screetching noise coming from underneath

Justin · Post by **Justin** » Sun Apr 18, 2004 6:34 am

Maybe you guys can help me pinpoint the problem. Just noticed it a couple of days ago and i think its getting worse. Whenever i brake and accelerate, a screetching noise is heard. It's not a solid tone but has a pulsing schreetch. I can't tell if it stays after 15 mph (because of the exhaust noise) but it is there at the most annoing part, when people see and hear it at a stop. I think it's coming from the rear end so I'm gonna jack the truck up, spin the tires and see if it is the axle which could be brakes or maybe bearings.....I hope its just the brakes

Post by **HenryJ** » Sun Apr 18, 2004 6:59 am

Rock stuck in caliper? Brakes worn out?

quickbiker · Post by **quickbiker** » Sun Apr 18, 2004 6:26 pm

HenryJ wrote:Rock stuck in caliper? Brakes worn out?

Yea, try reverse. I had some'm like dat, and I just reversed and it fell out.

Justin · Post by **Justin** » Tue Apr 20, 2004 8:28 am

ok i took one of the rear wheels off and noticed that the pads were still in pretty good condition. the outside pad looked new but the inside pad had half wear. On the other hand, the rotor looked horible. It was terribly uneven throughout the face. Some of the rotor had deep scratches. I think I'm going to replace all brake pads and have the rotors machined..then see how that works

Justin · Post by **Justin** » Tue Apr 27, 2004 7:04 pm

well i said screw it... Replaced rotors and pads in the rear...fronts looked brand new... Can anyone describe why my rear rotors and pads went at 40k and my fronts look new.. I mean i realize my brakes may have been improperly setup but why would the rear brake more than the front...shouldn't it be opposite on trucks???

smokinjoe · Post by **smokinjoe** » Tue Apr 27, 2004 7:10 pm

well im not sure if the same applies to all disc brakes but with cars or trucks with rear drums and front pads, the rears give about 70% of your stopping power.like i said though im not sure if the same applies to all disc brakes

Mat73GNZ · Post by **Mat73GNZ** » Wed Jan 04, 2006 12:09 pm

I had the same screaching coming from the rear of my truck, turned out to be the brakes also. The same thing happened to the rear brakes as did the front (which I had recently replaced both rotors and pads). The caliper slide pins are dry and sticking, allowing only the inside pad to make full contact and stop the truck. Both rotors are completely shot along with the pads. There are very deep grooves in the rotors and they are so deep, it's almost scary.

Just a reminder for you guys, like what was said in another thread, lube those slide pins!

I can't believe I have to replace these so soon. Just five or six months ago, there was at least 60-70% pad left. Figiured they were fine and wouldn't touch them. Now I wish I had lubed those pins...

Anyways, is there an easy way to get the rear rotors off? I have them coming off almost all the way, but they seem to be catching on the shoes for the e-brake inside the rotor. Should I just use a pry bar and pop it off, or is there an easy step that needs to be taken in order to remove it?

Mat73GNZ · Post by **Mat73GNZ** » Wed Jan 04, 2006 1:04 pm

Nevermind about getting the rotors off. I just used a BFH and a pry bar and it came off. The bad thing that I now found is my passenger side axle seal is leaking... will it never end with this truck?

Now I know why my e-brake wasn't working very good, there was oil all over inside the rotor hat.

I'll shoot a couple pictures of what happened to the rotor and pad because of the sliders a little later.

EDIT: Well, after I got off the rotors I took apart the calipers. The drivers side just had one slider stuck, but was easy to take apart. The passenger side caliper is completely frozen, both sliders will not move. Quite a bit of fussing and swearing later, it still will not budge. I lifted the rubber boots as much as I could on the sliders and it is packed full of rusty colored grease. I shot some PB BLaster inside the boots and I'm going to see if I can seperate it in the morning. If not, I'll have to hit up a junkyard... This is getting expensive!

killian96ss · Post by **killian96ss** » Wed Jan 04, 2006 5:20 pm

smokinjoe wrote:well im not sure if the same applies to all disc brakes but with cars or trucks with rear drums and front pads, the rears give about 70% of your stopping power.

You kind of have this backwards. The front brakes do about 70% of the total braking while the rear does 30%. If the rear brakes are wearing faster than the fronts then a couple of things could be wrong. Stuck caliper slide pins and air in the front brakes. I mentioned this in another thread, but it is very important to lube the caliper slide pins periodically. I do it every other oil change, or at least every 10k miles. Brake fluid needs to be changed every other year as well since it does break down and absorb moisture.

Steve

F9K9 · Post by **F9K9** » Wed Jan 04, 2006 5:37 pm

killian96ss wrote:................................................You kind of have this backwards. The front brakes do about 70% of the total braking while the rear does 30%. Steve

That is what I understood the workload to be on the front and rear braking systems but, awaited a more knowledgeable source to arrive on the scene.

I had a 97 2-dr tahoe that would eat front pads at 4K until a good tech noticed the rear drums were basically not working.

killian96ss · Post by **killian96ss** » Wed Jan 04, 2006 7:37 pm

A popular mod on the SS like I have is to remove the delay spring and plunger from the front/rear proportionig valve to achieve better brake balance. In stock form my SS had about 80% front brakes and 20% rear. After doing this mod I ended up with 60% front and 40% rear brakes. The improvement was amazing and the back brakes never lock up before the fronts. I have considered doing this to the Crew, but my only worry is the light back end we have, unless your using a camper shell or have something heavy in the bed at all times. You definitely don't want too much rear brake.

I might still do this mod to the Crew, but I will likely add an adjustable rear proportioning valve so I can adjust the rear brake pressure according to the weight in the bed. At 71k miles my rear brakes are still at about 60% while my fronts are about 20%. This alone tells me that I need better proportioning.

Steve

rlith · Post by **rlith** » Mon Jan 09, 2006 5:05 am

Killian, except the prop valve on our trucks is inside the ABS unit itself...