97 K Burb, soft brakes
 

I know this comes up every now and then and I have yet to see an absolute cure for it.
Once again I am looking to make mine better. Pedal moves too far and feels mushy. It did have better brakes but that changed when I replaced the pads. I went from a ceramic pad to a good Wagner pad. I changed these again to another pad hoping to get that better brake feel back. Did not. I pushed the pistons back into the calipers to get the new pads in like I always have done. I read that is a mistake as it can push trash up into the abs controller. So I bled, bled and bled some more trying to get it back.
So far I replaced calipers, rubber hoses, master cylinder and readjusted rear shoes, front pads numerous times. Fluid is clean and clear.
I see mention of a dump valve on a 98 Burb. Can that be purchased separately or does it come with the whole abs shebang?
Next thought, is the abs controller the problem and can I take it off line to see how it then performs? Plumb around it.

I see real similar symptoms in this thread but I don't think new rear shoes and drums are the cure. In his case it surely helped however.

http://67-72chevytrucks.com/vboard/s...ghlight=brakes

Re: 97 K Burb, soft brakes
 

Mushy brakes on chevy's are the norm. My wife's Durango will throw you through the windshield. Seems we have over boosted steering and under boosted brakes.

May want to either look into a proportioning valve or increasing the vacuum to the brake booster.

All I can think of.

Re: 97 K Burb, soft brakes 4 wheel ABS
 

I found some disheartening info in a lowly Chiltons manual.
The Kelsey Hayes 4 wheel anti lock brake system is a complicated beast. It cannot be serviced.
The Electro-Hydraulic Control Unit controls the pressure within the brake lines. The unit is made up of 2 types of valves, isolation valves and dump valves. The valves are controlled by micro computers within the EHCU. The EHCU operates by receiving signals from the wheel speed sensors and the brake lamp switch.
In a severe brake application the EHCU valve will either allow pressure to increase within the system or maintain (isolate) the pressure within the system or release existing pressure through the dump valves into the accumulators.
Bleeding the EHCU valve requires 3 special tools and a Tech 1 scanner or it's equivalent. Bleeding cannot be performed without this equipment.
It says the abs control unit (EHCU) has to be bled itself before bleeding at the wheels can be done in order to completely remove all air in the system. 15 step procedure.
These ABS control units are quite pricey. Some going for several thousand $ on high end vehicles.
A new control unit is not a viable option for this 14 yr old vehicle. I have another unit from my wrecked 97 GMC but it's the same age and I still have to have those dealer tools to bleed the system. Taking this old truck to the dealer will cost a fortune also as they will want to replace the WHOLE brake system even though many parts are new.
I don't think I can disable the ABS (plumb around it) without the dash light staying on.
So at this point I am using the truck as is until such time as I learn of a better way to get the good brakes back.

Re: 97 K Burb, soft brakes
 

been rockin my mushy pedal for a while. i have my mastercylinder over filled with a little tape over the lid because its broken but it helped some. it doesn't help i have almost nothing for shoes. and my pads arent to happy about taking most of the braking. like 90% because of lack of shoes.