Hydro-Max Brake Assist *pics added* (long read)

[gentrysgarage]

Hi Rusty,
I will back up and list what I have, then my ultimate goal...

On my M135 I have acquired the following:
B700 Rotors
F550 Calipers
HydroMax master.
I will be keeping the 4 15306 brake wheel cylinder brakes on the rear as stock.

Ultimate goal:
I seem to drag alot of non-operatable vehicles home...it's even worse than the OD Disease! And have always wished for trailer brakes that operate with the towing vehicles brakes. I have seen the electric trailer brakes in wrecking yard trucks and they all where melted or outright burnt up. So once I learned about the M105 trailer braking system I knew that is what I had been searching for.

Ultimate Ultimate goal:
Is to copy a picture I have of a WW2 Airstream trailer (used as a mobile pigeon coup actually!) that had M105/Ben Hurr axles...but that's aways down the road.

So I am in the search of that hydraulically piloted air valve that is smaller than an airpack and keeping with my under 10,000 weight goal I wish just to have just a valve piped in somewhere in the braking system. I am quite new to the medium duty truck braking systems so please forgive and educate me!

Thanks!

 

[rustystud]

AHhhh, but it uses the air to push a diaphragm that actuates a master cyl. The m105 has juice brakes

You answered your own question. It "uses" air to apply the brake master cylinder on the trailer. So all you need is "air" from the deuce to apply the brakes. That is all the booster is doing. Redirecting air to the trailer. That is why the deuce has "glad-hands" in the back. To connect your "air" lines too.
That is also why you can tow a M105 trailer with any 5 ton which has all air brakes.

 

[Heath_h49008]

The air-pack does 2 things... the hydraulic pressure opens the air to flow to both the air pack large air cylinder, and the line to the glad hand.

So as long as you put hydraulic pressure to it, and air supply to it, it will activate the gladhands for the M-105 etc normally.

Why re-invent a wheel that isn't broken?

 

[gentrysgarage]

The air-pack does 2 things... the hydraulic pressure opens the air to flow to both the air pack large air cylinder, and the line to the glad hand. So as long as you put hydraulic pressure to it, and air supply to it, it will activate the gladhands for the M-105 etc normally. Why re-invent a wheel that isn't broken?

I guess could plumb the outlet side of the airpack back to the remote reservoir, but it would be awfully clunky affair.

If I don't find the Bendix valve, I will probably mount a treadle valve actuated off the brake pedal as the lightest and easiest move.
Thanks for the suggestion!

 

[rustystud]

I guess could plumb the outlet side of the airpack back to the remote reservoir, but it would be awfully clunky affair.

If I don't find the Bendix valve, I will probably mount a treadle valve actuated off the brake pedal as the lightest and easiest move.
Thanks for the suggestion!

OK, I'm confused here. Which is happening more often then not lately . Are you trying to convert your truck to "all" air brakes ? I thought that was what you where going for. Or are you trying to convert to a hydraulic "Hydro-boost system" ?

 

[gentrysgarage]

OK, I'm confused here. Which is happening more often then not lately . Are you trying to convert your truck to "all" air brakes ? I thought that was what you where going for. Or are you trying to convert to a hydraulic "Hydro-boost system" ?

Hi Rusty and all,

On my M135, I am going to be using a hydraulic brake system utilizing a Hydro-Max booster and master cylinder from an International. This in turn will be piped to the Ford F550 calipers to stop the Ford B700 rotors. The rear I will still use the M135 4 wheel cylinders (2 each Drum) .

I want to have the M135 set up so that I can pull military trailers and maybe vehicles with the connection of the Glad Hands on the rear of the truck. To that end, after last night, I have ruled out using an airpack as a feasible system. What I am leaning towards is installing a arm off of the brake pedal and pulling the foot pedal off of a treadle valve have the arm off the brake pedal actuate the treadle so in effect I have 2 separate systems one for the truck (hydraulic) and one only for towing (air). The air supply run from the compressor to the air tanks from there run through the "modified" treadle valve thence to the rear glad hands. Of course I would have a tap off for auxiliary air supply front and rear.

Does this sound good?

 

[rustystud]

Hi Rusty and all,

On my M135, I am going to be using a hydraulic brake system utilizing a Hydro-Max booster and master cylinder from an International. This in turn will be piped to the Ford F550 calipers to stop the Ford B700 rotors. The rear I will still use the M135 4 wheel cylinders (2 each Drum) .

I want to have the M135 set up so that I can pull military trailers and maybe vehicles with the connection of the Glad Hands on the rear of the truck. To that end, after last night, I have ruled out using an airpack as a feasible system. What I am leaning towards is installing a arm off of the brake pedal and pulling the foot pedal off of a treadle valve and having the air supply run from the compressor to the air tanks from there run to the treadle valve thence to the rear glad hands. Of course I would have a tap off for auxiliary air supply front and rear.

Does this sound good?

So you will have two brake apply units ? One hydraulic and the other air ? That does not sound good. You would be better off staying with the stock "airpac" . It is set-up to apply the trailer brakes with the proper amount of air pressure matching the hydraulic pressure in apply force.
I'm sorry if this sounds confusing. I just had hand surgery 9 hours ago and I'm still very rummy from all the drugs.

 

[gentrysgarage]

So you will have two brake apply units ? One hydraulic and the other air ? That does not sound good. You would be better off staying with the stock "airpac" . It is set-up to apply the trailer brakes with the proper amount of air pressure matching the hydraulic pressure in apply force.
I'm sorry if this sounds confusing. I just had hand surgery 9 hours ago and I'm still very rummy from all the drugs.

Yes, EXACTLY!!!! I was completing a sentence I thought I had typed as you were replying! The air would only be for towing through the glad hands.

PS I hope your hand gets better!

 

[rustystud]

Yes, EXACTLY!!!! I was completing a sentence I thought I had typed as you were replying! The air would only be for towing through the glad hands.

PS I hope your hand gets better!

You would be using a treadle valve not calibrated to our deuces system. You do realize you must have the same apply force out to the trailer as you do to the drive vehicles brakes.
Also, thanks for the well wishes !

 

[gentrysgarage]

You would be using a treadle valve not calibrated to our deuces system. You do realize you must have the same apply force out to the trailer as you do to the drive vehicles brakes.Also, thanks for the well wishes !

Good Point.

OK, lets see how I can make my idea work.

Questions:

1) Are treadle valves linear? i.e. 25% movement = 25% flow, 35% movement = 35% flow etc.
2) I looked at the tms for the M105 and the only test was holding for 2 mins at 60psi and the M35 compressed air unloader test at 120psi. Does anybody now the pressure at the glad hands?

Now my thinking is if the treadle valve is linear, if we measure the air pressure at the glad hands at 25% brake pedal, 50%, 75% 100% (which I think is going to be linear). I just regulate the pressure from the tank to the treadle valve....Ideas? Suggestions?

 

[rustystud]

Good Point.

OK, lets see how I can make my idea work.

Questions:

1) Are treadle valves linear? i.e. 25% movement = 25% flow, 35% movement = 35% flow etc.
2) I looked at the tms for the M105 and the only test was holding for 2 mins at 60psi and the M35 compressed air unloader test at 120psi. Does anybody now the pressure at the glad hands?

Now my thinking is if the treadle valve is linear, if we measure the air pressure at the glad hands at 25% brake pedal, 50%, 75% 100% (which I think is going to be linear). I just regulate the pressure from the tank to the treadle valve....Ideas? Suggestions?

That sounds reasonable. You should get some readings from a Deuce with a good braking system. Then you could compare it to the treadle valve you end up buying. That way you would know what needs to be done to make it fit the deuce.
And yes, the treadle valve and 'air-pac' both operate along a linear application of pressure to the brakes.

 

[gentrysgarage]

And yes, the treadle valve and 'air-pac' both operate along a linear application of pressure to the brakes.

THANKS!!!

Now I will wait for a kind steelsoldier to measure his deuce. No rush, I am still working on the rear suspension and then changing the engine trans..so alittle while to go!!

 

[grendel]

Just read this complete thread... looks like I can do this on my M816 too. The 816 uses 1.5" front wheel cylinders and 1.75" rear cylinders. I'll leave the air pac in to operate the towed air brakes.

Giving Precision Rebuilders a call on Monday... fell Pirate and all.

 

[77 AMG]

Greetings, all. First post here is to let everyone know that I spoke with Tim today at Precision Rebuilders, and he does recall this thread and was wanting to know how well the conversion had worked out. I told that I was still looking into that myself, but, I was going to go ahead and see about getting the parts list together and get the ball rolling on this for my 1977 AMG M35a2. We talked for over 20 minutes, and, he <really> knows his stuff about the Hydro brake systems. I am looking forward to getting the Email with the parts list in it, and I will post it up,if anybody cares to see it.

 

[yolner]

Definitely post it up. Always good to have more info.

 

[77 AMG]

I will. As of today, I am still waiting for the Email to hit my in-box. I will check back with Tim on Monday to check status.

 

[Superthermal]

Just saying I feel let down! After reading 11 full pages of this thread I was thinking I was going to be reading here in the end how the end product worked and a list of parts for us all to benefit! LOL, However I did find a ton of info I am very grateful for! Thanks all.
This month I will have had my M813 for two years. Still very much want a dual circuit brake system.
From this thread I will be looking for:
1. Freight liner Hydro max unit with 50/50 proportioning (Has the Pressure differential switch to notify a warning light letting you know there is a problem, and it has a low level brake fluid sensor. See post 125 on page 7 for details)

2. Custom mount for a 2nd Stock style NHC250 Power Steering pump which I already have.
Note: I have no idea how I would get belts onto this second unit seeing there may be a need for the belt to contact more than 1/4 of the pulley to not slip when under max load.

3. 24V emergency motor for the Hydro max unit, may need the positioning adapter used in these pages, but I am hoping not to as my assembly would be mounted to the firewall not on the frame where the original air/hydraulic unit is in this thread. HOWEVER that could change .

4. Firewall mount Wilwood pedal assembly or similar

5. 2" bore Master Cylinder with large reservoir.(The M813 5 ton I believe has larger wheel cylinders than the deuce and I am thinking this is going to be needed for the extra volume.)

6. Dual circuit proportioning valve External to the Master cylinder. I am not sure if this will be needed as the Freight liner MC unit is supoto take care of this so this will need more research for me... (50/50 seems best to match stock feel to the brakes)

7. Flexible brake line hoses from proportioning valve/or MC to frame rails as this M813 flexes like no other and the lines cannot be hard lined down to the frame.

8. Trailer brake mod to keep trailer brake function if I actually ever get a trailer. I already have a hand operated trailer air brake arm, which is intended to be mounted on steering column. to manually engage the trailer brakes. From what I understand this device is to manually engage the trailer brakes by themselves if desired. I was thinking this could be used to keep some way to have air brakes to a trailer. Since I do not own a trailer this doesn't seem very important at this time but someday who knows maybe I will.

9. Residual pressure valves for the brake lines. This is again a bit of a grey area as disc brake systems usually have these but any of my drum brake systems did not, but in this case it appears the Precision Rebuilders who are the experts leading most of the hardware options discussed here were thinking this is the right direction to go with 15lb residual pressure valves, one for each line.

Homework items, Seems important to know the Master Cylinder bore size on the original air/hydro-unit for the M809 series just to match that with the HYDROMAX bore size seems like a good way to go. Anyone know what the stock PS pumps on the 809 series put out in PSI and volume. Should ensure this volume and pressure are compatible with the PSI that will be created to ensure we can get a "stock" pressure at least to the brake cylinders.

Important! I have not seen anywhere in the discussions here what type of brake fluid is to be used. Our rigs use DOT 5 which is silicone based. These Hydromax units use other types. Anyone have any info on how this is addressed? I would think I would run DOT 5 still. @jesusgatos how did you fix this?