Single circuit to dual circuit brake conversion

[banditt1979]

A while back I rebuilt the air pack that came with the truck. The gasket that came with it for the rear plate was too small and broke when I tried to install it so I reused the old one. Then I removed the air pack and installed a rebuilt unit thinking there was something wrong with it. Removed the rear cover to inspect and tore the old gasket. Well this evening I carefully made a new one. I used my compass from college to make a circle on some gasket material I had (again, hot rod days) 4 1/2 " diameter and used an xacto knife set I bought in Pigeon Forge, and carefully cut the inner diameter. Checked to make sure that was good then notched the areas for the studs. All went well and another obstacle out of the way!

 

[banditt1979]

Doing some practice runs with my new welder I think the materials I have will work

Edit: I beat on this weldment pretty hard with a 3lb sledge and it didnt fail. I think what I will do with the actual mc bracket will be more than adequate.

 

[banditt1979]

Cut down a spare mc push rod and cut some threads on it. Should work perfect but may need to thread it some more for a lock nut

 

[banditt1979]

Got the mounting holes drilled and used a 2" hole saw to make the hole for the dust boot. Probably could have made it a little smaller like 1 7/8" but I didn't expect to be able to use the single mc boot. Just trim about half of the first "ring" off the boot and I think it will work fine. I'll need a zip tie or hose clamp on the small end to secure it to the heim joint

 

[banditt1979]

Big night last night got the old bracket trimmed up and the new mounting plate tacked on. Before I finish weld and add some gussets I'll try to climb under the beast and make sure it will fit. Its 4 degrees right now so maybe I'll wait until it warms up a bit.

 

[banditt1979]

Initial mock up looks good and the single mc dust boot fit is great and isn't going anywhere. I'll wrap some electrical tape around the heim joint to tighten up the dust boot fit. Very happy with the results so far

 

[banditt1979]

Gussets tacked in

 

[banditt1979]

I'm going to mount a third air tank and have a couple questions. I am going with an aftermarket tank since they seem to be 1/3 the price of NOS. Should I go with 5 gallon or 3 gallon tank? And how does the priority valve plumb in? TIA

 

[banditt1979]

I think I found the plate that mounts to the master cylinder for the remote reservoir. Went ahead and ordered it, nothing to lose here

Hydro-Max Master Cylinder Remote Reservoir Plate (for top of Master Cylinder)

The Bosch Hydro-Max brake system operates off of power steering pump pressure, and has an electric backup motor to supply you with brake assistance in case the engine dies. The Hydro-Max has come OE on most medium trucks since the mid 80's, that aren't full air-brake, including school buses...

www.powerbrakeservice.net

 

[banditt1979]

Got my mc top plate today. Unfortunately the round nubs that are supposed to fit down into the mc were a bit large. Ended up using my dremel with the sanding wheels to grind down the OD to get it to fit and also had to cut off a nub that I think ensures that you dont install it backwards. Little by little and checking with digital micrometers. But it now fits. Air tank from summit will be here tomorrow.

 

[banditt1979]

Some pics of my new 5 gallon air tank and etch primed mc bracket

 

[banditt1979]

Adapter plate fighting me the whole way. Went to bolt it on and the oring in the middle of the mc wasnt making contact with the plate. Ended up sanding off about .025" off of the round ports sticking out of the plate with my table top belt sander. If anyone is using a MC39577 mc and uses the plate from Sweeting Performance be aware that it will need to be modified.

 

[banditt1979]

Recieved this today from ebay for $57. Threads are 3/8" NPT I will be using 3/8" air brake hose down to the mc plate which uses 1/4" or 7/16-18" threads.

 

[banditt1979]

Check valves/priority valves: from what I've read I need something so if there is an air leak in the supply line the check valve would stop the tank from draining. I was planning on a tee at the tank that supplies the original air pack, run that to the new air tank with a check valve in between. Does that make good logical sense? Then the next question: should I go with copper or DOT air brake hose for the new tank? I like the idea of the dot hose but I haven't worked with this stuff and not sure of all the connections/transition at the tee.