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Topic: front wheel bearing preload? (Read 1702 times) previous topic - next topic

front wheel bearing preload?

I have an inner bearing seal that needs replacing. I have the jack to lift that corner and the wrench to deal with the lugnuts. Getting to and replacing that seal scares me a lot less that the 150/hr I got quoted to have someone else do it. What I haven't found is the procedure for setting preload. I can easily index the locknut and put it all back together as it is now but kinda doubt that is suficient. Can anyone throw some light on this?

Re: front wheel bearing preload?

Reply #1 –
Quote from: twobus –
I have an inner bearing seal that needs replacing. I have the jack to lift that corner and the wrench to deal with the lugnuts. Getting to and replacing that seal scares me a lot less that the 150/hr I got quoted to have someone else do it. What I haven't found is the procedure for setting preload. I can easily index the locknut and put it all back together as it is now but kinda doubt that is suficient. Can anyone throw some light on this?

.001-.005 runout on a dial indicator is what I understand the spec is. 

Now for a experienced guy who does these with an eye towards the dead spot in the steering elimination I have no idea where in that variance is used.

My x Foretravel guy probably does it by feel.  Someone posted the procedure here recently I think?

Heavy assembly.  Watch out.  Full disassembly allows synthetic lube to be correctly installed.

The outer level ring I understand is the correct level.  At the inner level once heated in use the oil pushes out of the seal I am told.

Correct seal has a metal ring that needs to be installed on the hub so that the seal rides on it not the hub itself.  Green Loktite for it

Re: front wheel bearing preload?

Reply #3 –
Ah, very good. That will help to decide whether to farm this job out or not!

Re: front wheel bearing preload?

Reply #4 –
I do it by feel. I keep it on the tighter side on steer axles as well. But, for the inexperienced, that video is good. They have to have a "standard" way to put in procedures instead of saying, "If it's loose and has play, tighten it up, but not too tight!"

Re: front wheel bearing preload?

Reply #5 –
Quote from: krush –
I do it by feel. I keep it on the tighter side on steer axles as well. But, for the inexperienced, that video is good. They have to have a "standard" way to put in procedures instead of saying, "If it's loose and has play, tighten it up, but not too tight!"

Exactly

Re: front wheel bearing preload?

Reply #6 –
Yeah allright, prettymuch like every other taper rollerbearingI've ever done, just bigger.

Re: front wheel bearing preload?

Reply #7 –
Yep, nothing mystical about it. I use Semi fluid synthetic grease in all of the oil type front bearings I do. Its a "flowable" grease, real tacky and a mess to deal with, but once you get it installed the only way the seal will leak is if it is completely gone. I use it in semi trailer and non drive axles, however if you change over to it you will need vented hub cap plugs (the rubber caps in the hubs) they can be had at any truck parts store. haven't had a problem with it in over 15 years.

Re: front wheel bearing preload?

Reply #8 –
Done properly steering axle bearings should not be a problem. 
Meritors' method (and it's excellent) is one way to skin a cat.

If the bottom line is an adjusted bearing that ends up being (just) snug, you have the idea.
My concern revolves around drivers (thinking) steering axle bearings are a "set it & forget it item".

After spending my entire working life as an OO and I tell anyone that goes down the road, you need to (at the least) look for signs of steering axle issues.  Air pressure, tire condition, bearing hub leaks, etc.. 
EVERY time you get out of your machine, lay the back of your hand on the bearing hub assembly to check for excess heat AND walk around it EVERY TIME YOU GET IN & OUT of it.

Typically, steering axles have 12,000 lbs., sitting atop them ALL the time. 

It's a miracle MH operators get away without having a CLASS A license.. pc

So much for my soap box.. pc

Re: front wheel bearing preload?

Reply #9 –
We use the same synthetic rear axle 85/140 or similar viscosity we use in our rear axle for the front hubs.

And we check the front axle fluid level before every trip, as well as coolant, oil, hydraulic fluid levels & Pressure Pro tire pressures.

We used a hole saw to cut out the center of the front axle hub caps, so we can view the fluid level.

We periodically replace the red rubber 'stopper' caps, to be sure they are well sealed supple rubber. We keep the rubber vent clear with a paper clip. Since the rubber cap is visible in the hub cap's hole, we reduce vandal attraction to the bright red by painting the red cap black.

Re: front wheel bearing preload?

Reply #10 –
Quote from: pocketchange –

EVERY time you get out of your machine, lay the back of your hand on the bearing hub assembly to check for excess heat AND walk around it EVERY TIME YOU GET IN & OUT of it.


A purchased a harbor freight infra red thermometer and walk the coach and the tow car every stop to check things out.  $30

Re: front wheel bearing preload?

Reply #11 –
Quote from: Dave M –
Just snug is zero oil clearance, so the bearing will eventually Gall. Why the spec of .001 min. Oil clearance up to .005.

Preload, play, and oil clearance are all separate things.

Timken knows more than all of us, so see what they say about preload (if preloading took away oil clearance, why would they say it's acceptable?): http://www.pirate4x4.com/tech/billavista/PDFs/Timkin%20bearing%20pre-load.pdf

Quote
So, do you want preload in your wheel bearings?
It depends on the wheel end design and the
quality of the components used. If thetraditional design is your preferred wheel end, be
careful to avoid excessive preload, the risks are
serious. However, new wheel end designs
utilizing Timken quality components create
opportunities to safely use slight preload,
reduce maintenance costs and improve fleet
profitability.


Quote
"The one- to five-thou range recommended by RP 618 is a compromise between too loose and too tight," Stangl says. "At zero, we're into preload and we can't measure that. Between zero and one thou, we could be measuring deflection and still be in preload. Between one and five, we know the bearing is not preloaded, and it's not too loose that it will cause other problems downstream."
http://www.truckinginfo.com/channel/maintenance/article/story/2011/12/are-your-wheel-bearings-adjusted-properly.aspx

The 1-5 thou comes from procedures that allow the masses to have a measurable dimension to use. If you read into the links, a slight bit of preload is desired....but it can't really be measured.

Re: front wheel bearing preload?

Reply #12 –
Slight preload seems to have been what my x Foretravel mechanic used as I have NO dead spot in the steering.  Full synthetic lube with the seals changed out.  7,000 miles.  Does not run hot at the hub.

Like timken said.  Its a feel thing. 

Re: front wheel bearing preload?

Reply #13 –
BTW,
it is an excellent idea to keep track of rear axle hub clearance.  pc

Suggestion.. do not fill you diff to the plug hole base line (rear seals will last longer). 
Keep in mind they (typically) contain FIVE gallons of gear lube.  pc

Re: front wheel bearing preload?

Reply #14 –
Great, got many talking about the various methods of perfection.  If I read that correct, there is no such thing as perfect taper bearing adjustment, just sone where between not too tight and not too loose. :o

So my favorite saying "Do what makes you happy", I sure do, I know what works for us.  The key is do your thing & enjoy life.

Re: front wheel bearing preload?

Reply #15 –
Quote from: Dave M –
Great, got many talking about the various methods of perfection.  If I read that correct, there is no such thing as perfect taper bearing adjustment, just sone where between not too tight and not too loose. :o

That sums it up! As I said earlier in the thread, "If it's loose and has play, tighten it up, but not too tight!" Where that point lies...well, it may be easier to debate politics or religion, HAHA.