Wheel bearing pre-load on tri-axle?

**Graeme** · 10th November 2008, 11:48 AM

Can anyone help with the procedure to set the bearing pre-load on a tri-axle hub after having installed new 22,000 LB bearings? As its on the rear axle of a 30' trailer, its going to take all the load when tipping so I'd like not to get it too far out of adjustment. Currently it requires approximately 5kg force on a wheel stud to keep it turning.

TIA

**Blknight.aus** · 10th November 2008, 06:44 PM

since Im now a qualified heavy vehicle mechanic...... (again)

whats it going to be doing...

nominal setup for heavy duty highway trailer axles is with a couple of thou of end float....

5kg of effort on a stud to keep it turning sounds a little high but if thats a calibrated elbow number it might be right depending on how long its been since you last calibrated your elbow..

you need a DTI with a good mag base to sort it out properly but you can "field" them in in much the same way as you do a landies wheel bearings when you dont have the right tools. do em up till it feels about right, take it for a run and see what the temp does.

If its hot back them off a bit, jack it up and if its rattly tighten them up a bit...

you also dont say if your running grease or oil fed bearings. the oil fed bearings will generally tolerate a 0/0 preload/endfloat where as grease likes to have the play.

**Graeme** · 10th November 2008, 09:50 PM

Thanks Dave.

Yes, elbow estimate but definitely no end-float, even after a lap around the paddock, so I'll back it off a little. I have both feeler guages and DTI but will probably go with the feel method due to the weight of the hub and drum. I've used EPL0 grease.

Graeme

**Blknight.aus** · 10th November 2008, 10:09 PM

also even on a tri axle tipper you should never wind up with the full load on the rear axle, if you have your in imminent danger of tipping the tipper...

I think (from shady memory) that the most the rear axle should ever see is something like 65-70% of the total load

if you want to actually get the DTI method to work the best way Ive found is to park the truck on a side slope and work the downhill side (only needs to be 5%ish) use a heavy duty jack to just get the wheels off the deck, then use or have someone esle use a crow bar to try to lift the wheels uphill on the axle while you watch the DTI.

Its not super accurate so so long as their is only a slight movement on the DTI you are probabley on the money... Keep an eye on the grease at 1000, 5000 and 10000 km and it will tell you if the bearings are happy or not.

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Wheel bearing pre-load on tri-axle?

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