Single reservoir master cylinder on deuces ?

[DanielP]

When was the signle reservoir master cylinder for deuces phased out in favor of the more modern / safer variety?

 

[clinto]

For the most part...never. The 1987-1989 USAF contract deuces and the later M35A3's used a dual master cylinder/airpak arrangement, but all other M44 series trucks are single reservoir.

There is more information out there on the forum about the dual cylinder arrangement.

 

[BugEyeBear]

I believe that the dual circuit system is only found on the A3 series.
Has additional booster(s), and also has a dual fill reservoir located on the firewall.

I could be wrong but I don't think a dual-circuit system was ever installed (by Uncle Sam) on an A2 series.

-Bear-

 

[Warthog]

When was the signle reservoir master cylinder for deuces phased out in favor of the more modern / safer variety?

They started installing the dual system in the Air Force Deuces around 1985-1986. I had it on a 1987 AF Deuce. These where manufactured until 1989??? I don't think the Army trucks ever had them.

When they started making the M35A3 (out of two M35A2s) they also installed the upgraded brakes.

YMMV

Warthog

 

[BugEyeBear]

I often wonder why no one has offered a dual-circuit brake upgrade kit for the single-circuit Deuces.

I'd probably buy one! (Assuming it doesn't cost as much as another deuce...)

 

[dabtl]

I often wonder why no one has offered a dual-circuit brake upgrade kit for the single-circuit Deuces.

I'd probably buy one! (Assuming it doesn't cost as much as another deuce...)

With winter coming on maybe we talk John Tennis into some extra project?

 

[Rattlewagon]

I often wonder why no one has offered a dual-circuit brake upgrade kit for the single-circuit Deuces.

I'd probably buy one! (Assuming it doesn't cost as much as another deuce...)

just a guess but I think liability has a lot to do with it.

 

[clinto]

just a guess but I think liability has a lot to do with it.

And cost. Go look on the (numerous) other threads on this subject and see what Memphis charges for replacements master cylinders and air packs.

 

[Rattlewagon]

And cost. Go look on the (numerous) other threads on this subject and see what Memphis charges for replacements master cylinders and air packs.

on top of that, in all of my research to find parts, I have never been able to find the correct proportioning valve. I'm sure that I could find one that worked but it would be guessing at best. If I knew the specs of the original it would make things much easier.

 

[FireFighterHill]

I often wonder why no one has offered a dual-circuit brake upgrade kit for the single-circuit Deuces.

I'd probably buy one! (Assuming it doesn't cost as much as another deuce...)

Do a search, a kit has been discussed but most people arent willing to pay what it would cost for new parts. And being that its safety related no vendor would be willing to sell used brake parts.

Therefore it is much cheaper to piece together yourself, and therefore you yourself assume all liability if the system fails.

 

[wdbtchr]

If someone ever figures it out maybe he could "anonymously" post a list of the parts he used to avoid liability. Just thinking, I sure would like to change over my two 5 tonners.

 

[G-Force]

on top of that, in all of my research to find parts, I have never been able to find the correct proportioning valve. I'm sure that I could find one that worked but it would be guessing at best. If I knew the specs of the original it would make things much easier.

Proportioning valves are only used on disc brakes. What is used is a pressure differential valve. This is only useed so if one half of the braking system fails the spool inside the valve is pushed to one side to activate the switch for the brake light to indicate there is a failure in the brake circuit.

 

[Keith_J]

Ever had a failure on a dual circuit system? I have, you lose more than half your braking ability.

It is like a small twin engined airplane, you are fine if the failure happens when you don't need 100%. But when if fails you in dire times, it can lead to more trouble, as in you THINK you can make it.

The most common failure point is the hoses. They are covered in rubber which protects the steel braid. Any break in the rubber lets corrosion in, then when the steel strength member is gone, the hose ruptures. It is far easier to see corroded tube steel lines, the paint blisters..

The use of silicone brake fluid is another problem area, it allows trapped water to migrate to the wheel cylinder, these don't catastrophically fail, they just leak BUT if you don't do correct PMCS, adding brake fluid every so often, it will eventually get you. And silicone brake fluid soaked shoes don't stop too well. Yes, you can clean the shoes with methylene chloride, IF you can find this solvent (hard since the Clean Air Act amendments and Montreal Protocol restrict its use). Or $50 for new shoes.

Finally, if you have a poppet breather on the master cylinder cap, consider retrofitting to the air vent line. Why? If you have a slow leak, a vacuum can build in the system. This will cause complete loss of braking since the wheel cylinders will retract to the point the master cylinder volume will not be enough!

 

[stumps]

Ever had a failure on a dual circuit system? I have, you lose more than half your braking ability.

It is like a small twin engined airplane, you are fine if the failure happens when you don't need 100%. But when if fails you in dire times, it can lead to more trouble, as in you THINK you can make it.

I have had a failure on the dual circuit system with my F250 PU truck, and I can tell you it wasn't fun. I lost the rear brakes, and my stopping power dropped to the about the same level as with the emergency brake.

The most common failure point is the hoses. They are covered in rubber which protects the steel braid. Any break in the rubber lets corrosion in, then when the steel strength member is gone, the hose ruptures. It is far easier to see corroded tube steel lines, the paint blisters..

Every hose I have seen is stainless steel braid. Are the deuces different?

The use of silicone brake fluid is another problem area, it allows trapped water to migrate to the wheel cylinder, these don't catastrophically fail, they just leak BUT if you don't do correct PMCS, adding brake fluid every so often, it will eventually get you.

That could happen, I suppose, but silicone brake fluid is so much better over the long haul than the glycol based (can you say water sucking) DOT3 brake fluid that I wouldn't recommend anything else for a seldom used vehicle. All of my historic vehicles get converted over to DOT5 as soon as I get them. Since I started doing that I haven't needed to replace a wheel, or master cylinder. Before I did that, they were always going bad from sitting.

And silicone brake fluid soaked shoes don't stop too well. Yes, you can clean the shoes with methylene chloride, IF you can find this solvent (hard since the Clean Air Act amendments and Montreal Protocol restrict its use). Or $50 for new shoes.

The same can be said of DOT3, or differential oil, soaked brake shoes. Each fluid wrecks the nice properties of the shoes until cleaned off.

Finally, if you have a poppet breather on the master cylinder cap, consider retrofitting to the air vent line. Why? If you have a slow leak, a vacuum can build in the system. This will cause complete loss of braking since the wheel cylinders will retract to the point the master cylinder volume will not be enough!

That poppet valve is probably the cause of most of the soft pedals you see on deuces.

-Chuck

 

[emr]

probably because the ones we have work just fine.U would have to build a new truck to get it as safe as a new vehicle, they requir maintenence and that is all part if having one,

 

[Mark3395]

Frankly, if you really want the dual circuit brakes the best route is just to sell your current truck and buy an 87 or 88 AF truck. Consider the cost in time, materiel, and risk of a strap-on system and I think you'll agree a truck switch is the way to go.

Then too, remember that the single circuit brakes have been very successful. Just watch your maintenance.

Good luck.

 

[m-35tom]

most brake hoses are fabric braid as the pressure is quite low. m-series rebuild has a kit but for you guys, well just don't ask the price. it is all new parts and about as much as another truck.

as for water in silicone fluid system?? i don't believe anything i have read is anything more than hysteria. in a good working system how in the world would any moisture get in there to start with?? almost absolutely impossible. and if you are that paraniod, put a water trap behind the master cyl.

my 3¢

 

[southdave]

I would just assumed switch to all air thought about installing airbrakes on the duece and half maybe even disk brakes Think member old shep has installed disk from a f-450 or 550 on his.

 

[Rattlewagon]

I would just assumed switch to all air thought about installing airbrakes on the duece and half maybe even disk brakes Think member old shep has installed disk from a f-450 or 550 on his.

4 wheel disks would be cool. adapting them would probably cost a small fortune though...

 

[southdave]

I don't know, there is bunch of med duty trucks in junk yard all over I know of some international that use air brakes and the same disk as f4-550