Headstud torque ?

I had two failures while torquing cold. One broke off in the block and one of the cap threads failed.
According to ARP when I sent them in for evalutation as Greg suggested (Thanks Greg for the reference) I got " those are not our studs, I have to send them to the lab", "yes it is our studs I tell ya what I'll sell you a new set at half price, we list them at $560." I said o.k. , then I started thinking that's more than what I paid for them two years ago. So I called them back and said I can buy them all over the net for $400-425. I told them I thought they were trying to help me not sell me a set at wholesale. Then they said "well honestly it looks like a mix and match of studs you gathered and threw together, and you sent too many" kip: " I know there was 1 extra." ARP: "no there was 6 extra". LOLLOLLOL

Did you see my post "ARP studs" looking for 6 extra studs. Out of the 154 people over here and 53 over on the Cummins Forum, nobody has 6 extra studs laying around. Seriously that's redicuous. I have the weight on my receipt when I sent them in and I'll weight them again when I get them back. It was over two weeks before I even heard anthing from ARP so I called them. Then they try to call me a liar and a cheat. Pretty piss poor service if you ask me. I originally bought them from Doug at PDW a couple or so years ago. I called Cory to see if any documentation was available for them but there wasn't. I'm sure Doug wouldn't want to be called a liar and a cheat either. He did the best he could when they failed and sent me another stud but they still failed on two occasions. I even have pics laying around where you can see the stock bolt in the head. I bought two torque wrenches, extra lube and a bottoming tap to do it right but yet I have a set I can't re-use. A-1 from now on and like I said it says in the instructions to torque them hot.
 
Kip,

I can send you a copy of the original receipt if that will help. All studs I ever sold were new ARP unless A-1 was requested by the customer. I will check with the records I have on file and see if I can find the original purchase order on your studs from arp.

Doug
 
don't worry about it doug, I'm sure I have all those receipts in my tax records but I haven't had a chance to dig them out. Appreciate it though. I bought two head gaskets and something else from you that year but can't remember exactly. I already bought some A1- H-11's from Pure Diesel Power. I'm going to stick these on the gf's truck and see how many more break.
 
kipo said:
don't worry about it doug, I'm sure I have all those receipts in my tax records but I haven't had a chance to dig them out. Appreciate it though. I bought two head gaskets and something else from you that year but can't remember exactly. I already bought some A1- H-11's from Pure Diesel Power. I'm going to stick these on the gf's truck and see how many more break.
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Odd how it works. some have trouble with arp, some have trouble with A1. I guess if it's your turn, it's gonna happen.
 
I'm surprised people prefer to argue over what to do instead of picking up the phone and calling ARP if the instructions provided are unclear or missing. I'd put much more trust in instructions from the manufacturer of the part.
 
When i did my HG last time i went 125 and then ran it for a while and went back and retorqed to 135 and it have been holding fine
 
There is a lot of R&D that goes in to the specified torque specs of a ARP stud, the number is 125 cold , . Never , repeat never torque a head stud hot, the torque values change dramatically.
While 125 is a percentage of yield value , yield, meaning the studs will stretch , and develop less clamping load , you can get greedy and torque to a higher valve , as the yield is usually about 85% of maximum, it is on your on to do so.


What ARP engineers usually find when checking studs that have failed , is a clear indications that the stud has been torqued beyond yield, at some time in its life cycle, due to either over torque , or inaccurate torque wrenches .
If you have questions , please call ARP , or PM me , ill get the straight skinny for you , and help as much as I can, Ill also check if you are treated with any thing less then a courteous manor.
99% or the time the failure is due to installation error, but ARP usually will make ever effort of help a person out.
 
Remember when you start to yield that fastener your typically decreasing the cross sectional area of the stud. From then on out your probably dealing with a weaker stud, as the stud will continue to stretch with less force each time since the cross sectional area is getting smaller with each time of yield.
 
I just got off the phone with a tech at ARP and he said a retorque was not needed...

So....who's right?

This was for the 247-4203 kit.
 
ride42 said:
I just got off the phone with a tech at ARP and he said a retorque was not needed...

So....who's right?

This was for the 247-4203 kit.
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You only need the retorque if your putting on a new head gasket, or fire-ringing or o-ringing the head. If you are simply replacing the stock head bolts without removing the head, take them out one at a time, put the ARP in, torque to 90-100 lbs, in sequence. Once these are all replaced and torqued to 90-100 lbs. Go back through and re-torque to 120, in sequence. Finally, go back over the same sequence, torquing to 125. There is no need for a warm up, and retorque because the head is already seated and the gasket is already crushed to spec.

About torquing hot, I would say whoever told you that may need to be re-evaluated for sanity. The elongation you get when hot results in a highly stressed stud when she cools back down, most likely yielding the material and weakening the stud. Torque cold only, please.
 
zstroken said:
Remember when you start to yield that fastener your typically decreasing the cross sectional area of the stud. From then on out your probably dealing with a weaker stud, as the stud will continue to stretch with less force each time since the cross sectional area is getting smaller with each time of yield.
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The main weakening comes not only from the decreased cross section, but what is going on at a molecular level in the metal. Then there's the problem of torquing hot, and my question is, how hot? This could produce drastically different results based on how quick you can disassemble the top end!

:bang

The only consistent way to know how much stress your applying to the stud is to torque cold, or typically what is considered standard room temperature. This is most of the time either 68 degrees F or 70 degrees F.
 
. About torquing hot said:
I had good luck with the ARPs after I torqued hot/warm, like I said they just felt a lot better than cold. They broke when cold.
The new A1-H11's I got say right in the instructions to torque hot..:badidea::umno::badidea::doh: ???
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Camotanker said:
how many times should you retorque for o-rings?
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The best answer is until you stop compressing the gasket. As far as the number of times... It depends on the gasket used (.020 over, .010 over, stock?), and the o-ring protrusion. It also depends on the stud and the amount of torque you are using.

Or just do three re-torques. :hehe:

Paul
 
kipo said:
I had good luck with the ARPs after I torqued hot/warm, like I said they just felt a lot better than cold. They broke when cold.
The new A1-H11's I got say right in the instructions to torque hot..:badidea::umno::badidea::doh: ???
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They felt alot better when they were warm because they're stretched out, and they will feel better because of this. The problem is, once they're torqued to spec when hot, the material then shrinks, and places waaaay more stress on the bolt, even when the truck is not running and cold.

As for the A1's, this is not good mechanical engineering practice to call out such a spec IMO. The problem lies in the variation in temperature that comes with trying to torque them warm. The hot torque of the A-1's would cause me to seriously reconsider this manufacture just because of this fact. If you torque at room temp, and the truck IS thoroughly cooled, the tensile stress in the stud is accurately known....subsequently, the RESULT is more controllable.

Don't get me wrong, I'm not saying your studs are going to fail because they were torqued warm, but it just scares me having been exposed to thermal expansion rates and their effects.
 
FYI, I just did a rough calculation using standard steel elongation percentages, and it turns out, for every 100 degrees above room temperature you torque your studs, it's like adding about a quarter turn to them if you torqued to spec when cold. I would be willing to be another quarter turn at 125 ft*lbs would increase it alot. This should be about the difference you should get when torquing hot/cold.

Hot...maybe 170 degrees???
Cold...70 degrees

Just trying to quantify the difference a bit here.
 
If you torque when the motor is hot, the head, block, and gasket are all "elongated" so the only real difference would be if the stud has a difference expansion/contraction rate than the head, block, and gasket. I suspect since all are of similar material, the elongation is similar.
 
In less words, when the motor is warm it grows. If torqued to spec when warm and then the motor shrinks, along with the stud, how much extra stress are you adding to the stud? 1%.... and then look at the chance of breaking a warm stud vs a cold stud and ask yourself, WHY Does A1 recommend warm torque...... They don't like replacing broken cold torqued studs!
 
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