'92 Ranger brake trouble

[irregularjoe]

A few days ago I started having problem when I braked. The truck feels like it is on a wet road.....ie: it skids forward.
I found that the front pads and rotors were severly worn and replaced both sides along with new retainer pins. I bled the fronts. I then inspected the rear shoes and drums. They were OK, and I adjusted them.
But I still have the same problem! Truck slides forward when the brakes are applied hard. And this happens at any low speed too. The wheels are locking up for some reason.
I heard that it could be a RABS problem. Does that sound like the logical diagnoses?

Any help appreciated.
Thanks
Joe

 

[ranger2001]

Front or back or all 4 locking up? Bleed the system again. Sounds like air in the system causing them to grab.

 

[irregularjoe]

I don't know.
I'll try bleeding again.
Thanks

 

[johnnydeb]

if the bleeding does't work check your calipers.

 

[DeRocha]

I heard that it could be a RABS problem. Does that sound like the logical diagnoses?

Any help appreciated.
Thanks
Joe

No it doesn't sound like it at all... ABS is the Exact opposite of what you are describing. ABS actuates a solenoid within the ABS hydraulic control unit to release pressure in a brake line for a wheel whose sensor indicates it is no longer rotating (compared to the other wheels)... so if ABS activated you'd feel the pulse through the brake peddle and hear it pulse..

Air in the system isn't the problem either... if air gets into the system the brake peddle will feel real spongy and drop to the floor..

Having said all that if all your brakes a locking it could be a problem with your master cylinder or proportioning valve.. If only one wheel is locking up then you need to recheck the calipers and slides to ensure you cleaned/removed rust from their slide tracks. If the pins and pathways get rusted they can prevent the caliper from releasing thus causing brake issues.

 

[irregularjoe]

Having said all that if all your brakes a locking it could be a problem with your master cylinder or proportioning valve.. If only one wheel is locking up then you need to recheck the calipers and slides to ensure you cleaned/removed rust from their slide tracks. If the pins and pathways get rusted they can prevent the caliper from releasing thus causing brake issues

Thanks. The mechanic said something about the proportioning valve also.
I just replaced the master cylinder last year, so I don't think it's that.
I'm bringing it to the shop today.
I'll post what happens later.
Thanks

Joe

 

[irregularjoe]

OK. Here's the latest.
Took it back to the mechanic yesterday. He pulled the front calipers, disassembled them and showed me the rusted and pitted insides.
Replaced them both (which I could have easily done myself when I changed the pads and rotors......)
But I figured just get it over with........
Drove off the lot, hit the brakes, SAME damn problem!
Brought it back again today and they found lots of air around the RABS valve.
Bled the entire system and finally it works.

Bottom line: New pads, rotors, calipers......although I needed them, that wasn't the cause. Not enough fluid getting to the rear brakes was.
Live and learn.

Joe