SM Weekend of Failure (wheel hubs)
 

4 Race old Timken decided it didn't want to play anymore. (~4hrs track time)

https://cimg1.ibsrv.net/gimg/www.mia...9543bd66ea.jpg

The back story is everything felt kosher on day 1 (practice, quali, race 1 then 1 hour enduro) Second day of the weekend now and towards the end of our morning warm up session I noticed what felt like a wheel balance issue or wheel bearing starting to go bad. "No way" I thought, I had just put new fronts on the second day of last weekend. Came in checked tire pressures, wheel torque, then jacked the car up and gave the wheel a wiggle, nothing. Hmm well maybe it's not the bearing then. Looked at the tire and saw a fair amount of rubber marbles and a few guys had said that sometimes they give you a good wheel vib so wrote it off to that.

Went out for the race and right out of the gate I'm thinking it felt worse! I start to give the tires a good side to side scrub and make it 3 corners before my driver front tire pops off and I slowly slide into the gravel, thank christ it happened on the out lap.

So post race analysis is why the fuck did this thing fail?

Cheap china metal? Hub torque too lo-hi? Wheel lug torque too lo-hi? Machined rear sections? Too much grip/wheel offset? ARP studs forced in wrong?

Looking at my old stock hub (new Mazdaspeed replacement looks same btw) the back side is straight cast vs the Timken machined, this section of the Timken is also 1mm thinner at the inside area of the studs vs the oem units, looks like a great stress riser to me.


https://cimg7.ibsrv.net/gimg/www.mia...d71d1ff262.jpg

So game plan is I currently have the cheapest pieces of shit on rockauto on the way, these were to be emergency spares incase a wheel bearing failed, curious to see how they look when they arrive. Going with the Raybestos hubs next as they are cast with the thicker shoulder sections, hopefully never have to deal with this kind of failure again.

I've never seen a Timken machined like that. That's turrible.

I did that to an OEM unit. A lot more hours though. Brought it in as soon as it started vibrating (way more than the typical tire booger stuff) and it also gave hellacious pad knockback (had to pump to get a pedal). I was cracked 75% around in the same pattern as yours.

There's some discussion about the stud holes being undersized on certain replacement hubs. When you press in the ARPs, you overstress and get some microcracks started. Maybe? Seems to me that bbundy posted about it.

I went all fancy and bought NTNs. The hub stud holes were undersized, even though those are supposed to be among the more legitimate.

I talked with an engineer at ARP on the phone, and he strongly recommended I ream the holes to .005 under the major diameter of the stud knurl. I bought the appropriate reamer and did it since I was afraid to press the studs into the small holes.

That being said, the backside machining on this hub is really unusual -- seems like a more likely cause than the undersized stud holes, since a lot of people have faced that stud issue.

Found it:

When was the last time you changed your rear hubs? - Page 10 - Miata Turbo Forum -Boost cars, acquire cats.

Pertains to rear hubs though. I've cracked those too. :cry:

Agree, I've never seen machining like that.

The stud hole sizes in aftermarket hubs seem to be a crap shoot. I replaced mine a couple of years ago, and installed ARP studs during the process. I had to bore out the rears, and the fronts were oversized, so I ended up returning them and going with OEM. Wasn't the usual 1.8/1.6 size differences, just wonky sizes from the mfgrs. I guess they figure if the stud is the right size/thread, the spline size/hole doesn't matter.

I feel if it was a ARP stud/hole size issue the cracks would propagate through them vs how it broke. And yea hornetball there was no knock back on the previous session when i noticed the slight vibs but I didn't recognize it fast enough on the outlap because it definitely had it then, learning experience I hope everyone here can take without having to experience.

I've sent Timken an email regarding the failure, we'll see what they send back.

-Dean

https://cimg7.ibsrv.net/gimg/www.mia...91d0ac3d8e.jpg

An arm chair analysis by a friend who has some experience with material failure stuff

tldr; machining bad

The material around the studs is still intact. Bad machining for sure.

Do you have a photo of the front side of the flange where the studs pass through? And also the back side of the rotors where the studs pass through?
Its possible with the back side of the hub flange machined the total flange thickness was considerably thinner. If this is the case, the larger knurled diameter of the studs would extend further from the face of the flange and possibly the rotors were only supported by the 4 points of the studs (where their diameter was larger) and were NOT clamped to the front face of the hub. As you did your first few sessions, the larger diameter of the stud base may have started to press into the back side of the rotor stud holes causing the wheel, to effectively become loose - vibration, increased stress loading on the hub, etc. When you torqued the wheels following the vibration were they already tight or did you have to add another 1/4 or 1/2 turn?

Another theory... It is preferable for a machined surface such as the back side of the hub to have a large radius from the back side of the flange to the cylindrical surface behind the bearing. A tight radius can cause stress concentrations which will lead to earlier fatigue failure. Using this theory however the total load cycles is way too low for something like a wheel bearing. (based on 2 hours of running time, less than 200 miles total distance). If this was the case, then similar failures would be occurring on regular road cars at say 20,000 miles. Sounds like a class action law suit in the making...

This is terrifying.

I hope these get finalized soonish
https://www.miataturbo.net/race-prep...2/#post1344681

Just a side story. I got the timkins from autozone with the 2 year warranty. every 3-4 races the hub bearings would fail and i would need to replace them. Last time i went autozone was out of stock. so they handed me the house brand. I've gone 8 races so far and they are still good!

Did you have any car-to-car contact after this hub was installed? Sorry if that seems like a dumb/obvious question, but this is SM we're talking about...

I tried the $30 heat-treated Centric hubs for a while and I won't use them again, even as spares. I didn't have any failures, but they developed significant play REALLY fast. I went through 4 or 5 in 1 year. Switched to Timkens and haven't replaced a wheel bearing in about 2 years so far. Based on internet pictures alone, the Raybestos and Moog non-ABS bearings look like the current best options. I think the Moog is just a rebranded Timken 513152. I'll be able to confirm that tomorrow after UPS shows up. I'm curious to see if it has this same machining on the back of the stud hole.

No wheel contact other than curbing, our LF takes a decent beating at the local track.

A spare for me if it lasts a day is good enough

Hub flange sits square and flush on the rotor face, just checked so not a concern but great thought. The lugs were torque checked and as far as I can remember none were loose.

Edit: WJB $20 wheel bearings just arrived, non machined just fyi

For those who don't stray outside the Race Prep section- update on the Moog here:

https://www.miataturbo.net/suspensio...2/#post1358131

@OGRacing did you repack them or run them as is?

did it both ways. first few i would re pack them with high speed synthetic grease. the last few where track repairs and i just stabbed them on.

So you've done 8 races on AutoZone Duralast hubs without repacking them?

woot. I can probably buy those for nothing. research time.

Pictures of my broken hub from TWS. Cracked 75% around. I'd rather be lucky . . . .

I cracked this hub early in my ownership of the Red car. According to the PO, the hubs are original to the car (1995 model year). They exhibit the same kind of machining as OP's hubs. Interesting. What's also interesting is that the bearings still turn smooth and tight. I've heard stories about the original bearings from years past being much better than what we're getting now. Maybe there's something to that.

https://www.miataturbo.net/attachmen...1&d=1473189540

https://www.miataturbo.net/attachmen...1&d=1473189540

https://www.miataturbo.net/attachmen...1&d=1473189540

Also, for Aidan, the grease seals on this hub had visible markings:

https://www.miataturbo.net/attachmen...1&d=1473189540

https://www.miataturbo.net/attachmen...1&d=1473189540

https://www.miataturbo.net/attachmen...1&d=1473189540

Update: I emailed Timken including pictures of the failure and after a couple emails I received this reply.

Wow….a failure like this is extremely rare. I would expect to see this from a heavy impact of some sort.

The challenge I have in this situation is that Rock Auto is not an authorized Timken Distributor.

I cannot with certainty tell you that what you purchased is authentic Timken product as we do not know who Rock Auto is purchasing from (nor will they tell us).

I am awaiting instructions from our product team as whether they want these hubs back for failure analysis and determine if they are in fact Timken.

That being said, I will send you a couple replacement hubs.

Can you send me your mailing address and I will get these to you asap.

Thanks

Patrick

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The photos have been reviewed by our Technical Trainer and based on what he sees, his view is that the hub failed as a result of the vehicle being used on a racing circuit. This is a common failure in this environment.

Before I can proceed, I will need additional photos of the vehicle and a detailed explanation of how the vehicle was being operated when the failure occurred.
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I replied honestly about the use
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Nice car!

Our official policy is no warranty as the product is designed for normal use, not racing of any kind. It’s not relevant if the car is street legal.

I’m told this a very common failure point for Miata’s when raced.
I’ll still send you a couple hubs, only because I like to support racing where I can.
Thanks
Patrick

So I'm content with the result, hopefully they don't send the machined bearings though

That's funny.

"no warranty because racing. BUT I LIKE racing, so i'm going to send you hubs anyway."

Thanks for following up.

Now that's customer service. Some vendor should be taking notes on how to engage with the customer.

Lol just saw this. @hi_im_sean

That's awfully nice of them. Maybe you can compare the 100% legit Timkens versus the Rock Auto ones. I'd be curious if RA somehow ended up with knock-offs.

I'd be fairly surprised if RA sold me something else in a Timken box (edit: come to think of it they have fucked up some parts I've ordered before..), but as I posted earlier the $20CAD/each uber cheap Chinese stamped RA bearings don't have this machining feature so I don't believe that's the case. I think this is a ABS hub feature as someone else alluded too above.

Props to Patrick for being cool anyway.

You should email him a link to this thread.

https://cimg4.ibsrv.net/gimg/www.mia...f17521e4af.jpg

https://cimg7.ibsrv.net/gimg/www.mia...048969210f.jpg

My free hubs came in, going straight to the garbage.

But why?! Machined sharp edges and stress concentrations.

From what I understand Rock Auto is just a network of auto stores selling their parts online and "Rock Auto" themselves never actually hold product.

I had a few discussions with our sales department about them at my last job and they are not officially a customer so it's impossible to enforce MAP pricing.

Jeez!

Strike Timken.

So far so good on my Mazdaspeed HDs. 1 track day at MSR-C (1.7CCW) and 2 at Hallett (1 CW and 1 CCW).

As another data point, I went and purchased new Duralast ABS hubs at autozone. No machining where the studs go in, but.....

https://cimg4.ibsrv.net/gimg/www.mia...61afda8623.jpg



Dafuq? Why would they machine them there?

notable markings?

https://cimg2.ibsrv.net/gimg/www.mia...c5db2beaaa.jpg


@OGRacing do your auto zone parts store hubs have this machining on them?

Somebody in China is confused.

I have some Detroit axle front ABS hubs.

Attachment 231101
Attachment 231102
Attachment 231103
Attachment 231104

Almost all of the ABS hubs have that second machined section, which is why I'm ---- about getting non-ABS hubs. It's for a different tone ring that's shown in some of the pictures. I assume it allows the miata hub to be shared with some other vehicle.

https://images-na.ssl-images-amazon....1f1kjrVdaL.jpg

Interesting. Jpreston, it looks like the Non-abs hubs you got were still machined for our tone rings.

I have some non-abs Detroit axle front hubs at home also. I will snap some pictures of those tonight.

Do you guys think that second set of machining is a problem? Are OEM ABS hubs machined there? Don't have one handy at the moment...

Still paging @OGRacing to see if his surprisingly durable ABS Duralast hubs have the same machining mine do.

I hope so. I'd like to run them. Only paid $46 apiece for them.

OEM hubs do not afaik. I will check min tonight also.

..



oh sorry lol. the hubs are on the car. thrashing now to get it ready for Octoberber Nasa @road atl. If i get a chance I'll see if i can shine a light in there.

Pretty please.

My friend had a Timken hub failure at M@MRLS this past weekend.
Fortunately he managed to bring the car off track in a controlled manner.

https://lh3.googleusercontent.com/co...i8SRm97Q0=w800

https://lh3.googleusercontent.com/Mi...ZPH5gbmFI=w800

Carnage:

https://lh3.googleusercontent.com/c3...ZQMiy24BU=w800

He thinks there were only ~5 hours of track time on the hubs, which had ARP studs installed.

I was right behind him when that happened. We funny to watch but quite scary.

No pics. ??

Pics from me? I don't have video from that session unfortunately.

Ed. Answer your Facebook messages.

No, from scenturion. It looks like he was trying to show a picture in his post.

I see pictures.

Pictures are broken here.

--Ian

In light of this thread I just checked out last shipment of hubs. Out of 6 hubs we received 3 boxes that were made in Japan and 3 made in the USA.

Made in Japan hubs were assembled in 2015 and are correct:

https://cimg2.ibsrv.net/gimg/www.mia...a0f874c933.jpg


Made in USA hubs were assembled in mid 2016 and are not good...now being exchanged. I also noticed the made in USA hubs have bearings which are not stamped.

https://cimg1.ibsrv.net/gimg/www.mia...e6c7de93d2.jpg

I've seen this issue before. I am hosting the pics on google photos. Are you on mobile or the app? What browser are you using?

I'm on a regular PC using Firefox.

I could see them on a regular PC using Chrome, and also on my phone using Chrome.

Safari on a mac won't render them. I loaded the page source and pulled down the images, they appear to be 'RIFF' files, which is some proprietary Windows format with god-only-knows what embedded in it.

--Ian

Loads on Android, windows, and osx for me. All chrome.

Pics now render fine. Bizarre.

--Ian

I've got the pictures now too. Good grief, that's fugly! And the hubs show the same faulty machining and stress points.

Finally got the run down from some folks at Centric/Stoptech. NTN Japan only does ONE production run per year of the OEM hubs that are correctly machined on the back (likely who Timken was sourcing from as well). Centric ran out of stock on the NTN sourced hubs this year and switched to Timken as a substitute supplier which is why there was a change in between batches. It is very likely Timken is sourcing their latest batch of hubs from someone else as well. It will be at least a few months before the correct hubs will hit market again but the good news is the folks at Centric are contacting them now and making them aware of the failure point to avoid this in future batches.

You guys just forced me to pop into my hub repack thread and grab a pic:

https://www.miataturbo.net/attachmen...ine=1381162291

Well, I can breathe easier.

I added a link to this thread, but its all the way at the end. My thread is from 2013 and I can't edit it so I've requested mod assist for an edit. The more places we can get this information out the better!

Thanks G, now I'm 2nd guessing my recent timken replacement I had installed. :squint:

Not an issue since you're not tracking your car.