Tuesday, September 12, 2017

MGB - master cylinders (Part 2)

Today, we continue documenting the work on the master cylinders, and perhaps more importantly, the pedal box between them. In Part 1, I covered removal and disassembly. Today, I'll cover clean-up, painting and re-assembly. Unlike so many of my posts lately, this one might be a little shorter.

Parts Order
With the various major components apart, its time to consider the condition of your bits and pieces, and place a parts order. We're starting with the 2 master cylinders (MC). The whole point was replacing them, so let's start there. As of today, a clutch MC costs about $35. A brake MC costs anywhere from $60 for an aftermarket (read: Chinese) up to $220 for an Original Equipment Manufacturer (OEM) part. I like OEM, but I don't like spending a premium if I can avoid it. Look around. Moss isn't the only supplier, and you can find the OEM for less than that.... like my new friend Basil.

How does your brake booster look? Does it look like mine, all rusty and nasty? Considering a new one is $250, you may want to consider cleaning and maybe even painting your original.

I get new fasteners when I see rusty ones, and fasteners around brake fluid always rust up, so I encourage new bolts for holding the box to the car, and screws for the lid. You will probably need 2 new cotter pins. I found that the bolts and nuts dedicated to the pivoting of the pedals were perfect, so I didn't replace those. You may want to. Get new pedal pads; they're like $3. Depending on condition, your pedal return springs (which I forgot to mention in step 1) might need replacing. Mine were rusty, so I got replacements. Consider that there is supposed to be a seal both above the box and under the lid. These are also cheap, so get these too.

My parts list was the 2 master cylinders, pedal pads, seals and a couple of handfuls of fasteners. All in, I was under $150. I got the MC's from Basil, pedal pads and seals from Moss and everything else from Ace Hardware.

Prep and Paint
assembled box, from behind
First, complete the dis-assembly, if you didn't as part of your parts order step above. Remove the pedals from the box and then the sleeves from the pedals. Remove the pedal pads if you didn't during the pedal box removal. Remove the seal from the top of the pedal box / bottom of the lid (depending on which one it is stuck to). The pedals, box and lid should now be bare. I scuffed the remaining original paint from those pieces with a mostly-spent 100-grit sanding pad after removing the rust with 60-grit sandpaper. The mostly-spent pad removed the deep scratches from the 60-grit and created and edge for the paint to adhere to. I shot the pieces with Simple Green to get the sanding dust off and then wiped them down with Mineral Spirits before shooting them with a basic gloss black. I have found that shooting smaller pieces in one shot is efficient without sacrificing the finish. For the pedals, I run a short stretch of wire through the pivot hole and hold it by the wire so I get full coverage. I did the same thing with the pedal box and lid, but short the pieces in stages, shooting the inside first and then following with the outside after the inside had dried. I left these pieces cure for a long time since it was about here when I discovered the floors were rusted out... or it was about here when I discovered that the front suspension was bushed with window insulation.

I didn't mention the brake booster in the paint list. When I painted the other pieces, I was still considering my options. I decided I would try to give the original piece some love and see if I could bring it back to looking fairly good first. I started with the same pattern of low-grit paper on the rust and 100-grit pad everywhere. It took a couple of hours, but the rust came off and the whole piece started to glow. After the spent 100-grit pad, I started polishing with steel wool. This was the magic. The steel wool took away the tiny scratches left behind by the spent pad, and removed the little bits of grime that the other efforts didn't. The end result is pretty incredible. I thought about shooting it with clearcoat, and concluded that it survived years in a barn and many more years of weather and still returned to such fine condition without it. It could go another 40 without it.

inside the pedal box
After the paint had cured (sat idle without people poking at it for a few days), I put the new rubber pedal pads on first. You could do this at the end, but the box goes in the same whether the pads are on or not, and (a) I wanted to see how they looked semi-finished and (b) I was able to make sure they were completely seated without having to lie on my back under the steering wheel to do it. I used a paint can opener to help the rubber lip around the edge of the pedal. After admiring the new pads, I mounted the brake booster to the box. Next, I attached the brake pedal to the brake booster with the clevis pin and cotter pin. Then, I attached the pivot bolt, and tightened it down.

The clutch master cylinder is next. For consistency of appearance, I threaded both bolts from the outside of the box in, so the top bolt which threads into a nut, has the nut inside the box. Next, I moved to the clutch pedal, attaching only the clevis pin and cotter pin to the MC, leaving the pivot bolt to last. For this, I put all the parts together and lightly threaded it into the captured nut inside This was just to get the box into position.

I'll cover the install in another post, so that's it for today. As always, thanks for following along...

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