How dangerous is it to keep a single port master cylinder system?

[WH23G3G]

While my 73 Charger is in the shop I'm trying to get my 65 Valiant roadworthy again. Got it running. Now I'm working on the frozen up brake system. I got the rear drums renewed. All new cylinders, hardware, adjusters, drum, shoes, new lines, hoses. I will now do the front but have been made aware of the dangers of keeping the single port master cylinder. I was hoping someone made a kit that would have bolt on pre-bent lines, the new block, and master cylinder. But I've checked all that I know and no one makes a kit, only for disc upgrades. It doesn't have any power upgrades on the engine or suspension. It's just a stock plain 170 4 door 65 Valiant with 9" manual drums all the way around. If everything is all new on the brake system should there be any hesitation in keeping the single port system? One brake line company asked me why did I want to change it over and that they never heard of an all out failure. They said even if you have a dual port master cylinder and a cylinder or something is leaking the pedal is still going to the floor no matter what. I'm going to at least get a brand new master cylinder, not a reman. Should I using a different brake fluid to guarentee more life out of the system or more safer, like silicone brake fluid? I will mostly be driving around town not highway driving unless this car turns out to be really reliable and trouble free I may drive it all over the place. I do like it's simplicity.

[JB400]

The stock brake system should be fine if everything has been replaced. They've worked for years.  The only deal is, if you have a leak, you have little to no brakes.  With a dual cylinder, even if you have a leak in one line, you'll still have some brakes, but will notice the soft pedal.

I highly recommend pumping the brakes when coming to a stop when using a single cylinder brake system.  Allowing more room to stop is a good idea as well.

[flyinlow]

New dual mastercylinder...$100,  lines and other hardware,$150.....  Sense of relief stopping 10 feet behind the car in front of you after a single failure on a dual system...priceless.

[Mike DC]

 
I wouldn't be afraid to drive it with just one cylinder.  

But I also wouldn't spend a bunch of money freshening up the system without switching it over.



IMHO the front drums would bother me more.  The single cylinder would only be a problem if it ever fails, whereas the drums are a drawback every minute you drive the car. 

[WH23G3G]

Yeah eventually I want to do a front disc swap. Right now I'm just freshining up the original drum brakes because they were all frozen. I got all the new parts for the whole brake system probably well under $300, including new lines and master cylinder. I just came across the articles on upgrading to a dual port master cylinder but I'm not the best at bending lines so I didn't want to get into all that and messing up would probably put me in the whole more than just replacing everything. So it kinda made me paranoid about driving it at all. Then I thought well back in 65 they weren't scared to drive them and the car is still around. I'm not sure I'd be willing to take it through the mountains in the summer on a long trip. But if someone offered a bolt on kit with lines, block, and master I would look into it. But they only offer a disc conversion which isn't in the budget yet and the car probably isn't worth the expense yet. It's definitely just a knock around car that was handed over to me that happens to run pretty good now with little work. Guess I can always practice pumping the e-brake handle in a parking lot somewhere if I want to. That's what the owner's manual says if a brake failure occurs. 

[Scaregrabber]

I have a 66 Hemi Coronet I drive a couple times a week with the single pot system. I replaced everything that could leak in the system and check the level once a week as well as watch for leaks all the time. If you don't maintain it I'd worry, if you do maintain it I see no problem.

Sheldon

[Cooter]

In a word...VERY.
No reason today to be running a single piston MS. With all the kits out today.

[Ghoste]

I'm the exact opposite of Mike, I'd be much more worried about the single pot mc than the drum brakes.  I've had drums fade after hard use and I've had half of a dual master cylinder go bad.  I'd much rather take my chances with reduced brake effectiveness from fade than to have no brakes whatsoever from a master cylinder failure.
The only place for a single pot master cylinder is on a show car that came that way.

[Steve P.]

My first 65' Coronet 500 had the single squirt jelly lar. All was well until it was not. No leaks in the system until it did and I found out at about 100 MPH coming up on a "T" in th road. Down shifting and being lucky as hell kept me from putting it in the Erie Canal.

I won the race and nearly wrecked. If I were doing a 100% restoration of a classic I would go back to the single port jelly jar, but it would not see road time. ANYTHING I WILL DRIVE will have the twin master without any doubt whatsoever..... 

Bending brake lines is really pretty easy. Watch some YOUTUBE VID's and you will be a pro in no time.

[ACUDANUT]

In a word...VERY.
No reason today to be running a single piston MS. With all the kits out today.

I agree.

[WH23G3G]

Any comments on this tech article? I was going to follow the instructions give on the Early Valiant Barracuda Club. http://earlycuda.org/tech/dualmaster.htm if you look at that article it seems pretty easy. I was wondering if I only may need to bend my own line for the front to rear brake line. It says to run the line from the rear straight to the front port on the  master. I've got my new rear axle lines installed and a front line kit from Right Stuff. If I plug the rear port on the distribution block, and  use the original front right, front left, and master cylinder ports on the block could I still use the new OEM lines for my 65 I got from Right Stuff? I know it would be plumbed a little different the suggested orientation in the article photo but should still work the same right?

[Dmichels]

It  all depends how you intend on driving it. If you plan on driving it fast and hard then upgrade the brakes. I drove a 65 imperial for years with single circuit brakes. Be a good mech and check everything. You will be fine.
Dave

[Steve P.]

I just want to remind you of one thing. NO CARS ever come out of the factory anymore with a single master. There is a very good reason for that. For what little bit of money and work it would take to make the car MUCH MORE SAFE, I would not even be thinking about going original. But that is just me.... And every auto manufacturer in the WORLD!!!!!!

[ws23rt]

I just want to remind you of one thing. NO CARS ever come out of the factory anymore with a single master. There is a very good reason for that. For what little bit of money and work it would take to make the car MUCH MORE SAFE, I would not even be thinking about going original. But that is just me.... And every auto manufacturer in the WORLD!!!!!!

I agree. There are many things on older cars that are potential safety issues but the brakes are one that needs to be counted on.
When you need it the most is when you don't have time to pump it up.
Kinda like you don't need insurance until it is to late to buy it.

[Baldwinvette77]

i would recommend dual, i lost my front brakes in the middle of a drive because of a slow leak on a loose fitting still had my back brakes to keep me front hitting a pickup infront of me. i personally wouldnt keep a single line system simply because of that experience, i guess its just one of those things, you had to be there to understand 

[ws23rt]

BTW back in the day when us kids drove stuff that was not road worthy I lost brakes several times. In none of those instances did I remember the emergency brake.
It may not have worked anyway but it just came to mind. So maybe it is sometimes called a parking brake for that reason?
Anyone been saved by the E brake?

[Ghoste]

I have but only because I end up in so many old cars with no brakes that I always get into them assuming it has no brakes.

[John_Kunkel]

Speaking as a guy who started driving at least five years before the first tandem MC, I'd say the single systems is safe IF they're well maintained. Lots of owners who want original cars are stuck with the single-pot MC and I don't see an epidemic of failures.

I've had two complete failures and was saved by the parking brake, in one case with only seconds to spare and the other case a second pump of the pedal got enough stopping power to give me time to grab the brake handle.

In recent years I've had two cars that I left the single-pot on for the sake of originality but both had brass-lined MC's and cylinders and I would replace the fluid on a yearly basis.