Brake specialists / hydraulics insight needed

[TechnoWeenie]

So, for those not familiar with the M35a2 deuce and a half.. it has an Achilles heel - Its brakes.

It uses an air over hydraulic system that's prone to leaks, and is single circuit. Lose air = lose brakes. Brake fluid leak = no brakes... GOOD LUCK EVERYONE!

So, I saw they make parking brakes for the pinion shaft.... couple hundred bucks .... These are open diffs so braking the pinion shaft while moving won't have the desired outcome...

But, I'm trying to figure out a way to have more reliable parking brake (which also sucks), while having an emergency brake that can at least start to slow the truck down.


Is there a way to tee into the existing hydraulic brake lines with a manual hand brake, or a small electric pump that you hit a switch and it just charges the line to 1000PSI and essentially locks the brakes? Any way to limit that? Adjustable pressure regulator that I can set to whatever I think is reasonable pressure, eg maybe just before they lock up so I can still slow down fast in the event of a main brake failure but not lose control?

Thoughts? Ideas?

I don't know shit about any of this, and I'm slowly finding bits and pieces but I'm not grasping the whole picture here.

[Massivedesign]

CQBGopher knows a bit about hydraulics. <—- that is the most I know.

[Old Growth]

Remember that the pinions in your deuce spin 6.72 times faster than your brake drums do. Pinion brakes run HOT if used for stopping the truck. They have lots of leverage though.

You can just fabricate a hand operated master cylinder to actuate the pinion brakes. Just like a “cutting brake” or buggy type of brake used by off-road folks for rock crawling or turning during wheelies.
Just a pull-lever mounted to a master cylinder. We have one on our skidder that operates the brake on the winch.

I have deuce axles in our mud truck and put pinion brakes on it over 20 years ago. It has 16.00x20s on bead locks (53” tall) and stops great. But they get hot if you drive on the street.

[Old Growth]

This is our ol mud pig. It’s been around for about 25 years.

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[Old Growth]

I built this one about 20 years ago as promotional/show truck. I think we used the “Chucks Trucks” pinion brake kit on it.

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[hartcreek]

I am familiar with single circuit brakes. Why do you not replumb your brake lines so that you have dual circuit? Instead of using air for the booster you could use hydraulics like a P30.

[TechnoWeenie]

I am familiar with single circuit brakes. Why do you not replumb your brake lines so that you have dual circuit? Instead of using air for the booster you could use hydraulics like a P30.

Because there is no point when there's only one output from the master cylinder?

I'm not opposed to finding a way to integrate a dual circuit master, but 2 axles in rear and one up front would result in less power to the rear and more to the front... correct? Unless a proportioning valve is used...?

I'd like to do away with the airpack and single circuit altogether, at a reasonable cost..... But settled on asking questions about things like the pinion brake as an emergency/parking brake..

[Rix86]

I built this one about 20 years ago as promotional/show truck. I think we used the “Chucks Trucks” pinion brake kit on it.

I thought Odie built that.

[Old Growth]

I built this one about 20 years ago as promotional/show truck. I think we used the “Chucks Trucks” pinion brake kit on it.

I thought Odie built that.

Odie owned it, but I built it. Every inch of it. Next time you see it, notice it has my old shop name CNC engraved into the front frame crossmember/spring hanger. I also built Odie’s red tacoma to.
These are the day it left the shop on rollers. That’s Odie strapping it down.

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[CQBgopher]

https://zips.com/docs/default-source/pa ... ad64cd.pdf

https://www.mico.com/products

Ditch the air-over parts and do a hydromax retrofit out of a medium duty truck (Topkick, F750, FL70, etc)

Possibilities are endless. Especially if you go with wrecking yard parts and scour eBay, etc for the MICO stuff.

https://www.hanksdeuce.com/hydroboost_install.htm
https://www.hanksdeuce.com/disc_brake_conversion.htm
https://www.steelsoldiers.com/threads/h ... st-1549904