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-   -   When was the last time you changed your rear hubs? (https://www.miataturbo.net/race-prep-75/when-last-time-you-changed-your-rear-hubs-72613/)

codrus 03-07-2017 10:21 PM


Originally Posted by ryansmoneypit (Post 1397354)
Ok, now I'm freaked out. Is it the hub or a bearing failure? I have replaced the bearings on my 95, but not the actual hub.

The hubs fail.

--Ian

supersuckers 03-07-2017 11:18 PM


Originally Posted by ryansmoneypit (Post 1397354)
Ok, now I'm freaked out. Is it the hub or a bearing failure? I have replaced the bearings on my 95, but not the actual hub.

The hub. https://cimg3.ibsrv.net/gimg/www.mia...559754551.jpeg

BEAVIS 03-09-2017 03:27 AM

Crikey......

Glad you are still in one piece and perceivably the damage was not too extensive.

nbfather 03-09-2017 03:38 AM

Glad you are all right Supersuckers!
That is just disturbing to watch!
Jeez!

GeneSplicer 03-09-2017 08:39 PM

Holy crap! Stock OEM? Original or have ​​​​you replaced at some point?

Stealth97 03-11-2017 11:26 AM

That's scary as hell. Can't believe you did not flip. I for sure would have needed new pants. How bad is the rest of the car?

supersuckers 03-12-2017 07:09 PM


Originally Posted by GeneSplicer (Post 1397804)
Holy crap! Stock OEM? Original or have ​​​​you replaced at some point?

Likely OEM.Car has 60k and ~120 hours track time.

supersuckers 03-12-2017 07:34 PM


Originally Posted by Stealth97 (Post 1398068)
That's scary as hell. Can't believe you did not flip. I for sure would have needed new pants. How bad is the rest of the car?

Car is in surprisingly good shape. A little sheet metal damage in the wheel well, frame rail is a little deformed, busted CV boots, a slightly scuffed control arm, and the wheel and tire are toast.

I suspect one thing that helped me is that I had replaced the factory brace behind the diff with a 1x2" piece of steel for greater exhaust clearance. The custom brace is an inch lower than the factory brace and took the brunt of the impact and kept the car a little further up off the ground. Also a great jack point. (Diff pic is post repair)https://cimg2.ibsrv.net/gimg/www.mia...5035c64029.jpg
https://cimg4.ibsrv.net/gimg/www.mia...30d143ca17.jpg

Morello 03-15-2017 05:58 PM

Had you ever inspected it? I look at mine for cracks before every track day... not sure if that would catch it though.

supersuckers 03-16-2017 12:14 AM


Originally Posted by Uncle Humjaba (Post 1398895)
Had you ever inspected it? I look at mine for cracks before every track day... not sure if that would catch it though.

I'd inspect them when I changed the pads. Moving forward I'll replace every season. The juice ain't worth the squeezing if you try and run them longer.

aidandj 03-16-2017 12:31 AM

Reading back through. Do we have a part number for the ARP extended studs needed for use with the Doorman larger stud hubs.

And should wheel studs be replaced with hubs? I assume so, but figured I'd ask what the norm was.

Zajicek 03-19-2017 05:46 PM

According to Bundy, it appears to be 100-7717. looking through the specs of the stud they look right for the reported changes in the Dorman hub. I'll be purchasing both shortly and follow up.

Yes. worst case is you spent an extra couple bucks for no reason.

engineered2win 03-19-2017 08:26 PM

Ok, so I just bought a few of the Dorman 930-550 rear hubs from Rock Auto for around $15/ea.
They are made in China.
https://cimg4.ibsrv.net/gimg/www.mia...030cdae84d.jpg

They are drilled with a ~0.552" hole for the wheel stud.
The closest 'murican drill sizes are:
35/64=0.5469
9/16=0.5625
The closest metric drill size:14mm=0.5512
https://cimg7.ibsrv.net/gimg/www.mia...e88697cd35.jpg

I then measured the knurled diameter of the original stud to be 0.571"
https://cimg1.ibsrv.net/gimg/www.mia...bccd14164b.jpg

These are the ARP wheel studs which are specified for the 94-05 rear.
https://cimg2.ibsrv.net/gimg/www.mia...bc7ab85694.jpg

ARP says they have a 0.579" knurl diameter, so that means I can measure good.
https://cimg5.ibsrv.net/gimg/www.mia...4003030fb9.jpg

I really don't know what size stud they should be.
The ARP 100-7717 has a knurled diameter of 0.565", which is 0.006" smaller than the original studs. The 100-7720 is 0.008" oversize.
I had no issues installing the 100-7720 with my hazard fraught ball joint press. Either will fit in the end. I didn't see anything in the machinist's handbook about press fit with knurling, so I'm not sure if it functions the same as a standard interference fit joint or not. I don't know how to measure the inner diameter of the knurled stud, unless I cut a stud in half so I can get the calipers on it.
Anyone want to start cutting studs in half to measure for the good of the internets?

I looked on the ARP site and the only sizes are 0.565 or 0.579/0.580, so take your pick.

hornetball 03-21-2017 12:12 AM


Originally Posted by aidandj (Post 1398991)
And should wheel studs be replaced with hubs?

Meh. I just run whatever studs come with the hubs.

afm 03-21-2017 02:31 AM

When I called ARP to ask about mis-sized holes on front hubs, they recommended that the major diameter of the knurl should be .005 bigger than the ID of a round hole. Not sure how that applies to a measurement taken off a hole that's been deformed from previous stud installation.

codrus 03-21-2017 02:33 AM


Originally Posted by hornetball (Post 1400068)
Meh. I just run whatever studs come with the hubs.

Once you add spacers and aluminum hats (which are a few mm thicker than stock steel rotors), there aren't many threads left on a stock stud.

--Ian

codrus 03-21-2017 02:35 AM


Originally Posted by afm (Post 1400091)
When I called ARP to ask about mis-sized holes on front hubs, they recommended that the major diameter of the knurl should be .005 bigger than the ID of a round hole. Not sure how that applies to a measurement taken off a hole that's been deformed from previous stud installation.

I'm not certain, but I would expect that properly-sized studs are sized to keep the hub in the elastic deformation zone (ie, will return to original shape when you pull it out). Once you get into plastic deformation, the strength drops.

--Ian

afm 03-21-2017 02:47 AM


Originally Posted by codrus (Post 1400093)
I'm not certain, but I would expect that properly-sized studs are sized to keep the hub in the elastic deformation zone (ie, will return to original shape when you pull it out). Once you get into plastic deformation, the strength drops.

--Ian

The (front) hubs I've seen have all had visible ridges from the knurls of the original studs after they were removed.

I'm not saying the hub is changing shape and stretching out, just an indentation, so the necking phenomenon past yield in a tensile strength test wouldn't apply.

ryansmoneypit 03-21-2017 10:41 AM

I am interested to know how many rear hubs rock auto has sold in the last two weeks because of this video. I know I got a set.

bigben 03-21-2017 10:43 AM

Do you guys always replace the bearings at the same time?
That was scary indeed...


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