Master cyl, dual vs. single

I was looking through some adds that showed a 1994 M35A3 with a dual chamber master cyl. Is it possible to install that system instead of doing dual single chamber master cyl. and dual air packs? It would seem to be more simple than a dual single setup. I thought the more experienced guys here would know the in's and out's. Thanks.

yeah you can install it.. .... Try to find one first.

Oh. Now that sounded like a challenge......Seriously though that makes more sense. I just did not know the dual masters existed. If it is just a matter of low availability and serviceability then the dual singles discussions make a ton of sense. That's why I asked.

The military set up are as rare as hens teeth. I will be starting on my M211 resto in a couple months and I plan on finding a Dual civy unit. I think the way to go is hit the books and search the A1 Cardone catalogs

September 5th, 2009.

Jolly Roger:

I don't think the comment above was a challenge as much as a statement. The dual or split systems were applied to the ESP (M35A3) trucks, and apparently there are few spares around for conversion. The 800 or 900 series used a similar set up, with a top hung brake pedal. A lot of us feel that the stock M35A2 brake has no redundancy built in on the hydraulic side, air side yes, hydraulic side no. On a stock duece, if you loose any hydrualic connection and fluid loss ensures, well, pick your wreck site carefully. Many of us have tried to provoke the parts manufacturers to come up with the necessary kits to split the system, but they are somewhat affraid of the liability question. Perhaps we would do better to approach KIA MOTORS in Korea, as they are producing the M35 currently for other armies, and they may have the parts we need. Just my 2 cents worth, for what it is worth.


Cheers,

Kyle F. McGrogan

The system on the -A3 is the same as the system on the late -A2s. Never seen the dual master cylinder system you speak of. You need to replace the pedal assy for that master to bolt on. Then you need 2 air packs and a proportioning valve and add appropriate brake lines. The TB is in the Tech Manual section, starts with SMARPI.

I was just saying it was a challenge as a joke. I figured you all knew better than I. I was just contemplating this question while I was coming down a tight switchbacked mountain road when I preran into hunting camp. My crash site would be a 1000 foot drop off. Others have gone off the edge and died. I would prefer to not be a statistic. Bad news in any case. I had seen some of the discussion about the dual singles and then saw the add with the dual chamber master cyl truck and thought eureka. Then I thought there must be a catch to why guys would go to all the trouble of a dual single setup. Now I know why. That's what is the greatest thing about this website for me. All the experience and information from all the people on here. For that I thank you all.

Look for posts by Spicergear. He hung a peddle from another med. duty truck and used a hydro boost brake system. He has said it works well.

I was wondering if one could take a master cyl from a later model truck and mate the air pack to it. I like the air system. I have been contemplating power steering and brakes with a dual master for my M-37 for quite some time. I also saw a duece air setup on an M-37 in Phoenix AZ where I bought my M-37 11 years ago. He had a 3-53 Detriot with a deuce tranny, air system and gamma goat tires. The truck was bad a**. It sounded like a 1950's trash truck. Straight pipe was louder than a deuce cause it is supercharged. Ran right at 70mph. People got the H E double hockeysticks out of the way when we got onto the highway.......Anyway. I will have to contemplate this awhile.

Just noticed above the 900 or 939 series was mentioned, it does not use a master cylinder.......its special...

You can get the master cylinders from memphis for about $250. The problem is the mount/pedal you can't. AM General makes them but will not sell to individuals. I am betting Tom at CSI can order the mount through AM General but you will pay for it. Remember they sell to foreign govt's so it will be spendy.

hndrsonj said:

You can get the master cylinders from memphis for about $250. The problem is the mount/pedal you can't. AM General makes them but will not sell to individuals. I am betting Tom at CSI can order the mount through AM General but you will pay for it. Remember they sell to foreign govt's so it will be spendy.

Click to expand...

has anyone ever seen the mount or taken pictures of it? Or better yet, have one on their truck?

There is a pic in the TM for the dual circut brake system . (not the standard TM's, but the one just for the dual brakes) TM SMARPI 9-2320-209-14&P

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

I don't believe the -A3 master cylinder will accommodate the -A2 transmission mounted PTO shifter. It only affects trucks with that PTO, and prolly not a deal breaker if you're fabricating anyhow, but worth noting.

Emmado22, I have that TM already but without seeing one in operation I’m lacking a certain context to imagining how it is going to work after modifications.

I agree Jake; I would happily fabricate something for the pto if it meant taking advantage of dual circuit brakes.

Another thing I would like to discuss is the proportioning valve. Without it I don’t believe an adapted system would function up to expectations.

I could probably source a dual circuit master cylinder based on information from existing MC's but if they are difficult to source, how easy is the prop valve going to be? And how would I know if I were sizing it correctly?

I’ve fabricated or adapted many things in my life but for some reason I always left brakes alone…

anyone have any thoughts on the prop valve?

dan

Well if they are no way to get the dual set-up short of buying a A3,Wander if a disk rotor could be mounted to the drive flange on the front or rear axle,mount caliper and master cylinder,only to be used when single system fails.Would be better they going off the cliff
and being headed to the funeral home.
I have studied the diagram on the dual system,if you came up with pro valve,the master cylinder,the linkage,where would you get the RH air-hydraulic booster?I was a auto mechnic for 28 year so making the line would not be a problem.

Boosters are the same for both sides. Once could always shop for an -A2 with dual circuit brakes, mid to late 80s deuces had them and there are many folks here that have them. Emmado22 did a nice thread about the unique features of the late trucks, he has one and I think he's put the winch on it too!

Dwight, there is an outfit whose name eludes me at this moment that produced a pinion brake. but the problem with those is that the differential in the axles are open so if you locked up the pinion brake one wheel would turn forward while the other would turn the oposite direction.

With that said, I completely agree with you. How could it hurt?

As for the airpack, just source another airpack from someone here or ebay and plumb it up.

I guess my biggest questions would be from a fluid dynamic standpoint, how much flow of brake fluid is needed to the different zones and at what pressure to function normally?

I just do not have the knowledge to answer those questions. But I am a fast learner!

dan

Yes the later model M35A2C's do have the split brake system. More specifically the '87 and '88's have them. My particular truck's dual MC has provisions for the PTO engagement handle attachment.