Brake locks in very damp rainy weather

Have a 1995 Caravan that has developed an issue where one of the brakes will
lock even with just very light pressure on the brake pedal. After two to
three stops or driving for a block or so this will go away and they work as
normal. Any ideas would be appreciated.

PC Medic

 

Hi...

Been a GM owner all my life until a couple of weeks ago, so if
a GM experience is of help?

Olds 98 Regency. Even thinking of touching the brake pedal would
make the driver side rear lock up tight. Lock the wheel solid at
30 mph, scare everyone for miles around

Turns out that the cylinder had a miniscule leak, a bit of brake
fluid (invisible to my old eyes) was on the shoes. Tried everything
trying to salvage the almost new shoes. Cleaned 'em with brake
cleaner, sanded them with a bit of sandpaper and cleaned them again.
Cleaned the drum as best I could.

Wasted of time and effort; the only cure was replacing the cylinder,
cleaning the drum thoroughly, and replacing the pads.

Take care.

Ken

 

Front brake? Rear brake?


Matt

 

Rear passenger side. Only happens when wet/rainy out and only if vehicle has
sat for an hour or two.
Sunny days no problems


PC Medic

 

That is a weird one. Have you removed the drum and taken a look at it?
I'm wondering if the shoes are badly worn and they are "caming" when
you apply them? However, I can't think of any reason why being wet
would make any difference, other than the wet road might let the tire
slip more easily whereas even though the brake is being over applied on
a dry road, it may not be enough to lock up with the greater tire traction.


Matt

 

No haven't pulled the drum yet.
Brakes were just done in the spring (including all new hardware) so would be
surprised if had warn , but guess anything is possible.
I find it odd not only that the symptoms occur only when rainy out, but also
goes away after 2 or 3 stops.

 

Hi...

Answered once, just after you posted, but just in case that message
got lost in cyberspace

Brake fluid is hydroscopic. Absorbs every bit of moisture it can
get a hold of, even moisture from humid air.

Willing to betcha anything you like that you have a microscopic
brake fluid leak from the wheel cylinder, and the shoe/pad has
traces on it. Once that happens the only cure is to thoroughly
clean the whole area, change the pad/shoe (waste of time and effort
trying to clean or even sand it down), change or rebuild the
cylinder, clean the rotor/drum thoroughly with brake cleaner, and
you'll be good to go.

I'm new to Chrysler, used GM only for the past 50 years, it happened
to me on on an Olds 98. Just thinking about touching the brake pedal
locked up the rear wheel. Instantly, and completely. Woke people
up for miles around. Dreaded a yellow light

Take care.

Ken