45 replies to this topic

[WilsonSteele]

All,
In the midst of winter projects, getting next season's front hubs prepared for the 2013 spares bin. I like the smell of CV Grease in the garage, so I do these myself.
On a whim, I got one hub from Amazon last yeat (which stayed in the box all season), but I normally use Mazda parts with our discount.

In this round of hub prep, I noticed that the Amazon part (half the price after discount) seems to have tell-tale signs of a second zone of induction hardening on the outer-most race, that the Mazda part dosen't not. Which I would assume means a better race surface on the ID for the outer-most balls, and perhaps better life.

Anyone care to comment on life differences between Mazda parts and Amazon/Chinese/???? parts? I haven't noticed this before, but haven't had good luck with Amazon hubs in the past....

Anyone from Mazda or hub engineering care to enlighten me/us on differences in Heat treat, or where the induction coils get placed prior/post machining for this hub?

Thanks all (and yes, this seemed important enough to stop lurking and make my first post after 4+ years...)

Cheers,
Wilson

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[FTodaro]

I would not take the chance, on the cheap hub. A buddy of mine tried them and he got like two weekends on them. To me its not worth setting yourself up for a failure.

The Mazda hub is an NTN hub, you can get the same hub for less from outside venders.

What ever you do, never get a hub and install it without first repacking it with good grease, the stuff they use is crap.

[Jamz14]

Frank,

I got one weekend out of a set of Mazda OEM hubs.

J

[Jamz14]

I forgot to mention though that the OEM hub came out of the box with a very large pit in the middle of the race though. I am sure the pit expedited the hub failure. Got two weekends out of the hub on the other side.

[Jim Boemler]

I got one weekend out of a set of Mazda OEM hubs.

I got almost three years, on the stock grease. No, I can't explain the difference. Might have to do with weather, track surface, or number of off-track excursions.

[Bench Racer]

The more interesting issue to me with THESE TWO HUBS, is the outer race induction heat treated with the Mazda hub? The heat treating color closer to the non Mazda hub flange is the approxmate location of the outer outside diameter bearing race. If your answer is yes his race is heat treated, where did the color remnants from induction heat treating go?

[Keith Novak]

I got almost three years, on the stock grease. No, I can't explain the difference. Might have to do with weather, track surface, or number of off-track excursions.

I suspect bearing pre-load may be involved. Slightly different animal but when I rebuilt bike hubs with high end bearings, I had to be very careful about not tightening too much. Even with very slippery grease, you could tighten the hale out of them and couldn't tell a difference in friction but if the cones were too tight it would quickly destroy the races. Over-torquing the hub nuts could do the same thing.

[Keith Novak]

<double post>

[Jamz14]

Jim, Keith,

Thank you for giving me something to consider. I certainly could have over torqued them.

[SaulSpeedwell]

Things I think we know:

1. Fact: OEM part variation is huge over the ~25 year life of this part. We've seen Koyo, NTN, SKF (and maybe F.A.G.? Or that was aftermarket?) supply Mazda bearings, and at least 4 design revisions that affect ball size, ball number, and shields/seals (not counting provisions for ABS tone rings or not, which don't matter to us).

2. Generally scientifically agreed upon: 100% too much grease is worse than 20% too little. Grease is expensive, substandard suppliers will skimp on it. DIYers always use too much.

3. Unproven opinion/anecdotal evidence: CV-2 ain't the best you can do. The brief time I spent running CV-2 lined up with the only times I had unusually frequent bearing failures. I've used a lot of greases without issue, but my favorite is still Dad's old, smelly, couldn't-be-made-today-due-to-environmental-concerns, Mobil aircraft wheel bearing grease. Anything smelly and illegal to make in 2012 has to be good. If you have any chrome cleaner left over from the good old days, you know what I'm talking about. If you have tried taking on a swarm of wasps with modern "non-toxic" wasp spray, you have experienced the converse of what I'm talking about. You better be able to outrun them for "3 Mississippi" or so.

Interesting thread apprently started by one of our compadres over here: http://www.bobistheo...&Number=2773888

4. Unproven opinion: Towing is bad for bearings. Start keeping track of how often you lose a bearing shortly after a long tow.

5. Speculation: The extra weight and grip of Hoosiers are causing an increase in bearing failures.

6. Safe to assume: This bearing wasn't designed for constant 100 mph hitting rumble strips 7 times every 2 miles, 1g cornering and braking 10 times every 2 miles, with 7" R-compounds with an extra 20mm+ of wheel offset.

We are lucky that Mazda put as much "overengineering" into this bearing as they did - if this was a BMW, the entire wheel/suspension would simply fall off (ask Al Ferragonio!).

[Jim Boemler]

Towing is interesting. My usage is unusual in that the car has never been towed; perhaps that's part of my bearings' long life. I'm curious about your assertion that "100% too much grease is worse than 20% too little", though -- can you expand on that? Intuitively it would seem that more would always be better, figuring that the chances of starvation would go down. Most times I take apart any bearing (even ones that still work), I find less lube on the balls or rollers than I hope for, with most of it flung where it does nothing.

[Glenn]

I'm curious about your assertion that "100% too much grease is worse than 20% too little", though -- can you expand on that?

I would be intrested in hearing the logic on that one too......

[DrDomm]

I would be intrested in hearing the logic on that one too......

Me three, and I'd like to hear what is the "right" amount...and why.

[davew]

From Saul:

#1, Totally agree and if you figure in aftermarket versions there are countless more.

#2, I agree 100% more is bad, 20% more won't hurt, 20% too little is bad.

#3, I do not knock CV2, I use Schaeffer grease and have had better luck and it is cheaper. I agree, if it was good in the 70s and illegal now, the legal replacement is probably crap.

#4, I agree in part. If you tie down using the wheels for long distances is could put a repeated pounding on one particular spot on the bearing. But I will admit to never monitoring it.

#5, I don't think the weight of the Hoosiers effects it at all. The added grip is a likely culprite in my opinion.

#6, 100% agree. We are vastly over using and abusing these things. WAY beyond their design criteria.

Clown, your street driving miles do not count. They are well within the design criteria. Your street driving may actually help after a rain race, as it gives the moisture time to escape.

I have found drivers that turn in very hard, very late are the toughest on front bearings. They put all the weight on the outside front wheel and the bearings are just not able to take it.

I have found an increase in bad bearings during 2012 as compared to previous years. I assume this is due to Hoosiers.

Dave

[TEAM MEDICARE]

Me three, and I'd like to hear what is the "right" amount...and why.

one more

[SaulSpeedwell]

Too much grease causes heat build-up, and not enough causes the bearing to run dry. Google your heart out, any bearing or grease expert will tell you generally the same thing. There are always exceptions.

The Miata bearings, both front and rear, have some room for too much grease to find a home in between the races - and this is the only thing saving those that believe "more grease is more better".

Skeptics will find comfort here: http://www.ntn.co.jp...en_a072-079.pdf

Quote:
As a rule of thumb, bearings should be filled to 30 to 40%
of their space and housing should be filled 30 to 60%.
Where speeds are high and temperature rises need to
be kept to a minimum, a reduced amount of grease
should be used.

Excessive amount of grease cause
temperature rise which in turn causes the grease to
soften and may allow leakage. With excessive grease
fills oxidation and deterioration may cause
lubricating efficiency to be lowered.

[SaulSpeedwell]

Most times I take apart any bearing (even ones that still work), I find less lube on the balls or rollers than I hope for, with most of it flung where it does nothing.

This is one of the things I question about CV-2 for this application. It doesn't seem to stay where you put it (not as much of a problem in a CV joint?), and it also seems to experience more separation of the thickeners and "oil" when compared to the other 15+ wheel bearing greases I have on the shelf.

But - also realize that the more grease you pack in, the more heat and pressure you will generate in the ball/race volume, which will push the grease out of the ball/race volume and to those places where "it does nothing".

With too much grease to start with, it's going to look bad to you, because your "hope" of finding more lube on the balls and rollers is the opposite of what NTN's engineer intended!

[Jim Boemler]

The engineers clearly know more than I do about this, but it bucks common sense. Then again, I thought it bucked common sense to spend our way out of national debt, too.

Clowns are often wrong about these things, but at least we can provide a bad example.

[Chris70]

We used to have front hubs that lasted 3 years with no issues.
Starting some time late last year we have had a terrible time , some have lasted as little as TWO sessions of 20 minutes each.
Always used Mazdacomp factory hubs and all had the usual repacking. Tried a couple of the aftermarket ones and they were just as bad or even worse. Mazdacomp states that they are using the same supplier from Japan and that there were no changes to the specs.
What seems to work is rebuilding old take off hubs from donors.
I do agree we use them above and beyond their intended use and that the lateral forces we are subjecting them to are very high, however it was not an issue previously.
Ademir
S.A.C. racing

[Bench Racer]

How come? No one wants to talk about the photo in post 1 that shows 1 hub with 2 induction hardning bands and 1 hub with 1 induction hardning band. Everyone likes to talk about grease, Hmmm.