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

[Unforgiven]

International Harvester


Freightliner


Notice that my Topkick (Kodiak) booster posted previously uses a lunette-eye push rod to connect to the pedal.

The IH & Freightliners use clevis push rods. I would suggest getting the booster & the pedal from the same vehicle.

Here's a link the the HydroMax pdf manual. Either wait for it to load or right click Save As:
http://rb-kwin.bosch.com/us/pool/usa/pdfs/HydroMax_Hydraulic_Brake_Booster_Manual.pdf

 

[Ditch Baby]

where can you source parts for these if you dont have a junkyard local?

ball park figure on cost?

 

[spicergear]

Since the thread got kicked up again I'll offer an update: Over three years later and my HydroMax braking system is still working great!

...and Jake, thanks for answering some questions in my absence. You did good!

 

[jesusgatos]

Thanks for all the info Unforgiven. Very helpful. After re-reading the PDF and looking at your pictures/measurements I'm pretty confident that I'll be able to mount the Hydro-Max master-cylinder and booster assembly under the cab, either connecting it to the stock brake pedal linkage or re-creating some type of similar pedal linkage. Looks like I'll almost certainly have to hack-up the forward transfer-case mounting crossmember, but that shouldn't be too much trouble (especially since there's no cab on mah deuce right now).

Going to try calling Bosch Corp to see if I can get ahold of anybody that works on these systems. Not sure if they'll talk to me, but would like to get some kind of official word on how they would spec components for this type of application. Would also like to confirm a few details about things like the pedal linkage ratio and that sort of thing.

Another thing I'd like to do if at all possible, is to remote-mount the master-cylinder reservoir/s. How are those secured to the master-cylinder Unforgiven?

 

[Unforgiven]

Another thing I'd like to do if at all possible, is to remote-mount the master-cylinder reservoir/s. How are those secured to the master-cylinder Unforgiven?

Four bolts from the underside. Nothing substantial. If it's American I'd say it's about a 1/4 x 20, maybe even smaller. Likewise metric.



Notice the pot metal reinforcement under the plastic. I'm not sure if the bolts thread into the pot metal or directly into the plastic.





Internal shot of the rear reservoir (obviously with the cap removed). Top of photos are firewall side.

 

[jesusgatos]

Awesome, thanks.

 

[jesusgatos]

Talked to Jeff at Howe Performance about my project today and he told me that running the hydro steering + hydro brakes on the same pump should be no problem. He suggested plumbing from the pump straight to the brakes and then to the steering. Said that on some high-flow systems, the hydraulic brake booster can become a restriction, but didn't expect that it would be an issue in this application (am going to try to dig-up some numbers on flow-rates and pressures to send him to make sure).

 

[mudguppy]

this was my concern also, which is why i'm running a big cooler.

no problems to date.

 

[jesusgatos]

Got ahold of somebody at Bosch that's going to try to track down an engineer that works on the HydroMax systems for me. Will let you all know what I can find out. They're probably going to want some information about the brake system, so if anybody can help me out with that I'd appreciate it. I know there are two different sized wheel cylinders for the A2 & A3, but don't remember what size they are off the top of my head. Would guess I'll need to get some info about the brake drums too? Anything else?

 

[MrArmyAnt]

Ok so I love this thread, but got bored in the proportioning section and it being a common system since my deuce will be bobbed. Couldn't you then run the separate systems?

 

[spicergear]

Absolutely! It is a separate front and rear system for a two axle truck in it's original application so I would say to pick up an adjustable proportion valve from Jegs or Summit and slap it in the rear line and adjust it until you're satisfied with the braking results.

 

[Jtspendy]

spicergear can you post some photos of the final assembly? I am looking at updating the brakes and I figure I will start at the top by splitting the system now, and possibly switch to disk brakes down the road as money permits

 

[bighippo]

Great write up how have things been holding up?

 

[silverstate55]

Didn't see this posted earlier, but it's a great description of the Hydro-Max system including some plumbing & wiring diagrams:

ftp://164.106.79.2/Instructors/Rscoville/Bendix/Hydro-Max%20Power%20Brake%20System%20(SD-20-6602).pdf

I have the chassis for a 1994 Chevy Kodiak sitting in my yard right now, and it has the full Hydro-Max setup along with a metric power steering box on it...however, it is already earmarked for use on another project (rebuilding my GMC pickup with Detroit Diesel 4-53T). I am going to try to source some more of these for my Deuce & the eventual rebuilding of my worn-out Deuce dump truck.

 

[jesusgatos]

Got ahold of somebody at Bosch that's going to try to track down an engineer that works on the HydroMax systems for me. Will let you all know what I can find out. They're probably going to want some information about the brake system, so if anybody can help me out with that I'd appreciate it. I know there are two different sized wheel cylinders for the A2 & A3, but don't remember what size they are off the top of my head. Would guess I'll need to get some info about the brake drums too? Anything else?

Has anyone done any more research into sourcing master/booster units from any of the six-wheeled medium duty applications? Never got anywhere with Bosch, but called again today and left another message. Got my chassis back from paint, and am ready to buy some components and get to work on the brakes. Obviously just want to pick the right parts to use...

 

[jesusgatos]

Didn't see this posted earlier, but it's a great description of the Hydro-Max system including some plumbing & wiring diagrams:

ftp://164.106.79.2/Instructors/Rscoville/Bendix/Hydro-Max%20Power%20Brake%20System%20(SD-20-6602).pdf

Bendix? Thought these components were made by Bosch? Have I been trying to get information from the wrong company?

 

[silverstate55]

Don't know, I just assumed that different companies were manufacturing either new for manufacturers or replacement parts under license.

 

[jesusgatos]

Just called and left messages with tech support at Bosch and Bendix. Going to get to the bottom of this.

 

[jesusgatos]

OK, here's the deal: Bosch acquired the Hydro-Max brand/line when they purchased several hydraulic divisions from Bendix a few years ago. Bendix no longer has anything to do with Hydro-Max, and Bosch is still actively developing Hydro-Max systems - but they're only working with manufacturers. Does not appear that they're willing to offer any type of support to technical assistance for anything related to aftermarket applications. Understandable. Still, am going to contact the corporate division on Monday (they're closed today for some reason) to see if I can get through to anybody that might be able to help us out.

 

[quickfarms]

Today is good Friday

There lack of aftermarket support is probably an economic and liability issue