andy z

I have a 97 chev 3/4 ton 4x4 pickup. When the weather is damp and I apply the brakes the first few times in the morning, it seems to get full brake pressure to the rear wheels, even with the lightest touch of the brakes. It hits so hard it throws you forward into the steering wheel if you are not ready. After a few stops they start working correctly. This is the second chev truck I've owned with this problem. Any ideas on a cause?

MDTAHOE

Clean and adjust the rear brakes. For some reason GM products lock up the rear brakes when they are under adjusted.

andy z

I've had this truck for 6 years with no problems. The last year the adjuster was froze solid on the left rear(I knew this because my e-brake went to the floor). I still had no problem like this when it was out of adjustment. It literally jambs the brakes on with just the very lightest touch of the pedal and only does it when it is very damp out. Even so, I will crawl under and adjust the brakes. I can see the mechanics of what you are talking about, but am perplexed at why it does it only when damp or humid.

BDaddy

I have this exact same problem in my '98 2500 4X4 truck. For me in Colorado it happens usually during the winter (usually our wet time of the year with melting snow/ice). I nearly ran into the back of my wife's car at a stoplight because the rear wheele locked up, then triggered the ABS and gave almost no stopping ability to the truck. This was on wet pavement, not ice. My mechanic looked at the brakes, cleaned them and said they were fine - usually the brakes out of adjustment which he said will readjust after backing up. I stopped using the emergency brake, thinking that might have caused an issue with adjustment. Nothing has fixed it for me. I have considered disabling the ABS fuze because of the risk of not having any brakes when it locks up.

Post if you find a solution.

maxxman04

you guys live in a climate that gets really cold in winter, which causes the fluid to freeze just a bit, not frozen per say, but it gets really cold which makes it act like it's thicker, not releasing pressure right away cause it can't move very well.

bsballfn172

I've had the same problem in my '98 1500. I would tap my brakes as I came to the end of my driveway and they would just completely lock up. It would only do it if it was kind of damp out and hadn't been driven in a while. I always just put up with the problem 'cause it would stop by the time I left the driveway. If you do figure out the problem though, please let me know. It would be nice if I didn't look like an idiot stopping short every time I took the truck out in the morning

andy z

Well guys, I crawled under and finally adjusted the rear brakes (the left rear wheel adjuster is not working). It did seem to help the problem, but I haven't had a good test. I don't use the truck much (4000 miles a year). The other day it was damp out and the left rear locked again, but not as violently as before. The right rear wheel adjuster is working fine (don't know if it locked up or not). I will be using the truck this whole week, but it is going to be warm and dry so it will not be affected. I'm wondering if it doesn't have something to do with the age of the shoes. Mine are about 4 years old and the cheapest ones I could find. Are they possibly soaking up dampness and locking? Let me know if you try anything and how it turned out for you.