what causes hub bearings to fail so often ?

KEEBZ489

Registered Member
this will be the 2nd time in less than 2 yrs i am replacingmy driver side hub , and im using delco parts. i read a lot of people consider them wear and tear maintence parts , what causes failure so much ?

i just started having noise last week and was afraid it was my disconnect getting worse so i replaced it and the axle ( surpised it didnt completley fail it looked so bad ) but today driving to work the noise is still there , and im 95% sure its the driver side.

i was afraid it may be the differential , but reading other posts and seeing some youtube vids on differential noise it isnt clicking , it sound like mud tires , and yes , i checked my tread when it started last week.
 

cornchip

Hobbyist
I'd say it boils down to part quality more than anything. Trusting an AC Delco more than another brand is kinda a false hood when the original part that failed was a Delco. I have FAG branded hubs that are re-boxed Timkens, and they have held up a good 80,000 miles thus far. I believe they were made in the US, but again that is not an indication of quality.
 
Possibly incorrect torque of the hub nut (too tight) causing a slight compression force which during the bearing heat / cool cycle may cause run problems which then increases the temp further over time... just my guess with failures to date. I am currently running with a "re-used hub" that I took off thinking it was failing so I had replaced both. One was indeed bad but the other appeared to be OK. The two "non-names" both failed in a little over a year, hence the current state, one new replacement and one "pre used".
Of course, the quality of the bearing components (balls, I think but could be pins) is also some cause as I believe the "ball process" is a science.
 

Mooseman

Master Blaster
Moderator
It also depends on who supplies them to ACDelco. Over the years, they probably changed from one maker to another. They don't make any parts. They're just rebranded from other makers. I know for sure that brake pads and rotors are from Raybestos, spark plugs from NGK and their fuel pumps from Bosch. Who knows who supplies their hubs but was long suspected as being SKF but that could have changed. For the most part (pun not intended), their parts are quality pieces as I would imagine they don't want to put their name on junk.
 

littleblazer

Gold Supporter
Working on the Vette... most of those front end parts were stamped with their OE manufacturers name on it even though they had GM numbers. The suspension components are Alcoa, the hubs NDH, and on and on. It was actually nice knowing it was a company rather than whatever GM reboxed for cheap. Probably why they stopped doing that lol.

Timken only makes taper roller bearings to the best of my knowledge allegedly so any other style of hub they buy the parts from other manufacturers. At least for the vette parts anyway. The older hubs for my car were also stamped NDH. Now they're stamped China and most of the guys running them say they last a weekend of track use... for a 130$ part that sucks. But they're all medium duty now and SKF only makes rears.

As for saying the stub nut torque messes with the bearing... that whole center is cast and impacts no bearing preload. I suppose you could warp the housing but you'd have to go way too tight to do that. Last time I did my truck I wrenched one down and the other torqued to the 4t lb ft reccomended by the manual... they both have almost 100k on them now so we'll see lol.
 

TollKeeper

Gold Supporter
Been wondering that same thing myself. I am on my 4th set in 111k miles.
 

cornchip

Hobbyist
For my own information, did the 2wd GMT360's have dummy stub's installed in the front hubs? Or are that a completely different part # altogether?
 

TequilaWarrior

Active Member
Premature failures occur for one primary reason: bad design.
Modern engineering focuses on economy instead of longevity. So, they squeeze every bit of material out of the design they can, specifying the lightest duty components that will meet a specification. If you would've shown me a GMT360 wheel bearing 30 years ago, I would've sworn it was out of a small import car, not a 2 and half ton American SUV. That any of these bearings make it past 100,000 miles is frankly amazing to me. 40 years ago, if a set of bearings made 40,000 miles, THAT was impressive.
 

Mooseman

Master Blaster
Moderator
For my own information, did the 2wd GMT360's have dummy stub's installed in the front hubs? Or are that a completely different part # altogether?
Only the 2wd TBSS did. Possibly because they thought it might be subjected to extra lateral forces while cornering. Others were left empty.
 

Mektek

Hobbyist
Possibly incorrect torque of the hub nut (too tight) causing a slight compression force
I tested this. With most of the metal parts that retained the bearing cut through, it still took nearly 20 tons of force to push apart the hub. So you would need an industrial duty impact gun and deliberately overtighten it to risk damage.
It is a very complex and precise manufacturing process to through-harden the outer bearing race. It is machined out of the same steel as the body of the hub so normally too soft for this application. Some chinese factories really cut corners on this with minimally trained workers and that results in low prices and short lifespans. :mad:
 

littleblazer

Gold Supporter
Only the 2wd TBSS did. Possibly because they thought it might be subjected to extra lateral forces while cornering. Others were left empty.
Learn something new every day. I don't get why but... I guess it was for some reason. :confused:
 

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