Dual Circuit Master Cylinder For 59/60

[76eldo]

I did a search but did not find a step by step listing for converting a 59/60 to a dual circuit master cylinder.

I have been contemplating doing this for a while, keeping the drum brakes on all 4 corners, but having the added safety of the dual MC.

David Greenburg mentioned installing a 1968 booster/cylinder and only having to slightly enlarge the holes in the firewall for the mounting bolts.

I met a fellow club member while looking at a 60 Coupe at the Atlantic City show last friday and he wants to make his 59 safer to drive.

I'd appreciate hearing from anyone who has done this and would like to share what they did as far as running the lines and maybe some photos.

Thanks,

Brian

[David Greenburg]

Brian:

I did do that, and I highly recommend it. There is a step by step tutorial on it that I will try and dig up later this evening.  If I can't find the link, I may have a hard copy floating around. I don't know if the '68 booster/mc assembly is still easily available, but a few years ago it was $135 at AutoZone.  A bargain for the piece of mind.

[David Greenburg]

Brian:
Try this link (click on the '60 Caddy). These are the instructions I used. http://www.photopaige.com/edscars

[bcroe]

A dual MC will assure the brakes will always work, if not at the performance level of discs.  It might
be a lot easier to find parts & info for the popular front disc conversion, which covers a lot more
bases. 

I haven't done it, but the 68 setup ought to work for a comparable car.  Any tendency for the rears
to lock up first can be adjusted out with a proportioning valve.  Don't forget the combination valve
with its BRAKE fault light.  good luck, Bruce Roe

[76eldo]

Bruce,

Can you elaborate on the light?

Brian

[bcroe]

Bruce,

Can you elaborate on the light?       Brian         

If you follow the lines off any dual master cylinder (before anti lock brakes) down, they go to
the combination valve, a brass block with ports for everything.  One thing it has is a switch
to detect severe imbalance between the 2 halves, probably brought on by a leak.  The switch
will turn on the red BRAKE light, or check brake, or brake fault?  There is a wire between the
valve and the light of course.  Bruce Roe

[The Tassie Devil(le)]

I had Dual Circuit brakes on my '60 CDV and still ran the drum brakes.   Worked a treat.

Bruce.

PS.   I used a Holden Booster with attending M/C.

[Gabe Davis]

I did this conversion on my '59 using the part listed on the page here:
http://www.photopaige.com/edscars/60caddy/CaddyWebSitev2_files/NewBrakes.htm

2020 EDIT - the above site appears to be long gone. Here is the Archive.org link. The photos are missing but you can read the original inspiration for this modification still:

https://web.archive.org/web/20141123113113/http://www.photopaige.com/edscars/60caddy/CaddyWebSitev2_files/NewBrakes.htm

As others have said, the '68 booster and master cylinder work beautifully. The holes in the firewall do need to be widened a little and I used a rat tail file to do that. The page above mentions shimming the bracket that the pedal mounts on by 1/4" from the firewall. I did that using stacks of washers. I also had to get new nuts as the threads on the '68 booster are coarse and the '59 was fine.

A note on the booster - apparently Cadillac had a couple of different versions for '68. There was a disc/drum and a drum/drum version. I was sure to get the drum/drum version so I did not have to deal with a proportioning valve. It was re-manufactured by A1 Cardone and their part number is 50-1117. I got mine at Rock Auto.

For plumbing I used pre-flaired sections of brake line from Napa and bent them to fit. The original single master cylinder output goes down to a block mounted to the frame where it splits to the two front wheels and a line that goes back to the rear wheels. I disconnected the line that goes to the rear and coupled that to a new line that connects to the rear wheel output of the new master cylinder. I was able to find a fitting that capped the port on the block on the frame so it now just splits the input to the front wheels. The front wheel output port of the master cylinder then goes to the block as the original single input did.

One of the most difficult parts to find were the adapters for the output ports of the master cylinder. They are two different sizes and neither are the 1/4" that is on the car. I ended up finding them at Napa. I brought the whole assembly into the store and the manager took me back to the cabinet that was filled with the brake fittings. We were able to find one. The other was not in stock so after a trip to two more stores I finally had both fittings.

My car does not have cruise control so I did not have any fitment issues with the booster. The '68 is a good bit larger than the '59. I also removed the check valve and T to the reservoir tank on the vacuum line as the '68 booster has the check valve and reservoir built into it.

A few thousand miles later and she still stops like a champ. It is good to know that there is the safety of the dual master cylinder on the car now. Hope this helps a little!

Edit: Found a couple of pictures. They are mid-install as you can see I had yet to find the second adapter fitting.

[76eldo]

Thanks for the info and links. That's the same link Dave sent.

Seems like the way to go.

Thank you guys.


Brian

[Coupe Deville]

Here is the thread from when I converted my dads 59' to the A1 cardone 50-1117. It has worked extremely well since I installed it. Just a few minuets with a drill and a filing tool and it bolts right in. Best of luck!

http://forums.cadillaclasalleclub.org/index.php?topic=125835.0

-Gavin

[59-in-pieces]

Brian,
I did not see if you said your car has cruise control and or air ride.
I remember the distance out from the firewall to the end of the dual MC, when the lines are on is tight with the back of the cruise control, and took some finagling.

Have fun,
Steve B.

[76eldo]

My 60 convert has no air and no cruise.

The 60 Seville has air but no cruise.

Thanks,

Brian