Disk Brake Manual Master Cylinder

[TWAMONACO]

There is a lot of stellar info on the disc brake upgrade on this site, but I am having limited luck in finding a concrete consensus on the type/brand/year of Master Cylinder to us on the '73 Disc Brake conversion when sticking to Manual Brakes.

I'd prefer to use a stock looking Master Cylinder with the stand-alone adjustable Proportioning and not use a Wilwood/Mopar Performance style.

Car is a '66 Monaco with Discs brake components for a '73

Thanks

 

[Polara_500]

Give Dr Diff a call, he set me up for mine although I haven't installed it yet. DoctorDiff Drivetrain Components

 

[Ross Wooldridge]

Technically there is NO factory manual brake disc master... at least the setup was never offered by Mopar from 65-73, disc brakes were always power brake setups.

What you need to make sure is that you have a true manual brake pedal set, as used in a manual drum setup. That way you have the proper leverage built into the system. At that point, I would say any of the dual reservoir disc brake master cylinders would work fine.

I used the special 68 Charger with discs/10" rear drums master cylinder due to my Autopilot setup (line ports are on the engine side), but I would be confident that a 70 Dodge disc brake master would work great for your application.

 

[TWAMONACO]

Perfect -Yes, it's a manual pedal set-up from a parts car.

Thanks!

 

[Ross Wooldridge]

Excellent. Keep me posted. PM me if you've any questions.

 

[70bigblockdodge]

Make sure it has the groove to retain the pushrod so it does not pop out and then it does not go well from there.

 

[cantflip]

I used the special 68 Charger with discs/10" rear drums master cylinder due to my Autopilot setup (line ports are on the engine side), but I would be confident that a 70 Dodge disc brake master would work great for your application.

I wanted to "agree" but I can't with that statement included. Drum brakes can "self energize" in some designs. If the car switches to disc brakes, you still wouldn't have all of the braking force the factory had designed into the system without the booster.

There is a lot of stellar info on the disc brake upgrade on this site, but I am having limited luck in finding a concrete consensus on the type/brand/year of Master Cylinder to us on the '73 Disc Brake conversion when sticking to Manual Brakes.

I'd prefer to use a stock looking Master Cylinder with the stand-alone adjustable Proportioning and not use a Wilwood/Mopar Performance style.

Car is a '66 Monaco with Discs brake components for a '73

Thanks

IMO, if you want the discs.. do the full swap. Otherwise, please consider the drum brake dual master swap to stay w/manual. I am sure things can be cobbled together enough to stop the car, but as has been said in some of those other threads... you really need to have the full force, panic stop/lock up ability.

 

[Ross Wooldridge]

Contrary to my confidence before, based on CanfFlup's cautions I'm recanting my previous statement.

We need to be VERY VERY careful when it comes to brakes. If there's even a hint of doubt then get the power pedal set and a disc brake booster.

Then you know for sure it is properly matched parts.

 

[saylor]

https://www.hemmings.com/magazine/hmn/2010/05/Master-Cylinders/3184381.html



For converting Mopar vehicles to manual front disc, use a 1-inch manual cylinder for one of these models:



• 1971 Chrysler 300, Sport Fury
• 1971-'72 Road Runner
• 1971-'73 Newport, Monaco, Polara, New Yorker, LeBaron
• 1971-'74 Challenger, 'Cuda, Satellite
• 1971-'75 Charger, Coronet, Fury
• 1972 D-100 pickup
• 1973 Gran Fury
• 1975 Cordoba



try not to die -

- saylor

 

[Ross Wooldridge]

Great info Saylor! Thanks.

 

[cantflip]

These conversations about disc brake conversions start to get me pretty nervous when someone tries to make a mod that is too far from a factory set up. I can understand the desire to have a simple bolt on upgrade... but the likelihood of proper function is small.

If you convert to a brake system from a similar weight car, I can see where that would have a good chance of success. When someone tries to swap to something that never existed based on convenience, cost and parts availability... I have to say "don't do it".

I admit, I have a lot of skepticism of the aftermarket companies who do this stuff professionally... but I do assume they have at least mathed out a system that could work.

No math, simple hydraulic force principles...

1- The pedal ratio will determine how much force is applied to the master.

2- The bore of the master vs the bore of the slave(caliper) will determine the force multiplication.

3-The bore of the slave(wheel cylinders) on the rear will also be affected by master bore changes.

4- A duo servo type drum brake also will increase braking forces, so you cannot simply match the force brought by the drum master to effectively operate discs.

5- The process of multiplying force using a smaller piston to move a larger piston will require the smaller piston to travel farther in it's bore. This could cause the movement of the pedal to be farther than floor would allow or require a master cylinder to be extremely long to make the required pressures... or require an exceptionally strong human to be able to operate it.

Disc brakes are going to need thousands of psi at the pads to operate correctly... I would encourage anyone doing this sort of thinking to spend the time doing the math. I won't say it is impossible, but ask that you please don't drive the results too close to my car.

This kind of tool is used in place of pads to diagnose pressure concerns... I suppose you could invest in a set to verify you are getting enough pressure... I'm not sure where you would get specs for earlier cars though.
Tool review: Disc brake analyzer - Automotive Service Professional

 

[Ross Wooldridge]

All of the above applies for me, albeit in a simplified way - I recreated the factory power assisted disc system for my car. No guess work.

Stops fabulously and is safe.

Personally, even though I made a "guesstimate" earlier for the OP, I would not make a such a guess for any of my own cars.

Sorry to be an armchair quarterback!

 

[cantflip]

All of the above applies for me, albeit in a simplified way - I recreated the factory power assisted disc system for my car. No guess work.

Stops fabulously and is safe.

Personally, even though I made a "guesstimate" earlier for the OP, I would not make a such a guess for any of my own cars.

Sorry to be an armchair quarterback!

It's the internet, my friend... everyone's an expert...

You give lots of good information and I like that I see you refine your statements as you see flaws... I would trust you more than the guy in the tire store to do this job.

 

[Ross Wooldridge]

Why thanks!

 

[70bigblockdodge]

Small piston recommendation is so braking pedal pressure will not be too great. Chrysler was selling cars to a lot of different shaped people.
I would use the biggest piston you feel comfortable with, if you have good umph in your leg 1 1/32 or 1 1/16 should not be a problem. I would rather have to put some more effort into the pedal that have to move it 3 1/2-4" every stop and less effort.
If your 100# wife or girlfriend is going to drive the car well maybe error on the side of caution and go 1"

 

[cantflip]

Small piston recommendation is so braking pedal pressure will not be too great. Chrysler was selling cars to a lot of different shaped people.
I would use the biggest piston you feel comfortable with, if you have good umph in your leg 1 1/32 or 1 1/16 should not be a problem. I would rather have to put some more effort into the pedal that have to move it 3 1/2-4" every stop and less effort.
If your 100# wife or girlfriend is going to drive the car well maybe error on the side of caution and go 1"

If building for the track, I would buy that... a street car needs to be reasonably driveable and have a margin of safety regardless of who is at the wheel. Lou Ferrigno couldn't make enough pressure if the math was against him...

 

[saylor]

Master Cylinder Math

 

[70bigblockdodge]

If building for the track, I would buy that... a street car needs to be reasonably driveable and have a margin of safety regardless of who is at the wheel. Lou Ferrigno couldn't make enough pressure if the math was against him...

But I don't build cars so other people can drive them. I agree that the math must work. With a I believe 6:1 manual brake pedal ratio you would have to have a pretty weak leg to not be able to operate.

 

[TWAMONACO]

Thanks for the info. I have some calculating to do