M185 Brakes TM and best current parts source?

[FLYWHEEL]

Hi all, I don't want to hijack this thread but I am looking to buy a set of brake shoes for my M35, and I noticed that on a certain aution site that there are shoes listed under two different part numbers. #12301170 and #75321767. My question is are they the same item just under a different part number or is there a difference between them ?

Hi again, done some more reading of the parts TM'S. It looks to me that #12301170 is the part number for a complete axle set and #75321767 is the number for individual shoes.
It's amazing what you can find out if you take some time to read the TM's

 

[rustystud]

It sounds like it might be easier to just have the truck running, let the air packs assist and have someone pump the breaks while I open and close the bleed valves, is that an acceptable approach or will I break the brakes?

If you have someone to help you that is a perfectly acceptable way of bleeding brakes. Just watch the master cylinder fluid level. It's really easy to blast out all your fluid that way.

 

[maxpanic]

If you have someone to help you that is a perfectly acceptable way of bleeding brakes. Just watch the master cylinder fluid level. It's really easy to blast out all your fluid that way.

Since I have a dual system from the Air packs down, what is the correct bleed pattern? My guess would be to bleed the Air pack on the left then the rear left cylinder, then the middle left cylinder and then the front left cylinder with the same idea on the right from back to front after the air pack. Is that correct?

 

[SCSG-G4]

From the pictures you posted, you have a dual master cylinder, and dual air packs! You can only get to the front cap on the MC with ease. Usually the front cap will be to the front brakes and the rear cap will feed all four of the rear brakes. Maxpanic, please take the skid plate off the bottom of the MC and post a good side shot of that unit so the others can see what I'm talking about. It may change some of the advice you've been given.

 

[Jeepsinker]

I bet that your truck is an 87' or 88' model and someone put the wrong data plate on it. Those parts are too cleanly installed for someone else to have cobbled it together.

 

[maxpanic]

From the pictures you posted, you have a dual master cylinder, and dual air packs! You can only get to the front cap on the MC with ease. Usually the front cap will be to the front brakes and the rear cap will feed all four of the rear brakes. Maxpanic, please take the skid plate off the bottom of the MC and post a good side shot of that unit so the others can see what I'm talking about. It may change some of the advice you've been given.

Now I am unsure how many master cylinders there are.

 

[Jeepsinker]

You only have one master cylinder, and two air pacs. That's all there is to it. And that is a factory install. Your truck is an 87' or 88' model, no doubt about it. It was an air force truck.

 

[rustystud]

Yep, defiantly a 1987-88 Air-Force truck. That Master cylinder bracket has the special end for the PTO lever, and those brake lines are factory. As far as bleeding goes, bleed out the left side air-pac (under the master cylinder) first then the right side one. Then you would bleed out the front brakes (right front first), then go to the back. First rear drive axle then last drive axle.
Always bleed out the shorter lines first on the axles (left side).

 

[maxpanic]

That is really weird because all my paperwork says its a 68 or 69. It still has the numbers on the bumper, should I look up that? Anyone know how to do that?

 

[Jeepsinker]

These trucks being mislabeled and incorrectly titled is exceedingly common. Sometimes people would put an older year model on the SF97 so they could get it titled as an older vehicle for insurance or special titling purposes.

 

[peashooter]

From the pictures you posted, you have a dual master cylinder, and dual air packs! You can only get to the front cap on the MC with ease. Usually the front cap will be to the front brakes and the rear cap will feed all four of the rear brakes.

The reservoir has 2 caps but just one is accessible. Their is an internal divider between the 2 caps that only goes up 1/3 to 1/2 height of the reservoir. So as long as you fill it full it will fill both sides of the reservoir.

 

[peashooter]

I'm still a bit uncertain if these Air Force trucks were 100% new parts. I've got an '88 but there are a few things like serial number and some felt gasketing on one section of the van box (when all other sections had newer 3M rubber gasketing between the interior sheet metal panels and box framing) that makes me think the frame and box could have been reconditioned from 1972. I also had 3 van box Windows that had wood cores and 3 of them that had newer plastic cores. All the mfg dates on everything say 1988 but again I suspect somethings might have been reconditioned to new from old cores by AM General.

 

[maxpanic]

The reservoir has 2 caps but just one is accessible. Their is an internal divider between the 2 caps that only goes up 1/3 to 1/2 height of the reservoir. So as long as you fill it full it will fill both sides of the reservoir.

Is there a TM for the brakes on my truck?

How do I order a replacement Master cylinder? is it the same master cylinder and rebuild kit?

I have rebuilt the air packs Bled the brakes. Still not acceptable stopping ability. Advice and suggestions for getting these brakes squared away are appreciated.

Thanks,
Matt

 

[peashooter]

Is there a TM for the brakes on my truck?

How do I order a replacement Master cylinder? is it the same master cylinder and rebuild kit?

I have rebuilt the air packs Bled the brakes. Still not acceptable stopping ability. Advice and suggestions for getting these brakes squared away are appreciated.

Thanks,
Matt

These brakes sort of have a TM, you can find it here:http://www.steelsoldiers.com/showth...ke-system-TM&p=1155705&viewfull=1#post1155705
Also they are about the same as the M35a3 so you can go off any brake bleeding procedures you find for that also. The master cylinders aren't the same (single circuit A2 trucks, dual circuit a2 trucks, and dual circuit a3 trucks all have different MC). The truck you have (dual circuit A2 type) has a unique master cylinder, its dual circuit 60/40 split, small reservoir, and has built in residual pressure valves. The rebuild kits aren't that cheap and only include a few O-rings and a C-clip. Feel free to PM me if you are interested in a new M/C. If you brakes were okay before the bleeding procedure, then I would guess there is still air in the system, probably between the master cylinder and the airpacks. Due to the residual pressure valves built into the MC, these are a real pain to bleed. Also I haven't read this whole thread but if you haven't already checked and adjusted the brake pads that could be causing the issue. I found I had bad seals on at least half of my wheels so brake pads were soaked with oil & grease.

 

[maxpanic]

These brakes sort of have a TM, you can find it here:http://www.steelsoldiers.com/showth...ke-system-TM&p=1155705&viewfull=1#post1155705
Also they are about the same as the M35a3 so you can go off any brake bleeding procedures you find for that also. The master cylinders aren't the same (single circuit A2 trucks, dual circuit a2 trucks, and dual circuit a3 trucks all have different MC). The truck you have (dual circuit A2 type) has a unique master cylinder, its dual circuit 60/40 split, small reservoir, and has built in residual pressure valves. The rebuild kits aren't that cheap and only include a few O-rings and a C-clip. Feel free to PM me if you are interested in a new M/C. If you brakes were okay before the bleeding procedure, then I would guess there is still air in the system, probably between the master cylinder and the airpacks. Due to the residual pressure valves built into the MC, these are a real pain to bleed. Also I haven't read this whole thread but if you haven't already checked and adjusted the brake pads that could be causing the issue. I found I had bad seals on at least half of my wheels so brake pads were soaked with oil & grease.

thank you. My brakes were not stopping the truck well at all so I thought I would rebuild the air packs.

 

[rustystud]

These brakes sort of have a TM, you can find it here:http://www.steelsoldiers.com/showth...ke-system-TM&p=1155705&viewfull=1#post1155705
Also they are about the same as the M35a3 so you can go off any brake bleeding procedures you find for that also. The master cylinders aren't the same (single circuit A2 trucks, dual circuit a2 trucks, and dual circuit a3 trucks all have different MC). The truck you have (dual circuit A2 type) has a unique master cylinder, its dual circuit 60/40 split, small reservoir, and has built in residual pressure valves. The rebuild kits aren't that cheap and only include a few O-rings and a C-clip. Feel free to PM me if you are interested in a new M/C. If you brakes were okay before the bleeding procedure, then I would guess there is still air in the system, probably between the master cylinder and the airpacks. Due to the residual pressure valves built into the MC, these are a real pain to bleed. Also I haven't read this whole thread but if you haven't already checked and adjusted the brake pads that could be causing the issue. I found I had bad seals on at least half of my wheels so brake pads were soaked with oil & grease.

Hey Aaron. Do you happen to have the manufacturer and part number for the A2 Master Cylinder rebuild kit ? I tried to get the proper 'O' rings for mine but they must be an odd size and what are the 'O' rings made of ?
Thanks Aaron.

 

[Jeepsinker]

They would almost certainly be Viton. Nitrile rubber tends to swell badly when exposed to brake fluid, at least in my experience.

 

[peashooter]

Hey Aaron. Do you happen to have the manufacturer and part number for the A2 Master Cylinder rebuild kit ? I tried to get the proper 'O' rings for mine but they must be an odd size and what are the 'O' rings made of ?
Thanks Aaron.

The Seals for these (at least what was factory original) are EPDM rubber. The only repair kit I'm aware of that will work for the dual circuit A2 and A3 trucks is Raybestos MK1624 which is still a good number according to Raybestos but its tough to find any place that has these stocked any longer. Below is a picture of whats included in the kit.

 

[maxpanic]

These brakes sort of have a TM, you can find it here:http://www.steelsoldiers.com/showth...ke-system-TM&p=1155705&viewfull=1#post1155705
Also they are about the same as the M35a3 so you can go off any brake bleeding procedures you find for that also. The master cylinders aren't the same (single circuit A2 trucks, dual circuit a2 trucks, and dual circuit a3 trucks all have different MC). The truck you have (dual circuit A2 type) has a unique master cylinder, its dual circuit 60/40 split, small reservoir, and has built in residual pressure valves. The rebuild kits aren't that cheap and only include a few O-rings and a C-clip. Feel free to PM me if you are interested in a new M/C. If you brakes were okay before the bleeding procedure, then I would guess there is still air in the system, probably between the master cylinder and the airpacks. Due to the residual pressure valves built into the MC, these are a real pain to bleed. Also I haven't read this whole thread but if you haven't already checked and adjusted the brake pads that could be causing the issue. I found I had bad seals on at least half of my wheels so brake pads were soaked with oil & grease.

I would really like more info on bleeding the residual pressure valves that are built into the master cylinder on my type of dual circuit A2 system. Is there anything available? I didn't see anything on it in the TM you referenced. Did I miss it?

 

[peashooter]

I would really like more info on bleeding the residual pressure valves that are built into the master cylinder on my type of dual circuit A2 system. Is there anything available? I didn't see anything on it in the TM you referenced. Did I miss it?

Well how I did mine was to top off the reservoir (and keep it topped off throughout the process)
-1. Bleed front air pack (pass side)
-2. Bleed rear air pack (drv side)
-3. Bleed pass rearmost cyl
-4. Bleed drvs rearmost cyl
-5. Bleed pass center axle cyl
-6. Bleed drivers center axle cyl
-7. Bleed drivers front cyl (yes drivers side first on the front)
-8. Bleed pass front cyl
-9. And just to be sure I did it again.

I think it's easy for air to get trapped between the master cylinder and air packs so spend extra time at that step. Perhaps while bleeding, loosen the tube nuts a bit at the master cylinder and let some fluid (and hopefully any trapped air) bleed out then retughten and bleed air packs again then cylinders.