Warped Rotors over and over

Hi there,

I've joined this forum to attempt to find a problem to an ongoing problem I have with my truck. I have a '98 G1500 full size van (sorry, I'm posting to the Tahoe section, but it seems like a popular group, and these vehicles have a lot in common).

I have 215K miles. Original brakes lasted over 125K miles (lots of highway), were replaced, and lasted another 50K, and since then, have needed replacement ever 5-10K miles. It's getting ridiculous.

I have been diligent about putting on new wheel bearings with new rotors, and have tried everything from cheapy AutoZone rotors to really expensive high quality rotors made here in the U.S, as well as Canada. I've tried doing a final grind before installing, per other recommendations, to guarantee that the rotors are truly flat before install. Nothing works. They keep warping, at the same rate they always do.

My technique for installing rotors used to be tighten the bearing nut on the end of the spindle with a wrench, to a few foot lbs (maybe 10), then back it off, and tighten it as much as I can with my fingers until I can slide the pin through. I've been told to be more aggressive with overtightening initially, to guarantee that the bearings seat properly. That has not made any significant difference. I've also tried adding a little bit of extra preload to the bearings before pinning, with no luck.

I've been careful with torque on the lug nuts (i.e not overtightening the nuts). Nothing seems to make any difference.

I use high quality Napa brake pads, and have tried the crappy $20 Autozone pads in the past.

I've had similar experiences with past vans. Other mechanics hear my story and are not surprised. I feel like nobody knows what is going on.

I am wondering if the wheels bearing spindle could be affecting this. The spindle is definitely worn, probably from the bearings wobbling around during the worst vibrations. I have a hard time believing I'm the only one that has this problem, and find little evidence of this being a common replacement on trucks (spindles seem to be mostly sold as a complete disc brake kit for custom work). Has anyone been able to correlate this to warping rotors? I see no evidence of blown balljoints or steering joints, and the shocks are performing fine (I've heard lots of people blame warped rotors on front end problems, and I'm skeptical).

I'd appreciate any input.

Thank you,

Karl

I have had to replace the front wheel bearings on two cars recently, one a Corolla and the other an Impala... neither one had made it to 100K miles yet either!  Your spindles might be galled from previous bearing damage I should think.  I would also think that if you are not using a torque wrench to tighten to specifications.... well maybe that is a problem as well.  I would think also that the runout of the rotors would tell you if they are in specification.  A tech would put a dial gauge on them and spin them.  There should only be so much plus and minus from zero readings (ie, the runout).  Sounds like this is old news to you, but just trying to throw out some ideas.

An issue that can add to this in our older vehicles is the caliper not sliding freely enough to allow the outside pad to disengage completely from the rotor, causing the rotor to heat. 
 
Search this forum for some info on the proper lube to use to aid in allowing the caliper to float more freely on the pins.
 
I currently upgraded to SSBC calipers and rotors and we will see how that goes.

I'll move this to the Express section after a while. We have good techs that go all over the forum, so no need to post in the wrong section to get an answer.

Expresses and G vans have big problems with wearing out pads prematurely. You may want to try ceramic pads next time to see if you can cut down on the heat buildup.

Thats a good point about calipers needing to slide or glide to function properly.  If your pad wear is even then there is no issue, but I had uneven pad wear and the problem was rusty caliper pins that wouldn't allow the caliper to function properly.  Root causes are really nasty to determine, aren't they.  By the way, my ATV manual calls for silicone grease, if that can extend to car brakes, but ATVs are in the water more than a car, so maybe cars use something else.  A call to dealer service would advise you.
 
Then again, maybe a simple call to the dealer service dept. might tip you off to a solution, since they may see the issue frequently and know the fix. Some dealer service people are good about kicking around ideas on the phone, some aren't, so try a few if you haven't already.  Also, Euro's idea is good as well about the posts.

Thanks for all the input so far!

I don't have the info on the NAPA pads that I am using. I expect they are ceramic, but I might be wrong. They have a lifetime warranty (meaningless, really), and NAPA will give you replacement pads for the life of the pads. They came with all new lube and seals for the calipers, and prior to using these pads - these are the nicest set of pads I've ever seen for a van, and at $85, the most expensive.

I do make a point of re-lubing, and using a brillo pad on the glide pins if there ever were to be any rust on them. There is none on these, and they're nicely lubed. That does bring up a question though - it seems that an extraordinarily small amount of lube should be used. These pins have a fairly high tolerance, and if you put on a dab of grease, they tend to not pull in and out easily, since the lube fills the gap and creates a pocket of stuck air at the end of the pin, in the blind hole into which they insert. I wonder...

The spindle is not really galled - it's just worn, kind of like a cam lobe with high mileage. It's not worn uniformly though, so I worry about high tightly that inner bearing race sits on there, and the fact that it is clearly  rotating on the spindle (or a set of bearings did at some point, probably due to inadequate bearing preload), which I expect it is NOT supposed to do. I just hate to spend a small fortune replacing them if there's no indication that this is the source of my problems. I'll see if I can take some pictures - I think that may help y'all determine if this is at all significant.

Thanks!!

Karl

Have you applied slide lube to the surface of the spindle where the caliper rides? You should be able to move the caliper freely side to side after the install with little force. If the caliper isn't moving freely than the heat build up and uneven pad wear will happen.

A couple of things to check ( I had a 1997 Tahoe that went thru rotors also) service your rear brakes they help keep some of the load off the front ( 70% front 30% rear typical loading)
check your front calipers as they may be clamping down on the rotors differently and casuing excessive heat, don't forget to check the brake lines also the can sludge up after many years of not being bled.
given that the truck is 10 years old I'd consider replacing the front calipers and brake hoses along with servicing the rear shoes and brake assemblies and checking out the proportioning valve.