How would you split a brake system?

[3006guns]

My search for an M37 isn't going all that well and I'm seriously considering an M211 as an alternative. Heck, for the same money I can get a vehicle with a 2 1/2 ton rating that looks impressive as all get out. Now, everyone seems to have one of the "newer" M35's with the multi fuel engines but after a lot of poking around I discovered the M211.

Gas engine yes, but it's something I understand better than the diesels. Besides, it has that "vintage" military look to it. The only major improvement I'd like to make would be to split the braking system hydraulics, making the front independent of the rear for safety. I know the Air Force did this to the M35's they acquired, but just how difficult is it? Rerouting some lines and a double master cylinder I would suppose but would a proportioning valve be necessary? If there's a detailed thread on this subject I haven't had a lot of luck finding it.

Thanks in advance for any help or advice!

 

[USMC 00-08]

Welcome to the forum!

I don't have an answer to your question, but I think you have a good idea and would like to explore this more too. Hopefully someone will chime in on how to do it.

 

[Carboarius]

Your best bet would probably be finding an example off an Air Force M35 and copying it. Keep in mind the M211's have 12 wheel cylinders to the M35's 6. As compared to a modern vehicle the M211 has 3 axles, so twice the amount of brake fluid would be required on the rear compared to the front if it were split (as opposed to a standard 2 axle truck). If it were me I would just upgrade the e-brake to a disk brake type system instead of attempting to re-vamp the brake system if it was operable. Whatever you decide, please keep us posted as we would like to see what you end up with.

 

[m1010plowboy]

I'd like to use the words "just take a hydroboost of an 80's GM 3 ton and plumb it in" but I'm on the learning curve too. Since all the brakes get fed from the air-pak, it complicates just tying a line into a hydro-boost and running it to the front end....unless it provides the required pressure and volume the big deuce needs.

I did find a pile of single to dual circuit threads..... and a few good ones. Here's a start.

https://www.steelsoldiers.com/showthread.php?28531-Split-brake-system

and the results of a keyword search for """single circuit brake upgrade""""
https://cse.google.ca/cse?cx=partne...gsc.q=single circuit brake upgrade&gsc.page=1

It's been done so it'll be nice to find the easiest path to an Early Deuce upgrade.

 

[quickfarms]

I did find this

https://www.easternsurplus.net/GalleryDetails/511/M211-Full-Restoration

 

[3006guns]

Thanks guys.....the links give me something to study/learn about. Since I don't actually own a deuce yet I'm trying to gather as much info as possible before taking the plunge.

 

[hendersond]

I did find this

https://www.easternsurplus.net/GalleryDetails/511/M211-Full-Restoration

Thanks! I never would have thought of that in a million years, 2 air packs. I wonder if they run off a dual circuit master? This is worth looking into.

 

[quickfarms]

Thanks! I never would have thought of that in a million years, 2 air packs. I wonder if they run off a dual circuit master? This is worth looking into.

Yes, it is basically a copy of the M35A2C system

The air pack is essentially a booster

 

[Ashley P]

I'm a car mechanic and owner of a 211 that's been modded. Cars started dual piston/reservoir master cylinders in the late 60's. They divided front from rear. Later model cars often divide diagonally so that you aren't left dragging rear wheels for hundreds of feet on wet pavement (you'll always have one front and the opposite rear). On the 211, since the driveshafts/transfer case couple the rear axles together, if you apply brakes to one axle you will slow the other axle also. I would be tempted to split one front wheel to the rear axle and the other front wheel to the other axle.

My 211 is only used on the farm and at low speed. It has NO brakes on the middle axle but will skid those wheels in grass when unloaded.

 

[DUUANE]

Something interesting..

Well it took me a while to find it..this isnt the full diagram i was looking for but in past research on splitting the system on my WC62 i remembered seeing a diagram for a dual hydraulic system for a tandem axle application with dual servo (2 wheel cylinders per wheel) brakes.
The system was split upper and lower Vs. Axle to axle or diagonally.
One circuit for the upper wheel cylinders..the other for the lowers..it doesnt solve the issue of how you actuate it..and it would be a huge bunch of pumbing. The upsides i think would be diminshed braking distributed evenly over all braking wheels in the event of a faliure for more control on slick surfaces , and liabillity as its already a D.O.T. approved system available in the market as an o.e. product.

Some food for debate + $.02

 

[Ashley P]

More fuel for the fire: On our two cylinder per drum system, do both cylinders need to move in order to more the shoes enough for application?

 

[DUUANE]

A good question..we will need to compare the wheel end systems to understand fully how they operate. I will review the tm and see what i can gleen...

 

[DUUANE]

Ok..had a look at section 10 of the manual. If you took one wheel cylinder out of the picture the adjuster would act as a stop.With a correctly adjusted brake i would think you would still be able to make contact with the drum.
The functioning cylinder end of the shoe for sure, but the other end would remain against the adjuster so you wouldnt have a complete engagement of the shoe as you do with a regular brake application.
Soooo..yes i think it would brake..how much it would be diminished..i cant say. Maybe when i go through my brakes ill cap off the lower cylinders and stab the pedal a few times and see what happens.

 

[Ashley P]

It's been over a year since I was into my brakes, so my memory has faded. I do know that because my system is cobbed together (different master and vacuum over hydraulic booster) and still a "single" system, I came to the conclusion that I'd add another booster and split the system by dividing the rear axles. I know that as long as the driveshafts and transfer case are functioning that one axle is couple to the other mechanically, so brakes on one axle slow the other. Of course, that would limit all braking heat to the working drums, so the larger the braking load the more likely an overheat/brake fade. BUT, that's better than NO brakes, huh?

Of course, splitting the system "top to bottom", even if it resulted in less braking shoe pressure, would also be much better than nothing. So the potential gains are great either way.

Splitting the FRONT wheels "top to bottom" would be better for steering than my idea of diagonally splitting them where you'd get massive pull toward the braking wheel.

BTW, I bought my truck and drove it about 10 miles home, with a dangling brake pedal and a parking brake that barely slowed the truck. I took a tiny back road and went very slow and learned to appreciate a good brake system!

 

[DUUANE]

Agreed..some braking is always better than none. Glad to hear you made it home with no hassles..i used to do stuff like that. The cops here seemed to just enjoy talking to you and getting the walk around tour of whatever vintage junk you were riding home..now theyve gone and hired out of country for the force. Australia, New Zealand Ireland..or god help you if you run into one from quebec. Your wallet will get a beating with the sharp edges of the book.
We did lead and chase vehicles with 4 ways on..drove stuf home in reverse because that was the only gear available..had to drag my M37 15km on a chain after it spit a valve seat out of the block. All good times.