Seems like the "angle" method would be more accurate than taking the full torque with a wrench. When I worked at BMW a long time ago, their opposed twins would get the heads re-torqued at their 600 mile service. It was done cold and they would get loosened one at a time and re-torqued to ~40ftlbs and then ~180deg. Something like that. Its been quite a few years now and am not sure is those are the exact specs. But it does seem like you eliminate many more variables using this method.

Aaron

 

Thought more on the problem.

That is a hoop-stress failure instead of a thread-shear out(proper failure mode for a nut). I would have thought proper heat-treatment would relieve internal forming stresses. There's your problem..

Those nuts the threads are formed- similar to a tap, but it displaces the metal. I'd guess if you checked Rockwell hardness you'd find them soft.

Call the vendor back... it's not their fault and get a replacement set (from a different lot).

M

 

Dave, man i'm really sorry to hear about all the mess. I know how excited you were to put the twins on and then this!! I read through everyone's opinions and thoughts and i'm with the same opinion of samiam. It sounds like possibly a bad batch of hardware. With all the hotrod cummins trucks in the world who are running the same studs and nuts i haven;t heard any one with the same problems. Let me talk to some of my peeps at work and see if i could possibly have some of the studs and nuts tested using UT (ultrasound). There has to be a reason?????........Augie

 

Thanks for all the input folks.

The torque wrench I'm using these days is a K Tool International Digital Torque Wrench M/N ~ KTI-72132

Accuracy ~ CW:+/-1%, CCW:+/-2%
Resolution ~ 0.1N-m / 1 in-lb / 0.1 ft-lb

Lately I've been using the torque method the Garmon crowd uses. The gist of it being to pull things up from 100ft/lbs in 5ft/lb increments with a 30 minute "rest" between advances till the target value is reached (in my case, 135ft/lbs cold).

This particular wrench has an audible alarm the beeps when I'm within 5ft/lbs to the programed target value. When the target value is reached, the beep goes steady.

With liberal application of ARP assembly lube, I apply a constant pull on the wrench bringing it to the target value. With constantly holding the wrench at that value, combined with the wrenches resolution, one can clearly see the target value being reached and then see the torque value drop subtly as the stud stretches. Continued constant pull on the wrench has it creep on around until the wrench presents with a constant torque value. It might take a minute or two of constant pull to have the torque stabilize.

To better visualize the above, pulling the 25" long wrench up to say 125ft/lbs would have it initially beep as though the target value has been reached. Continuing such as described above has the wrench handle come on around perhaps an additional six to eight inches as the stud stretches and the torque value stabilizes.

Again, let it rest for thirty minutes and then take it up another 5ft/lbs till I'm at 135ft'lbs.


My experience has historically been with "Click" style torque wrenches and with acquiring the digital fella, and working it as such, . . . . the difference is like night and day in your face.



I just got off the phone with Mark @ PDR. As you might imagine, they've been selling the stuff for quite some time both the Haisley Kit and ARP and through the years, folks have called with issues of pulling threads from blocks, pulling threads from the nuts, and just plain pulling the studs in two. I'm the first with "Split" nuts. Mark's gonna call Haisley who hopefully will contact A1. All in the hopes of getting folks attention.


In the mean time, I'm planning on getting a set of ARP nuts and cut my losses.

 

Wow, very sorry to hear about this set back David. Good luck, you will get it nailed down.

 

If you want to know the rockwell hardness, I can test them for you... My Grandpa has the largest company in the US of making all the test blocks they use to calibrate the machines on assy lines... So, I have a few rockwell testers at my disposal and would be more than happy to test them just for kicks if you want...

 

Good call on the hoop stress, samiam4.

Unless the nut alloy is just junk, I bet the nuts were either spec'd or shipped with a thread fit class mismatched to the studs... like H1 or H2 nuts on an H4 stud.

Does the OP recall if the nuts initially threaded onto the studs by hand easily?

 

seems to me i was told they were having failures w the arp nuts but now they were using A1 nuts along w the studs [as in better?] haisley, that is.

 

OK, here's the deal. As one might expect, I'm upset that a nut popped (twice now) and at a minimum, requires repairs to the engine. Twice now, I've been VERY lucky in that no major damage has occurred. As you might imagine, I'm a bit "Gun-Shy" right now. Could you imagine the interest in this that a million dollar race program chief engineer might have? My little dinky mess, or their $125,000 primary engine, nuts and bolts hold it all together.

Yesterday I called Mark Wilson of PDR and filled him in on this latest nut failure. The nature of retail business has me dealing primarily with my vendor, this case being PDR. As was mentioned earlier, PDR bought the stud kit from Haisley Machine who makes the kit with A1 components. The point here being, Mark's gonna call Haisley, and they would call A1.

To help ensure the ball gets rolling if you will, I sent an Email to Haisley including a link to this thread as a "Head's Up" to expect a call from Mark. I also included my phone number should anyone at Haisley want to talk directly to me.

I got a call from Van Haisley (owner of Haisley Machine) this morning.

1st, understand how Haisley Machine fits into all this. Haisley is the original creator of a "Stud Kit" for the 5.9 Cummins. At the time, A1 was the more established fastener provider for the many different high performance needs. Working with Van, they came up with a stud that would best serve the need. Unfortunately, A1 didn't have a companion nut so ARP nuts had to do.
Generally, ARP may have been slow (to the tune of two years) to come up to speed in providing products for the 5.9 Cummins.
Anyhoot, A1 eventually produced a nut for the kit and Haisley went to A1 exclusively. (Don't quote me on the time-line).

Anyway, Van is very interested in these failures. There may have been two similar examples of the same failure in the last short while.

To make a long story short, Van wants to replace all the components in question for complete examination and testing. (Mrs Haisley just called to verify the shipping address so as to ship out the replacements next-day air so I could install them over the Holidays. KEWL!!)

A note to those who've posted with ideas on the actual cause of failure . . .
- Van's thinking there may be an issue with the hardness.
- They are in the midst of cyphering increasing the nut from a 9/16" wrenching to a 5/8". More meat being the obvious thing.


I've intentionally tried not to condemn the A1 product as I know this is an unusual event. In talking with Vann this morning, I feel a LOT better about my purchase and am confident efforts will be made to correct any short-comings in the product so as to serve me and YOU better.

NICE!!

 

Bigger nut? Ya think???

Glad to hear they man'd up. Alot of times with this type stuff they will just tell you to send it back for their inspection, only to later be told they found no problem and offer you more replacement junk.

Good deal.

 

Van's a great guy to deal with - he'll make it right!

The size of the nut isn't the problem, although an increase to 5/8" will no doubt mask the root cause.

Hardness could be an issue, since high-psi alloy tends to be more brittle unless a tough alloy is used, such as H11/L19/MP35... not sure what they use for the nuts.

CTDs present a harsh harmonic environment to materials - it's another case of what is acceptable in gasser tech doesn't work as well in diesels.

 

To help put things in better perspective for this coming Thanksgiving, here's a real pain in my neck . . .



DOH!!

 

Man i hate that for ya, ive had 2 c6-c7 fusions in the last year and a half and thier wanting to go back in now and remove all the hardware, all the plates and screws are causing my neck and shoulder muscles to never relaxe.?. Meds, botox, all the theropy, etc... no good.
Great advise would be IF you HAVE to have a fussion ONLY let them use Your own bone! My second surgury was due to using bone bank bone and my body rejected it, once my own hip bone was replaced with the other it started growing well. The hip pain aint great... but it beats another cutting on ya. Sorry for the off topic info, but wanted to give you the advise. Good Luck to you!
Ryan

 

I hope you didn't get that from man-handling the Cummins head!

I slipped one between 6&7 about 5 years ago. Just living with it. Starting to get used to it. I cannot imagine what that feels like.

 

I pulled a CR head off solo a month ago sans lift - one day I'm gonna be too old for this ****...