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8ntsane
11-09-2006, 10:27 PM
Hello guys

I have a 99 GMC pick up 1500 rear wheel drive. I have been having troubles with the front wheel bearing assemblies. I have replaced the original set back in July, and they have gone south again.

I figured that I was doing the rite thing by installing AC-Delco dealer parts, but no such luck. The bearing assemblies I had installed back in July felt stiff as hell to turn when I got them, but turned smooth regardless. I bought another set and the new ones turned much easier this time, but felt like there was crap inside the bearing, dirt, grit or something.

Again these purchased at the dealer ,AC Delco units. Didn't,t have much choice but install them, because the ones I took out where on the verge of locking up. GM swears they don,t make crappy parts, yea ok. I had to buy the second set from them and wait for some type of inspection before they will cut me a check to warranty the first set. I didn,t at all like the feel of these new ones, but I had to put them in, or put the truck down and wait till they brought in another set.

I can,t be alone with this problem. My questions are , Do you think its a lack of grease in these things? I have looked the assemblies over, and there is a metal cap on the back side. I could remove the cap and install a zerk so I can pump grease into it with a grease gun. The other thought was being that the ABS sensor mounts into the bearing housing, I could make up a plug to bolt in there with a zerk, to pump grease into the bearing that way.

What do you guys think? I,m kinda thinking I should do both. These supposedly greased for life bearings are making me wonder. If I am to do this, what type of grease would be the best to use ?, so many types out there.


Anybody else going through this same problem?
And no, I'm not one of those curb bouncers that kill wheel bearings, rims and tires on a regular basis.

What's your thoughts on this guys?
Cheers

Yankee1
11-09-2006, 10:50 PM
Hi,
How much torque are you using when you tighten them? When I tighten them I pry the washer from side to side as I tighten until I get a snug drag on the washer. This puts some preload on the bearings but not too much.
Then key the nut in this position. This is the way Mecedes says to do them.
Works for me.
Regards Chuck

8ntsane
11-10-2006, 12:12 AM
Hi Chuck

This truck is a rear wheel drive.
The bearing assembly comes as a complete unit, and bearing pre-load is not ajustable on these things. These come complete as a hub with studs & bearing assembly. The whole deal just bolts to the spindle with 3-bolts.

I think your refering to the 4x4 front wheel bearing assembly that has the CV shaft running through the middle, with the washer and big nut.

But thanks for tryin

Cheers Paul

pcarpenter
11-10-2006, 11:29 AM
Hmmm...I've never seen a standard front hub (no front wheel drive) that didn't allow for pre-load adjustment. In fact, it is usually the 4WD stuff with half shafts that have no adjustment ability. Who knows though...it is the new design.

I'd find a shop manual and see what they say. I have a 2000 Chevy Silverado, but mine is 4wd. I have a third party manual and can check to see what it says about the 2WD wheel bearings this evening.

I would also check to make sure they are not supposed to be disassembled and grease packed in some fashion before use. Standard front wheel bearings do not come grease packed. My next suggestion would be to find a Timken auto bearing distributor and see if they sell a replacement.

Paul

winchman
11-10-2006, 11:38 AM
You're talking about the part that looks like this?
http://www.autopartswarehouse.com/images/apw_performance/images/timken/SP550304.jpg

It looks like it's for front-wheel drive, but the listing says it's for a 2WD Silverado. That's a Timken unit shown, and it's available here: http://www.autopartswarehouse.com/bizshop/bp/sp550306/timken.html

That's pretty bad when you have to buy a $170 part to replace $20? worth of bearings.

Roger

8ntsane
11-11-2006, 12:22 AM
Winchman

Yes the pic you had posted looks much like whats in my truck. The one in your pic must be for a 4x4 as I can see the splines in the centre. Mine looks the same ,looking at it from that shot, with one exception, mine has a metal cap on that side.

The front side has just a snout to locate the brake rotor, thats it.
The 99GMC trucks are the same truck, new style as the 2000 on up.

There is no way to grease these things, or ajust pe-load as far as I can see.
I have been told this type of bearing assembly is not servicable, only replace-able.

Cheers Paul

Bguns
11-11-2006, 01:08 AM
Those bearings are popping up every where :( The intent is for assembly line _____ (insert favorite derogatory term) to slap on and be done, no greasing, no wheel bearings to adjust. Cheaper to charge customer to replace whole unit than adjust, clean, and reseal regular bearings. Pitiful design if you need to dunk under water out in the boonies, can't service grrrrrr.......The bearings can be replaced on some units with care and a press but, are custom ground for preload and nobody sells the special seals......... Another design problem is that since the bearings are so close together, the leverage of the tire/wheel is highly
loading the side by side bearings. Would you buy a lathe with ONLY one set of those bearings supporting the spindle, and nothing on other end of spindle?? JUNK JUNK JUNK JUNK.............

tryfred
11-14-2006, 07:20 PM
Went the “replace the front wheel bearing route” every year with my wife’s 1999 Blazer.
A friend that is a Master Mechanic at a Chrysler dealership said it was due to static electricity generated by the tires and arcing through the wheel bearing eating every thing up…. Solution was an anti static strip of rubber attached to the frame…dragging on the ground. Although I was skeptical I bought a strap but never installed it. The next year (like clockwork) after I put in yet another set of bearing I attached the strap…never had another problem…with the wheel bearings anyway.

Joe

wierdscience
11-14-2006, 08:36 PM
Yep,I see a lot of those,ditch the AC part and buy the Timken,they are better by a fair degree.

The trouble I see with them from the few I have taken apart is the outer race IS the mount it's self.The outside of the mount is soft and only the ball grooves are hardened.The design sucks period.

I mentioned ball grooves also because all of the factory units I took apart used ball bearings instead of rollers.I see this change being made for one reason only,life expectancy.Tapered roller sets lasted too long.My old 90' Rnager has 650,000 hard miles on it and the only thing I ever did to them was pack them and replace the grease seals in a brake job.

A.K. Boomer
11-14-2006, 08:42 PM
Tryfred that is a good point to bring up, also the little cars that get towed by dolley behind motorhomes cross country can have a rough life, a bearing needs to rotate or it will "brinnell" --- the ones that are sitting on the dolley actually have a great chance of failure because they are fretting away with no lube being distributed between the contact points and the contact points never change position...

BadDog
11-14-2006, 11:24 PM
Those are called "unit bearings" and they are the scourge of the automotive world for everyone except the MBAs. This is particularly true of the HD 4x4 trucks which use them. As mentioned, they can’t handle the loads and they have to be replaced as a “unit” which costs about 8 times what a set of bearings would cost. The silly mall wheeler/posers with late model 4x4s lifted and running large tires with positive offset go through them (among other overloaded parts) every 10k and sometimes less.

tryfred
11-18-2006, 08:03 AM
The wheel bearings were just one of the many problems we have had with our Blazers...how many hazard warning switches do you think we went through?...when the hazard warning switch goes bad the brake lights stop working...ABS problems...wiper motor problems...etc ...etc...Altough we have been a Chevy Family forever...we found the fix for all of this...Toyota...