1/2 ton to 1 ton master cylinder

gulfdawg

gulfdawg

Member
I was wondering if anyone knows if installing the brake master cylinder from a 3/4 or 1 ton truck will bolt in place. I have a 74 100 with a Dana 60 and 14 bolt. The stock master cylinder was working fine and the truck stopped with no problems. But a seal went bad and now she needs to be fixed. No one around here has one is stock to compare, so before I order one it would be nice to know. Thanks
 
Since no one has answered:

the only thing I can say is look at the pictures of the master cylinders on rockauto.com catalog and try to match it....

The "numbers" look like there might be some difference. But, there are a "good number" of mcs under the 200.

Two "issues" -- the placement / size of the brake lines into the mc -- the disc / drum brake mc and the drum / drum mc are different.
 
gulfdawg said:
I was wondering if anyone knows if installing the brake master cylinder from a 3/4 or 1 ton truck will bolt in place. I have a 74 100 with a Dana 60 and 14 bolt. The stock master cylinder was working fine and the truck stopped with no problems. But a seal went bad and now she needs to be fixed. No one around here has one is stock to compare, so before I order one it would be nice to know. Thanks
Click to expand...

The commonly available new master cylinder for the 100 series IH pickalls was also used on many years worth of dodge trucks and vans throughout the 70's and 80's. Including 200 and 300 series with d60 steering axles and both drum/drum and drum/disc brake systems. Any decent auto parts (and I don't mean pepo'rielshukragzone) should have your choice of new or reman on the shelf...scruu the reman stuff, go for only new in brake stuff.

With a drum/drum system, the mc pressurized through a "combination valve" which only served the purpose of providing a warning light system.

A disc/drum mc blew into a "proportioning valve" which serves an additional function, which is restricting pressure to the front brakes in proportion to the force applied in order to minimize rear brake lockup when the vehicle is not fully loaded.

If the oem master cylinder provided adequate hydraulic pressure previously, simply replace it with a comparable service part.

But...if you are replacing only the master cylinder (and not the booster as a set), you will have to re-adjust the mc pushrod between the master cylinder and the booster and that can be real tedious. Any time a replacement master cylinder is installed, the pushrod length must be verified...otherwise, you will either not be able to build braking pressure...or when the brake system becomes "warm" and underhood temps elevate, the brakes will be applied hard without pressing the pedal!

Here's a few pages from the service manual that describe the process for verifying the master cylinder pushrod "length" when replacing a master cylinder with a service part.
 

Attachments

  • MC Pushrod Adjustment.PDF
    2.4 MB · Views: 625
Thanks for the info guys. I ordered a new master off rock auto today. I did notice that the master listed as working on the 3/4 and 1 ton dodge and 200 International. So I ordered it. Thanks for the link Mike, I had not heard of adjusting the pushrod when a master is changed.
 
gulfdawg said:
thanks for the info guys. I ordered a new master off rock auto today. I did notice that the master listed as working on the 3/4 and 1 ton dodge and 200 International. So I ordered it. Thanks for the link Mike, I had not heard of adjusting the pushrod when a master is changed.
Click to expand...

I've replaced many masters on these and other vehicles. Even though you'd like to think that the position of the depression in the piston where the pushrod seats is the same dimension on all master cylinders (new or reman)...it's not! There are many variations in the design of that contact point on the piston.

Just 0.020">0.040" of a difference in pushrod length vs. Master cylinder piston contact will make or break this deal when the brake system "heats"! And I get an average two emails a week about this problem! No telling how many service part master cylinders are returned as "faulty" just because of this.

In every case whenever I've installed a service part master cylinder/booster assembly, the pushrod has been adjusted correctly, so it was just a simple r&r of the assembly and then bleed...no need to break apart the assembly and adjust the pushrod if the two parts came as an assembled package.

Another tip...always bench bleed a replacement master cylinder, otherwise you will encounter some bleeding difficulty.

And...you May have to move the transition fittings from your old mc to the replacement, be sure to move any residual pressure valve(s) which May be present on your old unit, to the replacement.
 
Alright I received the master cylinder from rockauto on Friday and installed on Saturday. I started by bench bleeding the master and verfied the length of the pushrod, which was correct at just under 2.2 inches. I started to bleed the system and here is where I ran into problems. I am using the mityvac hand vacuum pump. I even had another person pressing the brake pedal. I cannot get fluid to any of the wheels. The pedal is dead. I even removed the master and bench bled it again. I was able to get it stiff as the instructions stated. As soon as I installed it and started to bleed the farthest wheel from the master it just went dead. I am not getting any air or fluid at the rear wheels. I even left the bleeder open all night and no fluid came out. I am very frustrated and even worse I bought the master online which means I am at least another week out to getting this thing going. Any help would be greatly appreciated.
 
After you bench bled the master cylinder and installed it in the truck and hooked up the brake lines, did you endure that all the connections were tight?
 
gulfdawg said:
alright I received the master cylinder from rockauto on Friday and installed on Saturday. I started by bench bleeding the master and verfied the length of the pushrod, which was correct at just under 2.2 inches. I started to bleed the system and here is where I ran into problems. I am using the mityvac hand vacuum pump. I even had another person pressing the brake pedal. I cannot get fluid to any of the wheels. The pedal is dead. I even removed the master and bench bled it again. I was able to get it stiff as the instructions stated. As soon as I installed it and started to bleed the farthest wheel from the master it just went dead. I am not getting any air or fluid at the rear wheels. I even left the bleeder open all night and no fluid came out. I am very frustrated and even worse I bought the master online which means I am at least another week out to getting this thing going. Any help would be greatly appreciated.
Click to expand...

Disconnect each fitting at the master cylinder one at a time. Have a helper sllloooowwwwly push the pedal no more than 2/3rds of it's travel whole ya watch for fluid to emerge from the port. Keep your face out of the way and put a rag over the port to prevent fluid from blowing on everything. Repeat for the other fitting.

Then crack each line fitting at each junction point and check for pressurized fluid flow in the same manner, keeping the master cylinder full at all times. Don't forget the "junction" point at the proportioning valve we discussed previously.

This is testing that the mc is pressurizing the system completely in both circuits....and at all four wheels. If it's not, then the mc is faulty.

I'll say this...in all my years scruuin' with this stuff, I get a "bad" master cylinder about one-third of the time...and it makes no difference if it's new or a reman. But don't blame the fresh mc until you have determined no flow at any corner.
 
Thanks for the help guys, I have one more question before I go out and check the lines.the instructions that came with the new master cylinder stated, install the supplied plugs into the output ports. Fill resevoirs with fluid. Push piston in no more than an inch at a time, until there are no more bubbles coming from the holes at the bottom of the resevoir. The piston should not move more than 1/8 of an inch when the cylinder is bled. That is the bench bleeding procedure. I did this and the master cylinder did build pressure. Once it was installed in the truck and the lines were hooked up it wont build pressure. Just thought I would double check and see if the procedure seemed correct to anyone else. And to me if the master cylinder build pressure on the bench it should be good? Right? Thanks justin.
 
gulfdawg said:
thanks for the help guys, I have one more question before I go out and check the lines.the instructions that came with the new master cylinder stated, install the supplied plugs into the output ports. Fill resevoirs with fluid. Push piston in no more than an inch at a time, until there are no more bubbles coming from the holes at the bottom of the resevoir. The piston should not move more than 1/8 of an inch when the cylinder is bled. That is the bench bleeding procedure. I did this and the master cylinder did build pressure. Once it was installed in the truck and the lines were hooked up it wont build pressure. Just thought I would double check and see if the procedure seemed correct to anyone else. And to me if the master cylinder build pressure on the bench it should be good? Right? Thanks justin.
Click to expand...


I understand what those instructions say, but I don't agree with that process! Because with the ports blocked, there is no way to verify that the piston(s) will actually push fluid through the outlet ports and into the plumbing. And obviously yore mc ain't pushin' fluid ot!

I use (and always have) a set of those cheeseball plastic port "adapters" that thread into the ports, and then ya connect some really flexible pvc tubing to the nipples and lead 'em back into their respective chambers and hold in place with binder clips. That way ya simply recirculate brake fluid without spilling any. And ya do that in the same manner as described in short "pulsing" type strokes.

Once the bubbles are gone, then stroke the mc inna normal manner and ya can see it push juice all day long. Remount the cylinder to the booster after installing the booster to the bulkhead, while being careful to not spill fluid out. Then "quickly, pull each bench bleed fitting and install the plumbing connectors, you will spill some fluid but it's easy to clean up.


Here's a quickee "how-to":

how to bench bleed a master cylinder
 
I just returned in from checking out the lines. Here is what I found. I removed the outlet line at the proportioning valve to the rear brakes and it was dry. I removed the inlet to the rear brakes at the prop valve and there was fluid. I removed the outlet for the front brakes and there was fluid and the inlet for the front brakes there fluid present. I then removed the prop valve and inspected. I removed all the plugs and orfices. What I noticed, bear with me as I try to describe this, at the rear of the prop valve which feeds the front brakes, I removed a plug with a spring. Ok I looked in the hole and saw a piece of metal and directly inside, where the spring sits the center appeared to be broken out. It definetly was not supposed to be like that. It looks like the proportioning valve is bypassing at the broken area or at least not doing what it is supposed to.
 
You May be seeing the brake warning switch "plunger that has sheared, that will sometimes happen if the brake pressures are greatly "different" from each other. Or...the switch plunger May just has "set" and needs to be gently pushed back into position and reset.

Here's some more manual pages that describe two types of junction blocks. However, ihc did not use correct nomenclature when describing the operation of those devices, and there was one additional type valve used on split circuit, drum/drum systems also. A "combination" valve is only used to control the brake warning switch. A "proportioning" valve serves as a junction block, a brake warning switch control point, and a proportioning valve for disc/drum. But...not all IH disc/drum systems used a proportioning valve! They accomplished "proportioning" by reducing the diameter of the rear brake wheel cylinders.

Confused???

But the segment regarding bleeding the disc/drum system with a true proportioning valve is valid.
 

Attachments

  • Disc_Drum Brake Valve.PDF
    3.9 MB · Views: 3,463
Michael, I totally disassembled the valve. The broken piece is actually a piece of the casting. The shuttlte valve for the switch appears to be ok. Now I did find alot of rust and crap in all parts of the valve. In the manual illustrations, if you remove the bleeder valve, this is where the damage is. It looks like a spring is supposed to rest up against the broken portion. I took a couple of pics but it is hard to photograph deep in the valve.
 
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