My master cylinder was leaking at the boot at the plunger end. I bought a rebuild kit from Job Lot. Took the master cylinder off tonight. Took it apart. The cylinder bore looks OK on the inside. No sign of pitting that I can see.
I read the brief shop manual instructions. Any other tips or advice, for this my first MC rebuild attempt.
Thanks!
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abe
'54 F-100
bought from Grandpa in 1977 for $200
Abe, if the only problem was the leak at the plunger, the cylinder is probably OK. It would still be a good idea to hone the cylinder anyway to make sure it is not egg shaped and to break off any glaze on the inside. Be sure that you check for wear in the plunger shaft. Clean the shaft with a fine grit sandpaper. Work your sandpaper around the shaft of the plunger, not length wise. This will prevent linear scratches on the rod that will allow fluid to leak through the shaft seal (I'm assuming your master cyl. has a shaft seal). If the shaft is worn too badly, it may need to be replaced. If your cyl. has no shaft seal, then don't worry about the shaft. Make sure everything is cleaned and lubricate all surfaces and seals prior to assembly with brake fluid. You can bench bleed the master cylinder prior to installation by filling it with fluid and allowing the fluid to drip out the outlet ports until all the air is out of it. This will make the system easy to bleed. Hope this helps.
The rebuilding must be done under absolutely clean conditions. I did my honing and sanded off any burrs with 400 wet/dry, then cleaned the entire cylinder and all metal parts in clean diesel fuel. Then I washed them with Dawn dish soap and water, towel dried them, blew it ou twith compressed air, and gave the inside a light coat of NEW brake fluid to prevent flash rust. Perform the rebuild in a CLEAN metal pan, and only use NEW CLEAN brake fluid to lubricate surfaces an drubber parts during assembly.
I'm gonna second both Gil, and Julie. Keep it clean. Run a hone through it. If it's a ball hone, start your drill before inserting it into the cylinder bore. When we hone cylinders at work, we use warm soapy water, then spray some wd-40 in it to prevent the flash rust Julie's talking about. Then, we clean the cylinders out with brake clean and compressed air prior to reassembly to make sure they are free of any contaminents, uncluding the wd-40. You can also, to make sure it's good and clean, boil the master cylinder. Put it in a pot that will hold it, and boil it in ordinary water. The aggitation of the water, and the heat, will clean any crap off it you can't see. Roll it around every so often in the water, and you should put it in like a steamer tray to keep it off the pan bottom. I would actually boil it AFTER honing it, to remove anything you may have missed. Then, proceed with reassembly. Make sure to use only clean brake fluid from a new container. Poor some in a small dish, and let everything but the end boot sit in it while you rassemble the cylinder. DON'T FORGET THE SNAP RING, and make sure it's good, or replace it. I've seen people forget the snap ring and get the plunger cocked in enough to hold it in place, and wonder why it keeps coming apart. Fill it up. Now, these old units don't have to actually be bench bled, because it's a single line out, and no proportioning valves. It WILL make bleeding it a lot faster once installed though. Ever notice how on these old trucks, you can poor in fluid and just pump the pedal 'til it gets hard? That's because it's a single port system, and has a weak check valve, and no proportioning valve. Go to it, and let us know.
One guy who looked at it thought the cylinder bore looked pretty good. He told me to clean it up with steel wool or fine 400 grit paper. I did that and once I cleaned it up it looked worse. Some "unsmoothness" in the bore, not exactly what I would call pitting or grooves but not smooth when I run my finger over it. Took it to the garage that does a lot of work on my truck and he said it should be honed, so I ran it up to a guy that rebuilds a lot of engines and does machine work but by 12:30 today he was closed and tomorrow is the 4th and then Sunday so I won't be able to get it honed by at least Monday.... And my wife still has stuff in our garage from the yard sale she had last weekend so the truck is sitting in the driveway!
Oh well! Happy Fourth of July!!
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abe
'54 F-100
bought from Grandpa in 1977 for $200
You can buy a brake cylinder hone to fit your drill from napa and most auto parts stores. Cheaper than having someone else do it then you will have one for next time.
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