Brake Bleeding Problems

[Dennis Detweiler]

14244 has a horizontal bolt pattern and my mount is vertical pattern.  If I'm going to create more options I'll have to pull the mount conversion out and drill it out for horizontal bolt pattern, which is more common. Some are 3 bolt pattern. Speedway has a corvette style master specifically for manual disc/drum and is 1 1/8 bore. It is capable of left or right side ports. It's probably the exact master that I need. It has a horizontal two bolt pattern (#91031440). $60 plus shipping.

[Dennis Detweiler]

Speedway doesn't sell a rebuild kit for the 91031440 master. So, I'm not going there. It's probably China built.

I'm going to try Scarebird's original suggestion...."the original 39 Plymouth 1 1/4 master is a good match for the disc brake conversion." If it fails to be good, I'll have the conversion master cylinder mount out of the car and can drill it out for other master options. I don't see much safety advantage in the dual reservoir if a brake bleeder collapses the pedal. I broke a rear line on a 63 Chevy and I lost all brakes and had to limp home using the parking brake. The hand brake on my 39 locks up the rear wheels without a lot of effort. Right now I'm trying to find a master that will lock all 4 wheels. I have a rebuild kit for the original 39 master and the bore looks very good. Not pitted. Hone it and polish the inside and it should work like new. I have the original brass piston and a new aluminum piston. I'll mic them and see if one is larger than the other. I'll post the results.

[Dennis Detweiler]

I've been reading posts on other forums on the pro's and con's of single piston single reservoir vs dual reservoir masters. Consensus and experience of losing brake fluid in either case is false security and the emergency brake is still the best at stopping a car with a broken brake line. The dual master has to be pumped a lot and quickly to "slow" the car unless you have a valve that shuts down the low pressure line break. Too many don't have that valve and too many drivers don't know that the valve isn't there. Also, the safest emergency or parking brake is the old drum style that wrapped around the driveshaft. If a rear wheel cylinder blows out on a cable to shoe style parking brake, the fluid on the brake shoe will only give you one wheel emergency braking. Hence, the driveshaft style still stops with both rear wheels. I can easily stop both rear wheels with my driveshaft drum/band emergency brake. Similarly, a quick stop with a dual master with pressure drop valve allows for a two wheel brake.

There seems to be risk with either brake system. Less if you have the dual reservoir with pressure valve and a driveshaft drum/band emergency brake.

I drove single piston/single reservoir during my younger years before the advent of dual reservoir. I never had to experience losing a brake pedal. I recall having a master cylinder getting weak and having to rebuild it on one of my cars (47 Ford or 51 Studebaker?) I had a 69 Mustang with shoes front and rear with manual brakes and terrible stopping ability. Dad had a 61 Olds 88 with power brakes that you had to barely touch the pedal and it would throw you into the windshield.  

I rebuilt the original master yesterday for my 39 Plymouth and will pull the Wilwood master and conversion bracket out today and install the original, at least temporarily while I tap the bracket for a horizontal bolt pattern dual master. This gives me time , probably all Winter, to decide which dual master to buy. I need one with right side ports and most have left side.

[Dennis Detweiler]

Success! I rebuilt the original master and did  quick bleed with a vacuum pump and I got a solid pedal after engaging the brake pedal about 2 inches. I could never get the sponginess out of the Wilwood 1 inch bore after running 3 quarts of fluid through the system and using 3 bleeding methods. It must be a factory defective master? I'm sure the 1 inch bore wasn't large enough and that accounts for the longer pedal travel. However, the spongy pedal has to be a defective Wilwood master. The only thing I salvaged from the Willwood was the two remote reservoirs. I'm using one of the remote reservoirs with the original master. I removed the 6 reservoir top plate screws and replaced them with stud bolts and used nylon washers under nylon locking nuts to keep the fluid from seeping through. I installed a threaded brass nipple into the filler cap on the old master and connected one of the two Wilwood remote hoses. So far, so good. I'll do a two man bleed on the system and run another quart through it.  Maybe find a 1 1/4 bore dual master next year or maybe not.  I'll have to re-work the Wilwood mounting plate to fit something other than Wilwood. I spent most of the Summer trying to get the dual Wilwood to work and I'm burned out on it. Emergency brakes work great, so I'm not too concerned about single reservoir brake line failure.