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Adapting Mazda 3/4" wheel cylinders to rear drum brakes

By Steve Welsh, Princeton, MN

Ref . (SDCF99747) March 2017

////Is there anyone resleeveing the rear wheel cylinders on the disc brake cars with stainless sleeve's/////

//////I went on Dormans site and they show the 63-64 hawks and up to 71 Avanti repair kits being the same as some older jeeps cj's and 83-83 Mazda b2300's. So i went to rockauto and they show for the Mazda B2300 wheel cylinder repair kits as $1.33 and they had a closeout on some wheel cylinders that look like maybe they could be reworked to fit at $3.58 each.I ordered a set plus the repair kits and if they won't work I'am only out $12.00 with shipping.It does show that they are 3/4" and look to be where the brake shoe rides against them. They bolt on different but think I can change that. ////////

////////I got the new repair kits and wheel cylinders today. Kits are made in the USA and the cylinders from Japan. Which I will take over China any day. Looks like the new cylinder will work only thing I will have to make a template and drill a hole across from the upper one that is there and maybe seal where it fit to the backing plate as the center is cut just a little smaller. The shoe's fit into it just fine and size look real close. On the repair kits I will need to reuse the pistons but think you do on all kits. May have to trim a little off the back side of the dust seal as it looks to go in a little deeper but that should be easy. The spring looks a little heavier but that is a good thing.Going to try to rebuild what I have and then decide which way I want to go when the new brake shoes get here next week./////

//////Looks like all that will be needed on the wheel cylinders is to drill another hole at the other side on the backing plate and either a gasket or something to seal dust out right where it fits though the plate as the center area is just a hair smaller.I think everything else will work. Which would be great as there should be a lot of people making cylinders for b 2300 Mazda's for cheap. I only paid $3.58 for these. They are 3/4" and are the same distance across on the main body itself as the studebakers and the dust seal is a slight bit heavier but that won't get in the way. The old shoes fit the slot on the piston just fine and fit in the dust seal so that shouldn't be a issue. The stock set up the end of the shoe just rides against a flat spot on the piston. As I said I will trust Japan machine work over anything out of China. China stuff will be shot in a year. May have to use a metric line fitting where it hits the cylinder but I'am putting new lines on anyway so I can build what ever it needs.//////////

/////// I did some measuring and the body of the cylinder is 2 1/2" rubber to rubber. The line hole is dead center and the mount holes are 1 3/4 center to center and are both 7/8" from center. So if I just mark center of the hole in the backing plate and put a hole on each side 7/8 from there the cylinder should be centered.Where the cylinder fits the backing plate the hole is 1 3/8 and the new cylinder is 1 1/8 so I need a 1 1/8 ID 1/8 " thick spacer or sleeve .///////

//////////Got the E-brake cable and clips with new springs from SI yesterday. I made a plate for the backing plate at the wheel cylinder with 1 1/8" hole to support the wheel cylinder and mounted it on the outside of backing plate at the top. Used the two holes that where there and drilled two new ones. My modified plate is now held on with 4 bolts. Two 5/16 on the bottom and the two small ones at the top that hold the wheel cylinder on. Everything else fit together with out any changes and the drum fits and turns so I see no reason these Mazda cylinders wont work. Now just a matter of doing the other side and torque everything up and she's ready to go in the frame. The mod's would be a little hard to do on the car but if you where to remove the backing plate and do everything off the car and just put it back on as an assembly it would be easy.////////////

////Shoes are Centric 11101730 $25.79 a set new no cores, wheel cylinders Kelsey-Hayes 3/4" 1984 Mazda b2200 rears w-53506 and 507 $ 3.45 each all from Rockauto. Bracket on backing plate 18 gauge sheet metal sealed with black silicone before bolting to backing plate. E-cable and springs from SI.//////////