Trailer Wheel bearings float.

[davidpbo]

Well, they don't but in the manual I have been using to service them its says end float should be 1mm or 0.004 inches obtained by tightening axle nut to 20ft lb and backing off 1/4 of a turn.

Then I looked at the units 1 mm is approx .04 of inch isn't it? should the end float be 0.1 mm. I seem to remember that was the figure quoted for my Trooper's tapered roller bearings.

I am off the to the boat soon today (with trailer to bring her back) so may not be able to respond.

 

[NJMcK]

[ QUOTE ]
... end float should be 1mm or 0.004 inches...


[/ QUOTE ]

1mm is about 0.04 inches, not 0.004. Presumably the end float needs to be assessed to a reasonable degree of accuracy?

 

[Lakesailor]

If they are talking about 20lbft it's unlikely they are taper roller bearings. I would have thought they are thrust bearings, but stand to be corrected.

It's a bit subjective, but 1mm end float is just enough to sense as a very slight rocking of the wheel (jacked up from the ground) when grasped top and bottom. Not quite enough to clunk.

 

[davidpbo]

Sorry, they are cone roller bearings.

 

[srp]

They must be taper roller bearings if that is how they recommend setting up the end float. A deep-groove ball race can't be adjusted for end float by slackening off the nut. 1mm sounds an awful lot to me, and implies that the thread pitch on the axle nut is 4mm. An M20 metric coarse pitch is 2.5 mm, and metric fine is 1.5mm.
If I were you I would just back off a 1/4 turn as they suggest, unless you have a DTI to actually measure the end float, in which case I would set it to 0.1 mm, on the assumption that the person who wrote the manual can't convert from imperial to metric!

 

[halcyon]

From my distant past when I was designing trailer undergear, fitting taper roller bearings.
Tighten nut to 20ftlbs seasonable, but rotate wheel clockwise as you tighten, back of 1/4 turn or 1 & 1/2 flats, check wheel spins freely.
In passing filling hubs with grease does nothing, but leads to hot running bearings, to grease, put both halves together and using your finger, press grease into one side until it is forced out of the other side, thats all the grease you need.

Brian

 

[Lakesailor]

Well. I did say I stand to be corrected. /forums/images/graemlins/wink.gif

 

[VicS]

Agree with the others who had said 1mm is too much. Agree also that 0.1 mm sounds about right.

Over the years various manuals have given me different methods of adjusting the endfloat. It should be just perceptible and I have found a good way of doing it is to tighten them quite tight with a socket wrench while spinning the wheel then back off again until just loose then retighten by hand, no wrench, as tight as possible.

 

[Avocet]

Another vote for 0.1mm. That said, in my experiene of these things, it doesn't really seem to matter as long as you've got "some" play, but not enough to let the centre of the tyre tread move more than about 1mm sideways when you grab the top and bottom of the wheel and try to twist it in a plane at right angles to the axis of rotation. It's pretty vital to back off the nut after the "seating torque" has been applied though as they have a habit of welding themselves up as they get warm if they haven't got a bit of play!

 

[santeana]

Tapered roller bearings in auto related applications are usually set-up with a small amount of end-float. This ensures that in application the generated heat expands the tapered components (cups, cones, rollers) to take-up the end-float. In this condition the bearing can do its load carrying work with all rolling surfaces and roller end-cone rib in contact, albeit separated by a thin lubricant film. An end float of 0.003 to 0.005 (inches) is commonly used. When setting this it is important to spin the wheel and take several attempts to allow the bearing surfaces to bed down in the grease. Another way of getting end-float apart from the backing off method is to use shims or if you're really picky a dial indicator. Many precision applications of tapered bearings actually use pre-load to ensure that the "wobbly" end-float condition can never arise; but often at the expense of shortened life.

 

[davidpbo]

Thank you to everyone who replied to this thread. I think there was a discrepancy in the unit conversion and that the end float should be closer to 0.1mm which I believe is 0.004". With the bearing set as described, (torque 20lb and backed off 1/4 turn) it ran much cooler than before.