This has been discussed a zillion times before, but I am asking for an answer to a technical question. Obviously they are rusty, but the steel to steel mating and torque/stretching of the bolts probably offers some increased strength. ( I.e that's what Porsche engineers thought of in R &D) I bit the bullet and purchased some SS lugs which have a much higher Rockwell hardness than steel. Will this affect in any way the strength of the wheel attachment to the steel hub? I.e with the SS being so much harder will it be a looser connection, along with different flange mating characteristics of a malleable vs a harder substance?

BLUF....

Will my wheels be flying off under extreme conditions?

 

Granted, I don't drive my Porsches in salt and snow. But I have never experienced a rusty lug bolt, stud or nut in over 18 years of driving 911s. What are the rusty bolts to which you are referring?

As for the bolts in a bolted joint staying tight, one must understand the spring rate of the bolts and the spring rate of the abutment. For a bolted joint designer this is not a very complex issue regarding a joint as simple as to hold the wheel to an automobile, but it would sound like rocket science if I explained it in detail.

I see little reason for concern with standard OEM bolts or the stainless steel ones you have chosen. If you need to worry about something, ponder the engineering or lake there of with you IMS bearing and seals.

 

I understand spring rates but don't want to lose sleep over it. I would be interested in your detailed explanation. The Porsche mechanic said they wouldn't recommend it and I wanted a better explanation than that... Did you mean RMS or is an "IMS" another design flaw? I thought this had been dealt with in MY08, And yes I mean wheel lugs...

Thank you

 

buy the 10.9 steel lugs, or chrome lugs and they wont rust

 

Start with this.
http://www.fastenal.com/content/feds...t%20Design.pdf

 

The wife hates rusty nuts..gotta polish them regularly

 

SS is not known for hardness...

Curious who makes SS lugs w/ a rated hardness equal to or higher than the OEM wheel bolts? Link?

 

Thanks, interesting read.

 

It all depends on the stainless. For example, A286 stainless (it's some badass stuff) would be no problem, but if it's something like 316, then I'm not so sure I'd trust it.

 

Maybe the mechanic was concerned with a galvanic couple.

 

Potentially... Here are the specs...

"High Quality Cold-Forged And Heat Treated T304 Stainless Steel . These Lug Nuts are Extremely Strong and will remain Rust Free for Life . They Exceed 300 Hours of Salt Spray Testing"

"VMS Racing Stainless Steel are Manufactured to ISO 9001 QAS Standards and Surpass the Highest OEM Quality Standards and Have a Durable Long Lasting Finish*"

What's the verdict fellas as I have her up and ready for xchange....??

 

Forged is good, that means they've been worked hardened, but I'm no so sure you can heat treat 304. Which makes me wonder a bit about their claims. Maybe they mean the SS was annealed before forging.

But you're buying from a racing shop, so I'd imagine they'd stand behind them. If you were just ordering off McMaster-Carr then I would have been worried.

 

hardened 304 SS?

OEM wheel bolts are 8.9 ISO as I recall to which there is no SS equivalent.

Be careful...