1993 K2500 brakes

[ewordal]

I just replaced my front brakes on my truck for the 3rd time in the last 2 years. It keeps warping the rotors. This time I replaced the rear brakes as well. The truck has 180,000 miles on it and the rear brakes had never been replaced and they were about 1/2 worn out. I had already bought all the parts, so I went ahead and turned the rear drums and put new shoes and wheel cylinders. I still just don't understand why the rear brakes don't seem to be operating and it seems to be the reason for the front brakes overheating. Has anyone figured out a way to fix the problem? Maybe a new proportioning valve? It has Rear Wheel Antilock brakes, is there some inherent problems with those? Thanks, Erik

[trbankii]

How much do you run it loaded? Typically the front brakes do a greater percentage of the work, especially when unloaded, since the weight shifts forward when you stop. I can see that a 2500 would be "light" in the back without load and shift even more stopping work to the front brakes.

My Toyota has a load proportioning valve for the rear brakes that adjusts the pressure to the rear brakes based on load. Haven't gotten into my GM enough to know if it has a similar setup. If it does, perhaps this valve is not adjusted properly on yours or has stopped working?

[Hubert]

I am no brake expert but isn't there something about keeping the rear brakes adjusted. Something like the auto adjusting "star" mechanism siezes up with brake dust and rust etc???

Normal driving not loaded my rear I don't think adds a whole lot of stopping power. Only during heavy braking, if it rains, or I hit a bump while braking moderately hard can I skid the rear tires a little then the anti lock brakes dumps pressure and I have to stand on brakes (with pedal soft and lower than normal) to stop. Not a pleasant feeling.

I have a Mitsubishi that has over 245,000 miles on rear shoes and lost count on front pad replacements maybe (5) sets. It stops pretty good so I just put gas in it and check oil every day. I doubt the rear is anywhere near adjusted correctly but parking brake still holds ok.

I have generally heard to avoid the lifetime front pads and stay with OE or similar so pads wear and they don't wear front discs excessively.

[Turbo Al]

It is possible you have a caliper problem. Are you cleaning and lubing the slides when replacing the pads?? I actually take mine apart about once a year and clean the slides and put never-sieze on them.

I have 180,000 miles on mine,
Never touched the rear shoes 50% left
frount pads -- first set -- factory original replaced after five years when one of the pads FELL off of the backing due to rust.
The second set lasted about five years before they wore out
The last set is still about 80%

I have never turned the rotors just slapped the pads on -- Yes I know that is just plain wrong LOL The rotors do need to be replaced at this time.

Al

[jspringator]

The guys on the old v-mag suburban forum used to recommend manually adjusting the rears at every oil change.

[HANK1948]

I agree manually adjusting the rears is a must and I do this as often as I can and It makes a HUGE difference, The automatic adjusters dont work, eveytime I adjust the brakes I can make them click at least 10 clicks thats telling me that the auto adjusters are for crap!

[CaseyR]

In manually adjusting the rear brake shoes, how many clicks do you back off after getting the shoes snug to the drum?

[twaddle]

I agree with Turbo Al, you may have a front brake caliper fault that is causing the brakes to stick or just keep the brake pads against the discs which will cause heat.
When you have driven several miles stop gently so as not to heat up the brakes, check the front wheels and centre hubs for heat, all you need to do is touch the hub or near the centre of the wheel. If the brakes are sticking they will feel very hot . Let us know if they felt slightly warm, hot, very hot or "ouch" unable to touch hot?
Also try jacking up the front wheels right after a drive and feel if the wheels turn easily or not.

Are you generally running empty or very light loads? Running light usually means that the rear brakes get less pressure to them (helps stop rear lock up and prevents skidding) but increased pressure when loaded for more stopping power.
I have also found that the rear brakes last a lot longer than the fronts.

Good luck

Jim Twaddle
Biggar, Scotland

[ewordal]

I do haul loads and pull a trailer quite a bit (the trailer has it's own brakes though). It seemed to be when I was pulling the trailer that the brakes warped, but I am not sure. I put on new drilled and sloted discs, new AC Delco calipers, and Hawk Ceramic pads. I also replaced the brake shoes and wheel cylinders in the rear and had the drums turned. I will keep the shoes tight and see how long the front lasts. I just wondered about the proportioning valve or the RWAL system, if anyone had problems with those.
Thanks for the advice. Erik

[JoeyD]

Make sure the adjuster is free and not siezed and rusted as most are. Keep the rears tight and they will keep the front pads from a quick death.
I use a custom method for rear adjustment and it works great, when it's wet out a hit reverse and hammer the throttle to make the wheels spin fast then slam on the brakes and you will feel instantly a better pedal. You don't even need to move much as the wheels spin easy in the rain. Maybe back yard but works.

[signgrafix]

Don't forget about the brake lines. You know I had heard that for years and I always thought, Now how can a line go bad? It looks fine, it is not leaking.
Well it finally happened to me on my previous truck. It drove me crazy. When hitting the brake it would allow fluid in, but would not let it escape properly. Actually what happened was the metal clip that holds the line to the A arm began to build up rust on the inside of the clip. The rust started squeezing off the line. You could not tell by looking. I think I have the same problem on the truck I just bought. It pulls to theleft on braking and you can park on a slight hill and it will not move. Let it set for about a minute and it starts to roll. I am not taking any chances I am re-doing the calipers and purchasing new lines.
Another thing is where are you purchasing your rotors? Believe me there is a difference between Auto Zone (aka Auto Return) type rotors and a NAPA type rotor.

[ewordal]

I did get my rotors from Napa the first and second times. I bought their low cost rotor the first time (it had a lifetime warranty, so what the heck). After those warped the owner allowed me to get a credit on the better ones and I rebuilt the calipers on the second time around (thinking that might be the problem). When the second set warped I thought they must be a cheap replacement compared to the original chevy rotors, so I went to the local chevy dealer where they showed me the replacement rotors that they sell. I had already taken the rotor I bought at Napa off my truck so I brought it with to compare with the GM rotor (by the way Napa and GM both said they were made in America, Canada is stamped on the rotor, so I guess they mean North America??). Anyhow the rotors were identical, even the same number stamped on it. GM did offer a bosch rotor that was a upgrade over the stock rotor for around $150 a piece (they looked nice, but I headed back to Napa).....bored yet....hang on a couple more lines and I let you know what I I finally did. Napa turned my rotors and they warped again so I bought some Raybestos Brute Stop rotors that are drilled and slotted (rockauto.com), Hawk Ceramic pads that are supposed to disipate heat better (tirerack.com), new GM calipers (GM parts direct.com) and new front brake lines (Napa...and I am still waiting for them after 5 days, could have gotten them for half the price if they had told me that it would take 5 days instead of telling me they would be there the next day). On the rear I bought raybestos brake shoes and new wheel cylinders (rockauto) and cleaned and lubed the backing plates and adjusters. I hope after all that the brakes will actually work and not warp, but only time will tell. Thanks a lot al you guys who checked in and gave some help. Erik

[twaddle]

Erik,
Are you sure that the trailer brakes are definately doing their share of the braking?
I know that when I'm towing a heavy trailer I can feel the trailer brakes holding the trailer back when they bite and when they need adjusted I think it's never gonna stop.
As far as the truck is concerned you seem to have covered just about all the angles there is to cover.

During your investigation into the problem did you jack up any of the front wheels and try to turn them just to see if the brakes were binding?

Good luck

Jim Twaddle
Biggar, Scotland