repeated rear wheel bearing fail..any ideas?

[Bill Edwards]

Bearing quality and lack of grease, very likely, Trouble is these days you can't be sure that you are getting an item from a respected manufacturer, So many fake products, even in packaging identical to the original.

That's one of the reasons I like getting 99% of parts from a trusted, old fashioned motor factors where you can be sure it's come from the correct places.

 

[steveo3002]

That's one of the reasons I like getting 99% of parts from a trusted, old fashioned motor factors where you can be sure it's come from the correct places.

all very well if you have a decent factors ...ours would sell me a no name brand for 6x the price of ebay

 

[Gritineye]

New ones, not enough in my opinion.




So I pulled both inner seals and drilled/tapped the center of the bearing hub to take a grease nipple, gets greased until you can just see a weep of grease coming out of the outer seals. Blanking plug goes in the hole when in use, strange how they have outlasted the original setup tenfold and are still good.

Your modification may have worked for you, but that pic shows the recommended amount of grease for a sealed bearing, any more may cause overheating.

We were taught this during training, but Google is your friend here:

Too much grease volume (overgreasing) in a bearing cavity will cause the rotating bearing elements to begin churning the grease, pushing it out of the way, resulting in energy loss and rising temperatures. This leads to rapid oxidation (chemical degradation) of the grease as well as an accelerated rate of oil bleed, which is a separation of the oil from the thickener. The heat that has been generated over time along with the oil bleed eventually will cook the grease thickener into a hard, crusty build-up that can impair proper lubrication and even block new grease from reaching the core of the bearing. This can result in accelerated wear of the rolling elements and then component failure.

 

[pedrobedro]

any of the experts confirm the tightening method ?

no backing off or run it up the road and check again etc? seems rather tight

You tighten it to the recommended torque and the wheel feels too tight but this soon loosens up when you use it a bit. It's not like the old taper bearings where you backed it off when it got tight. Slackening it off will kill the bearing in no time as my nephew found out with his fronts on Sierra.

 

[8ob]

That is the correct amount of grease for a sealed bearing, any more will cause overheating.

We were taught this during training, but Google is your friend here:

Too much grease volume (overgreasing) in a bearing cavity will cause the rotating bearing elements to begin churning the grease, pushing it out of the way, resulting in energy loss and rising temperatures. This leads to rapid oxidation (chemical degradation) of the grease as well as an accelerated rate of oil bleed, which is a separation of the oil from the thickener. The heat that has been generated over time along with the oil bleed eventually will cook the grease thickener into a hard, crusty build-up that can impair proper lubrication and even block new grease from reaching the core of the bearing. This can result in accelerated wear of the rolling elements and then component failure.

You can keep the "Google" quote Mr eye The presealed bearing only has the correct amount of grease at the time of fitting and not enough to give it a sensible service life, we are not talking about packing a bearing until the grease cant escape or bog down the rollers/balls, we are talking about replenishing and you know full well any excess will just spew out of the pre sealed bearing shields as does the original grease. The grease in the top picture has long dried up and gone and to prolong life needs an occasional squirt of grease hence the successful mod. There is not a pre greased bearing on any of my kit that lasts. All the machines with greasable bearings go on for years. One particular machine has run for in excess of 6000 hours on 4" diameter bearings and has to be greased every eight hours, thats the only chance the bearing gets to flush out the old grease or debris which in turn prolongs its life. Just my observations from real life experiences with machines over many years and a bit of fun

Bob

 

[gordon stephenson]

The grease churning and causing overheating has a lot to do with the shaft speed I have found, I'd rather have a little too much than not enough,

 

[rtbcomp]

What does the workshop manual have to say about popping the seal and adding grease to new bearings? I really can't believe you should have to remove bearing seals to add more grease to brand-new bearings.

A trailer parts manufacturer I know had to scrap a whole load of hubs because of bearing failure, I scrounged a few for a machine I built and the bearings soon failed under low speed and load. They were just rubbish.

There was a thread on here a while back where it was suggested that too much grease would impede the rotation of the balls/rollers, leading to the problems @Gritineye mentions in post #23

 

[Gritineye]

Not dispu

You can keep the "Google" quote Mr eye The presealed bearing only has the correct amount of grease at the time of fitting and not enough to give it a sensible service life, we are not talking about packing a bearing until the grease cant escape or bog down the rollers/balls, we are talking about replenishing and you know full well any excess will just spew out of the pre sealed bearing shields as does the original grease. The grease in the top picture has long dried up and gone and to prolong life needs an occasional squirt of grease hence the successful mod. There is not a pre greased bearing on any of my kit that lasts. All the machines with greasable bearings go on for years. One particular machine has run for in excess of 6000 hours on 4" diameter bearings and has to be greased every eight hours, thats the only chance the bearing gets to flush out the old grease or debris which in turn prolongs its life. Just my observations from real life experiences with machines over many years and a bit of fun

Bob

Oh I agree 8ob, I have a friend who retro fits grease nipples to everything with a bearing and over greases them way all too often, he never has a problem with bearing life either!

I had already edited my post to what I really meant while you were typing yours. :-)

I distinctly remember that instructor (ex REME, yes I know) showing us how to grease a roller bearing with what seemed to us to be a very small amount of grease.

However, the often recommended method for greasing taper roller wheel bearings is to pack the race by palm forcing it in, then fill the hub cavity as well, go figure, as they say...

 

[wookie]

If I had to choose who to listen to for advise between an instructor and an engineer with many years of hands on experience I'd choose the engineer every time, "those that can do, those that can't teach" springs to mind.

 

[bricol]

My 25yrs of engineering experience says too much grease is as bad as too little. Too much will overheat and the bearing will fail. I'd suggest failing sealed for life bearings are running beyond their design capacity. Use many sealed for life units in our machines. They have a design life and recommended change interval. At 2 grand for a bearing set, you don't want to get the design load wrong on machines running 24 hrs a day, 360 days a year when lost production costs hundreds of thousands!

 

[8ob]

The results of some scientific research carried out by myself

A UJ off my telehandler with needle roller bearings on four corners, always assembled with grease from new . These are cross drilled so the one grease point lubricates all four bearings, the machine is an old one and I had noticed when I first got it that when greasing this UJ that grease would only come out of one of the cups. This was probably due to lack of maintenance from the previous owner and the cross ports becoming blocked with hardened grease. I had it in bits recently so changed it, now looking at the state of it I wonder which one of the cups was receiving the fresh grease and which ones were relying on the original fill as per greased for life UJ`s ? Sealed for life bearings are the work of manufacturers to prolong the sales of replacement parts, greaseable parts like balljoints, UJ`s, wheelbearings and just about anything you care to mention will outlive its pregreased counterpart. Like the overgreased original wheel bearings in my Foden thats done 1.6 million miles , not to be confused with the pregreased Transit connect rears that cant get past 50k.


Bob

 

[Bill Edwards]

all very well if you have a decent factors ...ours would sell me a no name brand for 6x the price of ebay

Yes, like most things in life they're not all equal...

 

[steveo3002]

anyone comment how they interpret that above pic....is the arrow saying goes on this way or this side on outer edge?

 

[pondy]

some are directional depending on abs system, some have a pick up build into the e bearing, usually a black magnetic strip which points away from the wheel

 

[cardiffrob]

You can order bearings by their part number (eg 6207 for Land Rover etc) and then add "2RS" to give you double rubber seals to contain the grease and if you order "CN" or "C-normal" rather than C3 then you'll get a closer tolerance bearing with less clearance between balls and cups, ideal if you don't get excessive heat expansion. If the bearing isn't marked "C3" then it should be "CN" by default, but this may not be a universal rule.
Getting the right thickness gasket also keeps the clamping forces correct.


I've just changed some Morris rear bearings to solve the oily brakes issue.

 

[steveo3002]

swapped em ....was way harder to remove than last time , had to run 2 beads of weld around the outer race and then it tapped out easy

see how this lot lasts

 

[steveo3002]

add to the above , nuts were still tight , no signs of water ingress , slight bit of grease had weeped out but wasnt dry , rollers looked good but some wear marks on the outer races , will see if i can get a pic but had to weld on them to bash them out so might be ruined

 

[steveo3002]

This is the worst markings if it points towards any issues

 

[Rig Pig]

Check the rim isn't bent and the tyre isn't deformed, just jack the wheel up and eyeball the runout relative to a pointer set close to the sidewall of the tyre, then repeat with the pointer set close to the tread.

 

[nickk]

swapped em ....was way harder to remove than last time , had to run 2 beads of weld around the outer race and then it tapped out easy

see how this lot lasts

as 8ob states, you can't dispute real world experience.
Don't think it's been mentioned have you checked the smoothness of the shaft,or any ovality.
Any damage there ,can be transferred to the bearing.