Looking for master cylinder suggestions on somewhat unique setup

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Map63Vette

Map63Vette

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I've got a 67 Dart I did a 5.7 Hemi swap in many years ago that has been trucking along well, but seems to have a recurring issue with the master cylinder leaking on the interior at the firewall. The first time it happened I just pulled it out, disassembled, cleaned, and reassembled it and it seemed to be fine, but looks like it has come back again. The car isn't driven super often, so thinking the sitting around is probably the reason it keeps seeping. That being said, I'm looking to potentially swap it out for an aluminum one as I think those would put up with sitting around a little better with less corrosion. However, that is where things get a bit complicated...

I have manual brakes with front discs off a 70s Challenger and rear drums (I think 10", but I'd have to look again, not sure it matters though). I also installed a hydraulic master cylinder on the firewall to run my T56 and it sits very close to the brake master, so the stock porting that comes off on fender side of the brake master is pretty much a no-go for me. I found a dual port iron master years back that has ports on either side and you just plug the ones you don't need, but that doesn't seem to be as common. If I could get something with a narrower body there is a chance I could fit it next to the clutch master, but that doesn't seem to be the norm and I really would almost just need 90 degree fittings to make that work. I can't flare a pipe with a nut installed in a short enough distance otherwise. The engine side is also very close to the valve cover mounted coil packs. I'm fine with adapting to a more modern 2 bolt style master, I just need to find one that will work, which is what I was hoping someone here might have a suggestion for.

So long story short, I'm looking for an aluminum master cylinder for front discs / rear drums with engine side ports that will match a Mopar bolt pattern (2 or 4, don't know if there are multiple 2 bolt patterns or not). One question I do have is whether it actually matters to get one that is disc / drum or could I use a master cylinder designed for 4 wheel disc? I know that typically only changes the reservoir volume, so I'm thinking that might be okay, but didn't know if there was some other internal porting in those for flow/pressure splitting or if that was all external. I found this GM one that looks nice and compact (1 inch Aluminum Master Cylinder w/ Plastic Reservoir for GM), but not sure if would actually be suitable or not. Seems like manual brake bore size is around 1", so also feels like it could be a decent match in that regard, but not sure if the spot for the push rod would match a Mopar one. I also question whether I need a different push rod or not if I get an adapter plate. I currently have a fixed length one for the manual brakes. It seems like the adapter isn't that thick, so guessing I could maybe still use it and the pedal would just start further down than it is now, but I know there are adjustable ones out there as well.
 
Look at the brake seller's websites. They make about anything. I thing a prop-valve will be in order....
 
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Rick eherenburg on eBay. Ricks mopars.
 
Yeah, I found something like that kit before, but I'm not sure the left side exit of the ports will work for me. It does look narrower then my current cast iron one, but not sure it would be enough. Tried checking the Wilwood site, but the only ones I found with right side ports seemed to have pretty small reservoirs for disc brakes, though can't imagine they would make something that wouldn't work with disc nowadays. Guess I can just take a chance and return it if it doesn't work.
 
Map63Vette said:
Yeah, I found something like that kit before, but I'm not sure the left side exit of the ports will work for me. It does look narrower then my current cast iron one, but not sure it would be enough. Tried checking the Wilwood site, but the only ones I found with right side ports seemed to have pretty small reservoirs for disc brakes, though can't imagine they would make something that wouldn't work with disc nowadays. Guess I can just take a chance and return it if it doesn't work.
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Well its made for a bodies. Did you go to the site and read the description? Send Rick a message and ask if he thinks it will work for your combination.
 
Better yet post a picture of your master cylinder and the clutch master cylinder installed.
 
Aluminum bendix style master



1962-74 Mopar Bendix Style ALUMINUM Master Cylinder


I recall there being a passanger side ported 4 bolt mc on B, C, E, F body cars (don't recall which)


as for interior seepage.

it should not happen if you have good seals and sealing surfaces.

my dart sat for 4 years and seeped fluid onto the front floor, it is still damp but with monthly use it doesn't seep enough to worry about right now.
 
Somebody made, and you could make, if you fab, a different clutch setup. You likely know that some modern clutch masters have a remote, tube fed reservoir. What you do is you run the clutch linkage "as per stock" with the pushrod down through the firewall, and the adapter bolts to the firewall with the angled pushrod activating the master. This gets it clear away from the brakes
 
Wilwood master I do believe have the ports on either side just not sure on the model or specs.I do have the 4 to 2 adapters for sale if you are needing one
 
If you do use 90* fittings, make sure you have a number of flare washers on hand, as you'll most likely need to use some between the MC and the fitting to get the fitting pointed in your preferred direction when it's tightened up.
 
Since Ehrenberg was brought up....he always recommends DOT5 fluid and that's what I've been using in my old junks for a long time. For cars that don't get driven consistently, the advantage is it doesn't absorb moisture resulting in less corrosion inside. And if it does leak, it won't damage the paint. I have an old Jeep Comanche and they are notorious for leaking brake fluid inside the firewall from the MC. The paint goes away, unnoticed behind the carpet or mat, and the floor rusts out. At least with DOT5, the metal wouldn't rust.

I don't think I'd use GM stuff unless it's a direct bolt-in. I've seen them in a couple Mopars and to me it sticks out like a sore thumb. That kit Eberg sells is what I would do. Oh wait, I did that except I used an old Direct Connection aluminum MC I bought from a drag racer. I had that car stored in a warehouse for 4 years and it hasn't leaked since getting back on the road.

Why can't you just relocate the clutch MC on the firewall?
 
Here are some pictures of my setup. I followed a design someone else had in the T56 thread down in the Hemi swap forum. I liked this design more because it actually mounts to the pedal box on the inside of the car. I welded a tab on the side of the box where the brake master bolts in. I was originally looking at a tilted master cylinder that mounts in the stock clutch push rod hole, but I was a little concerned about being able to bleed it as it's really not oriented in a good way. I also was a little less thrilled with the idea since it mounted it directly to the firewall with no real extra support. The top mount design really mounts it to the pedals and the firewall just happens to sit between them.

I do like the idea of the 90 degree fittings though. Ultimately I think that would be the most sensible setup as it would open up more options for master cylinders and let me run something more "typical" like those swap kits. A more modern narrow master with 90 degree fittings would likely clean that area up quite a bit.

And I know I should just drive it more, but the way things are set up at my house it's just a pain. The car sits outside under a cover and on a tender, so it's just a hassle to fold the cover up and unplug it and then plug it back in and recover it after it has cooled off every time I want to drive it. First world problems I know, but I figured if I could mitigate the issue with a more modern design it wouldn't hurt. This car is about as far from original as you can get, so if I can update it to make my life easier I figured why not? I have thought about the DOT5 fluid as well. Read about it several times and keep debating if I wanted to swap it into my older cars that sit around more, but how do you clean all the old stuff out? I thought I had read you really can't mix them at all, so wasn't sure if it was just "too late" so to speak.

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Can you move your tremec slave cylinder setup? If so that’s what I would do and then use a 15/16 bore aluminum master cylinder. Doctor Diff has, maybe rehenberg too
 
I might be able to move it, but I'd have to redo the whole setup at that point with a new master and a new bracket most likely. Was hoping I could just find a new brake master to work around it. Got some good ideas from this thread though, will have to go out and do some measuring. I think the main thing I'm interested in is the distance between the center of the bore and where the fitting attaches (picture attached). It seems wider on the cast-in reservoir style masters compare to the more modern plastic reservoir style. If the new style is narrower I think I could get a 90 in there and plumb things more easily.

Alternatively, I just found this bottom exit version that might be an even better option, but the mounting setup for it is vertical instead of horizontal. If the 4 bolt pattern was square I could just rotate it, but I'm pretty sure it's rectangular. Guess I could just make a custom bracket to adapt to a vertical bolt pattern. I'm not seeing much else for bottom exit masters, but I haven't looked super hard yet either. I'm still wary that anything not "Mopar" won't work with the Mopar push rod as nicely.

Master Cylinder Port Width.jpg


Bottom Exit Master Cyllnder.jpg
 
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If you aren't fussy about looks, I use Toyota M/C in my racecar builds regardless of breed.
Those m/c are like above, small, light weight, have a vast variety of mounting choices, outlet location, and bores, make pushrod to suit .
What I also found advantageous was the ability to use a remote reservoir, for room, and ability to get away from heat .

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toyota brake master cylinders - Bing

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Map63Vette said:
I think the main thing I'm interested in is the distance between the center of the bore and where the fitting attaches (picture attached). It seems wider on the cast-in reservoir style masters compare to the more modern plastic reservoir style. If the new style is narrower I think I could get a 90 in there and plumb things more easily.

View attachment 1716077588
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I have one of Ehrenburg's aluminum MCs and will get you a measurement later today unless someone get's it for you sooner.

Be aware that at least on my MC the caps leak a little. Doesn't seem to leak enough to get on the paint, but it's annoying to see it on the top of the MC. Seems like it is (was?) a common issue, no idea if there is a fix for it or not.
 
67Dart273 said:
Even if those are available (are you sure?) you have no control on where they get tight. They could point in any direction
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I wouldn't post it if it didn't exist, you should know that, and as mentioned by another member, a copper washer you know about, or I would consider an alum "pop-rivet" washer, as spacers to get it clocked right .
Cheers .
 
Thanks! I'll have to measure mine the next chance I get. Some of those Toyota ones look pretty interesting. Lots of different options on ports including some then even pointed up, which could make it easier to keep my proportioning valve location. Not sure I really care what it might come from at this point. My car already has parts from over a dozen different cars, all different brands and styles, lol. Just as long as it fits, is easy enough to get parts for, and works.
 
Ehrenburg talked up the MC he sells because it has the pushrod retaining ring machined into it. Might be something to keep in mind when looking at an MC from other makes. Hate to have the pushrod pop out of the MC while on the road.

Something else to look into was a strong warning I heard years ago about not running a MC off a FWD car. Unfortunately, I don’t remember what the issue is so can’t say if it is something legitimate.
 
Yeah, the push rod is the main thing I worry about when using anything that isn't Mopar at least, though I think I could probably also make a new one to use on something else if I really had to. I have seen that FWD thing as well but not sure I understand it either unless it has something to do with bias. Like it gives more or less to the front because then are driven (more to overcome) or engine braking (less so they don't lock)?
 
I merely make a guide, so it can't misalign , and/or something to restrict pedal return, like a brake light switch .
Some of the toyo ones have a circlip .
Cheers .
 
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