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Yesterday, fastener technology was pretty much “cut and try.”
Often times the thinking was, if it breaks go to one size bigger.
The game of substituting aircraft fasteners didn’t work either.
Although the quality was there, aviation fasteners simply didn’t
exist for across-the-board substitution. They still don’t.
In real life there was no bullet-proof manufacturer of fasten-
ers specifically for race cars. There were attempts by various
fastener manufacturers to
claim expertise on a few spe-
cial applications like rod bolts
and wheel studs. But in real-
ity, results were mixed, from
good to terrible.
It’s this simple; properly
designing racing fasteners
requires the skills of metal-
lurgists, stress analysts and
engineers. And to make them
requires special machinery and
manufacturing techniques. It
is also a fact that there is no
way to do this cheaply, or in
high volume production.
I was asked to be a spokes-
man for ARP. Because I had
never done this before, I made
it a point to visit the ARP manufacturing facilities to see if their
products were good enough for me to endorse comfortably. The
visit blew my mind. I’ve been around some nut and bolt joints
before, but nothing I’d seen before could compare with the quality
of inspection of the raw materials and their manufacturing process.
Examining the “Over-Kill” fallacy
If there’s one thing I’ve heard over and over from visitors to
trade shows and races it’s,
“Your fasteners are great. I’m not having
any problems but I’m being told, by your competitors, that ARP is over-
kill and therefore I’m wasting some money when I buy ARP pan bolts,
manifold bolts or just about everything except for certain critical
engine, drive train or suspension fasteners.”
My first instinct is to
say they are full of _ _ _ _.
But the subject is worth talking about. Cost is an important
consideration when you choose a particular vendor’s offering. Still,
if you use lesser quality fasteners and they were not subject to many
assembly and disassembly cycles, by people with varying skills from
professional to rank amateur. Maybe, just maybe, you could make a
case for minimum grade fasteners that are over designed, size-wise,
to allow a reasonably safe application for conservative usage.
Now, lets get back in our world. The real world. We can expect
the engines and vehicles to be leaned on, from a little to beyond
any sensible extreme. We can expect 10 or more assembly/disas-
sembly cycles. We can expect over-torquing, which will leave the
fastener looking 100% but actually in a condition RED, semi-
failed mode. We can expect some fasteners that are minimal in
quality to end up in a critical, high-stress area. We can’t expect
everyone to be able to look at a fastener and determine its quality
by looks, or even by markings. So we leave ourselves wide open
for expensive and possibly dangerous results. For the amount
of money saved by “type rating” every fastener’s capability, and
consideration of a long range view of the best mix of customers, I
recommend all fasteners be of a quality that
does
exceed the mini-
mum standards.
“It’s to your advantage to know fasteners.”
To thoroughly understand it all would require at least 4 spe-
cific engineering degrees and 20 years of hands on experience in
each. Nothing is forever, but take my word for it, ARP is the only
game in town today. Just about every successful racer I know today
uses their stuff 100%. You can help yourself in reference to mate-
rial specs, thread lubes and torque techniques, also in fastener
maintenance and handling. If you do a good job here, you’ll never
lose position in a race from fastener failure.
There are many “little things” to consider
1. When you use a locking chemical for studs, bolts or even nuts,
consider if you really need it.
2. If you are using a locking chemical, don’t force nuts off or studs
out without a proper first step, like heat or release chemical.
3. If you can’t easily screw a nut and bolt together by hand they
shouldn’t be used.
4. Consider the importance in regard to how many exposed
threads are left when fastener is set. Turns out this has a bearing
on necessary torque and ultimate strength of the fastener.
5. Gradually try to understand and learn the difference in the
various steels used in fasteners.
6. Turns out, the best way to consider a fastener as a spring of
correct elasticity for that specific job. Yup, a fastener works best
when stretched a specific amount.
7. You have got to start studying fasteners just like you do pistons,
cranks, rods, etc. There’s a lot to learn if you know what to
look for.
8. The more you understand all the design limitations of fasteners,
the better the engine durability will be.
9. If you can’t stretch the bolt enough, it can still fatigue, lose
torque or get loose.
10. Use a stretch gauge whenever possible. This is the only fool-
proof method of getting the correct clamping force.
11. Get access to a master gauge to check your torque wrenches.
You’d be surprised at how many torque wrenches read incor-
rect.
12. Don’t forget that you’ll get different torque readings when
using different lubricants.
13. Always use ARP fastener assembly lubricant whenever possible.
Get the “Inside Scoop” in Smokey’s book...
In addition to being one of racing’s most famous innovators
and personalities, Smokey Yunick was known for being opin-
ionated on many matters. He told it like it was, according to
Smokey. Before his passing, Yunick spent considerable effort
compiling anecdotes from his illustrious career. It’s a “must have”
book for anyone who is into auto racing. From Daytona Beach
to Indy, Smokey lets it rip!
TRIBUTE TO SMOKEY YUNICK
Hall of Fame Mechanic
“Smokey” Yunick
For many years “Smokey” Yunick served as a valued tech consultant and
spokesman for ARP. He was a popular host of our Tech Seminars at trade
shows, and his knowledge of fasteners was truly astounding. Smokey
passed away in 2001, but his wit and wisdom will live on. Here are a few
of his observations and tech tips. R.I.P, Smokey!
For details on purchasing
Smokey’s book or apparel visit
