Help needed setting front wheel bearing preload (1 Viewer)

[Kernal]

I buttoned up one side at midnight, left it at around 12 lbs preload on the fish scale. After redoing the preload four times each side I got worn out, got to get this back on the road. I'll try to recheck it soon.

 

[Tools R Us]

I did a quick experiment, it netted data, so posting it. Not exactly sure how it applies, so use your judgment.

Assembled a spindle/hub with oiled bearings, mini truck stuff, but the results should be equal to 80 stuff. No seals, etc, the point is to see only the bearing drag at different preload settings. Made an adapter to turn the hub with my in/lb torque wrench.

Torqued the nut to the setting and checked the turning drag: 10ft/lb = maybe 1in/lb (hard to read that small), 20ft/lb = maybe 2in/lb, 40ft/lb = ~4in/lb and 60ft/lb = ~6in/lb. This is consistent with other experience, like setting up diffs. When first setting up the pinion, your looking for ~12in/lb of rolling drag, torquing the nut to 120ft/lb usually nails it. The rule of thumb is 10ft/lb = ~1in/lb of rolling drag on this type of bearing.

This just reinforces my thinking that the fish scale method isn't the best. The point is to set the preload on the bearing, regardless of other drag and the fish scale method takes all of the other drags and method errors into it's reading.

 

[Cruiserdrew]

That's interesting. So even torqued to 20 foot pounds the rotational rolling resistance is only 2 inch/pounds?

How tight can the bearing be set up safely? The tightest safe set up would result in the least possible wear on the spindle, I think.

 

[landtoy80]

What ever method you chose to set preload, check the wheel to make sure it doesn't loosen up. I have one wheel that I can set the preload and some time after I need to reset the preload. It happens every time I pull the wheel off spindle and its on the same side. I have no idea why it happens but it does.

 

[Tools R Us]

That's interesting. So even torqued to 20 foot pounds the rotational rolling resistance is only 2 foot/pounds?

2 INCH/pound or 0.166666667 foot/pound.

How tight can the bearing be set up safely? The tightest safe set up would result in the least possible wear on the spindle, I think.

That's the unanswered question? I went to 20ft/lb just after installing the 37's, so ~4yrs ago. It has worked well, don't know that there would be an advantage to going tighter?

 

[Kernal]

Tools R Us: I'm having a hard time understanding your experiment but understand your point that there is a lot of drag in the system that isn't due to the bearings. I once watched an experienced mechanic adjust wheel bearings, he just went entirely by feel; spun one tire then the other, went back and loosened up the inner nut, spun the tire again, done. I don't remember him using a torque wrench and for sure no scale of any sort.

 

[Tools R Us]

Tools R Us: I'm having a hard time understanding your experiment but understand your point that there is a lot of drag in the system that isn't due to the bearings. I once watched an experienced mechanic adjust wheel bearings, he just went entirely by feel; spun one tire then the other, when back and loosened up the inner nut, spun the tire again, done. I don't remember him using a torque wrench and for sure no scale of any sort.

Yep, I was also an old school tech and was taught by an even older tech to do it the way your saying. Had never seen anyone use a fish scale until recently, my guess is it's a way to translate "feel" to the less experienced, but I don't see how it can be accurate or repeatable?

 

[Pin_Head]

We set the preload on thousands of wheel bearings just by feel in the shop I used to work in. You tighten up the nut to about 25 ft lbs and then loosen it until it is free and then tighten it to about 5 ft pounds and that is it. You can verify the tightness by moving the washer under the nut. If you can move it and there is no play in the bearing, it is OK. If you can't move the washer, it is too tight. All of these worked out fine. This means that setting the wheel bearing preload doesn't require an extreme accuracy. The whole procedure takes about 1 minute.

If it is too tight, the bearing will heat up and fail. It is hard to go wrong with the methods in the FSM, even if it might be more involved.

 

[harper68]

Maybe I am the only one with this problem but I have set my bearings to the FSM and eveytime I torque the outside nut the inside nut turns then the lock washer shears. I believe I have mine set at 10 ft lbs inside and about 40-45 outside. Just curious if anyone else has experienced this problem?

 

[Tools R Us]

We set the preload on thousands of wheel bearings just by feel in the shop I used to work in. You tighten up the nut to about 25 ft lbs and then loosen it until it is free and then tighten it to about 5 ft pounds and that is it. You can verify the tightness by moving the washer under the nut. If you can move it and there is no play in the bearing, it is OK. If you can't move the washer, it is too tight. All of these worked out fine. This means that setting the wheel bearing preload doesn't require an extreme accuracy. The whole procedure takes about 1 minute.

I forgot about the slide the washer deal. Out came the parts, I can slide the washer with a 6" screwdriver up to 60ft/lb, so I guess that would be too tight? The nut and washer that I'm using are dry, so could probably move it at 60ft/lb if greased?

Used a ~12" 3/8"dr ratchet and set it by "feel", then a dial torque wrench to see what my "feel" is. Repeated several times and my "feel" is between 18 & 21ft/lb.

If it is too tight, the bearing will heat up and fail.

In my experience that is going to take a whole bunch of tight. Mine runs in the same temp range at 10ft/lb as it does at 20ft/lb. It difficult to get an exact reading, ambient temp, how long at highway speed, amount of brake used, etc all come into play.

It is hard to go wrong with the methods in the FSM, even if it might be more involved.

If the FSM procedure works for you, use it. I have seen it cause lots of problems. The ones I have seen setup that way have been very inconsistent, often loose.

 

[Tools R Us]

Maybe I am the only one with this problem but I have set my bearings to the FSM and eveytime I torque the outside nut the inside nut turns then the lock washer shears. I believe I have mine set at 10 ft lbs inside and about 40-45 outside. Just curious if anyone else has experienced this problem?

I have seen this, often caused by burrs on the nut faces and/or being dry. I always flatten the nuts, put a sheet of fine sandpaper on a flat surface and take the high spots off, (I use the belt sander, but that's cheating). Put a skin of grease on the nut faces and washer before assembly then never see this.

 

[harper68]

Thanks, never would have though of that I will give it a try next time I get in there. I like the rear axle washer/nut set up a little better than the front seems a little more bullet proof to me.

 

[Tapage]

anyone have been checked at which point the outer nut torque start afecting the inner nut .?

I usually tight the outer at least 60 lb/in .. or so ..

 

[-Spike-]

anyone have been checked at which point the outer nut torque start afecting the inner nut .?

I usually tight the outer at least 60 lb/in .. or so ..

Inch pounds? I think you might be a little light.

 

[Chop Shop]

The pouter nut affects the set up allot.

The resistance will increase once the outside nut pushes the inside nut the other way against the spindle threads.


I dont like allot of the advice in this thread.

Too tight burns up bearings and the tire/wheel/rotor will pass you up.

Too loose and they will be, well too loose.

The guy tearing the titty off the washer.....

Go to the dealer for the next washer, the aftermarket ones are soft junk.

 

[Tools R Us]

...
I dont like allot of the advice in this thread.

Too tight burns up bearings and the tire/wheel/rotor will pass you up.

In my experience, that is going to take a whole bunch of tight. As long as the bearings are properly greased, otherwise setup properly, they can take tight. I know of two instances where the FSM was misinterpreted and all of the nuts were torqued to 47ft/lb. In both cases they were driven long term, including long highway trips. When the fubar was noticed, disassembled, the bearings/parts looked great, repacked, good to go, zero issue.

Too loose and they will be, well too loose.

The guy tearing the titty off the washer.....

Go to the dealer for the next washer, the aftermarket ones are soft junk.

Most issues are from too loose. The bearings are much weaker when run with play, the constant pounding of loose bearings is what destroys bearings, spindles, washers, etc. They need to be maintained so they are always running preloaded. How much preload is the question, 20ft/lb has been working well for me.

 

[-Spike-]

I also tighten my inner nut to 20 ft/lbs with no issues. After being told of some examples of similar bearings being tightened to over 100 ft/lbs and running at much higher RPM's, 20 ft/lbs of preload sounded safe to me. I can only think that the factory is looking for every possible way to save on rolling resistance for EPA specs (aluminum radiators, lower viscosity oils, etc) to explain why they spec it so low. I'm not concerned about getting the last hundredth of a mile per gallon I could get, I'm concerned with my bearings lasting longer. Higher preload keeps the bearing from rattling around and mashing itself to death.
I've had them set that way for a couple of years now. If they ever fail, I promise to post up.