Rain causes brakes to "grab"


I have a 1991 Chevy Astro Ext van, 2WD, 4-speed automatic transmission, approx. 130,000 miles. I purchased it used (But in very good condition) three years ago.

An annoying quirk it has had ever since I first got it (And that the previous owner also had) is…every time it rains, the brakes become over-sensitive, and begins to “grab” quite severely. For example, if I’m going 25MPH or slower and I barely touch the brake pedal, the wheels lock up and the van screeches to a halt as if I had suddenly slammed both feet against the brake pedal with all of my strength. If I’m going faster the wheels don’t lock, but there’s still a sudden lurch and slowdown, again as if I had slammed on the brakes. The problem eventually goes away after a few minutes of driving, only to occur again the next time it rains.

Now, I do know that the van does have antilock brakes, but that the antilock part no longer works (It’s been this way for years, since long before even I got it, yet the local auto repair shop for some reason says nothing is wrong with the antilock). Could this have something to do with it? Maybe the computer that controls the antilock brakes is getting wet and malfunctioning, causing the brakes to grab full-force whenever the brakes are applied?

Whatever the cause…it’s very annoying, and it’s only a matter of time before this problem causes someone to rear-end me. What can I do to stop this from happening?


if its just the rear brakes you might want to replace them and turn the drums. I had a truck do that and this fixed the the rear problem.


your answer is in the sentence:

“…yet the local repair shop for some reason says nothing is wrong with the aintlock.”

find another shop.


When you or a shop replaces the rear brakes, check the adjusters. With the age of this truck, they may be rusted tight or jammed. Mis-adjusted rear brakes can do this.

Also, with the anti-locks. Is the ABS light on? Does it even come on when you first start the van? If the light is on, there is a problem with the ABS, and the computer is trying to tell you that. Find another shop.


I had the same “problem” with the factory brakes on my 87 Ranger.

On foggy or rainy mornings the brakes would grab.

I would simply drive it at 50 MPH & lightly ride the brakes for a couple of seconds to dry them out.

After doing the first brake job at 140,000 miles the “problem” went away.


Apparently the factory brakes would absorb water, but the aftermarket pads/shoes that i used did’nt.

As dougie3980 sez the solution to this might be as simple as installing new brake shoes/pads.