Subaru field engineer says OEM wheel studs only good for 75 to 80 wheel changes
 

I was talking with a BRZ friend of mine recently that is a knowledgeable, experienced driver. He pays close attention to vehicle maintenance including wheel lug torque specs. He recently had a couple OEM wheels come loose on the track. Fortunately he was able to get the car slowed down in time to keep them from coming off. His wheels were damaged, so he spoke with his dealership about it. After giving him a hard time, he was finally able to speak with the field engineer about this issue. The engineer said the OEM studs and lug nuts are only designed to withstand 75 to 80 changes over the life of the vehicle. My friend actually had the failed studs tested and said the metallurgy is terrible. Here is an email I got from him about it:

re : the Subie engineer and my wheel studs and lug nuts, he was a pretty cagey dude. he would put nothing in writing for me despite several requests. Clearly, the design life of parts is not something they want to discuss openly. I felt pretty lucky that they replaced both ruined wheels as a "courtesy" rather than under warranty. He made it very clear however that our cars "arent designed for track use ". and "this car isnt a Porsche". of course I said they "why isnt all that in the owners manual ?" .
bottom line is the "design life" of the lug nuts and studs is 75-80 wheel changes, on average, in the lifetime of the car. "Kmart" parts used in quite a few places on a $25K car, I suspect.
In order for you to avoid my issues, I strongly recommend you go to ARP studs, kit # 100-7727 for FRS or BRZ. their tensile strength exceeds grade 10.9 steel so they are the best you can get.
For your information, I researched the stock studs and lug nuts. they are made from < grade 8.8 carbon steel. in short that means they are el-cheapo Kmart parts.
grade 10.9 alloy steel is generally the best steel other than "aircraft quality" . ARP has a tensile strength rating system and their's are better than grade 10.9.

Be careful out there, kids!

It happened also to me after removing different bolts. They were so soft that the head was deformed. I had to replace them with new ones. In fact the service manual suggests many times to replace the bolds. Does this mean that this car is cheap? No! Think about if all these bolts, studs and other parts of the car were made from high strength steel. Think about how much more the car would weight. Do you know the weight of a basic Porsche Cayman? :)

Mine didn't even last that long before cross threading.

Roughly 150lbs more than a BRZ Limited.

With build quality that is an order of Magnitude higher, much higher quality materials etc.

Go look up the video of Bill Caswell doing 50 straight, launch control starts in a 911 Turbo and the car never overheating, going into limp mode, etc. Try this in a GTR and watch the transmission puke on the ground after the 4-5th time straight you do it. You simply can't compare the build quality of Porsche to basically anything else.


They constantly rank number #1 in initial quality, quality of replacement parts, etc.


Sorry, it was 61 straight launches.

[ame="https://www.youtube.com/watch?v=A5DRCTW-Q7o"]THe 2014 Porsche 911 Turbo | Road and Track - YouTube[/ame]

High quality doesn't equate to high weight.
Aircraft aluminum
Carbon fiber
Forged wheels
etc.

Failed part lab testing? Access to a Subaru engineer? I must hang in the wrong circles.

Even Dorman's cheap aftermarket replacement stud specifically for our cars shows grade 10.9 on the head.

I'd be interested in hearing the science on what they found in the OE stud. I've heard of Subarus having these problems for years, but not so much on Nissans using 12x1.25 studs. I figured a finite number of subcontractors churned out the OE stuff.

I asked for more detail but that is all I was able to get, unfortunately.

@Pat did you do the metalurgical analysis done?
@JimR: R35 GTRs shear studs all the time.

Dorman's set of studs goes for $40. ARP's is maybe $200. Is there really much difference? As JimR noted, "Even Dorman's cheap aftermarket replacement stud specifically for our cars shows grade 10.9 on the head."
Generally you get what you pay for, but if the grades are the same, how much difference can there be?

What kind of tires was your friend using?

From my tracking experiences it is relatively common to break studs on many car platforms with sticky tires on track. 350z, 135i, mustang gt. They are basically a wear item.

Lol nice. I'll have to let Bill know that somebody used his video on this forum. :D

And ironically do you know who builds Boeing's wings? Subaru!

You guys, don't know what you buy. Do you know about their special ring-shaped structure? Firefighters are doing special training on the Subaru's because they could not cut their b-pillars. You can read more details here: http://www.firehouse.com/article/105...orcement-frame

If something really matters, then be sure that Subaru will do the best and use the best materials.

The E30 guys have followed Bill since his crazy rally race in Mexico. :D

lol... this guy in the video is funny! I haven't seen more ridiculous car review :bellyroll:


And where did you found that Cayman weights 150 lbs more? Cayman is in the range of 3,000 lbs which is roughly +400 lbs. And don't forget, Cayman is a 2-seater. 911 Turbo S is a nice car, but it is far away from the category of BRZ. We should be reasonable when doing comparisons ...