Replacement Hardware
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From: Rochester, MN
Replacement Hardware
I am looking for replacement hardware (nuts and bolts). I found a source <a href="http://www.boltsmart.com/" target="_blank">http://www.boltsmart.com/</a> that offers 8.8 and 10.9 tensile grade with a zinc plating. Does anybody know what the tensile strength of the original hardware is? I believe it is 8.8. Thanks
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Springer:
In Euro terms, a 8.8 bolt or hardware is roughly equivalent to US grade 5. Euro 10.9 is roughly US grade 8. Euro grade 12.9 is somwhat better than US grade 8. This is all from memory but I believe it is close, if I'm off a bit.
-- Wil Ferch
In Euro terms, a 8.8 bolt or hardware is roughly equivalent to US grade 5. Euro 10.9 is roughly US grade 8. Euro grade 12.9 is somwhat better than US grade 8. This is all from memory but I believe it is close, if I'm off a bit.
-- Wil Ferch
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It all depends on the application. Brakes and chassis usually 10.9, CV 12.9, and frequency of disassembly. It's hard to find 10.9 and 12.9 in yellow zinc. Plating hardware that has been heat treated to 10.9 & 12.9 grade introduces the embrittlement factor. If you plate 10.9 & 12.9 you must have the plater "bake" the hardware for @ 4-6 hours @ 350-400 degrees f. to release the hydrogen, otherwise your hardware will be brittle.
To the extent that pieces of the threads can actually chip off. Many fastener companies will not certify 10.9 or 12.9 if it's plated. These grades are often found in ablack oxide finish. This finish is not the best for corrosion protection. I had my 10.9 metric yellow zinc plated by areputable plater that sent certification paers with the order. Wurth USED to be a good source of yellow zinc hardware, but lately they have been buying from Taiwan(JH markings)and relabeling with Wurth stickers.
I found a lot of German and Italian fasteners from <a href="http://www.metricmcc.com" target="_blank">www.metricmcc.com</a> and <a href="http://www.metricscrew-toolco.com" target="_blank">www.metricscrew-toolco.com</a> . Sometimes they have time to tell you what head markings they have at the time. They have minimums so you'll be buying lots of 50 and 100 of each. I've spent @ $600 for a well stocked supply. Remember you'll need boxes to put your hardware in, good ones aren't cheap.
Sorry for being so long,
j.p.
To the extent that pieces of the threads can actually chip off. Many fastener companies will not certify 10.9 or 12.9 if it's plated. These grades are often found in ablack oxide finish. This finish is not the best for corrosion protection. I had my 10.9 metric yellow zinc plated by areputable plater that sent certification paers with the order. Wurth USED to be a good source of yellow zinc hardware, but lately they have been buying from Taiwan(JH markings)and relabeling with Wurth stickers.
I found a lot of German and Italian fasteners from <a href="http://www.metricmcc.com" target="_blank">www.metricmcc.com</a> and <a href="http://www.metricscrew-toolco.com" target="_blank">www.metricscrew-toolco.com</a> . Sometimes they have time to tell you what head markings they have at the time. They have minimums so you'll be buying lots of 50 and 100 of each. I've spent @ $600 for a well stocked supply. Remember you'll need boxes to put your hardware in, good ones aren't cheap.
Sorry for being so long,
j.p.
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Joined: Jan 2002
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From: Aiken, SC
Bolts can be a very dangerous subject because they fit perfectly under the heading of "If more is better than too much is just right". Catastrophic failures caused by an incorrect fastener are uncommon and if you have one you likely didn't realize that the fastener had anything to do with the problem. (i.e.> The wheel fell of when I hit the tree. Should it still be hanging on?)
Now that I am done banging the pulpit let me explain. When people look at a chart with the specs of different types of bolts they see the highest number and go "It is stronger. That's what I want." There are is a lot more going on here. A grade 8.8 (equiv. SAE 5) bolt has a minimum tensile strength of about 120,000 psi. A grade 10.9 (equiv. SAE 8) bolt has a minimum tensile strength of about 150,000 psi. (12.9=180,000+) What this means is the 10.9 bolt will take 25% more load before it starts to permanently deform. The problem is that the higher strength bolt won't deform as far before it completely shears. The grade 8.8 bolt should deform almost twice as far.
The bolts in a car will never get anywhere near their design limits unless the car has some sort of accident. So when that tire smacks the wall you want the control arm bolt to absorb as much energy as possible. It is much better to have the wheels attached with a bolt that looks like a question mark than just falling off.
My basic point is don't change the grade of any fastener that would deform during an accident unless you have studied the problem and have a very specific reason that it has to be done. The bibles for this kind of information is Carroll Smith's <a href="http://www.amazon.com/exec/obidos/ASIN/0879381434/" target="_blank">"Prepare To Win"</a> and <a href="http://www.amazon.com/exec/obidos/ASIN/0879384069/" target="_blank">"Nuts, Bolts, Fasteners and Plumbing Handbook"</a>
Wayne
Now that I am done banging the pulpit let me explain. When people look at a chart with the specs of different types of bolts they see the highest number and go "It is stronger. That's what I want." There are is a lot more going on here. A grade 8.8 (equiv. SAE 5) bolt has a minimum tensile strength of about 120,000 psi. A grade 10.9 (equiv. SAE 8) bolt has a minimum tensile strength of about 150,000 psi. (12.9=180,000+) What this means is the 10.9 bolt will take 25% more load before it starts to permanently deform. The problem is that the higher strength bolt won't deform as far before it completely shears. The grade 8.8 bolt should deform almost twice as far.
The bolts in a car will never get anywhere near their design limits unless the car has some sort of accident. So when that tire smacks the wall you want the control arm bolt to absorb as much energy as possible. It is much better to have the wheels attached with a bolt that looks like a question mark than just falling off.
My basic point is don't change the grade of any fastener that would deform during an accident unless you have studied the problem and have a very specific reason that it has to be done. The bibles for this kind of information is Carroll Smith's <a href="http://www.amazon.com/exec/obidos/ASIN/0879381434/" target="_blank">"Prepare To Win"</a> and <a href="http://www.amazon.com/exec/obidos/ASIN/0879384069/" target="_blank">"Nuts, Bolts, Fasteners and Plumbing Handbook"</a>
Wayne
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From: Nashua, NH USA
Wayne has it right. Fasteners are a bad place to "play engineer". Some thoughts on fasters:
* Another way to think about the higher grade bolt, (12.9 vs 8.8) is to remember that the while the 12.9 is stronger it is also more brittle.
* Stainless is not a better/stronger material for bolts, it just resists rust (and looks pretty).
* Titanium is notch sensitive. (Think of how glass breaks at a scratch.) Ti also galls easily. Not great properties for a fastener so the application should be designed for it and the faster should not be reused.
-Chris
* Another way to think about the higher grade bolt, (12.9 vs 8.8) is to remember that the while the 12.9 is stronger it is also more brittle.
* Stainless is not a better/stronger material for bolts, it just resists rust (and looks pretty).
* Titanium is notch sensitive. (Think of how glass breaks at a scratch.) Ti also galls easily. Not great properties for a fastener so the application should be designed for it and the faster should not be reused.
-Chris
