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View Full Version : How I learned that the Abarth wheel studs use a 12mm wrench!



Robert Nixon
10-29-2013, 09:08 AM
Sunday I ran an autocross on some new 17 inch tires. I put the wheels on myself and checked the lug nuts with a torque wrench. Drove the new tires for about 500 miles prior to the event. In 4 autocross runs I did well and really liked the feel of the Direzza IIs. After the event, I head for home and notice right away an incredible amount of road noise!

Pulled over to check it out, and didn't see any weird tire wear, didn't see anything rubbing, and set out again. Pull over and look at the tires again. Still huge road noise, but handling was OK, no vibration through the steering wheel, so I'm just guessing the tires are noisy once they've been driven hard.

Bottom line, when I switched back to the Abarth wheels, my left front had a loose lug nut, so I realize that I'm an idiot and that this was causing the road noise. Then I noticed that one of the wheel studs was missing! Holy crap, now I'm thinking I'm an idiot and almost killed myself, which would have really made me mad!

The stud was in the autocross wheel, and had somehow worked itself loose, and the other stud still on the wheel was loose also! So I learned that they bolt right back in with a 12mm wrench.

I hope that's the end of the story, but if you wheel experts know more, please tell me what I'm missing here or if I did something wrong, thanks!

Ryephile
10-29-2013, 09:31 AM
.... now I'm thinking I'm an idiot and almost killed myself, which would have really made me mad!...

ROFL :rofl:

Seriously though, glad nothing major happened. From this side of the monitor it seems your major "whoops" moment was not re-torquing your lugs after going for a test drive and re-torquing after at least the first auto-x run. Lugs have an incredible ability to work themselves loose after a heat cycle, so as long as you re-torque after that heat cycle, you should be good to go.

To go a step further, there are some wheels out there *coughKoseiK1cough* that have incorrectly machined lug seats and the lugs will eventually work themselves loose. Don't buy wheels like that.

JackandSue
10-29-2013, 12:14 PM
First you should always autox or track day with hubcaps removed. (most places it's a rule) That way you have a visual on the lugs when checking tire pressure etc. You should have a couple of extra lug bolts in your tool box also. I use Apex wheel studs with bolts on mine and torque them at 75 Ft Lbs. There is also a proper way to torque a bolt but that's another matter. It looks like you've learned a very valuable lesson. One time we were at a racing school and I was in a hurry changing tires and forgot to tighten one of the lugs and it flew off on course and was picked up by an instructor. "Who lost the lug nut?" Made me fill about an inch tall but it has never happened again :)

Tweak
10-29-2013, 12:43 PM
ROFL :rofl:

Seriously though, glad nothing major happened.

Exactly what I was thinking! :D

ABARTH TAMER
10-29-2013, 12:51 PM
Also learned the hard way to re torque lugs after a rotation. Front left actually lost a lug (that I found just down the street from my house). Get a torque wrench, believe 75 ft lb. Put some miles on it, repeat.

Robert Nixon
10-29-2013, 01:27 PM
Thanks for the tips, I had the wheel covers off for the tech and autocross, just didn't see anything wrong at that point.

rnddude
10-29-2013, 03:57 PM
Are you sure that those wheels were 98/4 and not 100/4?

dart1.4t
10-29-2013, 07:18 PM
any time i've had lug nuts loosen it was because of a mismatch between the nut and the seat in the wheel. check with the wheel maker to see what the seat angle is and i'm sure we can get the angle on the wheel studs for the abarth. i never did anything with heavy breaking to create heat so it could be like rye said, a re torque after they heat up may be all you need.

Robert Nixon
10-29-2013, 07:30 PM
The wheels are from TireRack and are supposed to 4 x 98

Tweak
10-29-2013, 08:39 PM
The wheels are from TireRack and are supposed to 4 x 98

I think it was mentioned that although listed as 4X98 they have sometimes done so with 4X100 as well, of course you would know if you were using conical or wobble bolts.

abarth&911
10-30-2013, 07:58 AM
Good that nothing happened. It’s always a good thing to check the torque before and after an AX.
There is plenty of pictures and videos on the interweb of car losing their wheel at an AX because someone forget to torque the bolts.
I did a tire rotation last weekend, yesterday I recheck the torque an a few where just slightly off.
Like already said, each time a wheel is pull off the car the torque should be recheck.

jguerdat
10-30-2013, 08:03 AM
I'm slightly confused. Are you saying you've switched to studs from the OEM bolts or are you still using the bolts? Neither uses a 12mm socket - the OEM bolts have 17mm heads (12mm x 1.5 threads) while the studs I'm using from Midwest-Bayless use an Allen wrench to get them into the hubs and then use a nut that has a 19mm head.

In any case, glad things worked out for you in the end. I've had too many issues over the years even when using a torque wrench to ensure proper torque. My '77 Fiat 131 had a slight tendency to loosen the bolts on their own - had it happen twice. My S2000 developed a habit of losing nuts (perhaps the wheel wasn't fully seated even though I checked it multiple times?) to the point that my wife got a trophy from the local region with some giant nuts on it, labelled "Jeff's nuts". Finally, I put on the winter wheels/tires recently and took a quick spin to the grocery store. On the way back, I got excessive noise like you only to find that I had torqued THREE wheels instead of four. Just shoot me now... :p

jguerdat
10-30-2013, 08:05 AM
There is plenty of pictures and videos on the interweb of car losing their wheel at an AX because someone forget to torque the bolts.

Similar but different - didja ever see the video of the RX-7 that lost all 4 wheels at once? I think it was due to incorrect nuts.

http://www.youtube.com/watch?v=eeADBRw9xCo

abarth&911
10-30-2013, 08:25 AM
Yes, he didn’t went far. Like you said it look like something was mismatch to have all 4 wheel go off like that.

Robert Nixon
10-30-2013, 10:52 AM
jguerdat: "I'm slightly confused. Are you saying you've switched to studs from the OEM bolts or are you still using the bolts? "

maybe I'm using the wrong term, but yes I have the stock 17mm 4 lug nuts, and then there are the two prongs that I called studs that also hold the tire, those are the little things that are 12mm to fasten.

jguerdat
10-31-2013, 08:06 AM
Those "studs" are simply locating posts to help position the wheels during wheel/tire changes. They don't do anything else. Some aftermarket wheels actually require that you remove them since they don't have space on the back side of the wheel for them to fit. The Ciaios I have for winter tires have clearance but it's just a big empty space so they don't even contact.