Front Wheel Bearing Wear From 4x4 Use?

[oski6754]

I have a 1972 GMC Suburban, 1/2 ton, 350ci/350TH/NP205 bone stock setup that seems to corrupt front wheel bearings after limited 4 wheel drive use. (my theory)

I went back country camping this past weekend and used 4 wheel drive for about 25 miles, only to return to pavement with a growl in the right front, which I believe is a wheel bearing.

Both L&R front bearings were replaced with high quality parts less than 2 years ago after using 4x4 under similar circumstances.

Has anyone else experienced anything like this or have any theories as to what might be going on?

[jeffahart]

Originally Posted by oski6754

I have a 1972 GMC Suburban, 1/2 ton, 350ci/350TH/NP205 bone stock setup that seems to corrupt front wheel bearings after limited 4 wheel drive use. (my theory)

I went back country camping this past weekend and used 4 wheel drive for about 25 miles, only to return to pavement with a growl in the right front, which I believe is a wheel bearing.

Both L&R front bearings were replaced with high quality parts less than 2 years ago after using 4x4 under similar circumstances.

Has anyone else experienced anything like this or have any theories as to what might be going on?

No that ain't right. Should get many miles on road and locked in offroad. did you replace outer races too? If you keep them greased they last.

[oski6754]

Originally Posted by jeffahart

No that ain't right. Should get many miles on road and locked in offroad. did you replace outer races too? If you keep them greased they last.

Yes, outer races were replaced too. Any thoughts?

[jeffahart]

Originally Posted by oski6754

Yes, outer races were replaced too. Any thoughts?

Jack it up and grab the tires and see if the wheels wiggle, like the bolt is loose. I'm assuming it's one wheel or the other, not likely they both went bad at once. If it's loose start working your way inward. If not, I would start eyeballing some other stuff, like the ball joints. Your little offroad excursion is just making a bad component show its wear.

[jeffahart]

I got cut off on my last little reply. So, also, does it grind when you jack up and spin the wheel. It could be as simple as a rock stuck up in around the backing plate or something like that. Just rule out the easy stuff first like rocks and loose nut. But if the wheel is loose, you should check the bearing and not just tighten it. If all looks good tighten the spanner to specs.

j

[70K10Hunter]

72 should have manual hubs, I would make sure they are fully disengaging,

[kwmech]

The bearings shouldn't care whether or not it is in 4wd, they are just supporting vehicle weight. Just like a full float rear axle, they just ride on the spindle. I think they are not being installed or maintained correctly

[oski6754]

Originally Posted by kwmech

The bearings shouldn't care whether or not it is in 4wd, they are just supporting vehicle weight. Just like a full float rear axle, they just ride on the spindle. I think they are not being installed or maintained correctly

It's certainly possible that they weren't installed correctly. What is the proper maintenance for wheel bearings?

[kwmech]

First off, the correct matching ones. Everything being stock on your truck, the inner should be 603049 bearing and 603011 race, outers are all the same from 68-91 with a 501349 bearing and 501310 race. Clean quality hi-temp grease.... races in tight and fully seated. Torque the inner nut to about 50 lbs with the hub turning. Back off the nut till you can turn by hand, tighten by hand until it stops. Install locking washer as you line up the pin holes, holes are offset to the keyway, so you can flip the washer over. Install outer nut and tighten to about 85lbs or so. Done. Install locking hub and bolt on the wheel. Been doing it this way for 40 years, never had a problem. Good idea to check them about once a year if you do a lot of driving

[special-K]

True, the bearing/races are independent full time move parts unchanged in 2wd or 4wd. Same thing as 2wd only different dimensions. I clean/check/grease mine annually, just to know I'm on top of it. I put over 8k on my '72 last year. I also clean and lube the caliper sliders at that time.

Any way, it's a mystery to me. All I can say is get it apart and look real hard. Show us what you see. Check part #s against each other. One thing that comes to mind are the spindle treads and/or nuts. I've seen the bronze spacers on the outside instead of inside. That shouldn't affect the bearings I don't think. The problem when I find this is 4wd doesn't engage.

[oski6754]

Thank you for all of your feedback. I believe the issue must have started at installation (over torqued) and just happened to show up after 4x4 use. As I get into it, I will let you know what I find.

[70K10Hunter]

As was stated the bearings don't know when you are in 4wd they will be in use when the truck is moved/driven.

[72MARIO]

I have had trouble with my plow trucks front wheel bearings. I think my problem is they get water past the seal and they get pitted and rusty. I haven't found a solution yet.

[El Dorado Jim]

is the noise only when you have your hubs locked , and in four wheel drive? if so it is probably your axle U-joint or joints....some of the original ones were non greasable, they make a growling sound when going bad

[oski6754]

Originally Posted by El Dorado Jim

is the noise only when you have your hubs locked , and in four wheel drive? if so it is probably your axle U-joint or joints....some of the original ones were non greasable, they make a growling sound when going bad

No, the noise occurs all of the time. I am 100% sure it is the wheel bearing going bad, but wanted to know if the cause of the premature wear had to do with 4x4 use. Sounds like that cannot be the cause and that improper installation or maintenance is the issue.

[RedRoad]

I had a similar problem on a 74 SWB K10 years back. Would be fine just driving around town no load but after a bit of thrashing off road they would be toast. Thought it was crappy bearings so got spicer parts but still the same. Went through the front end and replaced all bearings and seals, u joints and ball joints. After the rebuild the bearings would last a normal life span.

Not sure but maybe the wasted ball joints were to blame? On another truck changing from deep dish rims with heavy tires to narrow rims and tires also extended outer bearing life.

Make sure to inspect the spindle and hub, if hearings have spun in the past they may be damaged enough to need replacement.

[BILT4ME]

I had a 69 K1500 with a 75 front axle under it. I was having issues that the wheel bearings would be loose every 5,000 miles.

After having replace the bearings and races every time, I figured that the HUB had to be deformed.

I bought a NEW hub from GM installed new bearings and races, adjusted them per the 1975 FSM, and never had to adjust them again in over 40K miles.

In my case, I believe the hub was egg-shaped and caused failure because the races had been swapped so many times.

[oski6754]

Just to close the loop on this, the cause of the premature failure of the new bearings was due to piss poor, stupid, lazy installation.

The shop I was using at the time did not clean out the grease from the previously failed bearing, so there was still a ton of metal debris/shavings in the grease which quickly worked its way into the brand new bearing and caused it to fail. So dumb.

[Zoomad75]

That's good to hear. Such a simple operation I feel not many get to do anymore because the modern stuff all takes sealed unit bearings that eliminate the need for manual packing of the bearing and adjustment.