Thread: Wheel bearing tensioning

Tighten them up until the wheel just starts to bind when rotated, then back off 1/4 - 1/2 a turn.

Thanks for the reply.
I thought it was something simple like that.

It is a bit of a feel thing as well. If you keep an eye on the washer behind the nut it also helps. While rotating the wheel, tighten the nut until it is firm. This will ensure everything has seated properly.

Then back the nut off until it comes distinctly loose. Then retighten while watching the washer. At the point where the nut just starts to grab it and trys to rotate it (won't go far because of the 'keyway') the bearing tension will be about right.

Basically at the point of no preload, but not much paly either.

what they said but keep the wheel turning while your tightening up the nut and the lock nut...

If you have access to one use a dial test indicator to measure the endfloat and aim for the sy side of .1mm of movement.

And on your first run after adjusting them, do a few kilometres and then stop and check temperature - the hub should be no warmer than any other metalwork on the trailer, if it is, then the bearing is too tight (or short on grease, which should not be the case if you've just assembled it).

John

Just for a point of reference as well your drivers side hub and tyre will get hotter than you passenger side hub and tyre so dont get freaked out about that. It has happened with every trailer I have towed, all I can put it down to is the camber of the road. Tempratures will vary greatly depending on load and speed. For example I just did a trip from Moranbah to Brisbane towing my boat with a bit of gear in it. So we are talking long distance, high speed and more than normal weight. At 100kmh the hubs got hot enough that I could only hold my hands on them for about 10 seconds before it got a little to hot for me to keep my hand there. I then ran at 90kmh for the next few hours and the temps were so far down that I could hold my hand on there without taking it off. Your tyre temprature should be similar to the tyres on the car.

After you have done a few kilometres, at least 50k. Jack up the wheels and check them again if they have bedded slightly and there is a bit of play (judgement call again) that wasnt there, you may have to nip them up one more slot on the nut. This will happen more with new bearings bedding in. A bit of play is acceptable but if it is too loose it will then jump the wheel around and flog out the bearing.

Originally Posted by DiscoTDI

........A bit of play is acceptable but if it is too loose it will then jump the wheel around and flog out the bearing.

Well put. Too tight, the rollers have to distort too much and also squeeze out the grease so they are unlubricated, too loose and the bearings suffer from impact loads which is just as bad. The ideal is probably to have exactly zero play, but the problem with this is that you have no way of telling when you have this - and any pressure on the rollers from preload uses up part of the load carrying capacity of the bearings, and you don't know how much you have used. (preload is often used where the bearing is locating gears in mesh and any mismesh is much more important than bearing load, which is designed in - in these cases the amount of preload is very carefully set, usually by shims.)

On the other hand, play on the bearing, in this application, has almost no downside unless there is so much that it allows the two parts to rattle relative to each other and gain enough relative speed to cause impact damage when the play is taken up, or unless the movement off centre is enough to damage the seal.

John

most trailers are fitted with a slotted nut therefore most guys that do there own basic servicing do not have shims or differant thickness washers to adjust the preload just right.

The only option we have is when the bearing is adjusted and the hole does not line up with the slotted nut (I don't think I have ever had one) is to back the nut off till the hole lines up.

I have been doing it this way ever since I have owned trailers without a problem.

It would be good if they drilled an extra hole or had a multipul start thread