The Stovebolt Site Forums The Parking Lot Big Bolts Help upgrade to dual master cylinder

I have single master cylinder with 1¼" bore. What would be the equivalent in a dual master cylinder.Would a 1" bore be big enought.I have Canadian Chevrolet 1700. Thanks for the help

Why not look for a 1.25" bore?
I know there are bigger ones out there... I've got a 1.625" MC from about a 2004 F350 on my truck, but disc brakes.

Grigg

I'm doing a swap to a dual master, but keeping my drum brakes. Try mid 70s chevy trucks, they used a 1.25" dual master, its even an easy shape to keep under the floor.
Rob

Doing a swap to a dual master, but keeping my drum brakes. Here is the problem. The brake pedal is a pull and push (see picture)http://www.flickr.com/photos/old_betsy/5294667154/in/set-72157625553190073/ I need a dual M/C whith the port on the opposite side of the railing. I found some that would fit but they are only 1 in. bore. I also read that the dual M/C reservoir for drum brakes suppose to be the same size, is that correct?. Does it matter witch side goes to the front or back. Where do I put the Hydrovac?.

Hy Lieut DGoss, to start with I would not go smaller in the bore than the original cylinder. If you are not going to mount your new master cylinder directly to a vacuum booster unit, then you will need two hydrovacs, one for the front system, and one for the rear system. Most of the dual systems I remember have the primary system [closest to the pushrod] plumbed to the rear. The drum/drum master cylinders usually have two reservoirs of the same size. Make sure that the supplier knows that the master cylinder will be used for a drum/drum brake system [disc brake master cylinders do not have built in resisdual pressure valves, which are required in a drum system]. Hope that helps.

I'll send you some pictures this week of a dual circuit master that I have under my 46 2Ton with a vacuum booster. It's a 1.250 bore and is from a late 90's chevy 1Ton. I am using the vacuum booster from a 3/4 ton as the 1Ton's used a hydraboost and I didn't want to add a power steering pump! I am currently in the process of making a kit to convert the larger trucks to 15" front disc brakes, dual circuit vacuum boosted master that is kept under the floor and utilizes the stock rear drum's. You would need to run a residual valve on the front circuit to keep some pressure on the shoe's!

http://s1006.photobucket.com/albums...on/?action=view&current=100_4114.jpg

Photo's of the 1.250 bore dual circuit vacuum boosted master. I am planing on having these laser cut and formed once I finalize the design!

Nice job, I would be interested if I was going to disk brakes but I am keeping my drums for now.I have decided to install the dual master cylinder like the American model, it is less trouble that way. Will need to make a good strong braket. I will post pics when it's done.

You can use this set-up with front drums. You would run a 10 lb. residual valve in place of a 2 lb. residual valve.

I like this design from the standpoint of it mounts in the existing holes in the frame and you don't see it once it's done. I'm assuming your reference to the American model is the one that mounts to the firewall and has a pedal that swings down?

That method would work better, but doesn't look as original!

The US model the master cylinder plunger is facing forward (not backward like mine).All I need is a bracket like yours to bolt the cylinder too.I already have the stock swivel bracket.I will have to figure out the lenght of the two rods.