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Ray,IN · 05-08-2018, 09:10 PM

Any disc brakes are subject to calipers sticking when they sit unused for many months, especially if the brake fluid is dirty or contains water. it causes corrosion in the system, and the caliper corrodes where exposed to air(rusts) preventing it from releasing pressure on the rotor. Brake pads stick to the rotor when unused because the rotor rusts. BTW brake fluid has a natural affinity to attract moisture, brake fluid should be flushed out and replaced with new brake fluid every 2-3 years according to vehicle mfgrs.
We never hear of these problems with drum brakes because they have springs to break contact between shoes and drums, and there are no exposed pistons to corrode.
Non-use is the hardest thing we can do to a vehicle, especially a MH.

Hit_the_Rhod · 05-09-2018, 06:34 AM

Quote:

Originally Posted by Ray,IN

Any disc brakes are subject to calipers sticking when they sit unused for many months, especially if the brake fluid is dirty or contains water. it causes corrosion in the system, and the caliper corrodes where exposed to air(rusts) preventing it from releasing pressure on the rotor. Brake pads stick to the rotor when unused because the rotor rusts. BTW brake fluid has a natural affinity to attract moisture, brake fluid should be flushed out and replaced with new brake fluid every 2-3 years according to vehicle mfgrs.

DOT 3, 4 and 5.1 are glycol-ether based, and are all hygroscopic (means they attract water)

Silicone/DOT 5 brake fluid (the purple stuff) is hydrophobic (doesn't attract water) HOWEVER is not recommended for use in vehicles with ABS brakes due to a propensity to absorb small air bubbles during the rapid pumping action of ABS brakes operating in the anti-skid mode. Check your owners manual, DOT 5 may be a valid replacement for you if water in your brake fluid/corrosion of internal brake parts has been an problem in the past.

Motor7 · 05-09-2018, 07:06 AM

Quote:

Originally Posted by Hit_the_Rhod

DOT 3, 4 and 5.1 are glycol-ether based, and are all hygroscopic (means they attract water)

Silicone/DOT 5 brake fluid (the purple stuff) is hydrophobic (doesn't attract water) HOWEVER is not recommended for use in vehicles with ABS brakes due to a propensity to absorb small air bubbles during the rapid pumping action of ABS brakes operating in the anti-skid mode. Check your owners manual, DOT 5 may be a valid replacement for you if water in your brake fluid/corrosion of internal brake parts has been an problem in the past.

Interesting, yes the water absorbsion tendency of DOT 3, 4 and 5.1 is a contributing factor to the sticky piston problem. I have always read that DOT 5 was simply not compatible in those other systems, so I will have to do some research on your information.

Periodic lubing of the caliper slider pins and cleaning rust off the Caliper bracket so the caliper can move freely are also just as important as having "dry" fluid.