barfan1

Most of the full size truck hub assemblies are still tapered bearings inside of them, like traditional tapered bearing sets that used to be on the front wheels of rear drive cars. The failures I have seen of hub assemblies usually center on seal failures which let comtiminants into the bearing, ABS cable/sensor errors, and overtightening of the hub axle nut. The torque spec on the hub axle nut is critical on many of the GM hub units as they are not "roll formed" so the overall preload on the bearing can be altered if the axle nut is really over tightened, i.e. with an impact gun. There were a few TSB's on this where GM changed the design of the axle nut and lowered the torque specs on many models. Most hub assemblies are double row ball bearings which is a very robust design, almost all imported cars have used this design for many years, the exception with inports vs. domestic being these are single bearings pressed onto a spindle which is then bolted onto the car. GM wanted this all in one piece a long time ago and the design really puts the seal quality and installation critical to the longevity of the bearing. Also, many hub assemblies are damaged when people take a hammer and beat off rotors or drums when replacing brakes. This can pit the raceways on the bearing or damage the seal causing bearing failure down the road.

diskullman

Not true at all. Delphi does not have the capabilities of manufacturing bearing races.
These are integral bearing hubs, the bearing is only supplied with the hub, and is not servicable seperately.
There is some rebranding of bearings (You'll get an SKF in a Chicago Rawhide box, as SKF owns CR)
Stay away from Chinese bearings.

barfan1

I think my last post was too wordy, it is true Delphi/KBI does not make individual bearings, they only make assemblies. I was was trying to show that even though most bearings nowadays are ball instead of tapered sets, they are still durable. The bearings themselves rarely fail, it is the seal or ABS or installation error that causes the hub assembly to fail. And Delphi has not made bearings for 3 or 4 years, they sold the operation to KBI and exited the business.

asanti

Not to threadjack, but would a pulsing feeling when you apply the brakes be a need for new hub assemblies? I ask because I've got a fairly new set of OEM rotors and pads on my SS which went on after only 22K miles once the OEM pads started scraping metal. I've noticed lately that if I do a "hard stop" or slow down from a highway speed the steering wheel shudders as if the "rotors are warped". I'm leaning towards the brakes not being the problem, but as has been mentioned in this forum before, I may have a hub that's not true. Any suggestions, and is this still covered by the 5/100K warranty (I'm past my 3/36K already).

Thanks
Allex

hyperv6

It can be a bad hub bearing. They can be checked for play and only sould show 1-2 thou of play.

It also could be very well that the brakes were never seated in and pad material is embedded in the rotor surface. Too few people seat in the pad properly and this often leads to after a hard stop a spot where pad material will embed into the hot rotor and create a spot where it will grab and make for the pulse feeling you have.

By seating in the pads it leaves a even coating of pad material on the rotor surface all the way around it. This prevents you from getting one spot where the material sticks. One hard stop gettin off the freeway will do this as you stop and the hot rotor will bind with the rotor surface.

Think of it as if you spilled a coke on a kitchen floot and tried to slide across it. The coke will leave sticky surface that grabs your feet.

It still could be the hub as they do cause this but often it could also be the material on the rotor. Check the pay and you will know.

Greybeard999

@ Allex....... When this happens, especially slowing as you come down a freeway exit does the pulsing go away if you press harder on the pedal? Mine just started doing this and it doesn't happen all the time...... I'm on 30K with original brakes. Never had this before recently....... Not sure what to think because it's inconsistent.

And before hyper starts with the brake deposit story again... I know about it and I don't use the brakes that way where it would cause this..... Were they bedded properly? ask the dealer 30K ago.... answer would be "no" but this just started.

I've been thinking bearings just starting to go out, myself.

hyperv6

Deposits on the rotors are often only felt under normal braking. If you stand on them they will not show as much or at all. This sounds as if what your issue may be. Hot spots can create these in higher miles too.

As for the hubs it could be this too. All you have to do is check the play and you will know if they are good or bad. With low miles I would not really count on this one but it still could happen.

But note it is not the rotors that make the pulse feel. The bearings being out can create the conditions where rotor thickness variation is caused. This is where because of the bearings being out the rotor will wobble and bounce off the pads. Over time 10-20K miles it will let the rotors wear uneven and create a pulse feel. Only this one will not go away under heavy braking or come or go. One you have it that bad it is here to stay. Deposits can get better or worse depending on conditions.

Like I have stated before go to the tech sections on the brake companies web sites and they explain these things and even have videos to show what happen. Bendix has a great one and other have similar info. Knowledge is how you fix these issues and not repeat them. These things are no secerets and the info is available.

If you read up and learn the things that can cause and you will be better prepared to identify what is going on and correct it.

This stuff is not rocket science and is one of the most misunderstood issues there is today with the auto industry. Even by some long time mechanics that got behind on new issues.

As for not using your brakes that way it takes little to cause this use under the right conditions. I think you will find that the deposits are your problems if the condition comes and goes. RTV and bad bearings don't come and go.

asanti

@ Hyper: The pulse is evident only on hard braking at highway speeds (70-80 mph). If I'm city driving and stop for a light they're fine.


Later
Allex

bk94si

Thanks for this bit of info. I have wondered why I have to replace hubs eventually on all my cars now and almost never had to 20-30 years ago.

diskullman

Your hubs can be out too

http://www.brakealign.com/