Hey there,

I'd like to improve safety a little on my '61 Bonneville, without breaking the bank or modifying the car too much.

It is fitted with a single reservoir master cylinder behind the power booster (see attached photo) & has drums all around (standard set up, I believe).

What I'd like to do is fit a dual master cylinder, to provide some redundancy in case of a failure in the system. If I also gain some additional braking power that would be great, but not entirely necessary ( a the car brakes are fine for the way we drive it - it isn't a muscle car, rather a cruiser).

Due to cost/benefit, I don't want to go down the path of discs. While I know they will provide much better braking, by the time I buy/fit the kit & source new wheels/tyres to suit (I'm currently running the original 14's!), the cost is around $4000-$5000. 

My questions are:-

1. Does anyone know of a dual master cylinder that would fit? If so, am I able to buy one new or will I need to source a used one & take my chances with the condition?

2. What else would I need to fit in addition to the master cylinder, if such an upgrade is possible?

3. Are there any other recommendations you may have for me?

 

Any advice would be greatly appreciated 😊
 

What size wheels are you planning on running? Many brake kits required 15 inch (or larger) wheels. IF you are running 14 inch wheels, then this greatly reduces the possibilities.

Edited July 26, 20232 yr by Frosty

Paul, Fitzy  is doing the brake upgrade on his 65 as we speak !! 

back in my thread you will find, i had sorced a dual master cylinder from rock auto out of a later 1960s' chev , they have the correct bolt pattern and bore size for drum/drum set up.....sooooo.

keep an eye on Fitzy thread ! 

i have not fitted mine yet as i need for the 64 to be stock when it goes for its compliance checks, then i will swap out the single outlet master cylnder with the dual circut one.

it will make your brakes wayyyy safer, and brake better too !!

hopefully Fitzty sees your question 

This is the one I am using on my drum drum set up 

5 hours ago, Frosty said:

What size wheels are you planning on running? Many brake kits required 15 inch (or larger) wheels. IF you are running 14 inch wheels, then this greatly reduces the possibilities.

That's the issue - I want to stay with the original 14's...

1 hour ago, 64 kiwi boni said:

Paul, Fitzy  is doing the brake upgrade on his 65 as we speak !! 

back in my thread you will find, i had sorced a dual master cylinder from rock auto out of a later 1960s' chev , they have the correct bolt pattern and bore size for drum/drum set up.....sooooo.

keep an eye on Fitzy thread ! 

i have not fitted mine yet as i need for the 64 to be stock when it goes for its compliance checks, then i will swap out the single outlet master cylnder with the dual circut one.

it will make your brakes wayyyy safer, and brake better too !!

hopefully Fitzty sees your question 

Thanks for that - I'll check out Fitzy's thread

 

1 hour ago, 64 kiwi boni said:

Paul, Fitzy  is doing the brake upgrade on his 65 as we speak !! 

back in my thread you will find, i had sorced a dual master cylinder from rock auto out of a later 1960s' chev , they have the correct bolt pattern and bore size for drum/drum set up.....sooooo.

keep an eye on Fitzy thread ! 

i have not fitted mine yet as i need for the 64 to be stock when it goes for its compliance checks, then i will swap out the single outlet master cylnder with the dual circut one.

it will make your brakes wayyyy safer, and brake better too !!

hopefully Fitzty sees your question 

Thanks for that - I'll check out his thread 🤙

For what it's worth...

I'm 99% sure starting in 1959/60 forward...That all Cadillacs with power brakes  used a Delco dual circuit master cylinder as standard equipment...Of course you would have to use the matching Cadillac portioning valve...Could very well be a direct bolt on...

Edited July 28, 20232 yr by TWO LANE BLACK TOP

2 hours ago, TWO LANE BLACK TOP said:

For what it's worth...

I'm 99% sure starting in 1959/60 forward...That all Cadillacs with power brakes  used a Delco dual circuit master cylinder as standard equipment...Of course you would have to use the matching Cadillac portioning valve...Could very well be a direct bolt on...

one moment caller ! i will go look under the hood on my 59 ........

My 59 has what looks like a very simlar single outlet master like the 64 Ponti has... got to be aware, i didnt build this car , so the master could or could not be factory !

what I do know is . The 59 caddy stops very well !!! I have had to test them . And she has big fat arse drums all the way round  

 

Edited July 28, 20232 yr by 64 kiwi boni

Did a little further research...I was wrong...Cadillacs started using the dual master cylinder in 1962...Not in 1959/60...Sorry for any confusion that I may have caused...

On 7/28/2023 at 4:07 PM, 64 kiwi boni said:

one moment caller ! i will go look under the hood on my 59 ........

Hey there,

While you're looking under the hood, would you answer me something if possible?

I've spoken to Summit Racing (who have the same master cylinder as you're planning to fit - a Centric 130.62016). They can't confirm If it will fit mine or not, but looking more closely at your photo it appears as if yours is a 2 bolt fitment? Mine is a 4 bolt - see photo.

 

 

GM used 2 different power braking systems...During that time period

The unit shown in your photo is the Bendix power brake system...Identified by the square reservoir/4 bolt Master cylinder...

The other unit used...Is the Delco-Moraine power brake  system...Identified by the round reservoir/2 bolt master cylinder....As shown on Kiwi Cadillac...

Both units are designed  to be fully serviceable and can be rebuilt if you can get the parts...

Edited July 29, 20232 yr by TWO LANE BLACK TOP

From what info that have able to gather....In order to upgrade to a dual circuit Master Cylinder...you would have to swap out the Bendix power brake booster...For a Delco-Moraine power brake booster...As far as the brake pedal assembly...I'm unsure if the Bendix unit would properly work with the Delco-Moraine booster...As it is very possible that the brake pedal ratio/angle on the Bendix system would be incompatible with the Delco unit and would require the brake pedal assembly from a car that was originally equipped with the Delco power brake assembly in order to maintain the proper geometry and pedal ratio for the system to work correctly... 

I can’t speak to the configuration of the attachment for the power booster to the firewall, most likely it would be different. So that would require an adapter plate. That’s not much of a big deal, at least from my first view. But with that in mind as an example, a 1969 Camaro 4 wheel drum brake master cylinder/power booster assy can be bought for around $300. This includes the distribution/proportioning block & bracket. The pedal configuration should not be an issue, but if it were you simply need to drill a new hole in the pedal arm. The weights of these two cars are close enough that there should be no disparity in braking. You can look at other GM 4 wheel drum cars as well to see if one would work even better. 
You should realize that these types of 4 wheel drum master cylinder are a sequential plunger type & employ residual pressure check valves.