Heads up to those who plan on running head studs

[RabbitJockey]

This is just my theory, but i think it could save everyone many headaches if they are planning on switching to head studs.


So I had a minor head gasket leak on my 81 rabbit with an 11mm 1.6d engine.  I bought ARP head studs to use they are Part number: 204-4701, and meant for use on vw 8v gas engines.  They were cheapest from LightningMotorsports.com, and they arrived very quickly.

first i got the head sat on and ran all the studs in to hand tightness

then i screwed all the nuts on to the studs by hand using a long extension with a 1/2" 12pt socket, so it was very easy to wind them on, no hang ups or anything weird, just made them hand tight with the extension.

after this, i went to do my planned torque sequence of 35ftlbs-70ftlbs-100ftlbs

35 was very easy, no qualms but i noticed that after i did #2 in the sequence the nuts needed to be spun down a little before they had any kind of tightness for the ratchet to work.  so the tightness of the center 2 studs definitely effected the others

70 took a little more effort, and i noticed the same thing, that after the first 2 studs the rest became alot easier,

at 100, the trouble started!!!!!!!!!!!!!!!!!!!!!!!!!!  the first stud was difficult how ever not impossible to turn, and i got it up to 100 ft lbs.  the second stud how ever would not budge.  i'll be honest, i have always been a scrawny guy, but seriously this one would not move, it ended up feeling like i was going to strip the 12pt shape of the nut so i stopped.  and i was like well i'll skip that one, and i did 3-4-5-6, then went back to 2, and that nut wouldn't budge, i ended up half stripping off the 12 pt shape.  so since that wasn't going well, i removed the nut and stud, the nut was very difficult to get off the stud, and when i looked inside the nut, all the threads were squared off.

My THEORY is that on that #1 stud, when the nut tightens down, it lowers the rear of the head, and this puts leverage on the second nut, since it is directly in front of it and well, i guess the head gasket is the leverage/pivot point, and the #2 stud is the opposite seat on the seee saw.  and that leverage is too much for the #2 stud/nut and screws up the threads.  This i have concluded after considering how much torquing one stud seems to effect another, how the outside bolts got easier and easier as i went.

So my recommendation, for all you stud wielders, is after 60-70 ft lbs, you should increase torque values in much lower increments, such is 5-10 ftlbs.  though it is a problem which will probably only effect 1 in every thousand of us, the extra 20 minutes you spend torquing the nuts slowly, is well worth the time you'd spend trying to get a warranty stud and nut from arp or raceware.

This also happened to crazy andy, on the exact same stud, tho his engine was an aaz.

please take caution when tightening, and save your self the aggravation of a warranty process that i am about to go through.

first off, i would like to apologize for all the broken families and aneurisms that this thread which I have created may have caused.

Secondly, i'd like to let you all know that i deeply care about every single one of you.

The depth to which i care, is exactly why i am about to make a sacrifice, that many would shy away from.  Many, simply do not have the balls to do what i am prepared to do for this community, whom i care so much about.

I will proudly wear egg on my face for you, vwdiesel.net.

the problem was my very own fault, as the nut tightens over the stud, the stud begins to stick up, i measured them at .240" above the nut at full tightness, and if you are not using a socket that is deep enough then obviously at some point its going to slip.  this is why like i said on the stud i had a major issue with, i couldn't tighten it with out it feeling like it was going to strip.  I failed to notice this is what was going on until today when i was retorque after warmup.  i realize its been about a month and a half since i initially posted this, but between making time to work on it, and a few other problems i had, plus waiting on parts and stuff i just now got to retorquing.

so in closing,

i still believe much care should be taken when torquing with studs, how ever it is much more important to use proper tools.

[RabbitJockey]

should this be stickied?  i think it should be stickied, i wish someone would have stickied  a thread like this before i took on my headgasket replacement

[8v-of-fury]

You just wrote the damn thread.. GIVE ME TIME MAN! HAHA

[CRSMP5]

ive always done 10 or 11 lb increments... 22, 33, 44.. 90* twist so on...

but why so much torque? the stock non tty bolts that had were not 100.... and the 11mm block cracks so nice when over heated a couple times.. i cannot see why the risk...

[ORCoaster]

Mod decided to stickie it someplace else.  Showed you who is da boss here. 

Interesting,  Don't plan to do another head soon but maybe good advice for this sort of torque.  Go easy at the end and save parts.

[RabbitJockey]

i went for 100, because the stud paper said 80 ft lbs, but since these are 11mm studs they are made for vw gasser engines, and 12mm diesel engines are rated for 125lbs so i figured i'd meet in the middle, because i certainly didn't want to over tighten on an 11mm, but at the same time i didnt want another head gasket failure.  also old threads about people running 11mm threads most were running 110 or more ft lbs

[745 turbogreasel]

i went for 100, because the stud paper said 80 ft lbs, but since these are 11mm studs they are made for vw gasser engines, and 12mm diesel engines are rated for 125lbs so i figured i'd meet in the middle, because i certainly didn't want to over tighten on an 11mm, but at the same time i didnt want another head gasket failure.  also old threads about people running 11mm threads most were running 110 or more ft lbs

Science like this should never make a sticky.
Did you use the right nuts? did you use the right washers?
What if any lube was used?
What's the thread pitch?
Why are you  trying to use 12mm specs in a 11MM motor?
How deep is the dent in the top of your head from the one you overtightened?
Never bottom the stud out.
Torquing is more accurate in one single motion.
Did you hang the  corner of the  exhaust manifold up on the block by any chance?

[RabbitJockey]

Science like this should never make a sticky.
Did you use the right nuts? did you use the right washers?
What if any lube was used?
What's the thread pitch?
Why are you  trying to use 12mm specs in a 11MM motor?
How deep is the dent in the top of your head from the one you overtightened?
Never bottom the stud out.
Torquing is more accurate in one single motion.
Did you hang the  corner of the  exhaust manifold up on the block by any chance?


woah woah.  this is a warning for those running 12mm studs as well, because like i said the same thing happened to andy, and he was following the directions directly


so to answer your questions, i followed the directs to a t, other than torque numbers( which it is not very specifici about other than the final number)

yes i used the supplied washers, yes i used the supplied ARP lube, which was put on all the threads and the bottom contact surface of every nut.  i have no idea what the thread pitch is, i did no use 12mm torque specs on the 11mm studs, i used lower specs than the 12mm, and lower specs than i could find anyone using on an 11mm diesel by search vwdiesel.net on the topic of studs.  never bottom out the stud?  i hand tightened them as the instructions say.  did not hang the corner of the exhaust manifold.

to be clear also, i didn't feel attacked by what u said, those are totally legit questions that you asked, im just discussing this stuff.  just wanted to make there wasnt a tone added to what im writing.  im totally open minded i just want to help keep people from being in the same shoes as me and andy.

[CRSMP5]

my only reason id run a stud is the rumor they sit further in the block...

whats a 11mm diesel torque spec?? why would this convert a 11mm into a 12mm setting?

ive had lot say this no work.. but i see it and tested it.. using the 11mm tty later 1.8-2.0 headbolts torqued to gasser specs with no issue...

but the 1 thing i know for fact.. over heat a 11mm block 1 time to many.. next head gasket may kill it... done quite a few in the day... that crack/snap is like breaking the injector boss off the head.. just sick feeling... so no way id ever try what you did... headgasket cheaper then bottom end...

[745 turbogreasel]

woah woah.  this is a warning for those running 12mm studs as well, because like i said the same thing happened to andy, and he was following the directions directly


so to answer your questions, i followed the directs to a t, other than torque numbers( which it is not very specifici about other than the final number)

yes i used the supplied washers, yes i used the supplied ARP lube, which was put on all the threads and the bottom contact surface of every nut.  i have no idea what the thread pitch is, i did no use 12mm torque specs on the 11mm studs, i used lower specs than the 12mm, and lower specs than i could find anyone using on an 11mm diesel by search vwdiesel.net on the topic of studs.  never bottom out the stud?  i hand tightened them as the instructions say.  did not hang the corner of the exhaust manifold.

to be clear also, i didn't feel attacked by what u said, those are totally legit questions that you asked, im just discussing this stuff.  just wanted to make there wasnt a tone added to what im writing.  im totally open minded i just want to help keep people from being in the same shoes as me and andy.

Supplied washers may not  be right for the application, especcally if you are ordering from another part of the catalog.  I know one guy who caved in the aluminum around the head bolts, because  the company he  got his ARP bolts from  found some with threads that fit, and include the washers   to match...and i'm sure those washers were just fine on an iron head.
IIRC ARP claims there lube to reduce the  needed torque 20-30 %, so it's like you went to ~130lb
Some studs like my Raceware are  fine pitch at the nut end, offering greater  strength, and about double the clamping force at a given torque.  Added to special lube, that would be like cranking the  regular bolt down to 260lb!
The only thing bottoming a stud accomplishes is to apply a jacking force against the threads of the block, and to insure it is stuck if it breaks.  Better practice to keep them 1/4 turn out.

Gasket crush  should be  less than 0.7MM, that is some turn on a nut, but not much.
was the nut that went bad  at the bottom of the  threads on the stud?
I can't help but think something wasn't right.

[maxfax]

Being the Head stud advocate for 11mm blocks that I am I'm gonna open my big fat mouth..  ARP (like everything else) ain't what it used to be..  In the last year I've had three out of five ARP fastener sets come with issues..  Two of them (main studs for a GM 5.7 Diesel and Rod bolts for a VW 1.6 Diesel) had the threads botched when they cut them.. The other (pan and timing cover studs for a GM LT1 5.7) came with the wrong damned nuts..   As far as past sets from years back, installed as per their specs and never an issue...

[burn_your_money]

Gasket crush  should be  less than 0.7MM, that is some turn on a nut, but not much.

I don't know what the pitch is on the ARP studs, but that has to be at least 1/2 a turn.

[RabbitJockey]

studs were just run into the block till they stopped turning using just an allan socket on the end of 3/8 extension, maybe it is best to undo them a quarter, but hand tight is what the instructions say.

ok looking at things more, the nut threads are finer than the block threads.

the washers definitely appropriate, they looked like the ones i had removed, and fit very tight down in the hole in the head and also tightly around the stud.

the stud threads look mostly ok but the nut threads are squared off looking.

i was going for 100 ft lbs because i had read from searching the forums many people running that number, or higher on 11 and 12mm studs both.

i just wanted to warn everyone that you should definitely step more slowly at higher numbers as this same thing happened to andy as well, and he was following the directions to a T.

[92EcoDiesel Jetta]

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at 100, the trouble started!!!!!!!!!!!!!!!!!!!!!!!!!!  the first stud was difficult how ever not impossible to turn, and i got it up to 100 ft lbs.  the second stud how ever would not budge.  i'll be honest, i have always been a scrawny guy, but seriously this one would not move, it ended up feeling like i was going to strip the 12pt shape of the nut so i

stopped.  and i was like well i'll skip that one, and i did 3-4-5-6, then went back to 2, and that nut wouldn't budge, i ended up half stripping off the 12 pt shape.  so since that wasn't going well, i removed the nut and stud, the nut was very difficult to get off the stud, and when i looked inside the nut, all the threads were squared off.(

 What do you mean it wouldn't budge?

 Weren't you using a torque wrench set to 100 ft lbs?
 
Did the torque wrench click?

[RabbitJockey]

...............
.
at 100, the trouble started!!!!!!!!!!!!!!!!!!!!!!!!!!  the first stud was difficult how ever not impossible to turn, and i got it up to 100 ft lbs.  the second stud how ever would not budge.  i'll be honest, i have always been a scrawny guy, but seriously this one would not move, it ended up feeling like i was going to strip the 12pt shape of the nut so i

stopped.  and i was like well i'll skip that one, and i did 3-4-5-6, then went back to 2, and that nut wouldn't budge, i ended up half stripping off the 12 pt shape.  so since that wasn't going well, i removed the nut and stud, the nut was very difficult to get off the stud, and when i looked inside the nut, all the threads were squared off.(

 What do you mean it wouldn't budge?

 Weren't you using a torque wrench set to 100 ft lbs?
 
Did the torque wrench click?

good question, it simply wouldn't turn, and no the torque wrench wasn't clicking, im guess this is because the 12 point shape was beginning to strip rather than the nut spinning?