1988 Air force deuce brake system rebuild

[rustystud]

I just posted about the seal kit.
Raybestos Brake Master Cylinder Kit MK1624 at $58.99 total with 30 day refund buyer pays return shipping.

"At the moment there is a RAYBESTOS MK1624 seal kit on the popular auction site with the funny seals mentioned by rustystud for under 60 bucks. Perhaps this seal kit is for the dual brake MC I don't know."

If I needed a seal kit for an AF dual brake MC I would just buy it to see if it is the correct seals.
View attachment 759981

Well I went ahead and bought this kit. It is the wrong one. Not only that but it doesn't have all the parts shown in the picture and the seals are "not" blue silicone like pictured. I contacted the seller after buying it and ask what was up here. He told me that "yes the seals are all just regular rubber" . No silicone seals, which our dual master cylinder Deuce uses.
Here's some picture's of what I received.

 

[frank8003]

Is the small 4 special seals on bottom left of photo/ bottom left in the plastic bag photo, the correct parts?
There is 12 parts shown in the auction photos, which one did not arrive in the package?

 

[peashooter]

I have the original Bendix drawings for the Master Cylinders from the A2 dual circuit and A3 trucks, they call out EPDM rubber seals. Perhaps some of the newer replacement units have silicone? I know you can get Blue EPDM O-rings though.

 

[Floridianson]

It is interesting the auction cross reference list that this kit fits more than 60 applications for this kit. As in Ford hydro boost F700 F800 Chevy B60 C60 C70 + B6P042

That is what I am finding out when I do a google search. Is there a number stamped into the master cylinder. All the pics of the Ford 1980-1998 F700 master looks close to what might be on the trucks. My A3 has been sitting for years now and will most likely need some TLC. Looking at the possible place for the numbers to be stamped into housing. Thanks.

 

[rustystud]

I have the original Bendix drawings for the Master Cylinders from the A2 dual circuit and A3 trucks, they call out EPDM rubber seals. Perhaps some of the newer replacement units have silicone? I know you can get Blue EPDM O-rings though.

I knew that didn't sound right ! I should have said "EPDM" seals. I've been on this stupid "30/10" diet (loose 30Ibs in 10 weeks) for three weeks now and my mind has gotten fuzzy lately. No fats at all. I know your suppose to have natural fats to keep your brain working properly and "olive oil" just doesn't cut it !
Yes "EPDM" seals.
Thanks Peashooter !

 

[rustystud]

Is the small 4 special seals on bottom left of photo/ bottom left in the plastic bag photo, the correct parts?
There is 12 parts shown in the auction photos, which one did not arrive in the package?

No they where not. This kit did not have the correct size of the special "wheel" seals and the "check valves" were missing(cannot remember their proper name right now). Also the seals themselves where just rubber, not "EPDM" seals like our Air force Deuces have installed in them.
Mailed it back today.

 

[redmudjeep]

If you need a master cylinder PM me, I have one that uses the larger fittings (11/16-18 & 3/4-18 )

Mike

 

[Floridianson]

Was the same master use on the AF Deuce as my A3. I have not crawled under it for 6 years. Was hoping to sell her as is but I might end up keeping it. If I keep her then a full axle service and check air pack and master. Tanks

 

[M37M35]

I'm converting my deuce to the Air Force dual circuit brake system. I already have all the parts from a donor truck.

I'm going to rebuild the master cylinder before I install it, but can't seem to confirm the correct rebuild kit. Earlier in this thread, and in this post, says that Raybestos MK1624 is the correct kit. But at the top of this page Rustystud bought one and it was the wrong kit. I found the MK1624 kit for a reasonable price, but I don't want to order it if it's not going to work.

Can someone who has successfully rebuilt an Air Force dual circuit master cylinder confirm what kit they used?

@rustystud, do you know if that was just a 'defective' kit you ended up with? Did you get another MK1624 kit with the right parts?

@peashooter, any thoughts on a rebuild kit? Can you still get aftermarket master cylinders if I have to go that route?

Thank you all!!

 

[peashooter]

I'm converting my deuce to the Air Force dual circuit brake system. I already have all the parts from a donor truck.

I'm going to rebuild the master cylinder before I install it, but can't seem to confirm the correct rebuild kit. Earlier in this thread, and in this post, says that Raybestos MK1624 is the correct kit. But at the top of this page Rustystud bought one and it was the wrong kit. I found the MK1624 kit for a reasonable price, but I don't want to order it if it's not going to work.

Can someone who has successfully rebuilt an Air Force dual circuit master cylinder confirm what kit they used?

@rustystud, do you know if that was just a 'defective' kit you ended up with? Did you get another MK1624 kit with the right parts?

@peashooter, any thoughts on a rebuild kit? Can you still get aftermarket master cylinders if I have to go that route?

Thank you all!!

As far as i know, the MK1624 kit is the proper one. However you can often get new master cylinders for under $200. Assuming you have the bracket from a dual circuit air force truck or a modified one from an A3 truck, you can use one of the master cylinders i have listed at the bottom. They would be the equivalent to what was on the newer A3 trucks except have a low height 61cu/in reservoir similar to what the air force trucks had. Any A3 owners could also use this master cylinder but they would have to remove the reservoir and put on the old remote top plate (there is a trick when doing this so the valves dont get damaged). Since this MC has the same guts as the A3 trucks 50/50 split,then you should also replace the Front wheel cylinders with the larger 1-1/2” size so that the front axle circuit and rear axles will require similar volumes of fluid when brakes are applied..... unless you have a bobber, then keep both front and rear brake cylinders the same.
This style also uses the more common size outlets (9/16-18, & 1/2-20) which are much easier to fit up to than the giant ones of the late 80’s air force trucks.
Look for:
CENTRIC: 130.83014
DORMAN: M12000
AC DELCO: 174-841
RAYBESTOS: MC12000

if it isnt one of these exact numbers, im not sure if it will work. A lot of brands like Cardone have equivalents to these but will have differences like larger reservoirs that wont fit.

 

[peashooter]

Oh, and if you want a nearly exact replacement for the 1988 airforce deuce, then get the Dorman M39477. It will be the same with the onky 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).

 

[redmudjeep]

I have an NOS Air Force master cylinder that I purchased and cannot use due to the larger fitting size. PM for more details.

 

[M37M35]

As far as i know, the MK1624 kit is the proper one.

I'll order that kit and see if it works.

Assuming you have the bracket from a dual circuit air force truck or a modified one from an A3 truck, you can use one of the master cylinders i have listed at the bottom.

I do have the elusive AF truck bracket! I'll see if the MC I have can be rebuilt. If not, I'll get one of the ones you mentioned.

Since this MC has the same guts as the A3 trucks 50/50 split,then you should also replace the Front wheel cylinders with the larger 1-1/2” size...

Do you know what the split is on the original AF MC? I was already planning to install the larger wheel cylinders on the front. Will this be a problem if I'm using the original AF MC instead of an aftermarket one that you mentioned?


Thank you very much for all the info! It's greatly appreciated!!

 

[M37M35]

I have an NOS Air Force master cylinder that I purchased and cannot use due to the larger fitting size. PM for more details.

Sent you a PM.

 

[peashooter]

I'll order that kit and see if it works.

I do have the elusive AF truck bracket! I'll see if the MC I have can be rebuilt. If not, I'll get one of the ones you mentioned.

Do you know what the split is on the original AF MC? I was already planning to install the larger wheel cylinders on the front. Will this be a problem if I'm using the original AF MC instead of an aftermarket one that you mentioned?


Thank you very much for all the info! It's greatly appreciated!!

the original 88 air force trucks had the 60/40 split (the Dorman M39477 does also). you are probably ok going with the larger front cylinders still, but a 50/50 split would probably be better, and a good time to switch to the more normal sized line fittings.

 

[M37M35]

As far as i know, the MK1624 kit is the proper one.

Just to follow up, this is the correct kit. $29.79 at RockAuto.

 

[2deuce]

I'm in a holding pattern. Summit has the Dorman on back order. With a projected ship date of 8/26.

 

[2deuce]

Update. I contacted Summit about the ship date since it is September. I asked them to check on it. Since it being shipped from the manufacturer (dorman) they said I would get an email telling me when it would ship. I got the email, it said I was getting a refund. Maybe it will be available in the future, but it isn't right now or in the near future.