Wheel bearings

Tiny
TULPA
  • MEMBER
  • 2007 CHEVROLET SILVERADO
  • 4.8L
  • V8
  • 4WD
  • AUTOMATIC
  • 157,000 MILES
I suspect my wheel bearing is bad. A few days ago it started with a light squeak while driving the yesterday it began to grind. I jacked up the passenger side and spun the wheel. Felt quite a bit of resistance and it made and awful noise. Took the tire off and the breaks and I noticed my rotor has been grinding into my caliper brackets. I have new brakes. Spun the hub and the noise is still there. I also noticed that the boot on the CV joint is a bit broken and grease is all over the place. Could water have gotten in through the boot and rusted the bearings? Bearing were replaced about four years ago.
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Monday, June 20th, 2016 AT 6:14 PM

7 Replies

Tiny
CARADIODOC
  • EXPERT
Nope. The bearing is a totally separate sealed assembly. The boot covers the CV joint. It has the ribs to squeeze the grease back into the rollers with every revolution, and to keep dirt and water out. A torn boot can be replaced, but it has to be done before damage occurs to the joint. Your mechanic will clean the old grease out and install new grease that comes as part of the kit.

Be aware that rebuilt half shafts today are uncommonly inexpensive so it no longer makes economic sense to replace a torn boot. A rebuilt half shaft can cost less than $100.00 and it takes about an hour to replace. A replacement boot can cost $30.00 and takes an hour to clean the joint and replace the boot, in addition you need to partially remove the shaft. By replacing the whole shaft, you will pay more for parts, less for labor, and have a better repair.

If there is still grease being flung from the CV joint, the joint has not had time yet to wear to the point it causes noise. When it does, in perhaps a year or more, you will hear a clicking sound when turning and mostly when backing up. CV joints never make a grinding noise. To be chewing up a caliper bracket suggests something else is wrong like the bearing assembly is coming apart. It is held together by the large nut on the end of the CV joint. That nut must be tightened to a very specific torque spec which is very high. Most cars call for around 180 foot-pounds, but some GM cars call for as much as 240 foot-pounds. A wheel bearing will become noisy when any vehicle weight is placed on it while that nut is not fully tightened. The noise will sound like the buzz of an airplane engine.
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Monday, June 20th, 2016 AT 7:20 PM
Tiny
TULPA
  • MEMBER
Thank you :-)
I figured it was the hub assembly. Why would it go bad so fast? Would it also explain why the brake pedal would sink to the floor if I did not pump it a few times before stopping?
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Monday, June 20th, 2016 AT 8:14 PM
Tiny
CARADIODOC
  • EXPERT
Absolutely. A wobbling brake rotor will push the piston back into the caliper, then you have to push it back out to apply the brakes by pushing the brake pedal further than normal. Pushing the brake pedal over half way to the floor can damage the master cylinder when it is more than about a year old. That is because crud and corrosion build up in the lower halves of the bores, and running the pedal further than normal runs the rubber lip seals over that crud and can rip them. The symptom at first is a slowly-sinking brake pedal, but that often does not show up for a few days.

This did not happen suddenly. A sloppy wheel bearing develops that slop over time, long after it becomes noisy. There is no way it can come apart unless the axle nut is not tightened to specs.
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Monday, June 20th, 2016 AT 9:39 PM
Tiny
TULPA
  • MEMBER
Thanks again, I will check out the master cylinder also.
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Tuesday, June 21st, 2016 AT 6:51 AM
Tiny
KEN
  • ADMIN
These bearing go out all of the time and the slop in the wheel can push the pads into the caliper which gives you the low brake pedal, here is a guide on how to replace the bearing.

https://www.2carpros.com/articles/how-to-replace-a-wheel-bearing-hub

Let me know how it goes.

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Thursday, June 23rd, 2016 AT 11:53 AM
Tiny
TULPA
  • MEMBER
Sorry for the late response. Yes I replaced the hub assembly, rather quickly actually. And it was bad I could almost pull it apart by hand.
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Sunday, July 17th, 2016 AT 2:28 PM
Tiny
KEN
  • ADMIN
Good to hear, saved a couple bucks as well, glad we can be of assistance come back anytime we are here to help.

Best, Ken
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Sunday, July 17th, 2016 AT 4:04 PM

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