Fasteners

shelby racer · #1 (**permalink**) 03-22-2009, 11:59 PM

I am looking to replace the m10 x 1.5 metric cap / socket head fasteners
in the front suspension of my cobra. I think the old ones are stainless
and are of undeterminable grade. The best stainless ones I can find are
A4-80 which is apparently around grade 8. Does anyone have a source for
better ones? Do I need stainless fasteners? are there mil spec ones
that are batter that I can use? Thanks. John(;-)

PANAVIA · #2 (**permalink**) 03-23-2009, 01:39 AM

here is a chart for how strong metric bolts can be and their gradings.

http://home.jtan.com/~joe/KIAT/kiat_2.htm

for getting bolts, you probably can find a specialist in your area or go to

http://www.mcmaster.com/#

and GEEEEK out and order.

remember 10.9 = about a grade 8 , and 8.8 = a grade 5. -- so very very few places on the car will require a 12.9 grade.

--Steve

sllib · #3 (**permalink**) 03-23-2009, 06:00 AM

ARP has a web site and a 800 number and they'll ship small orders.
Bill Stradtner

shelby racer · #4 (**permalink**) 03-23-2009, 10:50 AM

Thanks steve,
I will follow up. As far as upgrading the bolts, do I know the others were inadaquate? No. Would I feel better with belt and suspenders on a mission critical piece after having had a problem, yes. What is my piece of mind (+/- safety) worth ? who knows. My mom says priceless

Thanks sllib
I would love to get fasteners from ARP, but they don't make what I want and I think it would be pricey to get them to make them custom.

John(;-)

Silverback51 · #5 (**permalink**) 03-23-2009, 12:08 PM

Please remember that sometimes stronger is not better. We have situations were we use a Grade 5 bolt instead of a Grade 8 bolt due to a Grade 8 bolt being more brittle.

What it comes down to is the loads it will see, and in suspension components, the fatigue loads. Suspension components see a lot of cycles, which is the main factor in fatigue failures.

DougD · #6 (**permalink**) 03-23-2009, 12:54 PM

If I was going to the trouble to replace the fasteners in my suspension (and I'm not), I'd use AN and nothing else. If you plan to use hardware store fasteners in a suspension application, you're taking more of a chance than I'd be comfortable with. I'd suggest reading one or more of Carroll Smith's race car preparation books (Prepare to Win, Engineer to Win) as to why and where. In suspension applications, grade 5 and grade 8 may not cut it when you factor in the physics they're exposed to. Even the basic design of these fasteners precludes their use in some instances, i.e., bolts that are threaded for their entire length, etc.

Rick Parker · #7 (**permalink**) 03-23-2009, 12:55 PM

Grade 8 fasteners are not permitted to be used in Suspension components in SCCA Club racing. In several informative sources on fasteners they state Grade 8 is only intended and designed to be used in tension applications. They are very brittle. Do all the current production CSX cars have metric fasteners or was it only early production?

bobcowan · #8 (**permalink**) 03-23-2009, 12:58 PM

I agree with Doug. There's really no need to change any of the fastners, unless the don't fit right.

Get ahold of a copy of Carroll Smith's book, "Nuts, Bolts, Fastener, and Plumbing Handbook". Very enlightening. Grade 5's work best in a shear situation. Grade 8's should only be used in conjunction with dowel pins - like bellhousing to block.

According to Carroll, "There is no place on a race car for a grade 8 fastner". Not sure I agree with that, but applications are limited.

shelby racer · #9 (**permalink**) 03-23-2009, 10:31 PM

I read the smith book on engineer to win when he talked about fasteners. My cobra mechanic and I discussed it and all the bolts have been replaced. Wish me luck.
John(;-)