Rust in wheel cylinders - The 1947 - Present Chevrolet & GMC Truck Message Board Network

JimKshortstep4x4 · 10-09-2002, 09:27 AM

Rust occurred in the rear wheel cylinders from the time I rebuilt them until the the truck was on the road, (approximately 4 months). They were on the rear end which was assembled with the wheel cylinders/brakes/drums etc. installed. This is a first for me, having rebuilt hundreds of them.

The procedure that I use is pretty standard, clean, hone with mineral spirits as a cutting fluid, clean with mineral spirits, (more than one time), clean with alcohol, and clean with brake fluid.
Assembly is done using liberal amounts of brake fluid, (Prestone).

I am concerned that there is a problem with the brake fluids anti-corrosion properties and I am looking for experienced suggestions or ideas. Are there better corrosion resistant fluids that you have had experience with?

Any input would be appreciated.

Jim

Fred T · 10-09-2002, 09:42 AM

The problem is that DOT3 and DOT4 brake fluid absorbs moisture. Therefore, when brake fluid is left exposed to air, it absorbs the moisture from the air. Since you don't want any contaminants in the fluid, after assembly of the cylinder I would completely fill the cylinder with brake fluid and cap the bleeder hole.

You could consider using DOT5 which is silicon base, but don't mix the 3 or 4 with 5. And the hydraulic proprties of 5 aren't as good as 3 or 4, so you get less actual shoe pressure.

JimKshortstep4x4 · 10-09-2002, 10:50 AM

Fred,

Good point on the moisture potential!

The cylinders were installed with the bleeders tight and the lines in place. Moisture would have to have entered through the lines from the front end, although my practice of taping open lines was followed in this instance. Taping may not be the best solution, but 3M masking tape should seal any moisture out and the completed frame was inside at all times awaiting the cab.

Jim

Willy Prost · 10-09-2002, 05:00 PM

My suggestion for next time would be to use vacum caps that would fit snugly over the ends of the brake line.

That should be a better way to keep moisture out than masking tape.

10-09-2002, 09:27 AM	#1
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Rust in wheel cylinders Rust occurred in the rear wheel cylinders from the time I rebuilt them until the the truck was on the road, (approximately 4 months). They were on the rear end which was assembled with the wheel cylinders/brakes/drums etc. installed. This is a first for me, having rebuilt hundreds of them. The procedure that I use is pretty standard, clean, hone with mineral spirits as a cutting fluid, clean with mineral spirits, (more than one time), clean with alcohol, and clean with brake fluid. Assembly is done using liberal amounts of brake fluid, (Prestone). I am concerned that there is a problem with the brake fluids anti-corrosion properties and I am looking for experienced suggestions or ideas. Are there better corrosion resistant fluids that you have had experience with? Any input would be appreciated. Jim

10-09-2002, 09:42 AM	#2
Fred T Cantankerous Geezer Join Date: Aug 2002 Location: Bel Aire, KS Posts: 6,264	The problem is that DOT3 and DOT4 brake fluid absorbs moisture. Therefore, when brake fluid is left exposed to air, it absorbs the moisture from the air. Since you don't want any contaminants in the fluid, after assembly of the cylinder I would completely fill the cylinder with brake fluid and cap the bleeder hole. You could consider using DOT5 which is silicon base, but don't mix the 3 or 4 with 5. And the hydraulic proprties of 5 aren't as good as 3 or 4, so you get less actual shoe pressure. __________________ Fred There is no such thing as too much cam...just not enough engine.

10-09-2002, 10:50 AM	#3
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Fred, Good point on the moisture potential! The cylinders were installed with the bleeders tight and the lines in place. Moisture would have to have entered through the lines from the front end, although my practice of taping open lines was followed in this instance. Taping may not be the best solution, but 3M masking tape should seal any moisture out and the completed frame was inside at all times awaiting the cab. Jim

10-09-2002, 05:00 PM	#4
Willy Prost Senior Member Join Date: Jan 2000 Location: Arlington, VA Posts: 398	My suggestion for next time would be to use vacum caps that would fit snugly over the ends of the brake line. That should be a better way to keep moisture out than masking tape.



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