M35A2 BRAKE MASTER CYLINDER TECHNICAL CHALLENGE

January 31st, 2008.

Gentlemen and ladies:

I desire to place before the group of M35/M818 owners the following questions:

1. WHAT WILL IT TAKE TO COME UP WITH A SUBSTANTIAL, HEAVY DUTY REPLACEMENT or a NEWLY ENGINEERED MASTER CYLINDER TO SPLIT THE BRAKES FRONT AND REAR on the deuce to gain a FAIL SAFE CAPACITY??

2. WHICH PARTS MANUFACTURES WOULD BE WILLING TO TAKE THIS ON, IF THERE'S
ENOUGH INTEREST? WOULD EASTERN, BOYCE & Co. be willing to help underwrite it, in order to be able to upgrade their commercial rebuilds??

3. HOW MANY OF US DUECE/5/10 Ton OWNERS ARE WILLING TO BE COUNTED IN, IF THE UNIT PRICE IS REASONABLE OR COMPARABLE TO SAY, A PAIR OF LOCK-OUT HUBS (NEW)??

ARE WE WILLING TO RISK THE 1951 Design BRAKE SYSTEM IN REGULAR SERVICE? While it was normal in 1951/2 to build heavy trucks with only hand brakes as reserve, IS IT PRUDENT for us to continue to use a system wth no inherent fail safe? DO YOU WANT TO RISK A 13,500LB TARE WEIGHT CAR CRUSHER when the brakes fail? EVEN with maintenance, there is no viable back up on these heavy trucks except an unboosted or inoperative hydraulic brake (compressor failure) or(line or hose failure)?

I treat EVERY STOP AS A POTENTIAL FAILURE, because even with correct maintenance, due to age and materials/design, the potential's always there. IT AMAZES ME that when these trucks went through their MWO's in the late 1980's, early 1990's, Uncle Sam didn't take the opportunity to retrofit these trucks with a better brake system, at small additional cost to the taxpayers to gain more redundancy in normal and combat operations. GRANDFATHERED doesn't feed the LAWYERS nor keep them off your back if you're involved in an accident that would be avoidable with a small outlay in dollars.

WHAT set me to thinking was an article the other day in Steel Soldiers where a gentleman picked up an M105 trailer with his deuce which had developed an air compressor line leak due to abrasion against the headlight bucket, apparently he held enough pressure to run her, but the point was justly made that ANY FAILURE of any BRAKE SYSTEM COMPONENT
should be cause to stop the truck and have it repaired or towed due to the lack of redundancy in the design. CAN WE COME UP WITH A MODIFICATION TO OBTAIN THE NECESSARY REDUNDANCY???

THE LARGE TYPE IS TO EMPHASIZE THE NEED TO CONSIDER THE QUESTION, It's not bad manners or shouting, I just feel it's important enough for all of use to consider before one of us, our families, friends, and others are injured or killed in an avoidable accident.
By definition, accidents are avoidable, incidents are beyond our control.

PLEASE DO give it some of your time and best thoughts, and please do reply in the Duece or Five/Ten ton columns as necessary or possible. I and others would benefit by the discussion of this critical subject before we get bad press due to an accident, and WE
will get it if we have a visible one. I remain, as always, indebted for the many insights, kindnesses and considerations shown me and my questions by you most learned owners of the Deuces.

I Remain,
Most Sincerely,

Kyle F. McGrogan
1963 Mercedes Benz Unimog S404.114 (Swiss)(Which has a one port master cylinder, but which has a two port as an option- so I'm thinking here too!)
1971 KAiser Jeep M35A2 Wo/W "Saddam's Nightmare", Vietnam and Desert Storm Veteran
Deuce and COLD WEATHER LIZARD!.

Kyle,

There is an improved brake system for the M44 Series Vehicle. This manual in the TM Section will show how the system is set up:

http://steelsoldiers.com/index.php?module=pagesetter&type=file&func=get&tid=1&fid=file&pid=85

The system was used on limited number of Extended Service Program trucks (mostly Air Force) and was standard on the M35A3.

Hope this helps you in your quest for safer brakes.

One major reason I got a 1988 M35A2C (ex) USAF truck.. Had the dual brakes from the factory.

I’ve looked into doing this... Problem is that cost will not allow 97% to afford the conversion... The cylinder is the easy part, you need dual air packs to split the system. Boyce, Eastern, Memphis, etc have the parts available to them to install these in their trucks as do I…

A "manufacture" like myself cannot use "used" parts on something like this so that means I have to put a kit together with 2 new air packs, a new master cylinder, new brackets, a valve and new lines... 1500-2000$ IF SOLD IN QUANTITY!!!

Being that air packs are not in production I would need 200+ to get them produced…

And… Even if I sold these at cost I would never recover all of the money in my life time.

If you really want this on your truck their easy enough to cobble together from spare parts. I do think this is a safety issue, but most will not put the money fourth to maintain their stock braking system let alone lay the cash out to upgrade it.

Like Mark said... Get an A2C... I think he laid out ??? 19,000$ for his...

Actually, you only need 1 additional airpack, as the stock "single brakes" truck has one already..

Yeah but for liability reasons... both would need to be replaced (IMHO)

I do understand the concern about the brake systems on our trucks and I wish there was another reasonable way around it. I have had many vintage vehicles with single master cylinders and honestly have never had a brake failier. But on the other hand I have always completly replaced all brake lines, master cylinder,rebuilt wheel cylinders and kept up a very good brake inspection on a regular basis. If you own and are driving a truck of this size, this is something you must do to insure that safety is first. On my GMC, that was the first major project I tackled before considering even hitting the road. On trucks this old anything can happen but if preventitive maintenance is done at least you can drive with a clear conscience.

devilman96 said:

A "manufacture" like myself cannot use "used" parts on something like this so that means I have to put a kit together with 2 new air packs, a new master cylinder, new brackets, a valve and new lines...

Click to expand...

No one needs a "kit". Just sell us the dual circuit master cylinder. We will take care of the rest. There's no point in trying to make up the hard lines as a kit. There are too many variables and one may not want to install the second air-pak at a given location. Secondly, if one needs to buy a hard line kit, it would indicate to me that they are in over their head.

devilman96 said:

Yeah but for liability reasons... both would need to be replaced (IMHO)

Click to expand...

Following that argument, every part of the truck needs to be replaced...And installed by an "OD Iron authorized technician".

What of the air-pak, M/C, and wheel cyl rebuild kits that you sell?

This makes my head hurt.

February 1st, 2008.

At least the discussion has begun.
While I can see the liability issues, If the U.S. Air Force M35's has a dual system originially, or gained it in the ESP rebuild, how hard would it be to duplicate the system parts or adapt Civillian heavy truck master cylinders to the job? Is it a proportioning problem, as all the plumbing comes togather at the MAster Cylinder/Airpack unit, and all wheel cylinders seem to be the same size on the M35A2.
Why do we need a second airpack, if all we are doing is splitting the original load from one master cylinder port to a two port master cylinder? The load should remain approximately the same if nothing else changes in the system design or make up. AND PERHAPS, IF BOYCE AND EASTERN ALREADY HAVE THE COMPONENTS, perhaps it behooves us to inquire there for the necessary parts to upgrade our trucks brake systems.
The 1963 Mercedes Benz Unimogs had either one or two part master cylinders with vacuum assist, but the Swiss Army chose the one port system, along with no cab roof canvas, framing, or cargo bed or framing and tarpaulin, to save paying the Germans more money, BUT the Swiss 404.114 can be easily adapted to use the more sophisticated system. I will be adapting the Swiss Unimog's brake system, but at least with 7.65 to 1 final gearing reductions in the hubs, the transmission and hand brake can quickly master a brake systems failure, I doubt that the reductions in the axles and the transmission band brake could say the same for the M35 series.
If I could come up with a proper poll question(s), at least we could survey the 2-1/2 and 5/10 ton owners to see how many would be willing to bite on the modifications?? I absolutely guarantee that even with preventative maintenance, these trucks have a sufficiently poor incorporated redundancy that failures are just about guaranteed due to the design and materials used. An air side failure leaves you with no power on the hydraulics and an almost unmanageable truck, a hydraulic site failure guarantees an unmanageable truck, particularly at speed, on grades, or under loads. UNCLE SAM exempted himself from liablity when he sold them to us, but we aren't able to exempt ourselves likewise.
The discussion should continue and a poll should be created by those with more computer savvy then I, to ascertain the matter more closely. If we can't afford to come up with an upgrade or adapter for the brake system, maybe we ought not to be running these trucks much longer- THEY AREN'T TOYS, contrary to some opinions, they are the equivalent in size and danger (potential) to a 7 to 22 ton locomotive moving at the same speeds, and the damage they can do to the smaller lighter cars of today and tomorrow is considerable.

I look forward to hearing more discussions on the matter.

Sincerely,

Kyle F. McGrogan

February 1st, 2008.

CORRECTION: 7 to 11 Ton Locomotive with a 0 to 57 MPH Speed Range.

Sincerely,

Kyle F. McGrogan

Memphis has the dual MC in stock. Ask them for the one for the M35A3. It's the same as the USAF Dual MC.... get that, the perportioning valve, and and airpack, and make the lines, and your golden. Memphis has all the parts, just add the lines, and your set.

without 2 airpacks, your only going to have 1 circut for brakes to do it how the USAF did it.. Without it, your back to one item that if it fails, your screwed... with 2 airpacks if 1 fails, your still "stoppable"

The fluid comes out the MC sperately, goes to the perportioning valve seperately, and then on to the airpacks sperately, then to the front axle (1 circut) and the rear axles (2nd circut) Look at the diagram in the Dual brakes TM.

problem is that most people simply aren't up to doing the work required. most probably don't even check for rusted lines or rotten hoses and if they have to add fluid every few months, that's ok with them. the people on the forum who can do a dual upgrade mostly already have. i put dual circuit brakes on all my trucks as soon as i get them, but i also replace wheel cylinders, hoses, steel lines, all fuel and air lines, etc. these trucks are after all 30 to 40 years old and the military really didn't change \ repair anything that didn't break. as to doing it the way the military did, buying the few parts needed to do it is the way to go. if you want real power brakes however, then design your own. by the way, memphis only has the master cyl, nothing else, and it does not have remote resevoir. what is the casting number on the a3 cylinder??

Does anyone know the diameter of the master cylinders, both the A3 and the A2? Stroke?

Is the Men. Equip. master cylinder new or N.O.S.?

They are new, and you DONT need the remote res. It's all one piece, just like the one on the USAF M35A2C's.

$$$$ Do you know how much they want for one?

It would be easier and cheaper to just replace all the lines and wheel cylinders on the truck, then you know everything is fresh. Yes you still have a single circuit system, but sudden failures occur due to rotted brake hoses and lines. These parts don't cost any more on the deuce than they do for a civvy vehicle. Cheap insurance. I didn't take my deuce anywhere until I replaced these parts and went through every hub.

Didn't someone on here make up an air/hydraulic system using a treadle valve and pots operating master cylinders?

Febraury 2nd, 2008.

ANYONE SEEN THAT GROUNDHOG I HIT UP IN PENNSYLVANIA WITH THE DEUCE ON A BRAKE FAILURE? OOPS, WAS THAT PUNXSAWTAWNEY PHIL???
NOW I know that MEmphis might also be able to supply the conversion items also, Thanks for the information.
Does anyone have a serviceable copy of the SMARPI 9-2320-209-14&P "Supplemental Maintenance and Repair Parts Instructions "Split Air -Hydraulic Brake System (Modified M44A2 2-1/2 Ton series truck) for sale? I looked over the lead supplied by CRAZYGUYLA above (Kudos for the leads and the information) as this seems to be a monster publication in terms of pages & c, but usefull in any case. Admittedly the design is 1949-1950, but the modifications and rebuild considerations can't be much worse then overhauling the present system wih it's inherent weaknesses.
It seems that the Army pinched pennies much more then the Air Force in terms of maintenance and upgrades, but one item I do find odd is the added windshield washer pump and reservoir on the M35A2, which, I am fairly certain, wasn't on the truck when built. GO ARMY HOO-RAH!
If you have an air ride driver's seat I also suspect you have better then the spring ride and box seats. I guess comfort ain't high on the Army's list, but apparently the M35A2's much later got padded cushions for the troop seats. Well, Monday's the Day for telephoning for new parts to convert the Brake System.

Thanks again, As always the collective wisdom on this site is incredible, and I am indebted for the many kindnesses and assists,

I am, Gentlemen and Ladies,
Most Sincerely and Respectfully,

Kyle F. McGrogan

Kyle,
You can find the manual in the TM section. Let us know the prices when you call.

900 series treadle valve on firewall