Brake porportioning valve

I have a '96 Blazer with 210K miles on it. I"ve owned it since 73K miles, so am quite familiar with its quirks. One of the things I've put up with all these years is the inability for the thing to stop very quickly. When I loan it out to others, they are astonished at how long it takes to stop from road speeds in traffic. I also noticed that the rear brake shoes last FOREVER. It leads me to suspect that not enough pressure is being routed to the rear.

The Blazer has ABS, so is it perhaps an electronic problem or adjustment to be made in the ECM?

Is there a way to verify this? Is the valve adjustable, and if it is how can it be done. I really need to fix this.

Thanks,

Al

I have a '96 Blazer with 210K miles on it. I"ve owned it since 73K miles, so am quite familiar with its quirks. One of the things I've put up with all these years is the inability for the thing to stop very quickly. When I loan it out to others, they are astonished at how long it takes to stop from road speeds in traffic. I also noticed that the rear brake shoes last FOREVER. It leads me to suspect that not enough pressure is being routed to the rear.

The Blazer has ABS, so is it perhaps an electronic problem or adjustment to be made in the ECM?

Is there a way to verify this? Is the valve adjustable, and if it is how can it be done. I really need to fix this.

Thanks,

Al
Rear wheel or 4W ABS?
Most of your stooping power is in the front pads.
Also OEM rear shoes last a long time.

Has front pads ever been replaced?
ANY air in system?
Does it have good good pedal and good power on brake booster
Any ABS lights or red brake lights on or comig on?
On a hard stop can you feel ABS kick in?
Have you checked the rear shoes adjustment.

Does rear wheel slide on a hard stop?
A ABS capable scanner will show any problems with the ABS stuff.

I've replace my front pads at least 3 times in 160,000 + miles, my back ones are still good. I asked around about the back brakes, I was told its quite common for the 1 generation Blazer for the brakes not to adjust up automatically. I knocked out the adjustment plugs and adjusted the manually, even though my brakes have always seemed real good, even pulling a tractor on a trailer a few times. Mine is a 92 S10 4X4.

Aside from what's mentioned above, I've had slave cylinders rust up solid before.

Try several hard stops, then get under the truck and feel if one or both of the drums are cold. If it's cold, it's not braking.
You can remove the drum and hold pressure with both hands on the shoes while someone slowly presses the brake pedal. Check that both pistons move out with pedal pressure.

Rear wheel or 4W ABS?
Most of your stooping power is in the front pads.
Also OEM rear shoes last a long time.

Has front pads ever been replaced?
ANY air in system?
Does it have good good pedal and good power on brake booster
Any ABS lights or red brake lights on or comig on?
On a hard stop can you feel ABS kick in?
Have you checked the rear shoes adjustment.

Does rear wheel slide on a hard stop?
A ABS capable scanner will show any problems with the ABS stuff.
I'm not sure if it has 4W ABS. I have never been able to get the rear wheels to lock up on a hard stop, even on gravel. That doesn't seem right at all. One thing I have notice though is that on snow it stops quicker if I downshift to low while stopping. That means the rear wheels are stopping better than they do without the down shift. This is in 2wd, too. ABS system definitely works. No ABS lights are on. I replaced pads some time ago. I also replaced the rear shoes and had the drums turned, because they were glazed, but it didn't help. Maybe manually adjusting the shoes is the answer.

Most likely your 96 has ABS brakes. I'm not sure what year it was but they became standard equipment. And many have had much trouble out of their ABS brakes. I did at about 147,000 on the Blazer I bought new in 92.

Here is some information on them from Auto Zone.

http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?chapterTitle=Four%20Wheel%2 0Anti-lock%20%204wal%20%20System&partName=Brakes&pageId=0900c1528003de98&partId=0900c1528003ddb0

If you will do a search of '95 S10 Chevy + ABS brakes' you will come up with many hits and find much information. I found this topic on this forum about our lovely ABS brakes.

Here is many topics about ABS brakes on this forum.
http://www.automotiveforums.com/vbulletin/search.php?searchid=3132087


I did a bit of modification to mine after I bought a used EHCU/BPMV from a wrecking yard having it last about 6 months them it did the very same thing my original one did. The Chevy house wanted better than $1000.00 for a rebuilt EHCU/BPMV.

I did get a new master cylinder out of the Chevy house, they replaced the master cylinder thinking that was the problem yet it wasn't, and they did not charge me for it.

Jerry,

You might be onto something there. Perhaps if I just get the system bled by a pro, using the proper tools, my problem might go away.

Thanks for the hint.

AJ