View Full Version : Miata Hub Failure, How old are YOUR Miata's rear hubs? Public Service Announcement
kung fu jesus
05-06-2013, 01:05 PM
There is a rash of rear hub failures, especially on older model Miatas. This isn't just happening on high, high HP Miatas, but relatively stock HPDE cars:
http://www.youtube.com/watch?feature=player_embedded&v=RQHyjr-ybJk
And Keith at FM at M@MRLS:
http://www.youtube.com/watch?feature=player_embedded&v=3k2u2zaIA3c
and another:
http://www.youtube.com/watch?feature=player_embedded&v=NWvqu3askGs
I borrowed this information from other sites to help others prevent this from happening to them. When my NB had it's rear bearings start to fail, I had a local shop warn me they had been seeing these failures last summer. When they replaced my flange, they showed me the old ones (wish I had taken pictures, now). It was blued from heat and showing signs of stress. This car was autocrossed by the previous owner and only saw DD duty since we bought it. Apparently the other side had been replaced by the previous owner, according to the same shop.
So, if you are rebuilding your rear hubs, please inspect all parts for cracking or stress and be prepared to replace them.
Stay safe everyone!
KFJ
Phatmiata
05-06-2013, 01:09 PM
So is there a better option for everyone, stronger aftermarket version maybe?
kung fu jesus
05-06-2013, 01:17 PM
There is. There appears to be a part number in the Mazda catalog that supersedes previous hub flanges. This suggests Mazda made an updated design for them that is able to retrofit older, previous versions. V8 Roadsters had a thicker design that V8 Miatas are strongly urged to use. Theirs are 12 or 13mm (1/2") thick. I read the OEM is 9mm (3/8"). Racers are replacing their rear hubs annually with new flanges, which makes sense with race tires and racing conditions. The failures seem to be occurring more with hubs of unknown age or origin.
kung fu jesus
05-06-2013, 01:23 PM
Cracks seem to appear on the backside first, but I found this picture showing them on the front.
Big picture, but shows radial cracks at the transition:
http://farm9.staticflickr.com/8040/8061121059_099f4c1778_o.jpg
The Driver
05-06-2013, 01:35 PM
Suscribed!
treeafodo
05-06-2013, 02:55 PM
I've heard about this, thanks for more details.
SM16RMSM
05-06-2013, 03:48 PM
Oh wow, I never knew about this. Very good info here. I going home to check the Spec Miata now.
fwdtamiya
05-07-2013, 09:46 AM
Good info indeed
Demon I Am
05-07-2013, 10:00 AM
eesh, that would be traumatic on the street. Got me wondering if I should just order the full replacement instead of bearings only.
JLBMX5
05-07-2013, 10:41 AM
Every time I look at this site its costing me more money grrrr now I gotta look into replacing rear hubs as well
RuckkehrMiata
05-07-2013, 10:56 AM
Every time I look at this site its costing me more money grrrr now I gotta look into replacing rear hubs as well
My feelings exactly. Except I can't replace mine right now :(
Too many priorities!
I<3flippyheadlights
05-07-2013, 11:15 AM
Just another thing to scare me while driving. Awesome.
JLBMX5
05-07-2013, 11:18 AM
My feelings exactly. Except I can't replace mine right now :(
Too many priorities!
I'm in the middle of buying parts for motor swap. I'm about 250.00 away from my goal of having everything needed. I'm just looking at the fact that what's the since in putting motor in a car that the bearing are all worn out on. I just learned last week about the bearing failure on my car so it has now become my priority
kung fu jesus
05-13-2013, 02:42 PM
Found a quality replacement for the flanges.
Dorman makes a replacement rear hub flange. Made in Taiwan, a very high quality piece. Found on Amazon and free shipping, it is about 1/3 the price compared to
$91 from Mazda Competition.
http://www.amazon.com/Dorman-930-550-Wheel-Hub/dp/B0026M5TPQ/ref=au_as_r?ie=UTF8&Make=Mazda%7C80&Model=Miata%7C1110&Year=1999%7C1999&carId=002&n=15684181&s=automotive&vehicleType=5
Pfunk
05-13-2013, 03:26 PM
The hub, bearing, and seal "buy all three" option in Amazon: any idea if those other bits are quality parts as well?
I got low-mile units from partsgroup (no affiliation) to go with my diff swap. :)
Pfunk
05-14-2013, 06:38 AM
Went with Timken bearings instead; I honestly cannot recall the last time I replaced the hubs...
kung fu jesus
05-14-2013, 07:34 AM
I don't know Precision, Paul, but Timken has been good to me.
RuckkehrMiata
05-14-2013, 07:47 AM
My concern is why is this just becoming an issue now? Is it just that some of these hubs are getting to be 20 years old?
kung fu jesus
05-17-2013, 10:49 AM
I think the light shed on the issue comes from better information sharing among the communities. While not exactly a "new" issue, I was made aware of it through a sort of cross-pollination of different message groups I follow.
Sure, the use of sticky tires probably emphasizes the issue, but as the cars age, this is something to be aware of, even in street cars. A lot of the racing community uses parts from former street cars, and the typical process is to simply rebuild the existing hubs in the rear. It is known the front bearings are known to fail or head south more quickly than the rear, not the flange. Most people don't rebuild the fronts, just buy and replace the whole assembly.
This thread isn't meant to cause paranoia or fear, it is meant to highlight the issue and to be aware of it when you do maintenance to your daily driver. As mentioned above, I wasn't aware it was an issue, but when I had my rear hub rebuilt, I was a bit surprised at the condition of flange...and my car is 13 years old, not 20.
rossstang8808
11-01-2013, 11:41 AM
^+1
Like KFJ said, it's not some major recall worthy issue, just something that you should be aware of. Checking to see if your hub is about to fall apart is not generally considered a normal service inspection type of thing, so it could be easy for something like this to slip under the radar.
Pyr0monk3y
11-01-2013, 12:15 PM
Seems like a good thing to do while I'm replacing axle seals and installing ARP lug studs. I'll add it to the list with all the other "while I'm in there" items.
Pyr0monk3y
02-26-2014, 08:10 PM
I just got my hands on two dorman hubs from amazon like KFJ mentioned. It seems there are two varieties of dorman hubs with this part number because mine are marked "made in china" :(
I'm not too concerned with the quality, they look real nice. I'm just praying that the holes for the studs are the correct size. I don't have time to order replacements and I don't like taking drill bits to new parts.
haha.. that 3rd video is me.. and my 15 seconds of youTube fame.... and was my former 1990 Spec Miata that now lives in Houston..
10950
In my case, it was the original to car rear hubs at around 86k miles AND that driver side had been hit 4 times so well overdue to be changed (probably should have been changed after the 1st hit into that back wheel to be honest) ..so that was a 'my bad' but all things considered, the miata is damn tough to put up with that much abuse for so darn long!
... my running joke is I have the fastest lap time on 3 wheels crossed the start-finish line without a rear wheel at Gingerman!
Getting it loaded onto the trailer was interesting too but we had that darn thing fixed that night so we could be back at the track Monday morning (talk about quick change!!!)
10951
10952
10953
10954
10955
..for anyone curious, the TRM C1 wheels are touch as hell because that wheel kept going another 4 years on that car and still going today as far as I know (not bent or damaged)
10956
10957
10958
10959
..and yes, we ended up changing the right rear side 'just to be safe' after this incident.. lol
and oh yeah, I couldn't resist taking 1 final (look what I broke cause I'm good at breaking things) photo before the junkpile:
http://mazdaroadster.net/attachment.php?attachmentid=10960
...so folks always say, photos or it didn't happen.. this time I got photos because scary sad enough, this wasn't the 1st time I lost a wheel.. 1st time I lost a wheel due to hub failure was on my former 2004 SRT4 (and it was the left front in that case).. ever try to steer with 1 front wheel missing? ..didn't go well.. so the Miata rear wheel was a piece of cake in comparison.
Pyr0monk3y
02-26-2014, 08:47 PM
I have a TRM C1 with radial gouges similar to the one pictured in your post. It was on my car when I bought it. I ran 5 track days with it but I have since retired it to street use. I'm not sure what the story is behind it but I suspect a rear hub failure. The lugs studs on one side are slightly longer than the other side.
^ you don't have #50 spec miata do you?
Pyr0monk3y
02-26-2014, 08:57 PM
Nope, but the more I think about it, the more I suspect my car was the victim of a hub failure. Something about the right rear corner makes me think that something bad happened there.
I was gonna say, I know for a fact the rear hub replacements matched with same length ARP studs when we sold it to the new owner in Houston anyway (plus I didn't hide the 'crash' damage and put clear photos of it since it is a spec miata after all!)
Pyr0monk3y
02-26-2014, 10:23 PM
I just pressed the studs out of my dorman hubs. They are a .563 knurl diameter. They are supposed to be .579. What now? Drill press? Reamer?
kung fu jesus
02-26-2014, 10:37 PM
Reaching out to get some answers for your question, Andy. Hope to get a reply soon. Stay tuned!
Pyr0monk3y
02-26-2014, 10:43 PM
Wait, I think I'm an idiot. According to some other threads on other sites, a general rule of thumb is a hole .010-.020 smaller than the knurl diameter...
kung fu jesus
02-26-2014, 10:50 PM
Andy, message sent!
kung fu jesus
02-26-2014, 10:54 PM
IIRC, you had a decent press, 20t? That should do the trick.
Pyr0monk3y
02-26-2014, 11:05 PM
Ok, the actual knurl diameter on the dorman studs, after being pressed in and out is .563" -.570" depending on where you measure.
The diameter of the hole in the hub is .563"
The Knurl diameter of a new, never installed ARP stud is .579"
.579"-.563"=.016" The hole is only 16 thousands smaller, and it should be, because the knurling is a press fit.
Theoretically, everything is in spec and the ARP studs should press in nicely. :fp: I think my brain took a little siesta... theoretically
kung fu jesus
02-26-2014, 11:13 PM
I was thinking similarly. I wanted to get you a good reference so as not to destroy anything. Glad it will work!
Pyr0monk3y
02-26-2014, 11:21 PM
I was looking for a solid reference too. All I can find is suggestions on forums and such. I was hoping that ARP would have something to say about it on their web site but they don't. Fortunately, there is a clear consensus in most of the threads I've been reading that 10 to even 30 thousandths smaller is OK. I'm feeling pretty confident being in the middle of that range.
Thanks for your help man!
Slipstreem
08-16-2014, 11:22 AM
Scary stuff. Wear and tear is unavoidable but what are the chances of this happening on a strictly DD miata? Seeing as the videos are race spec miatas and they get pushed harder as opposed to a street driven miata.
kung fu jesus
08-16-2014, 12:58 PM
I haven't checked if this happens in DD Miatas, but if you plan to run sticky tires, like r-comps, it would good to be mindful of it. Also, if you need to change the rear bearings, it is good to inspect your rear flanges carefully, even consider replacing them, while you are performing that repair.
Tkblazer
04-09-2015, 02:15 PM
Well my.rear driver side bearing is bad so I just ordered the hubs and bearings Steve linked. Trying to decide if I should get arp studs for the hubs or not. Might as well right?
kung fu jesus
04-09-2015, 03:50 PM
You can, but measure the holes on your new flanges versus the diameter of the knurled part on the ARP studs. It's an interference fit, but to a degree.
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