Brakes: jeep master cylinder

[oldguy]

The mid 70'sjeep dual reservoir master cylinder has identical reservoirs.
Anyone know which should be the front, or does it matter?

[StudeRich]

It definetely MATTERS! On most cars including Studebaker, the front reservoir is always the REAR brake system.

I would hope that the Jeep is the same, but I always use AMC Matador, Ambassador Dual Master Cylinders because of the correct for Stude. engine side brake lines, so I do not know.

It also matters a lot wether your car and the Jeep are matched for either Drum or Disc. front brakes.

[oldguy]

Studerich - "It definetely MATTERS! On most cars including Studebaker, the front reservoir is always the REAR brake system. "

MY thoughts exactly. However, this car had a disc brake conversion and the master went bad (wouldn't release). I bought the 72-74 jeep master exactly as was on it, and I notice both reservoirs are identical. It is plumbed with the rear (closest to the bracket) plumbed to the front, as you note. But everything on this conversion was screwed up. Single flares, calipers upside down, incorrect adapters, I'm amazed it stopped at all.
So I am rebuilding the entire system and want to take nothing for granted.
BTW, I would consider this mc an "engine side ports" which mounted backwards on the frame puts them outboard where they need to be.

Wait.... to be clear, when you say "front reservoir" do you mean as typically mounted, or when mounted backwards on the frame? Rear reservoir being closest to the mounting face, front - farthest away.

[StudeRich]

Well you have remember that I am thinking firewall mounted, as these are all designed to be, I would never consider putting one of these UNDER the car on the frame, as it's a PITA in my opinion, but it is your Car and your money, not mine.

[oldguy]

OK, we're on the same page. As far as the "It's your car and your money". It's not, lol. Just helping a buddy. He bought the car 3 weeks ago and I'm helping him get it to a good "driver" status for his son. Who I think will be the King of Cool driving a 61 Hawk to high school.

[MCCAB1]

Up to at least 1975 Jeeps had drum brakes front and rear! The one for 72-74 Jeeps is a drum - drum MC.

[StudeRich]

Up to at least 1975 Jeeps had drum brakes front and rear! The one for 72-74 Jeeps is a drum - drum MC.

OK, that explains the same size reservoir for front and rear, Disc. Masters have Large for the front. Drum M/C's have residual valves in both front and rear.
So you are using the wrong M/C for a Disc. setup.

[oldguy]

Finally, the light goes on. We got the mc by cross referencing the part number on the old one, and it was a perfect match. How it worked before is a mystery, but we have had a low weak pedal from day one. Does anyone have the correct part number, or application, for a disc/drum mc that works?

[TXmark]

okay, this may seem obvious, call Turner Brake

[oldguy]

TXmark , good advice. Talked to Jim last night. The jeep MC I'm using is the best that will fit. He instructed me on how to properly adjust the pedal push rod. Did that and all my troubles went away. Amazing.

[woodysrods]

Hi Don
My new master Cylinder arrived today. Raybestos #MC390116
This is off of a Mercury Villager with remote reservoir and set up for Disc/Drum on Sandi's 61 Hawk. Agree that it is a PITA to have a master to fill under the floor.
If you check out some of the discussion on this you will see pictures of this MC already posted by "Junior".
Good Roads
Brian
PS I am still fighting the Coil Spring question.

[Flashback]

I kinda like fillin in the floor. If you spill it only hits the ground. But of course it ain't quite as trick
as the remote or firewall mount M/C. Course I am old school anyway. Here's the Jeep one on my
53. It works pretty good for me.

[oldguy]

Hi Brian. Couldn't find that number. Assume it is a remote fill model? That seemed the only other alternative to having enough room in there.
Is it a 1 inch? Since length is also a problem, I'd be curious if it pushed more fluid than the jeep model.
Now that it works, I'm done, but for future reference, having the reservoir under the hood would be handy, and also allow for a "gravity" bleed.

[woodysrods]

Hi Brian. Couldn't find that number. Assume it is a remote fill model? That seemed the only other alternative to having enough room in there.
Is it a 1 inch? Since length is also a problem, I'd be curious if it pushed more fluid than the jeep model.
Now that it works, I'm done, but for future reference, having the reservoir under the hood would be handy, and also allow for a "gravity" bleed.

Hi Don
Yes it is a 1" bore used on Mercury Villager & Nissan Quest 1993 - 97 Raybestos #MC390116 without Antilock Brakes (with Antilock brakes MC390115)
Also note that I am using 7/8" bore rear wheel cylinders on a Ford 8" rear end with 10 x 2 1/2" Drums and shoes.
Good roads
Brian