I am going to replace my front brake pads this weekend and have a few questions. when i change just the pads do i have to bleed the brakes? if so is there a special procedure for bleeding the brakes on the hydroboost system? what kind of fluid should i use? thanks for answering my questions in advance.also i wanted to take my rotors in to get machined but it seems a little hard to take them off and put them back on but i dont think i have the correct tools to do the job ,does anybody know if this is hard to do.thanks

IF you dont't loosen any of the bleeder valves or brakelines, then no, you will not need to bleed them. To change the pads, you will need to remove a bolt (allen head) to pivot the caliper up, and off the rotor, remove the old pads, and using a large C-clamp, compress the piston on the caliper. If you think the rotors need turned, then, I THINK, you can do this by using the above instructions to get the caliper off of the rotor--you MAY need to remove the caliper completely, but be sure to leave the lines on it and use a string or coat hanger to keep pressure off of the brake lines. To remove it completely, there's 2 allen-head bolts, maybe 3, that hold the caliper on. Take these 3 bolts out, and the caliper will slide up, and off of the rotor. The rotor should then "pop" off of the spindle. Not very hard, and sorry for the sketchy details, but it's been a while. I've not worked with the newer trucks too much. Be careful removing the rotor from the spindle--I've broken a few STUCK ones by hitting them a little too hard.

Rotors really aren't too much money to replace. What I've seen is the heat fins in the middle can rust so bad they will split the two halves.


On you're truck on the back side of the spindle you will find four bolts holding the rotor on. After unbolting them the rotor will now come straight off, sometimes rust will hold them on so a little persuasion might be needed.


Half ton trucks are much easier. The rotor slips off the wheel studs.

Most of the time it's the same price just to replace the rotors as long as you have the old ones for the core charge.

The rotors are wear items and don't carry a core charge. It cost about $7.00 each to turn them here and new one run bout 35.00 or so. Turning better than replacement at that price. Edited by: bowtie

The rortor are wear items and don't carry a core charge. It cost about 7>00 each tio turn them here and new one run bout 35.00 or so. Turning better than replacement at that price.


Is it the brakes then, I alway's thought there was a core charge on one of the two.http://www.dieselplace.com/forum/smileys/smiley5.gif

The rortor are wear items and don't carry a core charge. It cost about 7.00 each to turn them here and new one run bout 35.00 or so. Turning better than replacement at that price.


Is it the brakes then, I alway's thought there was a core charge on one of the two.http://www.dieselplace.com/forum/smileys/smiley5.gif The rear brake shoes have a core charge but not the front disc nor the brake rotors.

Look at your fluid. If it's cooked, bleed it from the rear first till you dump all that fluid.

Let me add something to this posting. Many of the application systems use either the Kelsey Hayes RWAL (rear only) or 4WAL (4 independent channel) ABS systems. The dump valves in these systems are notorious for failure due to contamination, and one of the surest ways to get the ABS modulator contaminated is to force old brake fluid in the reverse direction back through the modulator in the process of retracting the caliper pistons for new pad insertion.


The preferred method is simple: After removing the caliper and pads, position the caliper in between a big set of channel locks (sorry...a proper caliper piston depressor tool). Just begin to squeeze and at the same time open the bleeder screw. Now, as you retract the piston in the bore, the displaced fluid will exit the bleeder instead of up through the modulator and into the master.


Truth is that most moisture actually enters the brake system through the flexible brake lines (that are semi permiable). Since the water is heavier than the brake fluid, it settles in the calipers. So actually, retracting the caliper pistons in this fashion is good practice and allows for fresh fluid to enter the caliper.


Thanks,


Jim

.also i wanted to take my rotors in to get machined but it seems a little hard to take them off and put them back on but i dont think i have the correct tools to do the job ,does anybody know if this is hard to do.thanks





Is your truck 2 or 4 wheel drive? All the responses sound good for a 4x, but on a 2 wheel drive truck the procedure is more involved and involves repacking the front wheel bearings.......Don't try to beat a rotor off a 2wd truck!!!!!

I have replaced the calipers, master, all fluid and the hydroboost on my dad's K3500 '96. It recently lit the ABS light. I checked the wheel sensors and I think he only has two on the front brakes. It counts gears on the frontdrive axle or something. It was mentioned these were the most susseptable sensors to failure in the system.I was thinking of replacing both of them, any thoughts?

My '95 also has intermittant ABS failure light coming on. Sometimes it is good for days, then when light braking/coasting to a stop at a light I will feel the antilock vibrate the pedal, and the light comes on. I suspect a bad wheel speed sensor, but how to be sure? Are they optical or magnetic? How do you tell which wheel as I only have them on the front wheels that I have noticed.

Sensors are proximity sensors (inductive as opposed to Hall trigger). Memory serving they trigger off an impulse wheel (AKA tone ring) pressed onto the back of the front rotors. The closer the sensor is positioned to the tone ring, the higher the AC voltage signal generated. Make the following checks: Check wheel bearing runout. Excessive runout changes clearance. Check for buildup of magnetic particles on sensor tip and clean as needed. Check tone rings to be sure that they are not cracked. These are powder metal units pressed on and they can be susceptible to expansion coefficent changes and therefore cracking.


Jim

I reread my reply and realized that I didn't answer your question. To check a wheel speed sensor, simply disconnect the harness connector by the wheel and connect the leads of a DVOM across the sensor side of the harness connector. Place the meter on the AC volts scale. With the meter connected, rotate the wheel slowly...then faster. As the speed increases, note the voltage increase. Write down the rotated wheel RPM (like once per second) and the corresponding voltage. Do this for each wheel. While rotating the wheel, wiggle the harness connectors, etc to check for opens. I suspect that the reason you feel the ABS come on is that one of the WSS is dropping out intermittantly, and when you press the brake it's detecting a locked wheel.


Jim