farmersamm
Member
All settings are at ambient. No way to set a bearing at running temp, and get it right.So do you actually meausure the .0015 axial movement? And if its not at .0015 how do you possibly adjust end play that close when you have to line up the hole to the slot in the castelated nut? Then there is the ambient temperature v/s the running temperature that given the coefficent of expansion would probably change your setting by more than the .0015 you say you set at. The way to set your wheel bearings on trailer is a feel thing to determine when you have a slight amount of drag by rotating wheel when tightening up your bearing nut then backing it off till the cotter pin will go in. I am not saying your suggested .0015 is not good, its just not practical to achieve and know this is what you will have especially when it gets up to running temperature. That being said there are many applications were tapered roller bearings have to be set even closer than your .0015. Often a predetermined preload will be specified. However setting to 0 or a specified preload would not be done with a castle nut and a cotter pin. Heck depending on the pitch of the thread the clearance from cotter pin to the hole in axle and the slot in the nut would probably let it move axially .0015? Sorry about the rant I just dont want some young lads out there thinking they have to achieve .0015 on there trailer wheel bearings.
If you look at an axle spindle, it is generally a fine thread spindle. Same as a mic. Tight, or "just tight" plus the backoff to the next castellated nut slot will generally allow you to fall within the desired range. Count the threads, and you'll see where the nut will fall per revolution. Not necessarily by the same thou as a mic, but a predictable amount.
Or you can get out your Noga Boga, and actually measure endplay. Yeah................I'm this into it. The folks at Uranus Inc are down with the specs.
This was a shaft rebuild due to stripped threads. Total redo + making a new non standard bearing adjusting nut. Yeah.........I really get into this ***t. Chances are..................any tapered roller bearing WHICH ISN'T SPEC'D FOR A PRELOAD, will require some endplay. Keep it reasonable, and you're golden. Absolute minimal endplay, but still measurable endplay. I used to do the same for the bearings on the COE, and the trailer. And any other wheel bearing on the place. It's serious stuff. 80,000# toolin' down the blacktop at 70mph requires some thought.
To further muddy the waters.............let's talk preload on a machine tool. You crank that sucker down till you get the spec'd runout, then run it, and record the temperature rise. If it's getting too hot within a specified time............you back it off. Preloads are the devil's brew. Hard to establish the correct tension on the bearing. But it still has to have a preload.
Practicality enters into the picture. If that next slot takes you to 2-3 thou, you did the best you could do with the machinery at hand. The important thing is to avoid wheel bearing preload at all costs.
So, let's say you preload a wheel bearing, and it survives. The wear from that preload will most times give the required thou endplay. But you got there by wearing the bearing, and race. They use cartridges nowdays because of this. You can't get the morons to set the bearings right.
I love this crap, and I am not messing with you. I think it's a great discussion