50 year old brake fluid should have been changed 47 years ago, and every three years thereafter, only takes a couple of minutes. Flush the brakes while your waiting for the engine oil to completely drain.

I had never heard of changing brake fluid either, even my 96 F150 still has the original fluid in it. But after I did the brakes on my 85XJ I can say I will be flushing every vehicle I have from now on. The fluid in that one was brown and there was a nice layer of sludge on the inside of the master cylinder. Changed the front brake pads, calipers and rotors and flushed both front and rear lines and I can actually stop now.

Flushing was really easy using the one man flush idea, tube from bleeder into bottle with a little fluid in it to keep air from coming back up the lines. Once you get it flowing you can just let it siphon until the clean fluid comes out if you don't want to keep pumping the pedal.

Bleeding brake fluid out and replacing it every 30,000 miles is something that never caught on in the domestic market, but should have. As Doc mentioned, it is hygroscopic and denegrates with time.

We flush the system every two years on our fleet at work. BG makes a nice machine with a suction hose.

Silicon brake fluid should not be as hygroscopic, and it has been around for a long time, I wonder why it has never caught on? Too expensive maybe?

most applications that use silicone fluid use larger lines 1/4" as opposed to 3/16" and generally are 4 wheel disc.

Steel pistons function as better heat sinks for the pads - allowing them to dissipate heat more quickly, reduce net heating of the fluid slightly, and reducing outgassing & brake fade slightly (but measurably, on both.)

A steel piston, however, can rust - which negates the heat transfer advantages (degree directly proportional to amount of rust) and weakens the piston (the working fluid pressures in brake lines can be quite significant.

A phenolic (or other plastic) piston will NOT rust, but is inefficient for heat transfer (increasing friction material heating, outgassing, and fade potential) and is a bit weaker than steel.

Given a choice, since I'm down there at least once a year for inspection anyhow, I'll take steel pistons. Eventually, I may machine some out of aluminum bar (gotta design the things) to negate the potential for rusting - and a number of metals are more efficient heat conductors than steel anyhow (aluminum, copper alloys, ...)

I don't mind parts that "require a bit of extra maintenance," since I do annual inspections and am aggressive with maintenance anyhow. (My granddad bought a 1972 Datsun pickup, brand-new, for cash in 1972. When he sold it in 1994, it had the factory battery in it! This is the man who taught me...)

the difference in heat dismemberment is minimal, and the major reason was overall cost.

and another point is reducing heat transfer to the brake fluid, phenolic brake pads do not transfer heat to the brake fluid where as steel piston do.

True. But, by transferring the heat into the caliper body and fluid, the unit heat content of the system is reduced, and the heat is dissipated that much more efficiently (even the fluid plays a part - since it carries heat back up into the lines when you release the pedal. It's when you STAY ON the brakes that fade & fluid boil become a problem.)

wrong.

part wrong, your right about the fade, which also can occur if you fail to replace the brake fluid (flush) every 30,000 miles

Yah - because fade is a combination of outgassing (the gases being released from the friction material tends to try to form a cushion between it at the rotor) and heat in the fluid (because the boiling point depresses as the water content increases.)

But, what made you say I was totally wrong the first time? Let's discuss this - if I'm wrong, I'm willing to learn! (Just telling me I'm wrong won't do, tho - you now have an opportunity to teach...)

We all get the "hang of bleeding" every time we take tools to our XJs! Why, I think I've donated a few pints of blood to my garage floor. :cursing::cursing::laughing::laughing:

The Gods of Auto Repair occasionally demand a sacrifice. Some jobs just don't go well until you lubricate them with blood.

The catch? You cannot give the sacrifice, it must be taken. Cutting yourself to bleed on a job on purpose will make things MORE difficult, not less...