Brakes: After forty four years...........

[Hawklover]

Ok I have had it with the single master cylinder, and it's leaks!

So no rebuild, no new...........better!

Going to a dual master cylinder.

Some questions: If I go the route of R5 fluid and I blow the lines out from the R3 fluid, what about the small residuum of fluid left in the front and rear wheel cylinders?

If I stay with R3 fluid, how soon do you think rust pitting in the cyl walls will commence with the resultant effect of rubber perforation/leaks?

[jackb]

....if it is a later model car with lots of cylinders available....just keep the Dot 3 and flush every 2 years.....that is if you have a driver. I don't see your location, but if down warm where you can drive the car most of the year...no problem. If its a show car with valet service at car shows...do the whole thing NORS and Dot 5....

[SN-60]

I like Dot 5.....except for its tendency to find a way to leak even if there IS no way!!

[52 Ragtop]

If you convert to DOT 5, flush the lines out with alcohol, remove and rebuild the wheel cylinders, and or calipers, Check the dates on the rubber brake hoses, if no date, replace them! as DOT has required ALL brake hoses to be coded with both the date and manufacturer since at least 1977!

Jim

[Hawklover]

Jim,If I stay with DOT 3, would a 24 month complte fluid change prevent pitting and seal damage/leaks?

If you convert to DOT 5, flush the lines out with alcohol, remove and rebuild the wheel cylinders, and or calipers, Check the dates on the rubber brake hoses, if no date, replace them! as DOT has required ALL brake hoses to be coded with both the date and manufacturer since at least 1977!

Jim

[RadioRoy]

You could switch to DOT 4, which is similar to DOT 3, but does not attract moisture as aggressively.

[over50]

Over all the years and cars I've had, I haven't had any particular problem with brakes and DOT3/4. I don't flush brake systems. On "old vehicles" I've bought, I've always upgraded the systems as stopping and tires are the two most important safety features. I think the key is having a sealed brake system, not one that is vented to atmosphere. Be sure that the master cylinder cover or remote reservoir covers are the sealed type that have a bellows feature to account for expansion and contraction of the brake fluid. I wouldn't go thru the hassle of trying to use DOT 5.

Norm

[Dan Timberlake]

The Volvos I've known have had vented MCs. They specify Dot 4 and a brake fluid flush every 2 years or so. If left in longer than that the fluid gets progressively dark. When buying a used one real dark fluid is kind of a warning sign. Clear fluid does not guarantee the bleeders will unscrew and no pistons are seized, but I think clear is good.

[StudeRich]

The Vents in Master Cylinder Caps are there for a reason! The system has to breath, do NOT plug them.

[over50]

Years ago (60's and 70's) manufacturers got rid of vented caps and went to the sealed caps with a bellows arrangement to mitigate this problem. You either have to change the master cylinder to one with the sealed type cap or find a sealed bellows type for your master cylinder. If you read my reply, nowhere did I say to just plug vented caps.

Norm