How do you set/adjust preload on trailer wheel bearings? - Pirate4x4.Com : 4x4 and Off-Road Forum
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Old 03-14-2003, 07:02 AM   #1 (permalink)
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How do you set/adjust preload on trailer wheel bearings?

My mobile home axles have just an outer bearing, washer, then castellated nut and cotter pin.

But here's the thing......perhaps they are "unserviceable" due to the manner in which the bearings and hub are retained. That is to say, I can foresee problems setting the proper wheel bearing pre-load because of the lack of adjustability with the single-nut-and-cotter pin setup. Particularly if you look at the large distance between the slots in the castellated nut. There's obviously a pretty limited range of adjustment, because of this large gap, because if it's not quite right, you have to either tighten down or back off the nut quite a lot (in big steps) to reach the next slot through which you can fit the cotter pin.
Possible ways around this I can think of at the moment are:
1) Hope like hell you get lucky the first time
2) Use some thin shim-like washers between the nut and outer bearing to try and get it right
3) Do away with the cotter pin, and use some other method to prevent the spindle nut from losening. Possibilities include use of a double-nut setup probably with threadlocking compund or an outer lock-nut of some kind, or perhaps safety wiring the spindle nut.

How does it work on "proper" trailer axles?
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Old 03-14-2003, 07:19 AM   #2 (permalink)
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Well, in a FAR different app, we had the same setup. The landing gear on a UH-60 helicopter.

Our procedure was to tighten the nut till the tire drags, then back it off to the next castellation, and pin it there... worked well for me...

With clean, new hardware, the actual spec IIRC was to hand-tight, then turn to next castellation. That doesn't really apply to a trailer, so I'd use the first method.
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Old 03-14-2003, 08:20 AM   #3 (permalink)
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Thanks for the tip eskimo....sounds like the right procedure.

To answer my own question - here's the details from 2 trailer sites, the first, the second

6. You are now ready to slide the hub or hub drum onto the spindle. Clean the spindle with a rag. (NOTE: The inner surface of the bearing and the spindle shaft are machined to close tolerances. If the spindle is marred, unclean, or if the rear bearing is not square with the spindle shaft, the bearings may temporarily hang up as you slide the hub in place. Once the hub or hub drum is fully in place on the spindle, slide the outer bearing onto the spindle and into the hub. (Match the cone of the bearing to the race. DO NOT INSTALL THE BEARINGS BACKWARD!
7. At this point you are ready to pre-load the bearings. Whenever you install new hubs onto an axle, or whenever you install new bearings and races into existing hubs, you should pre-load the bearings. Pre-loading the bearings assures that the races in the hub are 100% in place against their machined stop points and keeps the hub from wobbling after a few miles.
8. To pre-load the bearings, install the spindle washer and spindle nut onto the spindle with the hub and bearings in place. Tighten the spindle nut finger tight (until snug) and then with channel-lock pliers or a crescent wrench, tighten the spindle nut another 1/4 turn or about 15 to 20 ft pounds of torque. Now turn the hub five to ten revolutions. This will fully seat the races. Now loosen the spindle nut very loose, then re-snug to finger tight, and engage the nut retaining device. (Some reverse lubricating spindles use a tab washer for the retaining device)
9. After 20 to 40 miles of highway travel, check to see if the hub is loose on the spindle. Pull the tire in and out a few times. If your hub is loose, you will need to re-snug the spindle nut and re-engage the nut retaining cotter pin or tab washer. NOTE: Never reuse the same tab on the tab washer. They are designed to be used one time only).
Never run your spindle nut to tight, this will cause your bearings to over heat. And never run your bearings too loose. A very slightly loose spindle nut will run adequately, but too loose and the individual rollers may come apart in the bearings, causing the hub to fracture.
You are now ready to install your dust cap. A short piece of 2" I.D. water pipe makes a good tool to install either a plain dust cap or the SPINDLE-LUBEŽ dust cap for the 3500# axle.
If you are installing brakes on a "plain" spindle axle, we recommend that you use plain dust caps and not "bearing protectors" (Bearing protector refers to the spring loaded dust cap device with a grease zerk fitting in the piston.) Bearing protectors add two to four PSI of pressure inside the hub cavity and in many cases, they cause grease to leak past the seal. If sufficient grease leaks past the seal on a brake hub drum, it will centrifuge out with some grease getting on the brake shoes. Grease on your brake shoes will drastically decrease your braking capacity.

Bearing Adjustment and Hub Replacement
If the hub has been removed or bearing adjustment is required,
the following adjustment procedure must be followed:
1. After placing the hub, bearings, washers, and spindle nut
back on the axle spindle in reverse order as detailed in the
previous section on hub removal, rotate the hub assembly
slowly while tightening the spindle nut to approximately
50 lbs.-ft. (12" wrench or pliers with full hand force.)
2. Then loosen the spindle nut to remove the torque. Do not
rotate the hub.
3. Finger tighten the spindle nut until just snug.
4. Back the spindle nut out slightly until the first castellation
lines up with the cotter key hole and insert the cotter pin (or
locking tang in the case of E-Z Lube.)
5. Bend over the cotter pin legs to secure the nut (or locking
tang in the case of E-Z Lube)
6. Nut should be free to move with only restraint being the
cotter pin (or locking tang.)
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Old 03-14-2003, 08:53 PM   #4 (permalink)
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I have spent many hours and miles playing with the wheel bearings in my trailer and 60s. Upon scheduled checks, I have come to the conclusion that the first lock after finger tight is the best.

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Old 03-15-2003, 06:32 AM   #5 (permalink)
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Excellent Dan....the voice of experience...that's what I need.

Cool - first after finger it is

Thanks all

PS - you meant first as in first as you're loosening after finger tight right?

Last edited by BillaVista; 03-15-2003 at 06:34 AM.
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Old 03-15-2003, 09:29 AM   #6 (permalink)
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Thats about how I do it; snug it down good and rotate it to make sure they're seated, back off, then finger tight. From there, if its real close to the next one tighten it just a RCH to get it to line up, if not, back it off to the next one (mine has the same setup as yours with the castelated nut). Essentially the same way I do the wheel bearings on the truck.

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Old 03-18-2003, 08:07 PM   #7 (permalink)
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The way we've always done wheel bearings is to torque them to around 40 ft pounds, spin the wheel, then back off to where there's just a very small in and out slop. IF in question, tighten it a bit, but there should be free spinning, and on the other end, there should not be visable slop. Most anywhere in between seems to be okay, athough the extremes woln't be very good for the bearings.
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