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

[jesusgatos]

The 1 3/4" master cylinder is going to build more pressure when used with the Hydro-Max 2 booster. It's the most powerful combination of parts, and the stock master cylinder is 1 3/4", so should have enough fluid volume. Gonna give it a try anyway...

 

[spicergear]

Yes, you'll have more power because you have less surface area for the resistence. Most people think the biggest piston is the best...not always.

 

[Lonesome715]

The word "custom" scares me. Custom = $$$$$

 

[jesusgatos]

The word "custom" scares me. Custom = $$$$$

Oh no, not at all. Precision Rebuilders didn't charge me any more than they would have for a stock rebuild. There's really nothing 'custom' about the setup I ordered - it's just a combination of parts that didn't come from any one application. They have a big inventory of all these type of parts though, so it was no big deal for them to give me exactly what I wanted.

Also, got an email from Tim this morning letting me know that he was able to track down the 24V backup pumps and he's got one on the way. Price was not unreasonable either, considering that we had to buy new parts directly from Bosch.

 

[Lonesome715]

Hmmmm, sounds as though this would be a worth while progect then.

 

[jesusgatos]

Received the all of the Hydro-Max parts (except for the 24V backup pump which is still on-order). All this stuff actually showed-up a few days ago, but I just finally got a chance to open up the boxes.

Not really much else I could ask for. 1 3/4" 50/50 master cylinder with pressure differential switch, set up for remote reservoirs, with a Hydro-Max 2 booster, and a 24V backup pump (not pictured). That was everything on my wish-list. Precision Rebuilders

Residual check-valves. Was told these are modified Ford parts. Tim said that increasing the line pressure from 11lbs to 15lbs helps to keep the wheel cylinders from leaking.

Tim also sent me a huge assortment of different clevis-ends so that I could figure out which one is best suited to this application.

Adapting these new components to the stock brake pedal linkage shouldn't be much trouble. A quick test-fit suggested that the best/easiest way might be to mount the new master/booster assembly to the crossmember that supports the transfercase, and just forgetting about stock master cylinder mount. Might end up fabricating some type of bracket to tie the stock master cylinder mount in to the crossmember where the new master/booster will be mounted, but not sure if that's necessary. Need to have my brother help me crunch some numbers.

Anyway, if I mounted directly to the stock master cylinder mount, would have to hack-up the crossmember in order to allow the master cylinder to pass-through. Can't see any reason to do that when mounting to the crossmember means that I'll only have to drill four small holes for mounting hardware. Also means that I'll be able to use a longer pushrod, which is not a bad thing (better geometry).

I know, looks like the brake fittings will be awfully close to the transfercase mounting crossmember, but it's only the camera angle. Plenty of clearance.

Am going to need to offset the whole master/booster assembly to the driver's-side by a small amount though. The mounting flange for the booster interferes with the mounting tab for the transfer-case mounting crossmember.

 

[jesusgatos]

Three different cleviseses are direct-fits, and the stock pushrod could probably be modified (turned down on a lathe) and made to work just fine too. But if I have to offset the master/booster to one side none of those options work anymore. Could switch over to a single-shear clevis, or have a custom clevis made. Not sure what I'll end up doing yet. Going to try to start figuring out how to mount everything up tomorrow. Might end up being easier to just make a new transfercase mounting bracket.

 

[jesusgatos]

The backup motor might also interfere with the transfercase mounting crossmember. Might end up needing to modify that too.

 

[Ditch Baby]

is there a spot on it for brake light switch?

 

[Lonesome715]

I pulled the rims off a school buss today because the lug pattern fit my deuce. I seriously thought about getting the complete brake system off of it as well. It has disck brake with hydroboost. The problem is it only has for calipers. Would that brakes system support six?

 

[jesusgatos]

I pulled the rims off a school buss today because the lug pattern fit my deuce. I seriously thought about getting the complete brake system off of it as well. It has disck brake with hydroboost. The problem is it only has for calipers. Would that brakes system support six?

Pretty sure, yes. If you can find two more rotors and calipers. Only thing I can think of that might be a problem is if the master cylinder maybe didn't have enough fluid volume for the extra calipers?

 

[Lonesome715]

I know where a six wheeled dump truck with hydro is. However, there was a fire in the engine bay and the hydro unit was right in the middle of it. I think the calipers on that truck might be different. But, if the hydro unit from the bus can support six calipers i bet I can locate a res from a parts place.

 

[jesusgatos]

Yesterday: Received the new 24V backup pump, so now have got all the parts needed to figure out how to adapt this Hydro-Max setup to mah deuce. Unfortunately, the backup pump interferes with the transfercase mount to the point where I'm almost definitely going to need to cut into things to make everything fit. Only saying 'almost' definitely because there's a slight chance that I might be able to flip the backup pump around (from side-to-side). Don't think that's going to work, but am going to call tomorrow to ask just to make sure.

Today: Precision Rebuilders to the rescue again. Tim confirmed that I couldn't just flip the backup motor around because it would pressurize the wrong side of the booster assembly - BUT - they have two different adapter plates that redirect the ports and allow the backup pump to be rotated 90 or 180-degrees. He's going to send me one of each so I can decide which one I want to use, but am pretty sure it'll be the 90-degree plate that will put the backup motor inline with the master/booster assembly.

 

[jesusgatos]

Need to start figuring out the pedal linkage, which might only require a custom push-rod, or maybe even just a little adapter that will allow me to mate the stock clevis to one of the threaded Hydro-Max pushrods. Going to reinstall the stock master cylinder so I can cycle the linkage and see what kind of angles I should try to mimic with the new setup. Really, the length of the clevis/pushrod is the only variable here. The stock clevis/pushrod is threaded, so allows for some range of adjustment, and am wondering if the manuals specify anywhere how that linkage should be adjusted. Can anybody point me in the right direction?

 

[jesusgatos]

Reinstalled the stock master cylinder and cycled the brake pedal linkage. The clevis/pushrod is threaded, so the geometry will change slightly, depending on how the linkage is adjusted. Not knowing how that is supposed to be adjusted, just cycled the linkage how it was adjusted when I took it apart. The stock master cylinder strokes about 1 7/16", and was wondering whether they set it up so the bell-crank would swing through an arc that would minimize side-loads on the master cylinder, or if they would have made it so that the bellcrank would be perpendicular to the push-rod at the end of the stroke (full compression). Shot this video to show what I'm talking about.

Had to drive down to Pacific Fabrication to use their shop press to find out that the new master cylinder strokes 2 1/4", plus 1/8" to depress the little plunger that activates the booster. Both master cylinders have 1 3/4" bores, so can't ever see needing the full-stroke of the new Hydro-Max master/booster, but will be nice to have a little reserve on-tap. Dunno whether there's much room for that though. Will have to see if there is any interference between the pedal linkage and the floorboards (at full extension and full compression).

 

[jesusgatos]

Bingo! Fits great now. Just need to paint the master cylinder and do a little bit of clearancing so I won't have to offset the master/booster, then drill a few holes and mount the whole Hydro-Max assembly to the chassis.

 

[jesusgatos]

Need to start figuring out the pedal linkage...

...wondering if the manuals specify anywhere how that linkage should be adjusted. Can anybody point me in the right direction?

Anybody?

 

[Lonesome715]

I am really looking forward to a ride report after the first drive.

 

[jesusgatos]

Me too! Cab is down in Salinas getting painted right now, but I have a lot of work left to do before this thing will be back on the road.

 

[Lonesome715]

I have the same tires. Your frame looks like it is sitting up higher than mine.