference a rear axle gear swap can make.


Next on the option list is an auxiliary transmission. These were popular with heavy haul over the road trucks back in the 40s through the 60s. There is an extensive thread on the subject on this forum with a lot of good information. I collected a lot of that information into one post that can be found here: https://www.ford-trucks.com/forums/5...l#post15438159. If you are interested in auxiliary transmissions you really should read the whole thread.
Also worth thinking about is what Chuck of Chuck's Trucks did for his 4X4 F-7. He didn't have any axle re-gearing options so he used an auxiliary transmission. His truck is documented in this thread: https://www.ford-trucks.com/forums/9...7-coleman.html

I don't think that replacing the main transmission is a good option for higher speed gearing. All of the overdrive gear boxes small enough to fit in your truck that I am aware of are way too light duty for the weight of your truck. Do not be fooled by horsepower ratings for transmissions, those are for use in light vehicles. You need a transmission as strong as the stock T-9.

I am skeptical of re-gearing your transfer case. I am aware of one off road after market transfer case that tried offering an overdrive ratio. They quit offering it doe to high failure rates. The basic design of the transfer cases is not good for high gear speeds and loads. Driving in the overdrive range wore out the bearings and gears even though they were the same bearings and gear material very successfully used for under-drive operation.

Please pardon the long post, I didn't see a way to make it shorter and still provide enough information to be useful.

 

5.14s and overdrive, you could drive with reckless abandon

 

Oh boy, that thing is great, bet Chuck's trucks can help as well as talking with Don Chew here in Colorado. wish that were my toy.

 

I am going check for numbers on the bottom of my diff. see which I have, thinking I have the 5.14's or hoping at least. Wish I had an overdrive for it. I have a friend with a 41 (1 ton) pickup that has a Lincoln overdrive, boy that thing moves but I don't think that overdrive could handle the loads of a 1.5 ton.

 

I called Chuck today. Boy does that guy know his stuff! He knows all about the MH's and has parts for most. He told me that my truck should have 583? gears in it already and that i won't have to worry about doing 55 with the tires I'm putting under it (255/70R22.5). Chuck also mentioned that I should leave the brake system stock as it will function perfectly fine for the truck I have.
I did call MH this week but was told that they could not provide me with any info or manuals for my truck as it was too old. Chuck however has all the manuals I require and is willing to sell them to me. Since he's also a Dennis Carpenter dealer I may as well put all my orders through him from now on. Now just to go get a second mortgage.

 

Another man made into a Chuck believer. Stu

 

was walking by the truck this morning and couldn't help but stare at the one feature that I love in these trucks. The front end.


There is no way I'm going to cover that front with a big bumper. If I can whittle up a set of bumperettes and leave the whole front open it will look great. I know it looks like hell now but trust me, it will look better.

 

I agree with leaving it exposed, this front end looks great. You aren't going to be crashing through forests or heavy brush.
But the big cow catcher bumper kept the grill in nice shape over the years for you to enjoy.

 

I've got a front bumper with brackets left over from my '40 1 1/2 ton which you can have if you can figure how to get it to Canada from SoCal.

 

Are you missing the hood latch lever? Mine was broke, found a member on Fordbarn with a whole box of NOS ones after bought one off ebay and I see there's another one on there.