Don M's studs
05-19-2004, 11:15 AM
#46
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Slacking to 96...LOL! Lets try again. If you were employed by a performance shop that sold 4340 studs for the Cummins and were asked to provide the TQ specs would you write them to say "use ARP lubricant and tq to 120 ft lbs?"
John, taking something from theory as in Banshees case here and moving it into the world of reality is some data we all need. Your data is good input. As time goes by...if things prove it out in the real world I may eventually recommend a higher TQ value for the ARP's. As it goes now...ARP feels the 75% region was the safest and I agreed. Of course the fastener can take more, but is it needed or wanted yet I dont know.
I suspect I will go ahead and build a fixture to hold the different fasteners to measure the stretch with a gauge and of course the clamp force being obtained.
Don~
John, taking something from theory as in Banshees case here and moving it into the world of reality is some data we all need. Your data is good input. As time goes by...if things prove it out in the real world I may eventually recommend a higher TQ value for the ARP's. As it goes now...ARP feels the 75% region was the safest and I agreed. Of course the fastener can take more, but is it needed or wanted yet I dont know.
I suspect I will go ahead and build a fixture to hold the different fasteners to measure the stretch with a gauge and of course the clamp force being obtained.
Don~
05-19-2004, 11:52 AM
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Don,
Okay, do I feel you can do it and have it work for you: Yes.
If I was an OEM and writing the specs, no, I wouldn't say 120. It's too close "on the edge" to recommend to everyone. A shop that knows what they're doing and does a lot of installs can push the envelope more than Mr. Joe Mechanic can. They generally have better tools and more experience using them. The torque wrenches used here are calibrated frequently, but Joe's might be a relic his granfather bought 40 years ago and hasn't been touched since. I'd say 105-110 would be as high as I would recommend to anyone wishing to install the studs.
IMO ARP "drops" to 75% to ensure a safety factor on the fasteners. There's nothing wrong with being conservative... we are forced by regs and specs to be conservative here on a lot of things, too. I believe their usage of 75% comes from the inherent in accuracies in torque wrenches as well the person using the wrench. 75% is a good rule of thumb for fasteners that are removed frequently since it doen't stress the threads too much and ruin them after 2 or 3 uses. The 90% is generally another safety cap to have a margin of safety in a conservative design, but when that isn't possible the "torque to yield" fasteners are used... max it out at 100%+ for max clamp with the least weight & size possible. The other idea is to use a stronger material and/or a larger fastener and get the same or more clamp without pushing the limit so far.
Okay, do I feel you can do it and have it work for you: Yes.
If I was an OEM and writing the specs, no, I wouldn't say 120. It's too close "on the edge" to recommend to everyone. A shop that knows what they're doing and does a lot of installs can push the envelope more than Mr. Joe Mechanic can. They generally have better tools and more experience using them. The torque wrenches used here are calibrated frequently, but Joe's might be a relic his granfather bought 40 years ago and hasn't been touched since. I'd say 105-110 would be as high as I would recommend to anyone wishing to install the studs.
IMO ARP "drops" to 75% to ensure a safety factor on the fasteners. There's nothing wrong with being conservative... we are forced by regs and specs to be conservative here on a lot of things, too. I believe their usage of 75% comes from the inherent in accuracies in torque wrenches as well the person using the wrench. 75% is a good rule of thumb for fasteners that are removed frequently since it doen't stress the threads too much and ruin them after 2 or 3 uses. The 90% is generally another safety cap to have a margin of safety in a conservative design, but when that isn't possible the "torque to yield" fasteners are used... max it out at 100%+ for max clamp with the least weight & size possible. The other idea is to use a stronger material and/or a larger fastener and get the same or more clamp without pushing the limit so far.
05-19-2004, 11:56 AM
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top notch info---if only we could understand it all--
banshee--are you saying torque down to 120 then loosen and retorque to 96 as a procedure or am I reading this wrong???
Don--I know it may be unwise to say here, but can these new studs be torqued to a higher value than the 96 stated and still function within its limits ---why not just give us the max that you would torque these two--one other thing-- these new studs are stated as being equal in clamp load to the 14mm studs or am I misunderstanding this also---if they are equal and guys are having good luck with the 14mm, then there should be no reason to go with even a better stud ---now with that being said your previous info you have answered for me would say get the better stud, which I believe would be smart---
also is it unwise to remove one stud at a time and reinstall the newer ones--
one more thing--what is the max torque that one should torque the old 12mm studs to--I have mine at 135 w/ ARP moly(1.5yrs) and yes I've seen one break at this setting--I don't think we we're using the ARP lube when we broke it though as HVAC got info about using it after the fact--but I could be wrong----
again this is a great thread -thanks to all who are dishing out the info---chris
banshee--are you saying torque down to 120 then loosen and retorque to 96 as a procedure or am I reading this wrong???
Don--I know it may be unwise to say here, but can these new studs be torqued to a higher value than the 96 stated and still function within its limits ---why not just give us the max that you would torque these two--one other thing-- these new studs are stated as being equal in clamp load to the 14mm studs or am I misunderstanding this also---if they are equal and guys are having good luck with the 14mm, then there should be no reason to go with even a better stud ---now with that being said your previous info you have answered for me would say get the better stud, which I believe would be smart---
also is it unwise to remove one stud at a time and reinstall the newer ones--
one more thing--what is the max torque that one should torque the old 12mm studs to--I have mine at 135 w/ ARP moly(1.5yrs) and yes I've seen one break at this setting--I don't think we we're using the ARP lube when we broke it though as HVAC got info about using it after the fact--but I could be wrong----
again this is a great thread -thanks to all who are dishing out the info---chris
Interesting discussion. I'm learning more about stress and fatigue on metals here than I am in college.
05-19-2004, 12:42 PM
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Having read all this GOOD STUFF, leaves me baffled. I am about to do a head job in a couple of weeks, primaryily to stop a leak. I am going to basically do a stock job, but I though about adding the studs. I am getting 45 lbs. of boost on 5x5 with DON'S 1.5'S. I just don't see spending the extra money to o-ring, etc.. I AM SATISFIED where I am with power & performance. Do you guys even see a need to use the studs versus the head bolts. If I were to use the bolts, do yall recommend getting new ones or should my old ones be OK? I APPRECIATE any help y'all can provide. THANKS, DANNY
05-19-2004, 12:59 PM
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Don, When you retorque a fastener do you back it off first then torque to spec or do you just put the wrench on it & torque it to spec.& do you think i should retorque my stock bolts & if so to what number Enterprise never told me if i should.Good reading guys keep it coming.
Kurt
Kurt
05-19-2004, 01:09 PM
#52
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The 14mm's will actually give more clamp force, but you gotta deal with the other issues, real or imagined, of distortion and lower block rigidity. The ARP and the 14mm H-11 have the same tensile strength.
Since I have not tested the ARP fasteners total stretch and clamping force applied VS the TQ you put on them...the spec remains what ARP has given us. 96 ft lbs using the ARP lubricant.
Permanent deformation of the stud will occur before it breaks or reaches the ultimate tensile strength. If you have your studs to 135 ft lbs and used moly they are too tight. The chances they are permanently deformed is high. This is what Banshee was talking about when he said "plastic" earlier. Yield, plastic or derformation mean about the same thing here. The bolt "yielded" or deformed.
I would say the best policy for the old studs would be to contact the manufacturer and get the low down from them. Do you still have the paper I wrote and sent to you back two years ago on head gaskets? I went back and reviewed the document and it reads to never exceed 108 ft lbs on the studs using moly. It does not mention ARP lube which is actually slipperier.
Here is the old text from back then on bolts and studs if you lost it:
"
STUDS VS. BOLTS
1. An improved fastening system can permit better clamping loads between the head and block. A stud with its shaft in block will always provide a better system than a bolt tightened into the threads of the block. The purpose of tightening a bolt or stud is to put tension into the shaft. The amount of torque that gets converted to tension is almost solely dependent on the amount of friction between the threads of the stud and the threaded hole in the block, and the friction between the cylinder head and the washer or bolt head. To gain maximum tension in the shaft the friction must be reduced as much as possible. A good molysulfide lubricant used in these areas will reduce the friction a great deal, so much in fact that we should reduce the torque values by 10% when using a moly based lubricant.
2. EXCESSIVE bolt loading can cause problems. Many mechanics think that if 120 Ft. lbs. of torque is good then 140 is better. In fact testing has shown that less is best in most instances. Indeed extra horsepower and sealing may be achieved by being "torque frugal". Why? The more torque that is applied into the block the more chance of distortion. This distortion is usually seen at the weakest places at the narrowest point of the bore and at the top of the cylinder. At the top of the cylinder where the compression pressures are always greatest any excess distortion will nullify any benefit of that extra clamping force. Recommended torque is started with all stud nuts taken to 66 lbs. Followed by 90 lbs. and finally to 108 lbs. if using a moly lubricant. If using engine oil the maximum torque values are 114 lbs. If you decide to use the stock bolts, the maximum torque values with moly is 108 lbs. And with engine oil it is 119 lbs. Engine dyno and long term everyday use have proven the 119 lb. torque value to be working very well with stock bolts."
Don Morrison Oct 23rd 2002..modified on Nov 24th 2002
These were the absolute maximum I would ever TQ these fasteners to with the data I have now. Its a theory they will work better at this level. A trade off between distortion and max clamp load. Opinions only! Some real world data and bore gauge use I had showed the distortion a real problem. This is why I contacted BHJ for a tq plate.
Yes you can remove one at a time to install the new studs. Since yours are more than likely roached...it would be a good idea.
The ARP tq is still 96 lbs using the ARP lubricant. Not the 108 mentioned above.
Don~
Since I have not tested the ARP fasteners total stretch and clamping force applied VS the TQ you put on them...the spec remains what ARP has given us. 96 ft lbs using the ARP lubricant.
Permanent deformation of the stud will occur before it breaks or reaches the ultimate tensile strength. If you have your studs to 135 ft lbs and used moly they are too tight. The chances they are permanently deformed is high. This is what Banshee was talking about when he said "plastic" earlier. Yield, plastic or derformation mean about the same thing here. The bolt "yielded" or deformed.
I would say the best policy for the old studs would be to contact the manufacturer and get the low down from them. Do you still have the paper I wrote and sent to you back two years ago on head gaskets? I went back and reviewed the document and it reads to never exceed 108 ft lbs on the studs using moly. It does not mention ARP lube which is actually slipperier.
Here is the old text from back then on bolts and studs if you lost it:
"
STUDS VS. BOLTS
1. An improved fastening system can permit better clamping loads between the head and block. A stud with its shaft in block will always provide a better system than a bolt tightened into the threads of the block. The purpose of tightening a bolt or stud is to put tension into the shaft. The amount of torque that gets converted to tension is almost solely dependent on the amount of friction between the threads of the stud and the threaded hole in the block, and the friction between the cylinder head and the washer or bolt head. To gain maximum tension in the shaft the friction must be reduced as much as possible. A good molysulfide lubricant used in these areas will reduce the friction a great deal, so much in fact that we should reduce the torque values by 10% when using a moly based lubricant.
2. EXCESSIVE bolt loading can cause problems. Many mechanics think that if 120 Ft. lbs. of torque is good then 140 is better. In fact testing has shown that less is best in most instances. Indeed extra horsepower and sealing may be achieved by being "torque frugal". Why? The more torque that is applied into the block the more chance of distortion. This distortion is usually seen at the weakest places at the narrowest point of the bore and at the top of the cylinder. At the top of the cylinder where the compression pressures are always greatest any excess distortion will nullify any benefit of that extra clamping force. Recommended torque is started with all stud nuts taken to 66 lbs. Followed by 90 lbs. and finally to 108 lbs. if using a moly lubricant. If using engine oil the maximum torque values are 114 lbs. If you decide to use the stock bolts, the maximum torque values with moly is 108 lbs. And with engine oil it is 119 lbs. Engine dyno and long term everyday use have proven the 119 lb. torque value to be working very well with stock bolts."
Don Morrison Oct 23rd 2002..modified on Nov 24th 2002
These were the absolute maximum I would ever TQ these fasteners to with the data I have now. Its a theory they will work better at this level. A trade off between distortion and max clamp load. Opinions only! Some real world data and bore gauge use I had showed the distortion a real problem. This is why I contacted BHJ for a tq plate.
Yes you can remove one at a time to install the new studs. Since yours are more than likely roached...it would be a good idea.
The ARP tq is still 96 lbs using the ARP lubricant. Not the 108 mentioned above.
Don~
05-19-2004, 01:14 PM
#53
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Originally posted by pro puller
Don, When you retorque a fastener do you back it off first then torque to spec or do you just put the wrench on it & torque it to spec.& do you think i should retorque my stock bolts & if so to what number Enterprise never told me if i should.Good reading guys keep it coming.
Kurt
Don, When you retorque a fastener do you back it off first then torque to spec or do you just put the wrench on it & torque it to spec.& do you think i should retorque my stock bolts & if so to what number Enterprise never told me if i should.Good reading guys keep it coming.
Kurt
Speak to them about their recommendations. I know your stock bolts, and a single o-ring will hold.
05-19-2004, 01:46 PM
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I'll buy the 108 on a 190ksi bolt as a safe max for the masses. That puts it right at 90% yield. I also agree that 135 is too tight... it's too far into the plastic region. 120 should be a max no matter what. Chris, the 120 is a value to get to and stop. As always, it's a good idea to step up in torque around the torquing pattern for the head with 3-5 incremental passes. When checking torque/retorqing set to the max torque and go around the pattern. As for reusing bolts... I'd say no. They have a gauge to measure how much they've stretched (so they've been in the plastic region), but adding in the strain from the twisting of the head weakens the bolts IMO. If you're going to spring for new bolts you might as well spring for studs instead. By the way... has it been mentioned that the head won't come off with the studs installed?
John
John
05-19-2004, 09:02 PM
#55
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I had told Don in a P.M. yesterday that IMO the use of the
stock Cummins head bolts with or without o-rings are suspect
in trucks like alot of ours with high H.P., boost and heat!
I realize they have worked on some of the members trucks.
"Timinva" is one example I can think of right away. But, they
DID NOT hold 60+lbs. of boost on my 96'. Sorry Don,.....
I am "slacking to the 96' again!"
I think Tim has
been extremely lucky and told him that back in December
when I last saw him. For those that are using the "stock"
headbolts with o-rings which are working O.K., I am happy
for you!
When my 12 mm studs were originally put in, the stock
Cummins Head Bolts were "stretched" pretty bad,
according to the Cummins specifications.
This was not true of the 12mm studs. I didn't check them
all but they were close to the original specs. (length etc.).
Because of all this, I will have the 14mm studs with the
"firering system" in the new/rebuilt engine in my 96'!
Yes, the block had to be machined for that, which is not
an option for some I know. But, I think with twin turbos,
a hotter cam, more fuel from the P7100 that the 14mm
studs are definitely the way to go if you are planning on
doing a "complete rebuild". The engine has to come out
for that anyway!
---------------
Don:
Your point about "taking all of this theory and moving it
into the world of reality" is very true! BTW,.......I appreciate
you posting the article on "STUDS vs. BOLTS". There is
some good information there. Thanks!
----------
John_P
stock Cummins head bolts with or without o-rings are suspect
in trucks like alot of ours with high H.P., boost and heat!
I realize they have worked on some of the members trucks.
"Timinva" is one example I can think of right away. But, they
DID NOT hold 60+lbs. of boost on my 96'. Sorry Don,.....
I am "slacking to the 96' again!"
I think Tim hasbeen extremely lucky and told him that back in December
when I last saw him. For those that are using the "stock"
headbolts with o-rings which are working O.K., I am happy
for you!
When my 12 mm studs were originally put in, the stock
Cummins Head Bolts were "stretched" pretty bad,
according to the Cummins specifications.
This was not true of the 12mm studs. I didn't check them
all but they were close to the original specs. (length etc.).
Because of all this, I will have the 14mm studs with the
"firering system" in the new/rebuilt engine in my 96'!
Yes, the block had to be machined for that, which is not
an option for some I know. But, I think with twin turbos,
a hotter cam, more fuel from the P7100 that the 14mm
studs are definitely the way to go if you are planning on
doing a "complete rebuild". The engine has to come out
for that anyway!
---------------
Don:
Your point about "taking all of this theory and moving it
into the world of reality" is very true! BTW,.......I appreciate
you posting the article on "STUDS vs. BOLTS". There is
some good information there. Thanks!
----------
John_P
05-19-2004, 11:51 PM
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So what's the proper method for the retorque? Must the fastener be backed off until there's no tension and retightened? Or would simply setting the tq wrench for the tq amount and going over every fastener work?
thansk!
brandon.
thansk!
brandon.
05-20-2004, 10:04 AM
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Correct me if I am wrong here...
1. These studs can be installed with the head on, one by one.
2. 96ft lbs. is the torque w/ARP lube.
3. The studs can easily be removed without removing the head, to make a gasket change.
?????
1. These studs can be installed with the head on, one by one.
2. 96ft lbs. is the torque w/ARP lube.
3. The studs can easily be removed without removing the head, to make a gasket change.
?????
05-20-2004, 10:19 AM
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Justin, you are right on all counts. The allen heads in the end of the studs makes removal easy and the studs are not tightened to start with. Brandon the nuts have to be loosened several turns check the the studs to be in properly and retorque the nuts to 96 ftlbs. Tim
05-20-2004, 12:34 PM
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Nope no o rings or fire rings. I am probably on borrowed time, but have been almost a year now. I been holding off to see if a permanent fix will come up, just studded it for more clamping force and would need to do it anyways. I see o rings and fire rings go out and as long as mine holds Im gonna leave it be. Hopefully if it blows at muncie someone will tow me home. Tim