ARP Studs (11 mm) Torque confusion

[745 turbogreasel]

R.O.R, what do you mean by "the real diesel studs"

Prior searches are what led me to ARP to begin with, but maybe it's time to troll again...

ARP makes regular 12mm studs, and ARP2000 diesel specific 12mm studs..

AKA: real diesel studs..

Thread pitch at the top of those ?
The RW ones are about 2x finer than stock, so 80 ft/lb on that is like 160 ft/lb on a regular bolt, it will deform the head before it pulls out of an 12mm block, maybe not on an 11?

[sparkoid]

The nut thread pitch is definitely finer than the 11x1.5 bottom, I'd speculate it's half.

Guess I'll have to sidle up to it like RustyCaddy did; heard back from ARP, they just repeated they have no kit for the 1.6, and were apparently unwilling / unable to do any lookups or analysis.

I've seen some torque-to-clamping force calculators on engineering sites, but so far none with input for lube, bolt composition, etc, so I don't know how realistic it would be to calculate the clamping strength the old bolt / old torque produced and translate that to my ARP mystery studs / mystery lube.

[R.O.R-2.0]

The nut thread pitch is definitely finer than the 11x1.5 bottom, I'd speculate it's half.

Guess I'll have to sidle up to it like RustyCaddy did; heard back from ARP, they just repeated they have no kit for the 1.6, and were apparently unwilling / unable to do any lookups or analysis.

I've seen some torque-to-clamping force calculators on engineering sites, but so far none with input for lube, bolt composition, etc, so I don't know how realistic it would be to calculate the clamping strength the old bolt / old torque produced and translate that to my ARP mystery studs / mystery lube.

ford cosworth studs...

you are welcome..

[monomer]

my 11mm block with undercut ARP studs went this way.

tightened all to 30, then to 60 and then to 90 using ARP lube.  Ran the engine to warm it up.  Backed each stud off a 1/4 turn or so then back to 90.

Later got pressure in the coolant so i retorqued to 95...more pressure..retorqued to 100 and haven't had a problem since.

That said, i had good threads

Hmmmm. I'm getting little pressure, should I retorque? Thought a little pressure was normal.


Clamping force has little to do with the threads. The force is between the nut and the washer.

[745 turbogreasel]

Hmmmm. I'm getting little pressure, should I retorque? Thought a little pressure was normal.


Clamping force has little to do with the threads. The force is between the nut and the washer.

Do not attempt a retorque till you understand how a ramp works, and why this applies to threads!!!!

[monomer]

Hmmmm. I'm getting little pressure, should I retorque? Thought a little pressure was normal.


Clamping force has little to do with the threads. The force is between the nut and the washer.

Do not attempt a retorque till you understand how a ramp works, and why this applies to threads!!!!

I can cut threads on a lathe, for christs sake!

There is force is against the washers - which should have got coated in the arp lube aswell. The studs and washers should have been cleaned before install, as they're oiled from arp (for rust)

The major force you're overcoming is the face of the washers to the nut, threads themselves have very little surface area. That's what I was getting at.

[R.O.R-2.0]

http://www.vwdiesel.net/forum/index.php?topic=7919.0

[sparkoid]

R.O.R, thanks for the thread post!  Now that I've seen it again, this is where I got the kit number to begin with.  Still skittish about anything over the Bentley torque spec, tho.  monomer raises interesting point re: washer friction vs threads determining torque.  At least the block threads are (should be) out of the equation for studs.

[RustyCaddy]

I'm getting little pressure, should I retorque?

It worked for me anyways...was surprised at that because had been told that coolant leaks deformed the head gasket permanently, but last problem was over 30,000 miles ago.

Lucas pointed out that the ARP lube is long gone with by the time of a retorque so when i went to 100 ft/lbs it was probably something different that it would have been with a new installation (but that gets to complicated for me)