Miata Hubs

I have a 95 Miata that I use for autocross, track days, and time trials as well as occasional street driving.  I've never had an issue with hubs but drivers in my local time trial club have had a few issues with Miata hubs recently.  Some have had bearings go bad but also some have had the hub flange itself break (very scary).  This makes me want to replace all 4 of mine as preventative maintenance but the more I read online, the more confused I get.  I've seen reports of brand new hubs bearings failing after 3 hours on track.  I've seen reports of brand new hubs breaking the flange with all sorts of theories on what's wrong with the new parts you can buy today.  I've seen people say that the expensive "blueprinted" hubs don't last any longer than the Rock Auto ones.  I've seen people say the old factory original hubs are the best and they just need to be rebuilt occasionally; but surely the flange doesn't have an infinite fatigue life. 

Can anyone help a very confused driver?  I'd like to buy something I can bolt onto my car and not worry about for some time; even if it's not the cheapest option...

Let me know if you figure it out.  :)

It seems the fronts are the biggest concern.  It feels like we're hearing more reports of hub flange failure.  The grippiness of the tires seems to have an impact on the durability of the wheel bearings.  A lot of people seem to swear by frequent repacking.  I have a Miata chumpcar and I've been pretty lucky so far, but the horror stories of others have caused me to replace bearings more frequently than I might have needed to.

The key to keeping the fronts alive is proper torquing, I think. I'm sure the Spec guys know a lot more than I, but IIRC it's a two-stage process. Add in a well-repacked set of bearings and you should be in good shape.

Flange failures are a lot less common but more dramatic. I've had it happen with a set of V8 rear hubs, right in the middle of T9 at Laguna Seca. For the rears, I'd get a new set of Mazda OE units.

Yeah, we properly torqued new fronts when they went on the car. And we still killed the right front at Hallett in one day with two drivers. 

It was whatever fancy ones you used to sell at FM. They were cool and replaced it, but it soured me. 

One cause of flange failures is cheap hubs that are machined stupidly and create stress risers on the back.  See photos in this thread:

https://www.miataturbo.net/race-prep-75/sm-weekend-failure-wheel-hubs-90331/

This kind of machining has shown up in many of the aftermarket brands available at Rockauto, you're kind of playing roulette to buy those.  AFAIK nobody has seen it in a Mazda-branded part yet, though.

People do break the hub flanges that have proper machining on them as well, but AFAICT that's mostly track cars that spend a lot of time bouncing off curbs for maximum lap time.  If that's you, then the general recommendation is to "life" them -- keep track of how many track hours they've seen and throw them away after a certain number is reached, no matter what condition they appear to be in.  I don't know what that number should be, though.  This applies to rears as well as fronts.

As far as the front bearings go, I have also not had great luck with the "blueprinted" hubs.  I'm told you need to retorque them after 100 miles, but what does that mean on a track car?  And why do they need retorquing?  AFAIK, the "blueprinting" is just replacing the grease in them, why does that change the installation procedure to require a retorque that the factory ones don't need?

The thing is, they last longer if you do the two-step torque procedure. 150 initially, then 200 after a few sessions iirc. I would do it to stock ones. 

Blueprinting is not always just repacking. 

Keith Tanner said:

The thing is, they last longer if you do the two-step torque procedure. 150 initially, then 200 after a few sessions iirc. I would do it to stock ones. 

Blueprinting is not always just repacking. 

Followed the 2-step directions that came with the hubs when purchased.  Called for a torque check after the first heat cycle IIRC. Which we did.

The one that failed was still useable, but I was bummed it already noticeable play in a short amount of time. 

It's a weak point on the car and blueprinting/repacking improves the mean time to failure - but it doesn't make them invincible. It would take a redesign to do that. So you do what you can to keep them alive, which includes the two-step torquing process. On average, they last longer that way. The first time we did Thunderhill with the 949 team, I think we lost 4 hubs across three cars. The next time, we didn't have a failure across four cars. The difference was new hubs with proper grease and (I believe) proper torquing.

There are a couple of groups working on roller bearings to solve the problem. I don't think anyone's got it nailed yet.

What else do they do to blueprint a hub?  Replace the balls?

What do people do about the staked nut when retorquing?  Re-stake it, or replace it?

I can't speak for everyone, but yes - some guys will change out the balls.

I don't know what everyone does about the staked nut. Ideal option would be to change it. I suspect most people just re-stake.