Front wheel bearings coming loose every 1000 miles

[BTraci]

Twice now, after being fine for 20,000 miles after getting replaced, the front wheel bearing tension has untorqued itself. After the first time, I reset torque but had to reuse the star washers, nuts, other hardware. It has now become loose again in just 1000 miles. Is reusing the hardware likely the culprit, or is there another common cause for this? Thanks greatly for any advice or guidance you may have.

Best,
Rob

 

[highonpottery]

Star washers have the protruding male tab on them to prevent them from being able to back-off -- is the little tab missing?

 

[gatormark91]

Star washers have the protruding male tab on them to prevent them from being able to back-off -- is the little tab missing?

Do you have two 54mm nuts? Dumb question, but if the nuts are torqued, and the star washer and claw washer are in the right place, it can't come loose.

 

[JunkCrzr89]

Are you bending one tab of the star washer back and another tab forward, so that it prevents both nuts from backing off? To answer your question - yes the star washer should be replaced every time

 

[BTraci]

Has both 54mm nuts and use star washers, tightened and bent; but the star washers are pretty chewed up; will re-do with new star washers.

 

[JunkCrzr89]

Has both 54mm nuts and use star washers, tightened and bent; but the star washers are pretty chewed up; will re-do with new star washers.

What are you torquing the nuts to?

 

[flintknapper]

What are you torquing the nuts to?

^^^^^

My question as well. IF the proper bearing pre-load is achieved, both 54mm nuts are in place and the star washer properly installed, then nothing can back off. Only 'wear' could cause looseness at that point.

BUT if the bearings are not properly pre-loaded....they will eventually displace the grease and 'seat' themselves resulting in a loose bearing.

 

[BTraci]

Was torquing the nuts to 47 lb-ft

 

[thebeedeegee]

Was torquing the nuts to 47 lb-ft

Did they get you to the proper break away? My torque ended up more than that I'm pretty sure to get the right breakaway

EDIT- nevermind I just checked my old post apparently I was at the same torque.

 

[gatormark91]

Did they get you to the proper break away? My torque ended up more than that I'm pretty sure to get the right breakaway

EDIT- nevermind I just checked my old post apparently I was at the same torque.

More torque than the FSM is going to be needed for used/repacked bearings. I think mine are up around >50ft/lbs right now to get 14lb breakaway.

 

[flintknapper]

Twice now, after being fine for 20,000 miles after getting replaced, the front wheel bearing tension has untorqued itself. After the first time, I reset torque but had to reuse the star washers, nuts, other hardware. It has now become loose again in just 1000 miles. Is reusing the hardware likely the culprit, or is there another common cause for this? Thanks greatly for any advice or guidance you may have.

Best,
Rob

Rob, I can only relate my experiences with wheel bearings on the 100 series.

It is important to start with good quality bearings and races when replacing (Koyo/Timken/etc), lesser quality bearings simply do not last.

When installing new bearings....I have found that it takes about 47-54 lb. ft. of torque to get them properly seated and the preload (roughly 12 lb ft) achieved. You will need to rotate the hub both directions quite a bit and check the torque several times before being satisfied all has settled.

When repacking used (but good) bearings.....I have always found that it requires MORE torque than stated above to get the the same 'break away' figure (12 lb. ft.). I don't have a good explanation for that....just that is has been my experience.

Remember bearing grease is a 'compressible' so DO work the hubs back and forth well to distribute the grease and let the bearings 'seat' before calling it good.

Hope you get it figured out.

 

[JunkCrzr89]

More torque than the FSM is going to be needed for used/repacked bearings. I think mine are up around >50ft/lbs right now to get 14lb breakaway.

x2 - I had to torque freshly repacked but used bearings to 54 ft-lbs to attain the spec’d breakaway.

 

[2001LC]

Twice now, after being fine for 20,000 miles after getting replaced, the front wheel bearing tension has untorqued itself. After the first time, I reset torque but had to reuse the star washers, nuts, other hardware. It has now become loose again in just 1000 miles. Is reusing the hardware likely the culprit, or is there another common cause for this? Thanks greatly for any advice or guidance you may have.

Best,
Rob

Saying "reset torque" indicates you're not following proper procedure. Torque is just a number we get indicating how much pressure we put on bearings, while setting breakaway preload (BPL). Spec is 9.5lb to 15lb breakaway preload. On a stock 100 series I shoot for 12.5lb BPL, on built with over sized tires and or wheel spacers. I shoot for the limit of 15lb BPL

Assuming wheel cavity 97% filled with grease, bearings packed, good claw washer, breakaway preload set (grease & bearings ~68F) with adjusting nut, lock nut torqued to spec and both nuts locked with lock washer with at least one tab bent over each. Wheel bearing do loosen as we drive. They loosen from 12lb breakaway preload to about 8lb in just a few thousands miles.

The clue to see if wheel bearings breakaway preload set high enough, is claw washer. If claw washer scored within 30K miles, enough to catch finger nail on. Breakaway preload set to lite (bearings to loose). Loose wheel bearings chatter (vibrate) eat (scoring) claw washer. This result in bearings loosening even more, which chatter even more, which loosens even more and the cycle continues.

The better the wheel bearings, the more broken-in the wheel bearings. The higher the torque on adjusting nut, to achieve the same breakaway preload. This is simple because bearings have less resistance (run smooth) as they are well broken-in. I've hit as high as 80ft-lbf of torque on very good, well broken-in wheel bearings. This is with OAT of between 65F & 90F degrees. If grease to cool or cold, we do get a false high breakaway preload.

My first (oldest) video, I still use same basic procedure.

 

[2001LC]

Don't forget to use a new snap ring every time (best practice) and set gap under 0.20mm.

 

[BTraci]

2001LC--thanks immensely, fantastic info. If the snap rings are worn and not tight in the ring gap, can that contribute to losing tension over time?

 

[ClassyJalopy]

2001LC--thanks immensely, fantastic info. If the snap rings are worn and not tight in the ring gap, can that contribute to losing tension over time?

No - the snap ring is to keep the axle from backing out. The tension over the bearing is solely provided by the big 54 mm nuts. In fact you can even drive the truck with the front CV axles completely removed and center diff locked!

 

[2001LC]

2001LC--thanks immensely, fantastic info. If the snap rings are worn and not tight in the ring gap, can that contribute to losing tension over time?

Snap ring, are Not a cause of wheel bearings loosening. But reusing snap ring, they tend to pop off. At minimum they don't seat all the in groove, and can damage axle. If wheel bearing loose and chattering (vibrating). Also snap ring gap greater than .20mm. Axle moves in and out past design limitations. That movement in and out along with chatter (vibration). Turns axle into a power saw. Which will eat hub flange and axle splines. Gets very expensive replace FDS (AKA CV) & hub flanges.

Hub flange splines worn. Due to improper wheel bearing service.

New OEM

New FDS outer axle

 

[2001LC]

Here's a bad wheel bearing service I'm working on now. To many mistakes to list at the moment. But two biggest issue.
1) Wiped grease from wheel hub cavities an failed to refill with grease.

bearing a bit cooked, from grease spinning out into wheel hub cavity.

54mm Nuts showing high heat discoloration, from lack of grease in bearings.

marks at inner outer tip of spindle, likely snap ring popping off. Which resulted in someone installing after market FDS (CV)

2) Used after market FDS (AKA CV's) busted the junk!!

 

[tech_dog]

The Toyota Factor Service Manual shows the front bearings themselves as non-reusable parts, but the service schedule shows bearing repacks at 30K service intervals. Can anyone explain this discrepancy?

Thanks,

T.

 

[flintknapper]

The Toyota Factor Service Manual shows the front bearings themselves as non-reusable parts, but the service schedule shows bearing repacks at 30K service intervals. Can anyone explain this discrepancy?

Thanks,

T.

They like to sell bearings.