How do I convert my 60 Lesabre to a dual master cylinder?

[joseph demeyer]

I want my 1960 buick lesabre to get a  power brake conversion from a single reservoir to a dual reservoir master cylinder...the present single reservoir master has a clip on cap so appears already to have replaced the original factory installed "box" reservoir that had a four bold attachment to the booster...this one has a two bolt attachment to -I guess- also replaced booster ; which I want to keep.  I do  also want to keep all the original front and rear brake drums- no disc conversion. I am having difficulty finding the appropriate dual reservoir MC: Previous -old 2015 posting - mentions AC Delco part: 18M1027; but it refers to a 1964 Buick Wildcat conversion...Anyone can recommend a dual reservoir MC for a 1960 Buick ?

[JohnD1956]

Split this topic into a separate thread.

[60FlatTop]

I have owned my '60 Electra since '02 and never considered modifying the brake system. I had my original master cylinder sleeved when I went through the brakes. If I ever need to rebuild the master cylinder and can't find a fresh kit I will buy one of the new offshore new ones with the poor casting and use the rubber parts from it.

 

My prickly point about these brake conversions is the transition from the common, older 1/4" tubing to the new small diameter tubing. There are many places that reduction can be made but I have never seen what Google would call "a scholarly article" addressing the difference in tubing diameters. It is a design affecting on the cube root so it is significant.

 

Since my '60 Buick was made about ten years before we put men on the moon and got them back I figure engineering was well developed at the time.

[joseph demeyer]

It is a prickly point indeed and when it comes to brakes...not something to take lightly !  This 1960 Buick went already through a conversion from the factory installed MC and booster (of the four bolts attachment types) to another booster with a two bolts attached single clip capped MC with integral brake switch - the two point sliding connector. (I have never seen that kind of brake switch integrated single reservoir MC again for sale). But most importantly : it kept the original 1/4" tubing....So any conversion to a modern MC with smaller outlet diameter would require an adapter in between and how that might affect the entire brake efficiency only physics (or hydraulics ) would know. ANY INPUT WELCOME !

I don't know what is meant by "splitting this topic into a separate thread "

[NTX5467]

OK, so we ruled out the desire for the 4-whl power disc brake conversions many are talking about these days.  That's good.

 

I also fully understand the desire for a dual-circuit brake master cyl, for safety reasons.  ALSO know that many of us lived-through those times when all we had was single-reservoir master cylinder brakes and lived to tell about it.  In a time where most service stations had open gallons of brake fluid on their work benches (as it could also absorb moisture).  So, several possible dynamics at play!  In theory and reality.

 

Many might not understand that when one of the brake fluid circuits is "lost", the remaining circuit still means that 1/2 of the braking power is gone, so stopping distances will be longer as a result.  A crash or collision could still result.  Yet this is one case where "something" is better than "nothing".

 

For an OEM-based upgrade, you might look at the earlier 1960s Cadillacs which used a factory dual reservoir master cylinder.  Perhaps that might be a viable alternative to use or install/adapt to your Buick?  Might be more period-correct, too, if that matters.

 

Although I had not researched it, I was not aware of any changes to brake line tubing diameters, over the years.  Certainly something to consider, as to hydraulic leverage and such.

 

NTX5467 

[NTX5467]

I went into RockAuto to learn the differences in the 1960 Buick master cyl and the suggested 1962 Cadillac master cyl.  In looking at the Buck cyl first, I noted that all have the 4 bolt mounting, with the pressure take-off on the top-side of the front end of the housing, with the brake line hooing to the bottom-side of that same end housing.  1.00" piston bore.

 

The 1962 Cadillac master cyl looks like a smaller version of the later drum brake dual master cylinders.  No place for a pressure switch brake light switch.  Same 1.00" piston bore.

 

The Cadillac mounting flange is only 2 bolts, one on each side of the pedal push rod.  When I re-looked at the Buick flange, those two Cadillac bolts match up to the location of the bottom two bolts holes on the Buick flange, which appears it should bolt-on as is.

 

Which further means that about all you'd need is to build the line adapters to run lines to the existing chassis lines past the f/r junction block on the frame.

 

The only other "minor issue" would be to adapt the Cadillac brake light switch to the Buick's brake pedal assy.  I suspect they might be very similar in design, but this is speculation.  But knowing how many unseen items were shared, it might just take a switch and some sort of braekt to make things work, aside from the wiring alterations.

 

Hope this might help!

NTX5467

[kgreen]

I always wondered why the cable operated emergency brake was never named parking brake which is the only time it seems anyone contemplates using it.

[NTX5467]

Probably because if you lost hydraulic brakes, it would be an emergency to stop, so the mechanical brakes could then be used, but only on the rear wheels.

 

NTX5467

[60FlatTop]

On 9/13/2024 at 7:08 AM, kgreen said:

I always wondered why the cable operated emergency brake was never named parking brake which is the only time it seems anyone contemplates using it.

Many, like 50, years ago I rode to a local plaza with a friend's girlfriend. The friend's name was Snake. When she stopped the car she said "The shifter is out of adjustment and Snake hasn't fixed it yet. Would you put that rock in front of the wheel?" I asked "Doesn't the emergency brake work?"

 

Suddenly life with Snake got just a little easier. Especially when she drove alone.

[40 66S CENTURY]

To kgreens comment- we had a 1952 roadmaster for sale at hershey many many years ago. my partners went home early in the modern station wagon but we stayed almost to dark in the flea market. Left for the trip to New Oxford, PA [50 Miles away.] When we went to get on the PA Turnpike the brakes failed@!! Yikes. WE used the "emergency brake" to get our ticket along with the super low on the Dyna flow. Stupidly we made the entire trip back to New Oxford using low and the emergency brake. The Lord was with us for sure. 2 piston MC is a must for some of these older cars especially for long road trips like from here to BCA Nats next year in Charlotte, NC. ]

[60FlatTop]

11 hours ago, 40 66S CENTURY said:

When we went to get on the PA Turnpike the brakes failed@!!

Just curious, do you remember what had to be repaired to make them work again?

[NTX5467]

NOT to be flaky, but we drove gajillions of miles with a single master cyl on our cars, for ages.  Yes, those single master cylinders were co-conspirators in many car chase movies where somebody wanted somebody to die in a "off the side of the mountain road" car crash, too.  So we KNEW to keep the systems in good working order, addressing any leaks and such when and IF they ever happened.  But that was also in the days when most every service station had an open gallon of brake fluid sitting on their workbench, with a rubber-bulb dispenser sealing the top.  No worries about moisture intrusion into the brake fluid, it seemed.

 

So, the single-circuit master cyl did NOT cause itself to fail.  The fact it was a single-circuit master cyl just made it more dangerous when it did.  A dual-circuit master cyl would still have needed some special attention to get the car stopped, if one circuit failed, so "special attention" would still have been needed.

 

I, too, am curious as to @60FlatTop's question of what it took to repair the brakes on the car.  Might the 1962 Cadillac master cyl (mentioned above) be adaptable to your earlier-year Buick?

 

NTX5467

[Oldtech]

Pipe diameter should have nothing to do with anything. It's all about the piston to cylinder ratio. 

[61polara]

All I have to add is that in almost 60 years of driving, I've never lost brakes from a broken line or wheel cylinder.  When I have lost brakes it was because of the master cylinder failing.  Dual or single chamber master cylinder, when they fail they fail.  Usually they will give you a sign, but many times it's only one stop before they are gone.  The safest practice is to maintain your brakes whether they are dual or single master cylinder.  Always keep your emergency brake in operating condition.  That is your final backup system. 

[EmTee]

In my experience following a single circuit failure of a dual-circuit brake system, brake performance of the remaining hydraulic circuit was no better than that of the mechanical parking brake...