H-11 headstuds breaking!!!!!

That's good if no twist marks, and a good old timer with a file can real surprise you!
 
Diesel Tech said:
That's good if no twist marks, and a good old timer with a file can real surprise you!
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funny thing is he wants me to have them rockwell tested he said somewhere in the stages he thinks the metal became to hard, that is why i called A1 to ask what scale they used and the hardness. i am gonna try to get them tested tomorrow to see if he is right. A1 also wanted to hear what my results were.
 
Ok so I had the studs Rockwell c scale tested this morning, they are suppose to be between 49-51 and these were 46 not sure of what that means. Anyway here is a pic of the end of the stud, the file mark on one edge is from the older gentlemen checking with a file.ImageUploadedByTapatalk1338983287.450660.jpg
 
Jimmy

When heat treating, things can go wrong. The higher the number the stronger to a point they become. The down side is they also become brittle. So there is a fine line of making them too hard. Think of a sheet of glass as an example, it's strong but a sharp hit to it and it shatters, thats too hard. Steel acts the same way as the hardness goes up. Now when you try to file a soft material it's easy and the sound is like a low thud tone, hard material doesn't file once you get above a point and the sound becomes more high pitched as you try to file. So a good old timer can tell pretty good where a material is with just a file!

When they are softer (low number) they will bend and give and the harder (higher number) they do not want to bend but will break easier. So you have to balance the two properties to get what you can live with. The "C" scale is just a range of hardness there is also lower scales for measuring softer items.

Hard to tell from your picture but it does look like a clean break all the way through the material
 
It is a clean break and don said the numbers are in check as you add 2 digits to the test when testing on the outside of the round. The other thing I am trying to figure out is the corrosion side.
 
H11 tool steel has never been good about corrosion. You might try to clean them well and then paint the none threaded area with high heat paint prior to installing the new ones. The high heat paint can help stop corrosion and will not melt away like grease and lube does. Since the ones your changing are right by the exhaust ports it may help a lot because of the heat around them.
 
Well that H-11 material is bad stuff, drilled for a couple of hours with not much success so I had dad weld to it and then just backed it out. Wish I would have tried it sooner.ImageUploadedByTapatalk1339276723.139098.jpg
 
kino_fab said:
not to get off topic, but has anyone tried the DNR Customs head studs? They claim to be the exact same thing as the ARP 625 studs, but almost half the price.
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A guy over on CF broke one of his studs and I think that it was on the initial torque of 90 ft lbs.
 
Jim Fulmer said:
Yep, I've done a few times, piece of small pipe and an arc welding rod.

Jim
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you were the one i got the idea from, guess we could call it the fulmer stud removal process.:rockwoot:
 
Sounds like they had one bad stud. That's covered under warrenty according to Jeff lee owner.

Heat treating might of messed up hell it could just be a Friday made part. If its one stud broken I will still try them out. If I have poor results you guys will know. I feel confident with them after talkin to him. They are 7% stronger than 625s according to the material they are made with. Hardness to a point is ok. Just not wanting brittle. They won't be installed in truck engine is out so I'm not terribly concerned.
 
ive had one stud break on h11 and every single set ive put in seem to me they strecth really bad even the 425 material hold up better on torqueing them they dont hold as much cylinder pressure but they dont stretch i have been trying out the new DNR custom studs i currently have 3 sets in 24v one set soon to be on my 6.7 with a s364. like ive read in this post already is theres a point to steel where it is too hard and will shatter kinda think of yukon axles on our pulling trucks.... they shatter well these dnr are a really hard steel and when you torque you go maybe a 1/4 turn from 100-125 but last i heard he is going to soften them up a little. non have failed on me or anyone else ive heard running them he just dont like the way they come up so fast on the torqueing end of things. I also have sent a stud back to a1 last year i was running a retorque on a 2.5 truck i built for a guy and snapped a stud at 100 ft # going in 5# torques and never heard anything back but patty did give me a new stud for free and it happened again and the customer had to buy the second one so we are kind of getting away from the a1's personally
 
Ether Man said:
anybody have bad luck with haisley h-11 12mm headstuds breaking? i just found my second headstud laying underneath the truck!!:nail:m Both that have broke have been on the exhaust manifold side, first was at the number 2 cylinder and today walked by and seen one laying under the truck and it is at number 4. Both broke right in the middle of the stud, the studs have less than 2k miles on them. Just wanted to see if anybody else has had this trouble. Everything was lubed properly and bottom tapped and blah,blah, blah.
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Are these studs the standard 12mm H11's or the 12mm HD H11's?
 
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