A Poor Man's Master Cylinder Upgrade

[Gerald Morris]

Great article. I am currently doing this very upgrade. I noticed a question regarding master cylinders for manual disc brakes. My 1973 Charger had manual disc/drums that worked like a charm, required minimal foot pressure and never caused me any concern during some 36,000 miles of hard driving (I was young). This is a fairly heavy car, too. A quick check of the parts books for that master might prove helpful. Can't wait to complete this upgrade!

Check it out. It may well be the same size as the '67 Bendix, but would be proportioned more heavily toward the front, where the discs are. The Dodge FSM for 1973 probably mentions the model and make of that master cylinder.

I suspect that if you went with anything like the old Budd dual piston calipers, those would HAVE to use a boosted cylinder, but I admit to having seen some stuff for manual disk brakes since I did my job that compels me to admit they may be done so. Mind you, I'm very pleased with the all drum system I currently have. If I ever were to install after-market disc brakes in any conversion, I likely would use Wilwood products.....

I pray your job works out well for you.

Happy Moparing!

 

[JimmyG]

I am pleased to say Mr. Morris, that I am staying with drums on all for corners, and am swapping to the 12" system. I am working on a '61 Newport one very slow piece at a time, using the same master as in your article.

 

[Gerald Morris]

I am pleased to say Mr. Morris, that I am staying with drums on all for corners, and am swapping to the 12" system. I am working on a '61 Newport one very slow piece at a time, using the same master as in your article.

MOST WISE! Did you get an original Bendix or the copy that I bought? Must say, after a year, its performed flawlessly. 12" drums should be PLENTY of stopping area to arrest motion. I'd just about sell a testicle for a Forward Look station wagon. LUV those old high compression motors too.

 

[mobileparts]

Whose testicle are you offering???

 

[JimmyG]

I suspect a copy. Bought it from NAPA,...no testicles involved.

 

[Gerald Morris]

I suspect a copy. Bought it from NAPA,...no testicles involved.

I'm sure it's a copy. The slave foundries of the East seem to have got their molds right for casting good copies of the venerable Bendix MC. Been totally Happy Crappy with mine, without so much as a malcontent wriggling gamete either! You have a good piston rod for the pedal, with the little retainer rubber and stuff?

I still trust NAPA as far as I can punt their staffers, unlike some of the more blatantly convenience store model auto parts shops.

 

[JimmyG]

Yes. I had an NOS Raybestos rebuild/replacement kit tucked away with new rod and associated hardware.

 

[JimmyG]

PART NUMBER UPDATE: Given that Weatherhead fittings can be difficult to find, I have converted to Edelmann fittings, and secured them no problem. Here is the conversion:
Weatherhead 7909 = Edelmann 258350
7910 = 258303
131X4 = 120400
302X3 = 123300
Hope this helps.

 

[Gerald Morris]

PART NUMBER UPDATE: Given that Weatherhead fittings can be difficult to find, I have converted to Edelmann fittings, and secured them no problem. Here is the conversion:
Weatherhead 7909 = Edelmann 258350
7910 = 258303
131X4 = 120400
302X3 = 123300
Hope this helps.

Good contribution for future upgrades!

 

[TxDon]

Gerald, thanks for leading me to this thread, your description and parts list is excellent and answers most of my questions about fittings.

 

[Gerald Morris]

Gerald, thanks for leading me to this thread, your description and parts list is excellent and answers most of my questions about fittings.

Quite welcome man! I composed this with folk like you in mind. Plenty C body fanciers like the 65-66 form particularly, which IS an EXCELLENT one in my book, but it still has a few legacy issues like the single brake circuit, which can be a FATAL fault.. So, an easy, affordable upgrade path serves the Community well.

 

[santts]

Hmmm, I will have to research this matter of manually driven disc calipers. IFF they can be driven with the Bendix MC without further complication, then such a solution would be desirable. I need to attend to other suspension issues first at any rate, and also the cylinder heads, but I will put researching manual disc brakes on my Agenda. That would be gratifying.



Yes, but at the price of added complication, which always increases the probability of something failing, though hopefully not anything of direct importance. The better solution here is to find disc brakes which can be driven by the Bendix cylinder in use. The front reservoir is larger than the rear anyway, suggesting that the designers had the proportion for drum brakes in mind. Looking in the 1967 catalog, one can see that the Bendix 2660809 clearly was intended to drive all drum systems with no mention of disc brakes. The cylinder at the top of the page was meant for that.
View attachment 392593

I remain suspicious of the notion that any disc caliper can be as well driven with the same fluid volume displaced by the front piston of this cylinder as the drum brake cylinder it was meant to drive. I may research this matter at some time, but doubt I will change my mind.

I was curious about this as well. I'm looking to just do the fronts to disc on my 65 fury and keep drums on back and keep manual as well. Is there a master for this ?

 

[Gerald Morris]

I was curious about this as well. I'm looking to just do the fronts to disc on my 65 fury and keep drums on back and keep manual as well. Is there a master for this ?

More important than which MC is WHICH DISK CALIPERS!

I discovered a solution in our 1983 Dodge D150 Miser, which came equipped w manual disk brakes up front and drums behind. It brakes very well.

The master looks no larger than the Bendix clone I purchased for Mathilda and now use on Gertrude.

The Thing to Do here is to look up the dimensions of those caliper pistons, and the master for the '83 Miser, then obtain something at these specs which can be readily bolted onto our C bodies. I suspect Wildwood and Eastwood will be the most likely brand and vendor for such parts, though now, other vendors may also carry the requisite parts.

We must obtain a larger domicile before I can experiment w another C body. The Babushka has Ruled on this matter and I shan't brook her will in this. Slavic she-bears take such sedition ill....

 

[66furys]

To add my uneducated notes here....great write up, with parts and some install specifics, also notes on the safety switch and brake lite switches all great. My only thought here relates to my current conunrum on my drum rebuild. I THINK that the drum cylinders have to move....that is, they push out, then the rear pads that are self energizing may then move toward the fixed anchor up top. This then might move the wheel cylinder pistons to the front, as the rear pad pushes to the anchor, forcing the front pad out harder, but to do so the wheel cylinder pistons must move.....my thought. And, there will be some large movement, at least compared to the disc brake pad. The disc pad is ONLY pulled away from the disc by the quad seals, and they dont move far. Meaning, that even though there is large diameter on the disc piston, there is small movement. So, this goes to the problem of fluid volume and diameter of the master. I am on the fence and think that there is NOT more volume req'd, but, with wear, you will need the reservoir to make up for that wear. But, all interesting to contemplate...even with destroyed synapses in the pea brain.

 

[Gerald Morris]

To add my uneducated notes here....great write up, with parts and some install specifics, also notes on the safety switch and brake lite switches all great. My only thought here relates to my current conunrum on my drum rebuild. I THINK that the drum cylinders have to move....that is, they push out, then the rear pads that are self energizing may then move toward the fixed anchor up top. This then might move the wheel cylinder pistons to the front, as the rear pad pushes to the anchor, forcing the front pad out harder, but to do so the wheel cylinder pistons must move.....my thought. And, there will be some large movement, at least compared to the disc brake pad. The disc pad is ONLY pulled away from the disc by the quad seals, and they dont move far. Meaning, that even though there is large diameter on the disc piston, there is small movement. So, this goes to the problem of fluid volume and diameter of the master. I am on the fence and think that there is NOT more volume req'd, but, with wear, you will need the reservoir to make up for that wear. But, all interesting to contemplate...even with destroyed synapses in the pea brain.

Well, the secondary springs should suffice to move the rear drums back to their rest position after the wheel cylinder pistons push them into the drum. I get from reading what was published on these things that they're supposed to press out symmetrically on each brake shoe, applying equal pressure. Anything in the brake mechanism which prevents this merits prompt remedy.

Disc calipers my vary according to their original design. I recall replacing the pistons in the front brakes on my Dad's IH Scout II, which had coiled springs behind them in addition to the hydraulic fluid which drove them when braking. They rode in loose contact with the rotors from the minimal pressure applied by the weak coil springs . Given the diameter of the pistons, very little travel distance still translates to considerable volume. Return mechanisms on disk brakes vary quite a bit.

I suppose the design of the disc brakes on my '83 D150 should be a good template for any manual disc brakes installed on a slab side C body Mopar. I think Mopar had figured out a great deal about how to design GOOD disc brakes for 2 ton vehicles in the 15 years after the deployment of Budd disc brakes, which I would avoid like syphilis. Those did well enough for their day, but I don't want anything like them on anything I drive.

I wonder how hard it would be to jimmy pickup truck calipers onto a slab side front wheel assembly....

 

[Mr onetwo]

lots of good info here Technical Help Page - Mark Williams Enterprises, Inc and here DISC-O-TECH: Stop on a dime
this mc works well for manual discs...15/16 bore from a 1992 Dakota. You would need a 2 bolt adapter plate... RAYBESTOS MC390188

 

[Gerald Morris]

UPDATE!! I had to replace a rotor on my '83 Miser last month, and discovered that the rotor-caliper combo used on that truck saw duty also on late '70s Formal C-bodies. I'm not surprised, and am gratified. I'll stick with all drums on my Slabbies, which are my All Time Fave cars, period.