42 replies to this topic

[SaulSpeedwell]

We replace the balls in our hubs with much higher grade. IMO it helps with rolling and makes a more efficient and "better" hub, but ultimately it is my opinion the failures are 90% race failures. The race is the weak link, not the balls.
Jim

The pile of bandsawed amd hardness tested hubs I have gathered over the years makes your opinion closer to a fact!

Here is a pile of facts/data/opinions:
1. I have seen failed front bearings that are Koyos, NTNs, SKFs, FAGs, "Timkens" (i.e. often one of the previous vendors thrown in a Timken box).
2. If the inner race says "ACME", it does not mean ACME casted, heat-treated, and machined the outer race. Thus, not all "ACMEs" are created equal - whether from a major vendor, or one of the SM-specific vendors that is tweaking things.
3. Overpacking is worse than underpacking (See NTN publication I linked to in other thread somewhere).
4. CV-2 is not the best, maybe not even very good, for this application. "Lifetime" greases used in OEM bearings is closer to the best you can do, but *generally* is not being sold or repackaged for retail in small tub quantities.
5. Towing is bad for bearings.
6. Towing with the car tied down to 10 times gravity with the balls sitting on exactly one spot for 15 hours is FATAL to the bearings. Chill out with the tie-downs.
7. Having a badly sealed bearing cap with your race wheels puddling water up against it until water gets in, is FATAL to the bearings. Put the cap on with RTV.
8. Messing with the seals until water gets in from the back side, is FATAL to the bearings. Try to buy bearings with modern metal face-shields, and save the seals if you have to. (They're out there, or at least they were).
9. "Re-packing" is not frequently necessary unless 7 and 8 are happening to you.
10. There is no currently manufactured vehicle still using the Miata front wheel bearing (as best I can tell).
11. The Miata REAR wheel bearing is still used, and "OEM" versions of this bearing have modern seals, modern (good, high $$$) grease.
12. Vendors (including Mazda) change suppliers overnight, so some of the above could change overnight, too!
13. Everyone thinks their tire gauge and their torque wrench are right, and about 20% of those people are right Click torque wrenches are the Anti-Christ.

Anecdotal Recipe for success: Put on the hub, torque to the middle of the spec WITH A KNOWN GOOD TORQUE WRENCH, leave the nut unstaked, leave the hubcab un-RTV'd, go run a session, retorque to the bottom of the spec, stake the nut, seal the cap, stop tying the car down to 10,000 lbs of equivalent "weight" tight on the bumpstops, and you should get better life regardless of whose bearing and grease and other voodoo you are using.

Extra Credit: Get a time machine, go back to 2001, and spec smaller tires and wheels and less offset

[AW33COM]

^ that

 

 

There is still resistance.

 

Chances are you, or someone else over torqued the hub nut, or even the wheel nuts.  Torque the big hub nut to 160, 180, then to 200.  Spin the wheel and measure the resistance each time.  You'll be surprised what a difference of 20ft-lb does to your bearings.  Torque everything correctly and see if it spins right.  If not, bearing is gone. 

 

You can remove the caliper if you're not sure where the resistance is coming from. 

[Tom Hampton]

The pile of bandsawed amd hardness tested hubs I have gathered over the years makes your opinion closer to a fact!

Here is a pile of facts/data/opinions:
1. I have seen failed front bearings that are Koyos, NTNs, SKFs, FAGs, "Timkens" (i.e. often one of the previous vendors thrown in a Timken box).
2. If the inner race says "ACME", it does not mean ACME casted, heat-treated, and machined the outer race. Thus, not all "ACMEs" are created equal - whether from a major vendor, or one of the SM-specific vendors that is tweaking things.
3. Overpacking is worse than underpacking (See NTN publication I linked to in other thread somewhere).
4. CV-2 is not the best, maybe not even very good, for this application. "Lifetime" greases used in OEM bearings is closer to the best you can do, but *generally* is not being sold or repackaged for retail in small tub quantities.
5. Towing is bad for bearings.
6. Towing with the car tied down to 10 times gravity with the balls sitting on exactly one spot for 15 hours is FATAL to the bearings. Chill out with the tie-downs.
7. Having a badly sealed bearing cap with your race wheels puddling water up against it until water gets in, is FATAL to the bearings. Put the cap on with RTV.
8. Messing with the seals until water gets in from the back side, is FATAL to the bearings. Try to buy bearings with modern metal face-shields, and save the seals if you have to. (They're out there, or at least they were).
9. "Re-packing" is not frequently necessary unless 7 and 8 are happening to you.
10. There is no currently manufactured vehicle still using the Miata front wheel bearing (as best I can tell).
11. The Miata REAR wheel bearing is still used, and "OEM" versions of this bearing have modern seals, modern (good, high $$$) grease.
12. Vendors (including Mazda) change suppliers overnight, so some of the above could change overnight, too!
13. Everyone thinks their tire gauge and their torque wrench are right, and about 20% of those people are right Click torque wrenches are the Anti-Christ.

Anecdotal Recipe for success: Put on the hub, torque to the middle of the spec WITH A KNOWN GOOD TORQUE WRENCH, leave the nut unstaked, leave the hubcab un-RTV'd, go run a session, retorque to the bottom of the spec, stake the nut, seal the cap, stop tying the car down to 10,000 lbs of equivalent "weight" tight on the bumpstops, and you should get better life regardless of whose bearing and grease and other voodoo you are using.

Extra Credit: Get a time machine, go back to 2001, and spec smaller tires and wheels and less offset

Mbpps