Need an insightful answer on axle nut torq/bearing

Messages
279
Location
Upstate NY
Need your help. Basic information: Car is 2000 Mazda MPV, and in the process of replacing the alternator, I found that when the dealership replaced the bad alternator (that was the second one, both the original and second one last 7 years each, I am working on the 3rd alternator). They re-used the single-use axle nut. The axle nut needs to be dented at a notch on the end of the shaft. So the dealership "rotated" the nut beyond the original dent about 30 degrees to make a new dent. In the process of torquing the new (my own) axle nut, I find that it takes only 15-degrees to go from contact to 175 ft-lbf of torque (175 is the spec). Additional 30-degree rotation could mean the bearing is extremely preloaded. The rotor now has visible run-out. Question for the B&B on this board is that: what do I do now? Should I torque to whatever to reduce runout? what if the runout does not reduce even I torque further? Thanks.
 
Messages
778
Location
Southeast Michigan
Get a new nut, torque to spec, measure runout. If runout is in spec, I'd still keep an eye on it, but you should be okay. If runout can't be brought back to normal, I'd say they killed the bearing.
 
Messages
4,597
Location
Manchester, England
if your'e stuck and you need it now, try packing it out with washers to take up.the space and torque to spec..but dont forget to go back there pronto and have.them repair everything.they damaged FOC.
 
Messages
186
Location
WI
Technically, yes, the nut should be replaced... but the only reason this is on these is to make sure they retain tension and don't come off...hence the staking - vs a castle nut with cotter pin arrangement. If it was installed originally and torqued properly it should be ok to place back at pretty much the same setting - as it was "adjusted" once properly at that preload setting. Oftentimes once it's set and torqued up from new (at time of bearing replacement), it should be good at that setting on unitized bearings - as opposed to separate bearings like a old rwd or boat. Rotor comment means nothing as far as this goes, because I believe it is a separate rotor and has no "bearing" connection as far as preload/warpage concern, etc. Basically what they likely did is remove it and retorque it and that is where it landed. Restaked it, done. It may be a bit tighter, but if it has been run in that fashion or "dented" it in a position it's too late to save it anyway... (It's probably fine)... Long story short, if it's tightened properly and torqued up it can be reused if STAKED properly...That is primarily the issue.. If it's quiet, I'd leave it alone.. If it makes noise, it probably needed one anyways as these are not the longest lasting bearings anyway....
 

windeye

Thread starter
Messages
279
Location
Upstate NY
Thanks for your quick responses. I do have a new axle nut. As long as bringing it back to the dealer, it's probably futile to argue that the runout is due to their improper torquing after 7 years. I'll try to put the old nut on and see where the notch lands, and compare to where the new one lands at spec'ed torque. will update later. Thanks again.
 
Messages
186
Location
WI
I rest my case... went 7 YEARS !! Not a lifetime, to be sure... but not a result of any improper assembly. These only seem to last so long on this style of bearing... Just think... one more and it'll be into antique status !.. if you still have it, and time to restore the whole car !! ;-)
 
Messages
580
Location
st louis, mo
Let me understand: you are discussing the relationship between axle nut torque and rotor runout? Is the wheel bearing loose and sloppy? I can't see the connection otherwise.
 

windeye

Thread starter
Messages
279
Location
Upstate NY
Update: compared with where the old nut stopped at spec'ed torque. Dealership definitely grossly over torqued, therefore the bearings overly preloaded. I went with the max of the torque spec, 202 ft-lbf, and test drove the car. Did not feel any ill effect, so will leave it for now. In case you wonder why I needed to deal with the shaft and wheel hub for an alternator replacement, it's in the design of the car. The alternator is wedged right to the RH exhaust manifold and just above the steering rack and the joint shaft near the firewall. The entire joint shaft has to be removed to leave room for the alternator removal, even that, the room is very very tight. I know there are members on this board who have the Mazda MPV, not just 2000 MY, it's 2000 to 2006 when they stopped production. Again, thanks to you all for your responses.
 
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windeye

Thread starter
Messages
279
Location
Upstate NY
Originally Posted By: brages
Let me understand: you are discussing the relationship between axle nut torque and rotor runout? Is the wheel bearing loose and sloppy? I can't see the connection otherwise.
No, bearing is tight, no play. The axle nut preloads the wheel bearing. Improper preload can and will destroy bearings. As of why for alternator replacement, see my earlier post. thanks.
 

windeye

Thread starter
Messages
279
Location
Upstate NY
Originally Posted By: BurrWinder
I rest my case... went 7 YEARS !! Not a lifetime, to be sure... but not a result of any improper assembly. These only seem to last so long on this style of bearing... Just think... one more and it'll be into antique status !.. if you still have it, and time to restore the whole car !! ;-)
I went with a DENSO alternator, don't want to do it over again for sure. The alternator dies due to road salt corrosion (MAZDA had a TSB, but dealer did not bother with it, I only find out about the TSB recently). Alternator should last longer than just 7 years, imho. Or they should've put the alternator in an easier spot. The alt in my Mazda3 is on the front, but under the thermostat housing, better but watch out when you replace the thermostat when coolant runs over it. My Camry has a better design, it's on very top.
 
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Messages
4,597
Location
Manchester, England
im still on my original alternator, albeit with a new belt, and all you have to move outta the way is the bonnet smile i like to consider ease of maintenance when i buy a car!
 
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