How many times can rod and main bolts be torqued?

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66fs said:
In the above, you are talking about ARP recommending replacing bolts with .001 plastic deformation. Then right after you talking about elastic deformation, which does not count towards plastic deformation.

Quality rod bolts have a smooth barrel, typically not a knurled shank, that is pressed into a bore of the rod which centers it in the bore. The cap is then installed centering itself, on the two rod bolts. This is as precise as you can produce a rod. Quality rod bolts have spherical "dimples" on both ends of the rod bolt which index the micrometer or stretch gage.
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Way to twist information around.... #-o


The reason that I "talked about elastic deformation" as you reference, is that the ARP write up says to measure a bolt stretch gauge when tightening the bolt. I am pointing out that this method is reading both plastic and elastic deformation. There is no way to tell how much plastic deformation is there with that method.


Please post up some examples with pictures of these "quality rod bolts" with dimples for measuring bolt stretch.....

Production tolerances on cold headed products is not accurate enough to use for bolt stretch studies. As I have said now for the third time, to do a proper bolt stretch study, you need to have the bolt ends ground flat and centered by a machinist.
 
Didn't twist anything. You are not correct about ends needing to be ground flat and centered by a machinist.
 
5th pass down the track with recondition rods and ARP wavelock bolts......

Scat rods 300 bucks.....junk iron 200 bucks a ton...rod cap broke

cranking out a whopping 6300 rpm..
 

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Jeez that doesn't look too fun, what rpm was that? Because I agree that aftermarket rods are better but i'm making mostly a street car under 6k rpm in most cases.

Didn't see the RPM before, but what caused that to happen?
 
70aarcuda wins on you never know.

Just put what you have together with RED loctite and run it.
 
If they have only been tightened twice, then don't waste time trying to establish bolt stretch, you are just wasting clamp loads. Use them.

The more you tighten them, the sooner you are going to have to replace them....
 
krazykuda said:
I don't totally agree with their write up.
They recommend throwing away a bolt that has a .001" of permanent stretch. EVERY BOLT GETS .001" OF STRETCH WHEN TORQUED PROPERLY. .....
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This statement is the only reason I said something. When you stretch an ARP bolt to their specifications I do not think you are getting into plastic deformation. That may be different for new production bolts. Pictures to follow.
 
krazykuda said:
If they have only been tightened twice, then don't waste time trying to establish bolt stretch, you are just wasting clamp loads. Use them.

The more you tighten them, the sooner you are going to have to replace them....
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True that ship has sailed...
 
66fs said:
This statement is the only reason I said something. When you stretch an ARP bolt to their specifications I do not think you are getting into plastic deformation. That may be different for new production bolts. Pictures to follow.
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I was talking to my dad about this (structural engineer) and he was saying that the bolts are not torque to yield like some others, and because of this they only deform in the elastic stage, so they will go back unless over-tightened. He said (like others have said to) that the point of this is to keep constant tension, so the bolt acts like a spring and keeps its self tight. Now over time the metal does fatigue, but this take lots of time. From his standpoint he thought I wouldn't have a problem re-using them.

He said alot of things, and that is all I really understood! LOL

I find this thread really interesting, am learning alot from it.
 
To reach proper clamp load, the fastener does get some plastic deformation. It is minimal.

A little plastic deformation won't hurt you, but as it keeps adding up, it will.

As in my first post in this thread, you can use them 4-5 times, after that you are pushing it...


This was also verified by the op calling ARP and they recommended 4 clamp cycles....
 
66fs said:
This statement is the only reason I said something. When you stretch an ARP bolt to their specifications I do not think you are getting into plastic deformation. That may be different for new production bolts. Pictures to follow.
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A rod bolt can handle more than .001" plastic deformation before it's strength is compromised. That's what I was questioning....

ARP has stated that their bolts can go 4 cycles before needing replacing. If you look back at my original posts in this thread, that is close what I said, we used 5 clamp loads before replacing the bolts.


I have worked with fastener engineering to perform the torque tests and set up the parameters for torquing different joints. I have designed and released bolts and worked with fastener suppliers. I also worked with the leading industry machine builders to set up set up equipment to run engine assembly lines and have run over 4 million engines on those lines with no problem with bolt failures. (As a matter of fact, I improved their fastening capability from what it was before I got there.)


What experience do you have in this matter????

Have you actually performed any bolt stretch studies yourself???
 
krazykuda said:
What experience do you have in this matter????

Have you actually performed any bolt stretch studies yourself???
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I am a senior design Engineer, having to do FEA on structures and having to justify bolt size and pattern and forces in all kinds of applications. As for doing studies that would be beneath my job specs. Although I have had them done by others. I've done all kinds of jobs on my way to where I am now. It was my love of cars that got me into Engineering. It amazes me how we jump to the internet to get an answer, when you can go to a world class firm like ARP who actually makes this information available. And as I suspected, they consider a fastener torqued past yield as a failed fastener, their published number is actually .0005 of an inch.

http://arp-bolts.com/p/technical.php

While you are on their site, go to their catalog and you can see the dimples in the head and threaded end to see what I was talking about.
 
sireland67 said:
70aarcuda wins on you never know.

Just put what you have together with RED loctite and run it.
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Red Locktite degrades at temperature so I doubt it will have any effect on a rod bolt. The critical thing to do is get the proper stretch on the bolt.
 
66fs said:
I am a senior design Engineer, having to do FEA on structures and having to justify bolt size and pattern and forces in all kinds of applications. As for doing studies that would be beneath my job specs. Although I have had them done by others.
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[ame]http://youtu.be/zANvYB93u2g[/ame]
 
Karl and 66fs, lets try to keep this on track. You both have contributed nicely on this thread, lets keep it nice and not get into a chest thumping contest. Just my opinion, and if you tell me to shut it and go sit in a corner I suppose I will just giggle at you!
 
straightlinespeed said:
Karl and 66fs, lets try to keep this on track. You both have contributed nicely on this thread, lets keep it nice and not get into a chest thumping contest. Just my opinion, and if you tell me to shut it and go sit in a corner I suppose I will just giggle at you!
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Well, you know I try not to belittle anyone and try to stick to the facts or what I have seen. I only answered the question, he just called out the wrong guy. You of course are completely correct. I think the difference began since Karl came from a production line where they are torqueing past yield, I know they do that with late model head bolts. But you basically can not reuse them. And he is right there, not sure what line he worked on. Most of our "old school" stuff was not designed that way. After reading the Tech section at ARP it was clear that they do not design that way either. It is a good read, if you want to know more about rod bolts. I know, what a Geek...
 
I took a lesson from Caterpillar many years ago. They will not reuse any bolts, studs or other fasteners in their engines and most of the drive train. BTW, Cat is renowned for making (yes they make their own) bolts in the world.
Just my two cents worth.
 
I run carr s6 bolt's in my carillo rods, I measure stretch by inserting a stretch gauge in the head of the bolt that has a counter sunk hole for a ball end and at the thread end of the bolt it has a tapered counter sunk hole to insert the pointed end of the stretch gauge, my bolt's are stretched to .005-.006, carillo told me these bolts can be torqued at least a dozen times before I even need to start worrying about it, I check stretch every time and so far the stretch is always perfect. but at over 100 dollars a bolt they better last a while
 
66fs said:
he just called out the wrong guy.
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I didn't call you out. :tool:

Everything I first posted has come out to be right. :evil3:


Have a nice day.... :)


I will be the bigger man and walk away from this one..... :D
 
thumbuster said:
I took a lesson from Caterpillar many years ago. They will not reuse any bolts, studs or other fasteners in their engines and most of the drive train. BTW, Cat is renowned for making (yes they make their own) bolts in the world.
Just my two cents worth.
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Caterpillar does some things right.


They have a great bar code system for tracking their blocks.


However they have a much smaller volume than what we ran.
 
I worked for Caterpillar also in one of there Paving equipment plants. I was in final paint, so I didnt get to put them together, but I was amazed with the assembly process. The torque guns with the multipliers on them and the amount of force they exerted was insane. I can see why they dont reuse any of there bolts.
 
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