Hub Failure @ WGI/Tire Failure @ NJMP
 

I don't know if anyone else here regularly tracks their car. I do about 30-40 track days per season. My car is not a street car. Full cage, Hoosier Slicks.
7 X 15 Kosei K1 wheels.

Had my car dynoed 2 years ago at 306rwhp. This past off season tweaked the carb, replaced the distributor, coil & module. Adjusted the timing and my seat of the pants dyno tells me I may have gained about 20 rwhp.

The past 2 weeks has been interesting. 2 weeks ago at WGI, my left front hub broke right at the apex of turn 1. My wheel/tire made it almost to turn 2--I did not. The car was surprisingly easy to control. I managed to track out and jump the curbing into the runoff area. Had minimal other damage. In addition to replacing the hub, had to replace the caliper & the wheel that cracked in the inside center. I did not know the wheel cracked till I had a tire mounted and it held air for maybe 2 or 3 minutes.My rotor was in 4 pieces. I have fender flares, the flare was in 3 pieces and also had some minor body damage. A buddy repaired and re-fiber glassed the flare. Looks like new. He also managed to fix up the body. Prior to the hub failing I had no idea these were a problem. The hub broke into 2. 1/2 staying on the spindle & other 1/2 stayed in the wheel. 2 of my friends who were with me are structural engineers. All they do is study metal fatigue for the military. Mostly ship and aircraft parts. These guys live for this stuff. Their careful trackside forensic analysis determined it was definitely not a bearing failure--which is the most common. It looks like the hub just reached the end of its useful life. I've had this car for 5 years and the front hubs were at least 5 yrs old. For all I know they may even be the original hubs. I replaced both fronts with oem. I had been watching the rear hubs as a precautionary thing and replaced them last year.

This past weekend I was at NJMP on Lightning. I was about midway through the bowl passing a car on my right and a Ferrari right on my bumper when my left rear Hoosier Radial slick side wall blew out. I did a 180 and wound up facing the Ferrari as he managed to avoid me and go up and around to my right. He had to go up onto the grass, the bowl is banked here and he went pretty high up onto the grass. I was very happy & lucky to not have hit or been hit by anyone. This time around the car was much more difficult to control. But I managed to back it off the asphalt and out of anyone's way onto the grass. I had only minimal damage, my outer CV boot disintegrated. I was unable to replace it at the track so my weekend was done. All should be fixed and ready to go for my 2 days @ WGI next week.

I tracked down the Ferrari guy in the paddock to apologize to him. He was cool with everything and said he had no idea his car had such good off road capabilities. Luckily he had no damage at all.

Been there! Last April I came out of a turn doing about 85-90, and the left IRS axle stub broke, and the wheel/hub fell off. That was fun.

Flyin' Miata sells an aftermarket front hub that is supposed to be much more durable. I have them sitting on my shelf, but haven't installed them yet.

It's definitely a wake up call and shock to the system. I looked at those hubs and it seems all they are doing is repacking them with a different lubricant. The engineers I spoke with did not think the extra cost of the repacked hubs was worth it. They also thought the oem lubricant was as good as the replacement. In my case they were positive it was not a bearing failure, but an end of life issue for the hub itself. As I mentioned, my front hubs were at least 5 years old if not even way older then that. From here on in I'll be checking them more closely. Maybe routinely replacing them at regular intervals.

These are the new hubs. Kieth told me when they used the stock hubs on the Targa car, they had to replace them about once a year. With these hubs, they go 3-4 years.

Are they better? IDK, that's what Keith tells me, and I trust him not to steer me wrong. And I don't have an old set of stock hubs to compare them to.

I added the ARP studs myself.

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FM refers to them as being "blueprinted" and "re-greased". All this means (to me) is they are checked to be at exact/tighter tolerances. I translate that to mean a large % of the oem hubs have fairly loose tolerances or poor quality control. ...being they are re-greased maybe some are more or less dry... Just guesses...

For a few extra $, if the Flyn Miata hubs give you piece of mind, then that's all that matters.

That is very true! Sometimes you just have to do whatever helps you sleep at night.

Good wake up call to us with unknown hubs on a 200,000 mile chassis. Thanks for posting!

Yes it is a good thread! I'm glad the OP shared the full details and his friends' informed opinions... Do AX or road race Miatas catch more hell when it comes to suspension abuse?

ToySnakePMC
I would think any kind of performance driving whether it's road racing or AX would put more stress on everything, especially the suspension. I currently have 2 track only Miata's. My other Miata is set to SM standards but not officially a SM. Prior to these I had another track Miata. These are all NA's and were street cars when I got them. I did very little to them before taking them to the track. In no time the shocks went on these and the springs were no where capable of giving me the support I needed for what I was doing. I replaced all of them with Bilsteins and way stiffer springs. The one car has SM spring rates and the v8 is stiffer then that. To answer your question: Absolutely.

But that doesn't mean you have to baby your baby forever Pat!

Even with lower power levels, I burned through my first set of front hubs at about 50k miles on the Mx-5. I am on set number two. Repack them with redline CV grease, is what I've been told. So far so good, but I am hoping the added size of the Rx-7/Cobra hubs helps alleviate this problem. OEM mazda hubs are rather small things, especially when you put them through much more grip forces than they were originally meant for in 1989.

Ya know this hub thing is starting to freak me out. My car has 200K on it and as far as I know the hubs are original. I've put 11k miles on the conversion now with lots of autox and romps past 125. I've rocked them side to side and rolled the hubs around to see if I could feel anything and they feel smooth as far as I can tell.

Is there some way I can check them for signs of wear? Is it just the front ones that are of concern?

The font one piece hub/bearings seem weak just looking at them, to me. You could magnetic particle test them, you can pull out the ball bearings and races and inspect for signs of heat and pitting, and you could do other material integrity tests as well, including harness tests I'd assume.

Any test with dye or mag particles looking for stress/cracks would be a good bet. Also cheaper than other fatigue tests. We use hardness testing on some high pressure iron to look for signs of strength loss, and mag particle testing on rods is fairly common as well.

I replaced mine due to weak bearings, and the new hubs I may have heat or cryo treated, I've yet to research this option, but it seems viable.