DEUCE BRAKE LINE REFERENCE GUIDE (Sizes, lengths, fittings)

[peashooter]

POST 1~ SINGLE CIRCUIT BRAKE LINES
POST 2~ DUAL CIRCUIT BRAKE LINES
POST 3~ BRAKE PARTS REFERENCE GUIDE
POST 32~ BRAIDED STAINLESS FLEX LINES/HOSES
POST 40~ DUAL CIRCUIT MASTER CYLINDER BRACKET INFO & CAD FILE

SINGLE CIRCUIT BRAKE LINE INFO

I've been selling Stainless Steel Braided Flex hose kits and Cunifer Hard line brake kits for a while now. I'd like to get away from making the hard line kits so figured I'd share my "secrets" with members so they can more easily make (or have made) their own lines. Attached is a cheat sheet that shows all the hydraulic brake lines on a M35A2 type truck. Many of the lines are the same on the late model dual circuit A2 trucks and A3 trucks as well (but not all).
The cheat sheet shows tube size, length, and fittings. **To my knowledge there is no info in the TMs regarding brake line lengths. I measured several truck's brake systems and took the average to come up with the listed lengths but they should all fit.


BRAKE LINE
I recommend using a high quality Cunifer (copper, nickel, iron) brake line as it will not rust, flares easily, and bends easily (by hand even). With Cunifer you should never have to worry about them again...ever. Cunifer will make install of the frame lines much easier also since you can easily bend it as you are installing it. The only 2 quality brands I know of are FedHill, and EziBend. ALL others will be a lower quality Cunifer that I would avoid as they are thinner, do not bend or flare as well, and are crack prone. AGS/Nicopp, JohnDow, and anything else that comes in a shrinkwrapped coil are going to be the inferior brands.
There is about 40' of hard brake line on a single circuit deuce. You might as well get a 25' coil of 1/4" tube, and 25' coil of 5/16" tube.

FLARING TOOLS & Hints
-Our trucks use SAE45 degree double flares (usually called Inverted Flares). Many auto parts stores will rent or loan out flaring tools (O'Reilley Auto has free loaners). If you want to spend more money on a nice setup, I like the turret style that is marketed under a few different names it makes a perfect flare very easily. Check out the Eastwood 25340 or Brakequip BQ351.
-Another handy tool is a Brake Tubing pliers and tubing bender (especially if you use steel brake tube). Check out Eastwood for these also (often cheaper on ebay).
-Also always use anti-seize on the tube nut threads and flare's bearing surface where the nut slides over to help prevent the tube from twisting when you tighten the nut.
-Make sure to get some type of plated steel tube nut. Stainless nuts are not as strong as steel and the threads will gall much easier.

SPRING ARMOR
Stainless Steel Spring Armor Wrap/Gravel Guard (like on the axle lines) can be found at summit racing in 20' lengths for around $30.
1/4" part number: GGS14S-20
5/16" Part number: GGS516S-20

DOT 5 Fluid
A good place to get inexpensive DOT 5 silicone brake fluid is from Iris Industries As of this posting, a gallon of it runs about $27, a case of 4 gallons shipped runs about $135. Unfortunately they do not take paypal or credit card (as of last time I ordered), so you need to mail a check in the old fashioned way.
Olga Iris Acevedo
Iris Industries Inc
46 Route 156 Suite#1
Yardville, NJ 08620
Tel: 609-228-3080
Cell: 609-972-2265
Email: Irisincorporated@aol.com

 

[peashooter]

DUAL CIRCUIT BRAKE LINE INFO

Here is a reference sheet for the late model 87-89 "A2" style deuces often called Air Force deuces. These trucks have a dual circuit brake system that consists of a different master cylinder, extra air pack, and a specialty outboard air tank with an internal baffle.
The late Model m35A2 (&M109a3) trucks use the same Axle lines (AL1 & AL2), rear frame line (FL3), and Flex hoses (H) as the earlier deuces. The below reference sheet shows the lengths and fittings needed for the other hydraulic lines specific to the late model A2 dual circuit trucks.


The TM specific to this brake system can be found HERE


*NOTE: The dual circuit A2 master cylinder has built in residual pressure valves and therefore the M/C side fittings of lines FL4 & FL5 are quite large (11/16-18 & 3/4-18 ) and I suspect custom made. I could not find replacements. You probably need to reuse those large tube nuts if those lines are remade.
** NOTE: The single circuit A2 trucks and dual circuit A3 trucks do NOT have Residual Pressure Valves in the system (master cylinder or Airpack), only the late model dual circuit A2 trucks have the RPV's. In speaking with Gringeltaube, RPV's really aren't needed due to the height of the reservoirs in relation to the Wheel cylinders. The A3 trucks have remote reservoirs mounted high on the firewall so they would have even higher "residual pressure" which helps prevent the wheel cylinder cup seals from leaking.

A nearly exact replacement for the 1988 airforce deuce is the Dorman M39477. It will be the same with the only exceptions being the reservoir will be labeled Dot3 (but dot 5 can be used since seals are EPDM), it will have slits in the reservoir cap seals to act as the breather, and it wont have the remote breather fitting installed (both of which you can add or modify on your own, but are only needed if you would be fording water deeper than the height of the master cylinder). These can be found online (such as Summit Racing).


I don't have any line length info yet for the m35a3/m109a4 trucks yet but will post it here if/when I get it.


M35A3 MASTER CYLINDER REPLACEMENT
Here are some options for master cylinder replacements on the A3 dual circuit deuces that are still available as of 2024. These will be high quality and have the correct casting, 50/50 split, and guts, but will come with a plastic reservoir that you need to remove and replace with the existing remote reservoir plate from the old unit. I think these have recently started being made in China so to my knowledge there are no longer any new USA made replacements.
-CENTRIC brand, model 130.83014
-Dorman brand, model M12000

A couple notes:
-Raybestos tends to do things different so if someone does a cross reference on these numbers and pulls up other brands they may not actually work correctly, such as Raybestos that will often have an aluminum reservoir that has a different bolt pattern.
-when putting a remote top (or reservoir) back onto a master cylinder, you will need to push the piston in about an inch with a large C-clamp. There are 2 valves that sit between the reservoir and the main casting body and the valves "tip" open when the piston is in its natural position. Once the piston is pushed in a little bit, then the valves will sit vertical and can move up and down on their own. If putting a reservoir or remote reservoir top plate onto the main body without first pushing the piston in, then you will bend the 2 valves as you tighten down the top plate/reservoir.

 

[peashooter]

BRAKE PARTS REFERENCE GUIDE ... (Updated as I'm able to)

FRONT WHEEL FLEX HOSE (2X), 19.75" OAL
Part #7409330

FRONT AXLE TO FRAME HOSE (1X), 18.5" OAL
Part #7373247

REAR AXLE TO FRAME HOSE (2X), 28" OAL
Part #7373248

BULKHEAD NUT FOR FRONT WHEEL FLEX HOSE (2X): 11/16-18

BULKHEAD NUT FOR FRONT AXLE FLEX HOSE (1X): 5/8-18



COMMON REPLACEMENT PARTS FOR THE BRAKE SYSTEM:

WHEEL CYLINDER (1-3/8" diameter, F&R A2, R only of A3 TRUCKS):
Inlet: 1/2"-20
Bleeder: 7/16"-20
NSN 2530-00-274-4511
Part #7348976, 12448554, 7411010, 4419, 172-361
NAPA:4419
DORMAN:W4419
Raybestos/Wagner: WC4419
1-3/8" W/C REBUILD KITS:
NAPA: UP45
DORMAN:
RAYBESTOS: WK45
(cup only: Dorman 857 \ UP 857)


WHEEL CYLINDER (1-1/2" diameter, FRONT only of A3 TRUCKS):
Inlet: 1/2"-20
Bleeder: 7/16"-20
NSN: 2530-01-441-4866
Part #37317M, 12448554, RCSK17128
NAPA:
DORMAN: W37317
Raybestos/Wagner: WC37317
1-1/2" W/C REBUILD KITS:
NAPA: UP44
DORMAN:
RAYBESTOS: WK44
(Cup only: Dorman 725 \ UP 725)


A2/A1 SINGLE CIRCUIT MASTER CYLINDER:
NSN: 2530-00-753-9267
Part #:7539267, 12368254, F111700, FE3527A
Rebuild Kit
NSN: 2530-00-753-9309
Part #:7539309


AIR PACK (LONG, OLD STYLE)
NSN: 2530-00-040-2188
Part #:8345003, 12368255, N4105H
Rebuild Kit
NSN: 2530-00-040-2190
Part #:28345007, RN25D

AIR PACK (SHORT, NEW STYLE)
NSN: 2530-01-384-3726
Part #: KN35010, N4105AG, KN35020~w/residual check valve
Rebuild Kit
NSN:
Part #: RN25T

MISC ITEMS
Bleeder caps: Allstar Performance 50855 (10 pack, about $4)
BANJO FITTING:
BANJO BOLT:
TEE FITTING (REAR FRAME RAIL MOUNTED):
TEE FITTING (FRONT AXLE MOUNTED):
TEE FITTING (BETWEEN REAR AXLES):
TEE FITTING (ON REAR AXLES): Part #7373249, NSN - 4730-00-737-3249
TEE PLUG (TO USE WHEN BOBBING A DEUCE AND REMOVING REAR AXLE HOSE):

MORE HANDY TOOLS FOR BRAKE SHOE ADJUSTMENT & BLEEDING:
-Bleeder screw wrench: 7/16" Deep offset box wrench (such as Lisle 10900)
-Minor brake shoe adjustment: 11/16" wrench
-Major brake shoe adjustment: 1-1/8" deep offset box wrench

 

[drmerc]

I'm having some kind of leak, this info will come in handy soon! Thanks!

 

[peashooter]

I updated the 2nd post with the 87-89 dual circuit specific line length/fitting info. I dont have any line length info for the m35a3 trucks yet, if anyone has overall lengths for the lines let me know and I'll add it to post 2. I know the fitting sizes for the a3's just not the lengths. TM for a3 system is 9-2320-386-24P Thanks

 

[rustystud]

Peashooter, I wish you would reconsider getting out of the brake line business ! Your lines and hoses are the best ! I know from years working in the automotive world. Yours are better then OEM !

 

[dslucas]

Any way we can get this stickied for ease of future reference?

 

[41cl8m5]

I agree with rustystud your lines are top shelf. I'm glad I was able to get a set.
Aaron, be expecting a pm from me on Friday on the stuff we already talked about.
chris

 

[brianp454]

As always, thanks and good work Peashooter! Can you add the following to your original post? It’s really handy to have all of the info in one spot.

Cup
1 3/8 Dorman 857 \ UP 857
1 1/2 Dorman 725 \ UP 725

There’s also the issue of the copper washers for the banjo fittings. Comparing my take-outs the NAPA UP 1245 matches the inner banjo washer (33/64 ID) and UP 1246 matches the outer banjo washer (39/64 ID). The new wheel cylinders I’ve gotten have a washer in the box that could work on the inner, yet has an inner diameter about 0.55 inch vs. ~0.515 for my take-outs. They will likely just be a bit off-center due to a bit of excess clearance fit between it and the threaded banjo fitting.


Notes:
The UP prefix to the p/n is the NAPA way of flagging the parts as related to wheel cylinders. I think Dorman uses W or WC for the same sorta thing.

Both my OEM and new NAPA UP4419 1 3/8 wheel cylinders match the photo lengths in your pic, i.e. both match in length regardless of the type of cup. The 1 1/2 wheel cylinders I got also measure the same as yours.

I’d like to get a p/n for those little condoms to put over the bleeders. I never liked the idea of getting a lot of crap in there and they should help keep them clean (and hopefully resist corrosion). I'll look for p\n for the other parts you mention as I have time.

I’ve also noticed that some of the rebuild kits for the 1 3/8 wheel cylinders have straight and others pigtailed ends on the springs. I like the pigtails better. Any thoughts one which is proper or better?

 

[peashooter]

Thanks for the info Brian, I'll add that to the top posts.... I agree that it's nice having a common location for all related items like brake part info.
About the springs, the ones with pigtailed ends act as cup expanders to help prevent the cup seals from leaking fluid out or air in, so they are better that the straight springs. I did get an Erik's surplus/Newstar wheel cylinder last year that had a straight spring with welded on metal cup ends that do the same thing as the pigtailed springs.

 

[peashooter]

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[peashooter]

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[Lieutenant Dan]

Hey peashooter do you happen to have a picture of the m35a2 master cylinder to air pack line? I bent mine up today using the info you provided and while it bent nicely and works it looks freaking stupid. My old one was all twisted and wasn't worth trying to copy.

 

[ke5eua]

Would this apply to the 809 series as well?

 

[peashooter]

Hey peashooter do you happen to have a picture of the m35a2 master cylinder to air pack line? I bent mine up today using the info you provided and while it bent nicely and works it looks freaking stupid. My old one was all twisted and wasn't worth trying to copy.

I just threw out my set of donor lines so I don't have any pics I can share. From your picture it look like you used a longer line there, it should be a 12" line. There is a 27" line that goes from the air pack to the tee fitting on the frame, maybe you used that line instead?


Ke5eua- I only have info on the 5 ton flex hoses but I'd really doubt any of the hard lines are the same.

 

[ke5eua]

My main thing was the schematic, I'll do all the measurements when the time comes. Your information is amazing on the brake system.

 

[Mike929]

Here are some pictures of a DUAL circuit brake system of an Air force truck that I had from last year. Might help.

 

[peashooter]

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[ah1955]

Perfect timing, I just blew a line along the rear axle, from the tee to right rear wheel. wanted the size and length to get parts. You drawings made that easy, everything I needed in one place. Thank you very much.

 

[peashooter]

So besides the standard 1-3/8" bore wheel cylinders, and the larger 1.5" diameter wheel cylinders used on the front axle of the M35a3 trucks, there is also a 1.75"diameter wheel cylinder that may fit (it may be a little too fat though and possibly rub against the shoe return spring. I'm not suggesting to use this as most 6x6 deuce brake systems may not have enough fluid capacity, but for Bobbed trucks and those with the skill and knowledge of their brake system who like to try different things here it goes: The DORMAN W1012 is the big daddy to the other 2 sizes as described in post 3.

***Edit- I ordered one of these to try out and they are too wide to fit in our trucks. Looks like the best way to get more stopping power would be 6x of the 1.5” bore units assuming a single airpac has enough volume.