How often is often enough?

[Werdegast]

For the most part how many years should one leave his brake fluid in the master?

To prevent potential problems.

Thanks in advance for the candor.

[Mike Van Veghten]

Years....?

I change the fluid in my bikes twice a year.
Same for the cars, though most don't.

As the fluid soaks up moisture, it starts to turn brown. The darker brown, the more moisture. The moisture or water that's in the system causes the fluid to strat to break-down. It looses it ability to withstand the heat generated by the brake system, and the less effective it becomes. The wet and dry boiling points fall rapidly.
I'd imagin a Google search will explain in great detail how often and why it needs to be done thAn every "few" years.

You can actually feel the difference (should be able to feel...!) in fresh fluid vs. two year old fluid.

So a long story short, flush out the old and replace with new when the fluid is amber and before it turns brown. Your system should last and work "properly" (not just ok....) for years maintaining it this way.
If you don't have a clear plastic reservour you may need a syringe or something simillar to extrace the fluid from the M.C. to check it's color.

Mike

P.s - most road and oval track racers flush the system... before EVERY race. Most Drag Racers flush their systems two or three times a year.

[N8N]

I believe that two years used to be the recommended limit, before manufacturers started trying to stretch maintenance intervals to make their cars look better on long term comparison tests...

nate

[52 Ragtop]

2-3 years, also Raybestes recommends replacing rubber brake lines every 3-4 years!

Jim

[Werdegast]

I had all the whl cyls and master ss sleeved......in the five yrs since I changed the fluid I have had no leaks.....but I knew that was pushing it so I changed the fluid yesterday. the car is garage kept and only driven maybe 500 miles per year. Opted for dot 3 as opposed to dot 4 or change to dot 5 .

[Aussie Hawk]

What's the procedure in changing over from the old style brake fluid to the silicone based fluid ? Apart from the moisture absorption is it woth doing ?

[StudeRich]

You should find literally hundreds of posts here with a search for Silicone Brake fluid or DOT 5, through FLUSHING is the key.

[Bob Andrews]

most road and oval track racers flush the system... before EVERY race.

Just my two cents- I raced on oval tracks for 24 years, up to 160 MPH winged Supermodifieds, and neither I nor anyone I know of ever changed the fluid like this. During the off-season teardown/rebuild the fluid would naturally be drained and therefore replaced. Never had a problem, either with the high-end racing brakes or the stock type in the lower classes.

Of course, it won't hurt anything, but I can't imagine it would make any difference; sounds like overkill to me.

[jclary]

During the off-season... the fluid would naturally be drained and therefore replaced...

Well Bob, I had to pick and choose only part of your last post to explain how I keep fresh brake fluid in my cars...in fact... all fluids in my cars kinda naturally drain!

[Paul Keller]

Check out the Dec 2010 issue of Hot Rod Magazine. Near the back in the tech (or some other name) area there is a great discussion on the pros/cons of Dot 3-4 vs. Dot 5 (which is the silicon based fluid), along w/ several cautions and a couple of web sites as reference. You can also check the major retro brake suppliers (such as Baer) for their recomendations. Dot 4 is a higher temp rated fluid, otherwise the same as Dot 3.
DO NOT CHANGE TO DOT 5 (Silicone) UNTIL YOU HAVE CHECKED TWO OR MORE OF THE ABOVE SOURCES!!! There are some serious potential problems.
Pau K