M35 Brakes. Warning signs ignored could have been serious

[sti-nkr]

How do you bleed the booster? I know I'm reviving an old thread but I just got a new master cylinder and I'd like to know exactly what I'm doing before i start.

 

[Katahdin]

The booster has bleeder valve (pointed skyward) like the wheel cylinders, don't mistake it for a grease zerk.

On my end I've built the pressure bleeder and replaced 5 rusty steel lines and 2 questionable hoses. My frustrations are around getting the new line fittings to stop leaking! Bleed...pump brakes...spot leak....adjust fitting....bleed....pump brakes....find a different leak.....bleed....

 

[hndrsonj]

How do you bleed the booster? I know I'm reviving an old thread but I just got a new master cylinder and I'd like to know exactly what I'm doing before i start.

Download the TM, all the info is in there.

 

[ATC]

When I get my Deuce back, I want to go through the entire brake system and replace all the lines with SS braided lines, new fluid, and a MC rebuild kit and possibly new wheel cylinders. When I had it the first time, I noticed the MC was usually damp, and I had to top it off once in the 3 months I owned it...

 

[namedpipes]

As I look longingly at the GL auctions, accumulating cash . . .

Has anyone converted the brakes to a two circuit setup either with a more modern MC or with two stock units operated by one pedal? Or is this just a bad idea?

As for the spoiled brake fluid, it sounds like that could be filtered and poured right into the fuel tank

 

[clinto]

Has anyone converted the brakes to a two circuit setup either with a more modern MC or with two stock units operated by one pedal? Or is this just a bad idea?

There have been multiple threads, covering what's entailed in such a conversion (using the stock components) or doing conversions using aftermarket components.

Steel Soldiers::Military Vehicles Supersite - Search Forums

I'd probably use the search query "dual AND circuit"-but be prepared, you will pull up a LOT of threads (including this one). Take some time to read them all.

 

[dcwilkie]

OK- I have everything to rebuild my brakes end-to-end.
1) Should I start with the wheel closest to the master and work my way back or does it matter?
2) Should I bleed them as I go or wait until I've replaced all the wheel cylinders/ hoses and then bleed?
All advice welcome

 

[Warthog]

OK- I have everything to rebuild my brakes end-to-end.
1) Should I start with the wheel closest to the master and work my way back or does it matter?
2) Should I bleed them as I go or wait until I've replaced all the wheel cylinders/ hoses and then bleed?
All advice welcome

If you are replacing them all, it doesn't matter where you start. I would wait until they are all replaced and then bleed the system, starting at the right rear and working your way forward. The Tech Manuals show you the sequence.

 

[MO MV man]

How much pressure do you all use with the sprayer pressurizing method?

I remember seeing 15PSI on the board before BUT.....

The TM says 22-25 PSI.

 

[Barrman]

I normall pump my tank up to 25 psi or so. Starting with a pretty dry M35, I will have to charge it up at least one time before I am done. Just remember to ssslllloooooowwwwwwlllllyyyyy turn on the fluid into the master. The secondary seal on the master piston is not meant to hold huge amounts of pressure and that is where any leaks will be in a normal functioning brake system. So, don't shock it. If you feel kind of leary, just run 10-15 psi and recharge as needed.

 

[MO MV man]

I normall pump my tank up to 25 psi or so. Starting with a pretty dry M35, I will have to charge it up at least one time before I am done. Just remember to ssslllloooooowwwwwwlllllyyyyy turn on the fluid into the master. The secondary seal on the master piston is not meant to hold huge amounts of pressure and that is where any leaks will be in a normal functioning brake system. So, don't shock it. If you feel kind of leary, just run 10-15 psi and recharge as needed.

The reason I asked was I did it at 15 (before seeing the TM's recommendation) and the bleed rate was weak at the wheel cylinders.

I plan to do it at 25 the next time I get the time and feel confident that'll make for a much more positive bleed.
I'm not happy with the pedal firmness presently.

 

[Barrman]

Firmness or travel? With no air in the airpack, the pedal will feel mushy because the air part of the system moves a little from the hydraulic pressure. Make sure you bleed the air pack too.

Travel is more a function of brake shoe adjustment. You can have no air in the system and the pedal will hit the floor if the shoes are too far from the drums.

not trying to insult your ability, just pointing out things people forget when they get shoulder deep into a brake project.

 

[MO MV man]

Firmness or travel? With no air in the airpack, the pedal will feel mushy because the air part of the system moves a little from the hydraulic pressure. Make sure you bleed the air pack too.

Travel is more a function of brake shoe adjustment. You can have no air in the system and the pedal will hit the floor if the shoes are too far from the drums.

not trying to insult your ability, just pointing out things people forget when they get shoulder deep into a brake project.

No insult taken, Barrman.
Thanks for the response.

I know my brakes could use an adjustment.
The pedal travel is not excessive, just not to my liking.

I pressure bled the system at least 10 times (at 15 PSI) and keep getting bubbles......so I took a break before I tossed the whole shootin' match into the woods.
No leaks anywhere.
The Master was full, zero fluid loss.
Fluid clean.

I'll re-bleed with 25PSI in the sprayer as soon as I get the time to do it.
I'm VERY confident that'll make for a more effective bleed.
I'd do a manual bleed for a test but don't have anyone available patient enough to do it.....my wife would laugh at me.

Next on the agenda is adjusting the brakes......again, as soon as time allows.

 

[CMS]

Why is denatured alcohol used to flush the brake fuild. I just flushed my system and the alcohol did not mix with or act as a solvent to fluid that is in my truck. I dont know what fluid is in there as my truck is a recent purchase but why not use something that acts as a solvent to the fuild? If there is a more appropriate thread on this please direct me elsewhere.

 

[farmall]

My M35 was discharged in 97. What fluid type is in it from its last Army maint. ? TM mentions WP046800 with no link.

 

[Barrman]

The military switched over to silicone BFS in the 1970's. Your 1997 truck should have it. If in doubt, put some of what is int he truck in a glass or clear jar. First off, it will be yellow/green ish or purple more than likely.

Add a little bit of water to the jar, shake it up and then let it sit. If the water stays seperate, then you have DOT 5 or BFS. If it mixes with the fluid, then it is DOT3.