bolts

Kritter

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Be sure to use bolts made in America...not imported crap.

Kris
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jeff

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Speaking of bolts... I was in a vehicle that snapped the 1/2" Grade 8 bolt that attached the passenger side Bilstein coilover to the upper mount - not pretty. Not only is the right fastener important, but make sure it's being used properly with correct length spacers and that it's torqued properly. This fastener appears to have been damaged previously and just decided to snap at the right time. Luckily when this one snapped we were on a pretty smooth section (50-mph ish) and the damage was limited to a T-p'd hood and some slight tire and wheel well damage. If you are lucky you might just catch some video of the repair. If it had happened about 5 miles earlier we would've been screwed.

This has made me re-think the way in which I'm going to mount my own coilovers - if you don't have experience doing this stuff ask for help from someone that does.

Aloha
 

ntsqd

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G-8 fasteners are rated to be 150,000 psi tensile strength (assuming you have a bolt that actually meets the spec) and are very brittle.
Most domestic Socket Head Cap Screws ("Allen bolts") are rated to be 180,000 psi tensile and HoloKrome brand bolts are 190,000 psi tensile. These are also not nearly as brittle as the G-8's. Meaning they will bend further b4 breaking. I'd rather have a bent bolt than a broken one. Where possible, always use an AN washer under the head of a SHCS.

Figure the shear strength is 57% of the tensile strength. So your G-8 is only good for 85,500 psi per shear zone. A G-5 (@ 120,000 psi tensile) will take 68,400 psi per shear zone. A SHCS will take 102,600 psi per shear zone.

I often, and to mostly deaf ears, make the arguement that if you're going to use SAE hardware, to use a G-5 and size it accordingly. G-5's are not nearly as brittle as G8's are. Most people think G-8's are the best out bolt there, truth is they are far over rated.
If you're locked into a given size and it's a critical bolt like a coil-over bolt, spend the money with Coast Fab and get a proper bolt for the job.


TS

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dezerts10

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Speaking of bolts and coilovers and the different grades out there where would the best place to get the bolts be? Also, all the bolts i have been getting recently have i believe 6 lines on the head? what does that mean? What do all these abrevaitons mean SHCS, AN washer? I guess any old bolt that fits outa dads bolt box wouldnt be the right thing to do. So if someone could help id appricate it.


Gregg
 

pciscott

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Grade 8 bolts are great for most applications, but aircraft bolts will give you more strength. The other nice thing is they have more sizes so you can set your bolts up for the best shear. Deering industries in Long Beach carries aircraft bolts, measure the grip you need from outside of tab to outside of tab and Mitch will set you up with the bolt you need including washers. Note if you do use aircraft bolts you will need to use the special beveled washer under the head of the bolt because of the radius that gives the bolt extra strength. We use aircraft bolts on all suspension pickup points and shock mounts. On my Protruck we would bend lower A-arm shock bolts all the time when we ran grade 8, We switched to aircraft and the bolts never bent and would go a whole season. The aircraft bolt is hard all the way through and has a higher grade than a standard grade 8. A grade 8 bolt is only case hardened. Aircraft bolts can cost more than 3 times as much as standard grade 8 bolts, but they will last longer and give you that extra edge in your high stress areas. The last benefit is they are stainless steel and 12 point so you can polish them up and they look cool, just make sure you have a set of 12 point sockets in your tool bag.

God Bless America

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blind655

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whats the deal with the F-911 bolts. how are they for strength?

Later
Mike

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ntsqd

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Three lines on the head = Grade 5
Six lines on the head = Grade 8
Two lines on the head @ 90* to each other = Stainless Steel. DO NOT use these for anything load bearing.

AN = Army-Navy originally, now means something else I can't recall. They are those gold colored, semi-hard, small OD, tight bolt shank fitting washers you've seen on race vehicles. Scroll thru the hardware section of the McMaster link posted in this thread. McMaster's tech pages have a lot of good info in them, search those out.

SHCS = Socket Head Cap Screw ("Allen bolts")
BHCS = Button Head Cap Screw; those like above only with a rounded head on them. also with an internal hex drive.
FHCS = Flat Head Cap Screw

TS

"It only seems kinky the first time"
-- Bumpersticker seen in Lost Wages
 

ntsqd

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Usually, but the gold color is no garuntee of being G-8.

TS

"It only seems kinky the first time"
-- Bumpersticker seen in Lost Wages
 
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