Technical Spindle bearing preload

Friend and I while in the garage got in discussion about this. What came about is vastly different ways of doing it. So this spark my curiousness. So with that said, what is your way for preloading your spindle bearing?

 

In fall of 1962 my auto shop teacher told us "neither tight nor loose". when adjusting wheel bearings. I usually snug them up reasonably tight, back them off and then just hit that spot where the wrench stops but I don't put pressure on the bearing. I've probably done ten thousand like that over the past 55 years and have had very few fail. Truth is I don't know of a good wheel bearing that I packed myself and adjusted myself that ever failed within the regular time/mileage frame for a wheel pack. That is on customer rigs. A few shots at trying to cut corners on my own rig with suspect bearings weren't so successful but those bearing should have been replaced the first go.

 

It's a "feel" thing, and hard to describe. "Finger tight" for an instruction manual, won't never do. That's why the instructions, if you bother to actually read them, are kind of inscrutable. I noticed, almost by accident, that my Ford Shop Manual actually had two different procedures. One was for replacement (new bearing and race). The other was for removal, cleaning, inspection, and repack of used bearings.

New (tapered) wheel bearings installation in the manual called for 50-80 ! ft lbs preload while spinning the wheel and then back off at least 1, but not more than 2 castellations and installing a cotter pin. Inspection and repack, re-using existing wheel bearings, on the other hand called for 20 to 30 ft lbs preload. Still quite a lot.

Since I was replacing everything, I thought I'd try "the book way". Seemed like a lot of torque or preload, but they wrote the book right? First thing, didn't get anywhere near past 50 ft pounds preload before the wheel stopped turning altogether. But it showed me that new wheel bearings need, or at least Ford thinks they can take, a lot more preload than used bearings.

If someone were to reef down a well used but serviceable bearing set to 50 foot pounds and back off to the nearest castellation, they are probably gonna smoke a spindle or two. New bearings, on that very first install, fit fairly tight, you can feel that when adjusting them, compared to say a well wallered out set last greased during the Ike administration. I gotta say I've checked wheel spin several times since then and they are smooooth turning and the truck tracks straight as a train.

Another thing that is kinda vague, most manuals or instructions and the bearing manufacturers themselves also specify to pack the inside wheel hub cavity with wheel bearing grease "to a level even with the inside race". But they don't say why. This is a shitload of grease, several handfuls per wheel. Also, fill the dustcap halfway with grease, no reason given. Not everybody does this. That's OK too, but I like to at least know what the reasoning is behind any rules I'm ignoring.

A lot of people say this is to provide extra lubrication to the bearings in extreme heat. But, I've never seen chassis or bearing grease flow or move from where it was put last, at least, it doesn't seem to. The only reason I can come up with, filling the hub with grease maybe prevents large amounts of water from collecting inside during and after fording a river, say, something like that. Corrosion protection then. In cold weather, a significant amount of ice collected in the hub would lead to a serious imbalance condition. Just WAG. The manuals are sometimes a little too cryptic on why things are done a certain way.

 

Back up for some interesting info.

 

50 to 80 ft lb or do you mean inch lb??

 

This is always an interesting debate. I was always told no play in bearings. A little loose on ball bearings and a little tighter on roller bearings. I was recently told I was doing it backwards. I have never noticed any comebacks on my work. I guess I should dig up some service manuals and read what is correct for each vehicle

 

Interesting read.

 

Taper roller bearings require preload , Ball bearings no preload . Tighten up rollers spin to seat the bearing back off until the cotter pin can be installed , (usually near 90 degrees ) if need be tighten until nut aligns with spindle hole , don't loosen more . Ball bearings tighten to seat the bearing , back off until 90 degrees until slight looseness is felt . Install cotter pin . This may not be the correct way spelled out in Service Manual but it has always worked great for me .


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Tapered roller bearings in a rear end require a bunch of preload. Tapered roller bearings used as wheel bearings don't require any preload...usuallly.

Ball bearings used as wheel bearings (angular contact) require preload.

I do what the book says for that particular application. What do you know...it works.

 

This is something that is easier to show someone rather than put it in print.

 

Early Ford front spindles say "spindle nut to 50 in lbs, and back off to first cotter pin hole"

Rich

 

I looked it up in the '64 Truck shop manual, memories can fade. This is the spec for the front wheel spindles, 2 wheel drive, drum brakes. Standard tapered wheel bearings.

Chapter 3-4, in Major Repair sez 50-80 foot-pounds for bearing replacement, and back off at least one, but no more than two, castellations to install cotter pin.

Chapter 20, in Maintenance, sez 15 - 20 foot-pounds for bearing repack, i.e. re-using the same bearings, back off at least one, but no more than two, castellations and install cotter pin.

I'm not going to argue that using the shop manual is wrong, but I believe some problems would almost certainly result if someone were to inadvertantly use the manual specification for new bearings as written when reinstalling used bearings. This has probably caused some "issues" in the past, ha ha.

But, I also believe that a new set of bearings and cups need to be adjusted with greater pre-load than is the usual practice. Sometimes those fine distinctions get lost in the translation. But the new bearings won't get smoked installed with a light touch either. When installed and adjusted properly however quality bearings last practically forever. It's amazing to me.

 

i've known guys who were so anal about it that they used shims to get 'em "just right"!

 

new 75 Lbft, used 25 lbft , while spinning the hub then back off till loose ( I do it 2 x ) and then hand tighten , then check hub for play , do this for big trucks and cars and no failures to date .both grease packed and oil bath .the spinning while tightening is more critical on the grease packed .

 

Sometimes once in a great while a cotter pin hole won't line up within the specified torque range on a given nut or fastener. First, try a different nut.

If that doesn't work, then adding a thin washer or peelable shim or two under the nut is the correct method. That's straight out of the A&P manual. A lot of folks will just reef a tie rod end or bellcrank nut or something like that, tight another 8o foot pounds past the max torque (if they bother with a wrench in the first place) and go to lunch, but that's not how it's spo' t' be done. It's pretty scary to watch people sometimes with a torque wrench, who should know better. It's obvious they are not clear on the concept, at all. A lot of things it probably doesn't matter, but on critical safety items why not do it right? And things like headbolts and manifolds and close fitting gasketed items a consistent and even clamping force means no vacuum leaks or other leaks and everything lines up like it should.

 

My way that I've done in the past is spin the hub until I couldn't spin it any more. Then back off a turn and finally tighten to just right to it being snug.

 

Depends on the bearing. Some do go to 50-80 FOOT pounds, and then back off 1/8-turn.

 

I just do 100 ft. Pounds, say a prayer and go to lunch.

 

I know this is an old thread but I can’t let this one go....please say you are kidding, if not you must go through a lot of bearings...


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Decades ago, when I was in VW Service School.......the procedure taught was to snug the bearing while turning the wheel, back off just enough that you could put a flat blade screw driver tip between the hub bore and the flat washer under the spindle nut, and by turning the screwdriver tip, move the washer side to side with light/moderate effort. VW early on used double thin nuts to lock the final adjustment in place. Later they had a split side ‘clamp’ nut with a small locking screw. Both provided near infinite adjustment compared to the more common castellated nut design. That was in the late ‘60s and I have been doing it that way ever since on cars, trucks and trailers with no known failures.

Given all the variations on the theme, all with claims of success, it would appear “close enough” is good enough.

Ray

 

Lots of oem stuff calls for a small amount of endplay in the bearings


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Over the years I’ve done thousands of wheel bearings from lawn mowers to semi trucks and everything in between. Too much clearance on any bearing will cause “ impact” on bearing surfaces, resulting in damage. Too much preload will cause extra strain on the bearings and not leave any clearance for the heat factor. Heat causes metal to expand, thus when the hub heats up, from hard use, or the hub absorbing heat from the brakes, it will expand, diminishing clearance.
What is the “ right” adjustment, we’ll that’s been argued many times. I like mine just a little “ snugger” than most.








Bones

 

with the exception of GM ball bearings, all require seating then backing off to get a little play. Angular ball bearings require a specific preload.

 

Thumb and forefinger tight for me. I like to use late model thin nuts with the sheet metal over cap with the 8 slots that can be indexed around to line up with cotter pin hole exactly, may adjust washer or nut thickness to get a line up to happen. Once in a while I check hub temp after a run.

 

Old thread but actually knowing to pack wheel bearings correctly has a lot to do with it.

I absolutely never wash a wheel bearing I think I will use again. You never get the solvent out and That ruins the bearing.
You would have laughed your head off at the looks on a class full of kids faces when I put a dab of wheel bearing grease in the palm of each one's hands and handed them a wheel bearing to pack after I demonstrated how I wanted it done.
I can always tell an armature packed the wheels before when I find the hub full of grease and the dust cap full of grease. That grease never moves into the bearings from where it sits no matter how long it sits there.

 

Timken says .001-.005 for tapered roller bearings

 

I did that just the other day on a Model A trying to get the bearings "just right" for a customer. I'd never done it before but I've thought about it a time or two. I've been called anal once and a while. I always consider it a compliment.

 

Something like that for most tapered roller bearings....

The thing is for automotive hubs, you don't want any preload, you want 0.001 to 0.010 free play, it has to do with how the bearings are loaded and thermal changes.
SKF has a great wheel end maintenance manual, it's available online for free. It's geared towards heavy trucks but the principles are the same.
Here is a snip of bearing life vs preload from the SKF wheel end maintenance manual:


For best results consult your FSM, otherwise I usually shoot for 1-3 thou freeplay...

 

No, the grease doesn't move, that's a fact.

But then, that isn't why it's there either.

Why do you suppose though all the OEMs, and the bearing manufacturers, always specify to fill the hub cavity with grease?

GM manuals called for filling the dust cap with grease halfway, I don't think Ford did. This filling the hub cavity business has never been 'splained to me. The only thing I can come up with that makes any sense is to prevent excess water from filling the hub. Crossing shallow creeks or whatever.

If you find a hub with grease, at least the amateur SOB apparently read the manual at some point.

 

To avoid that the grease in the bearing is pushed out into the dust cap? On the other hand, why not use a completely flush cap instead?