Dual Circuit Brake Engineering Thread

[Another Ahab]

If starting fresh and i had the money, id probably go the Hydro-Max route like Jesse did in the below links. This gets you simplicity from no airpacks, gives dual circuit, hydraulic pump off the engine, differential pressure warning switch, residual pressure valves, remote reservoir, and a 24v backup pump so you still have boosted brakes if the engine cuts out.

Do you maybe have a "horseback figure" (+/-) for that cost, peashooter?

You know, just rough and round?

 

[peashooter]

Do you maybe have a "horseback figure" (+/-) for that cost, peashooter?

You know, just rough and round?

Not sure, but I would guess it is in the $2-4k range for all the hydromax parts. Also needed would be a hydraulic pump off of the old 5ton lds engines.

 

[7bdiver]

Yea, that's the hydraulic type I was talking about.

I do not know how I missed that hydromax booster thread, cause I search a lot. Great discussion, except for having no feedback on how the system performed after everything was done.

It's looking more and more like the system I will go with, especially since it has the option of the electric backup pump. It doesn't appear that it is always running in the background and turns on only when it sees a pressure drop. I imagine it saving your bacon if you stall the truck up a hill climb or throw a rod down a mountain pass.

And, its all off the shelf modern stuff. The install didn't look bad at all either.
I'll be doing power assist steering, and will put a pump on my truck either way. Still going to keep look at everything I can first tho.

My main worry here is what pressure the stock brake system operates at. This hydromax system isn't going to go old faithful on the lines and stuff down there right? As I understand, lines already blow on these trucks often enough.

 

[rustystud]

Yea, that's the hydraulic type I was talking about.

I do not know how I missed that hydromax booster thread, cause I search a lot. Great discussion, except for having no feedback on how the system performed after everything was done.

It's looking more and more like the system I will go with, especially since it has the option of the electric backup pump. It doesn't appear that it is always running in the background and turns on only when it sees a pressure drop. I imagine it saving your bacon if you stall the truck up a hill climb or throw a rod down a mountain pass.

And, its all off the shelf modern stuff. The install didn't look bad at all either.
I'll be doing power assist steering, and will put a pump on my truck either way. Still going to keep look at everything I can first tho.

My main worry here is what pressure the stock brake system operates at. This hydromax system isn't going to go old faithful on the lines and stuff down there right? As I understand, lines already blow on these trucks often enough.

Stock brake pressure is around 800 PSI max. I have a pressure gauge on my system. Like Peashooter said, going with a Hydraulic HydroMax system is the "Cadillac" way to go but it would be pricey.
After awhile just taking your axles out and putting them under a modern truck for a 6X6 rigg makes more sense then all these modifications needed to make the Deuce a modern truck.

 

[rustystud]

Not sure, but I would guess it is in the $2-3k range for all the hydromax parts. Also needed would be a hydraulic pump off of the old 5ton lds engines.

Hey Aaron. I took your advice and decided to come back for awhile. See what happens.

 

[peashooter]

Welcome back Rustystud! Looking forward to your advice again and some updates on your truck projects.

 

[7bdiver]

Stock brake pressure is around 800 PSI max. I have a pressure gauge on my system. Like Peashooter said, going with a Hydraulic HydroMax system is the "Cadillac" way to go but it would be pricey.
After awhile just taking your axles out and putting them under a modern truck for a 6X6 rigg makes more sense then all these modifications needed to make the Deuce a modern truck.

Thanks for confirming that 800 psi. I think I heard that number on one of Hank's deuce videos a while back, that's why I was worried.

Yeah, most of these upgrades cost more than the original price of the truck often enough. Heck, I 've already got as much into mine as I paid for it, and am probably looking at another 6K for overkill. But I love the heck out of an old deuce. Something about them. You all feel it... between the fits of cursing and sometimes hopelessness. However, I hold my breath under ice water on the weekends for fun, so I understand if anyone shakes their head.

 

[7bdiver]

A point was recently made on another hydromax thread here about keeping your brakes on a separate hydraulic system than your power steering, if you have or plan on having power steering like myself. You don't necessarily want them on the same pump or fluid reservoir because the power to both systems would go down together in the event of a failure. This makes me think back on the air system. It's already separate.

Like the A3 has, I don't see why you can't just add a second airpack to an A2. I know you'd still be running a single master cylinder, but you should be able to run both of the airpack outputs into a standard combination valve, and then to your split front/rear brakes from there. If one airpack fails, or anything on that leg of the system does, the valve will keep you safe and shut off the bad side. It should also prevent the bad airpack side from hemorrhaging all of your single reservoir fluid. Depending on how it failed of course.

it's something to consider

Personally, I still kind of prefer the hydromax. Much less combined components and lines running all over hell.

 

[Another Ahab]

Personally, I still kind of prefer the hydromax. Much less combined components and lines running all over hell.

Simple is hard to beat!

Well, you know, other than mental capacity and all.

 

[banditt1979]

A point was recently made on another hydromax thread here about keeping your brakes on a separate hydraulic system than your power steering, if you have or plan on having power steering like myself. You don't necessarily want them on the same pump or fluid reservoir because the power to both systems would go down together in the event of a failure. This makes me think back on the air system. It's already separate.

Like the A3 has, I don't see why you can't just add a second airpack to an A2. I know you'd still be running a single master cylinder, but you should be able to run both of the airpack outputs into a standard combination valve, and then to your split front/rear brakes from there. If one airpack fails, or anything on that leg of the system does, the valve will keep you safe and shut off the bad side. It should also prevent the bad airpack side from hemorrhaging all of your single reservoir fluid. Depending on how it failed of course.

it's something to consider

Personally, I still kind of prefer the hydromax. Much less combined components and lines running all over hell.

I've read through this entire thread with interest. What you said makes sense. I imagine the single line coming from the master to a tee then each line off the tee goes to its own air pack then each air pack goes to front and rear brakes. Question is has anyone tried this approach? I saw where someone earlier in this thread mentioned this same idea.

 

[7bdiver]

I've been racking my little mind over this for many months now. I have made a couple misconceptions along the way. For one, it will not be possible to use a combination valve off a single split source. You would have to have a real dual circuit master cylinder.

Now I'm back to the safety valve ideas at the moment and I believe I have figured it out. I didnt want to keep blowing this thread up with half-cocked ideas, and wanted to test it for real before posting again. But... I'm fairly confident, and it will be much smaller than some previous ideas.

The short, is to use what is called a residual pressure valve. They are common to drum brake systems. However, to use it as a safety valve, it will need to be face backwards, and float over another seal seat downline. It will shut the line off if the pressure behind it drops below 10psi.

I can post a schematic when I get home. Hopefully you guys will try to point out if I made a stupid again.

Otherwise, I believe the ford F550 master cylinder should mount up pretty easy to the stock location with minimal fabrication. Then run a second airpack.

 

[banditt1979]

I found this while searching the dorman m12000 part number. You guys may already know about this


Price looks good and specs appear to match the A3 master



Will this bolt to the stock A2 bracket without the winch?

Only issue is that the listings say for disc brakes. So I don't know if it is self proportioning or what. I may shoot Dorman an email asking about that.

 

[7bdiver]

Ok, here is another concept for a valve that you could just put on each leg of you brake lines to shut one down in case of a failure, and keep the other functional.

The drawing is by hand, so not to dimension or anything, but the concept should be clear. This is to shut off fluid flow in the event the pressure on the other side of the valve drops below 10psi during braking.

P2, should be whatever pressure the drum return springs provide. Def more than 10 lbs. The line will be hydrolocked and stay at that pressure untill the pads make contact. The RPV (the red body) will not move in that state.

If all is good, the 10psi valve (green body) will open and brake fluid will flow. P1 = p2 from this point on, and the red body will stay put, especially with the spring behind it. That part is also possibly dependant on the green surface area being larger that the red. The drawing is not representative of that.

If the line return pressure from the drums is less than 10lb, the brass end that is screwed into the RPV will bottom out and shut off flow. Again, this is only while the pedal is pressed.

When not in use, the valve will reassume its resting position and let fluid flow freely back upstream. Your stock master cylinder already has a 10psi RPV in it, so you dont lose that nicetie.

I've designed a simpler version, but this one is based on an off the shelf valve you can get all day for 10 bucks. (Residual pressure valve) theyre everywhere.

Whooo!
Let me know what you think.

 

[banditt1979]

I've been trying to stick to the original concept of a dual master cylinder and air packs. Consequently I came across a combination valve that has the correct size and number of fittings for a stock replacement type. AC Delco makes pn 15835212 with 2 inlets 2 outlets with the 7/16 sized inverted flare fitting. Can be had at Summit for less than 50 bucks. FWIW

 

[banditt1979]

Otherwise, I believe the ford F550 master cylinder should mount up pretty easy to the stock location with minimal fabrication. Then run a second airpack.
[/QUOTE]

Do you happen to have a part number for this master cylinder?

 

[7bdiver]

This is the part interchange number that was listed on epay, if that helps any. The one I saved on my watchlist for 133 bucks, free shipping.

13082008, 138042, M630276

 

[banditt1979]

That looks identical to the M39528. The M630276 I can't find for less than $280. Wonder what the difference is. I found the M39528 for $133

 

[5tonpuller]

After reading all this, most of the parts are easily gotten, But the bracket for the master cyl. / peddle / frame is not.
Is there any one making them? A surplus?

 

[Ibexe666]

Currently finishing up my hydromax firewall design (1970 M35A2C) plate is being adjusted to allow for some tolerance differences on the knockouts, the pedal is a rough mockup, if anyone knows any specs on hydraulic clutch parts that would work so i can add mounting it would be helpful!

 

[GASCANS001]

Ive got a 88 AF truck with the split brakes, I havent read through this whole thread so Im not sure if its already been said or not but besides the extra airpack, different master cylinder, differential valve & warning light, one of the air tanks is 2 chambered for some reason (so there are a total of 3 drain valves on these trucks' air tanks)

I just inquired my 88 Air Force truck. I have split brakes as well. Having a hard time finding any parts whatsoever for the split brake system. Do you have any idea where I could find a master cylinder rebuild kit for a post that has some info listed?