Bolts for the front Eye Bracket Nuts - Team Camaro Tech
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post #1 of 23 (permalink) Old Mar 1st, 02, 09:46 PM Thread Starter
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Ken
 
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Does anyone know the size of the bolts that hold the rear spring front eye bracket to the front eye bracket nut. Also whether its a course thread or fine thread
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post #2 of 23 (permalink) Old Mar 2nd, 02, 06:10 AM
 
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Yes, Think they are about 3/8" x 1" or 1-1/4". If a 9/16" wrench fits, they are 3/8"! But please check b/c it's been a while since I ground the heads off and did the replacement with my springs.

I put mine back together with Stainless Steel bolts and washers to hold off rust! pdq67



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post #3 of 23 (permalink) Old Mar 2nd, 02, 07:37 AM
msb
 
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I could be wrong, not knowing the brand of bolts you used, but.... The average stainless bolt, like you buy at ACE, is only grade 2. A cheap steel bolt is grade 4-5, get some grade 8's and some antisieze compound. Grade 2 would be ok for mounting things like your windshield wiper motor, me I want grade 8 holding things on that my wheels and brakes are attached to.
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post #4 of 23 (permalink) Old Mar 2nd, 02, 07:27 PM
 
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msb,

Thanks for your concern.

But I gotta feeling that my ME degree, plus my hand's-on "Feel" torque wrench would have told me if the SS bolts I used aren't up to the job! I guess what I am saying is that I figure that they are about Grade 5's, imho.

They came from the (he, he, so expensive) one-off hardware trays full of specialty fasteners right next to the Grade 8 stuff so I'm going with them.

Heck, I can twist a 3/8" Grade 2 bolt in two with a 9/16" Craftsman box end wrench and these sure didn't feel like THAT! pdq67



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post #5 of 23 (permalink) Old Mar 3rd, 02, 04:32 PM
 
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The bolt is 5'' long, 1/2 X 2O fine thread grade 8, these can be obtained from classic industries or mcmaster-carr supply.
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post #6 of 23 (permalink) Old Mar 3rd, 02, 04:45 PM
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I'd forget the stainless, I sail and when stainless seizes which it does very easily, its 10 times harder to work with.

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post #7 of 23 (permalink) Old Mar 4th, 02, 03:23 PM
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What are the headmarks? If they're plain with no marks, they're Grade 2, with cut instead of rolled threads.

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post #8 of 23 (permalink) Old Mar 4th, 02, 04:13 PM
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Well, if he's got a Mechanical Engineering degree, he's probably got a pretty good idea on what do use!

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post #9 of 23 (permalink) Old Mar 4th, 02, 04:47 PM
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With all due respect, I disagree with PDQ67's assesment of fastener choice and scientific method.

Unless the stainless bolt is purchased from a manufacturer that will provide an engineering specification sheet the best you can hope for is 90ksi ultimate tensile strength. Grade 5 standard steel is 120ksi, Grade 8 150ksi.

How the bolt is lubricated during installation has a large effect on the torque required to shear the head of the bolt from the shank. The greater the friction between the bolt head-washer-mating surface the greater the torque will be before the head will shear. Lubricating the bolt head as well as the threads is the proper way.

Trying to "Feel" the torque or guessing the quality of a fastener is not something to be done on a critical application. Using properly selected, well lubricated fasteners tightened to the proper torque is a sure fire way to do it right.

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post #10 of 23 (permalink) Old Mar 4th, 02, 06:18 PM
 
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I give up, I give up!!

All I'm saying is that I feel safe with what I used and that's all.. I'm not talking about the spring-eye bolts or shackle-bolts here!

All points well taken.

Yes, SS does gall! BUT it doesn't corrode or rust! And yes, run of the mill SS is a low yield strength material! And yes, torquing by feel isn't the best way to do things! Along with different thread torque lubes all enter in on fastener torque spec'ing! pdq67



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post #11 of 23 (permalink) Old Mar 4th, 02, 07:25 PM
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Ah, this is why I love Boeing Surplus. Aircraft alloy fasteners, Grade 10.2 allen head screws, ahh yes...and spec sheets!

But one question though...couldn't a low-grade stainless steel fastener handle more torque loads than the flimsy clip nuts in the frame? To me (I'm still getting my BS in ME) I would THINK the clip nuts are the weakest link, even if a Grade 2 bolt where used.

But be aware that even fasteners with a Grade 5 marking does not tell you what fastener it is. SAE J429 Grade 5 will have anywhere between 105-120,000psi tensile strength. HOWEVER, ASTM A449 Grade 5 fasteners are as low as 90000psi! Ask the ACE hardware employee if they stock A449 or J429 Grade 5 hardware and he'd pee his pants.

Long story short, you cannot assume the specifications of any foreign made hardware. What you can assume is that SAE J429 Grade 8 is somewhere around 150,000psi, Grade 5 is less, and Grade 2 is less than Grade 5. How much less? Who knows, neither does the Chinese guy who made it.

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post #12 of 23 (permalink) Old Mar 4th, 02, 08:05 PM Thread Starter
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Ken
 
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I actually broke 3 of the clip nuts putting everything back together. They are Flimsy
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post #13 of 23 (permalink) Old Mar 5th, 02, 02:03 AM
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I can see my fellow ME Iowan needs some ME backup as I am the same.

I have also used and still using Stainless hardware in the same spot as well. Have been for several years after several hundred runs.
And never a galled thread, I use antiseize, b/c someday, I'll be removing it.

One has to figure the load of the bolt in this application. It is always in compression, no shear load is there. The spring pushes up on the pad against the body, there is a locating tab on pad to fit in a corresponding hole for shear movement. The purpose of the bolt is to clamp the pad to the body, no other forces (vectors) are there.

Now if the clip nut breaks, one can always go topside to the rear floor underneath the seat and drill a 1 inch hole and use a screwdriver and a 3/8 nut and through bolt the parts together. The clipnut is just an assembly line aid.

As far as torque, usually, when tightening a fine thread fastener, one will usually turn an extra hex flat after the lock washer has been compressed. This will usually place the proper amount of torque, w/in 10%, or the rating. Coarse threads will usually take an additional 1/2-3/4 hex flat while tightening. Adding lube to the same threads greatly changes the torque required, usually 20-30%, depending on type used.

One working with fasteners will gain alot "hands-on" knowledge and develop a technique(?) in assembly of same. Yes, we've all turned too much and either stripped the threads, broke off the head, or twisted off the stud. We felt it coming, but, to get that last clamping force, we exceeded the yeild strength of the material and now we have to use the dull high-speed drill bits to drill out the old and replace with new hardware.

I'm done now, thanks for listening and letting me vent....my tank is empty.

But, I must say this, this post is a darn good discussion, and everybody in it, has a good point. I have learned, thanks...

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post #14 of 23 (permalink) Old Mar 5th, 02, 02:17 AM
 
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Thanks, Everett.

I do occasionally go "shade-tree" every once-in-a -while! pdq67



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post #15 of 23 (permalink) Old Mar 5th, 02, 04:20 PM
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Everett -

I differ with you on the lack of shear vectors; axle transverse torque reaction tends to twist the springs, imposing an upward force on the brackets, which doesn't stress the bracket bolts, but the force that moves the car forward is horizontal, from the axle longitudinally through the upper spring leaf into the bracket, which imposes shear loads on all three bracket bolt shanks. In side view, the spring front eyebolt (where the horizontal load is transferred to the bracket) is exactly on the same plane as the interface between the bracket and the body reinforcement it bolts to, so virtually all the kinetic energy exerted from accelerating the weight of the car is applied directly in the center of the shear plane of the three bolts. I'm an M.E. too - great discussion! That's why the OEM bolts are Grade 5.

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