1985 Cushman Truckster New Brake Master Cylinder

I bought this Cushman May of 2022 and it has had a brake master cylinder leak for who-knows-how-long, certainly years before I got it. I figured it was time to fix it. Needing to move the beast to the garage, the engine did not want to start. I cleaned the points. I checked the spark at a plug wire. I made sure the fuel pump was pumping. I cleaned the points again. I bypassed the coil resistor. I checked for voltage to the coils. I put in more gas. I checked the points again, and yep, still a spark. Then out of the blue, the thing started up. Who knows what the problem was. But during that time of troubleshooting, I had to push the Cush out of its hole in the shed, and in doing so, I noticed one of the dump bed hinges seemed a bit off. Ok, add that to the list of things to do today. Once I got the engine running, I drove to the front of the garage and lifted the dump bed. Yep, that is a broken hinge.

The fix wouldn't be too terribly difficult, just clean up the rusty parts and weld it back together. Here's the finished product. That should hold for another 30 years or so.

On to the master cylinder. There was a skid plate under where the master cylinder resided, so that came off first with four bolts. Then the brake line, two mounting bolts, a wiring connector, and a cotter pin were removed and the thing came out. It's hard to tell, but this might be original to the cart.

The disassembly begins. Fortunately, with some heat and penetrating oil, I was able to disassemble the entire MC. There's a snap ring in there somewhere I think.

Yep, there it is.

The body of the MC has Girling cast into it. That company has been around forever. The internet says Lucas absorbed them in 1938 but kept the name and company going.

Well, that's not good. There's deep pitting in the bore. I could try and hone it out but my brake hone won't get into the small 3/4" bore, and honing wouldn't totally get rid of the pits. Time to order a new master cylinder.

I found a new "open box" master cylinder on eBay for $89.99 or "make offer". I made a $75 offer (plus tax of course) and it was accepted. Yay. The part number is correct for a 3/4" bore MC for my Cushman, so I'm fairly confident it will be correct. I may need to reuse the original push rod, or parts of it. We'll see when it shows up next week. I could have ordered a MC from Amazon but it was $95 (plus tax of course) and it was also a 1" bore, which I believe is for Cushmans with more than just rear wheel brakes like mine has. It would have worked and fit, and it would have been here in a day or two, but I wanted to stick with a 3/4" bore, as I think it will provide less braking effort than the larger bore. eBay did have a new-in-box 3/4" MC but it was $127 (plus tax of course). Other places online were selling the 3/4" MC for around $120 plus shipping. This time it paid to shop around.

Ok, it's the next week, and the new MC has arrived. It looks like it will work. I reused the brass triple-tee, as the one with the new MC was steel and I preferred the brass one. (Update several days later: something was leaking, either the brass tee was cracked or the old brake pressure switch was leaking. I removed the brass tee and installed the new tee, and blocked off the brake switch port, as the brake lights didn't work anyway.)

This final photo is of the MC installed. It works like a charm. Yes, it's nice having brakes that work all the time.