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Alright I have a question. I'm about do rebuild my brakes for my 50' 1/2 ton and i'm deciding whether to rebuild or replace my master cylinder.
any tips on rebuilding a master cylinder :confused: would greatly be appreciated. Also, I know somethings wrong with the brake system because the previous owner had about 3 empty containers of brake fluid under the seat. So I decided to replace everything lines, master cylinder, etc.
thanks for your help!

Sounds like you are on the right track to replace everything, there is nothing in the world like stepping on the brake pedal and it just goes to the floor
Are you going for bone-stock restoration or are you going to upgrade a few items like a dual master cylinder set-up?

Lou, unless you're planning a total restoration, a dual-circuit master is a necessary safety upgrade. My original master blew up on a downhill grade and I put it into a telephone pole to avoid pushing a Benz through a busy intersection. Sheetmetal is pricey, but cheaper than a lawsuit. If you decide to restore the stock single-stage master, make very sure that the parking brakes are capable of doing the job in a crisis.

There are many brake kits available, I chose a power-assist unit with an "offset bracket" that let me bolt it to the frame in roughly the stock location. I can't use the fill hole in the floor; the resevior is closer to the tranny cover, so I just pull out that section of the floor if I need to top it off. However, in the 3+ years since installed the new master and lines, not a drop has leaked (and no new sheetmetal purchases).

right now my plans are to just get it running and poke around town once in a while.

If you are replacing all the lines, it is not that much more work to upgrade to a dual master cylinder..

Personally, I would never rebuild either a master or a wheel cylinder. That is one area where upgrading to new parts is money well spent..

1950Lou,

If the cylinder bores (walls) on wheel or master cylinders are not pitted, I rebuild (never had a problem). However, the walls are usually pitted and you usually have to replace the cylinder.

You will need a drill-driven cylinder hone (two or three stone) to rebuild a good cylinder.

Tim

50Lou,
If you plan on keeping your orig lines, and there is no reason not if they are in good shape, you need to clean them out. Go get yourself some drug store alcohol and a syringe of some type. Push it into the line, let it sit for awhile and blow our with air. Cover the exit side of the line to keep the clumps from going all over. Then repeat until clean. This is the best way I have found to get all the junk out.

First, don't use drug store (isopropyl) alcohol. It contains water, either 10 or 30%. Use denatured alcohol, you can get it at the hardware store. I hope that's what 52 meant to say.

However, I would recommend following MetalMans advice. And if you replace all the components, lines, hoses, wheel cylinders and master cylinder, it would be a good time to go with the DOT5 brake fluid, unless you will be driving the vehicle at least every other week year round. The DOT5 fluid is silicone base and doesn't absorb water, but it also doesn't react quite as fast to the pedal pressure. Most people can't tell the difference.

And be sure the emergency brake works good. My brother-in-law put his 54 down a cliff about 100 feet when his luck ran out on his leaky brakes.

Part of the problem with DOT5 is that it doesn't expand rubber, which can be necessary in some MC and wheel cylinders for leak free operation. I can't use it in my motorcycle because of that.

I stopped using DOT5 for a few reasons, mostly because it is overpriced and isn't much better than DOT3.

True, it will not absorb water but water still gets into the brake system via condensation and puddles instead of being absorbed. Result, the puddles freeze in cold weather. It is also not compatible with lots of brake seals, especially older ones.

If you bleed your 3 system every couple of years to get junk out and fresh in it will last a long time and not cost a bundle.

I put a dual master cylinder in my GMC and filled the system with DOT 5. It took about a pint and a half. At $6.50 a pint , I am into the deal for about 10 bucks..

It will not eat paint from my newly painted frame or backing plates.. No flushing required. The pedal is as hard as in any vehicle I have ever driven..

I keep hearing the horror stories about DOT 5 but have yet to experience the horrors..

thanks for all the suggestions. When I took off one off the brake hoses the insides looked like a clogged artery.