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Engine Specific Info and Questions => IDI Engine => Topic started by: sparkoid on October 03, 2012, 07:03:29 am
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So after multiple block thread failures while torquing head bolts on my 11 mm block, I've finished drilling/tapping for time serts. I have a set of 11 mm ARP studs in hand. These are the 204-4701 kit mentioned elsewhere in the forum. Note that while the studs fit, they are spec'd by ARP as for an '82 1.8 (gasser?); ARP says they do not have a kit for *11 mm* 1.6's (?!?). So I'm reluctant to use their torque spec on my block.
I noticed my threaded block holes are ~ 32mm deep, even though the stock bolts only engage ~12 mm of threads. The studs will do ~20 mm if I leave minimal extra threads above the nut, and my theory is more threads in the block = less stress per thread. So I'm waiting on some 22mm inserts to show up rather than use the 16's that came with the kit.
What's confusing is the torque spec that came with the studs. ARP sez to torque to 80 ft lbs (in 3 equal steps). My Bentley only gets to 66 ft lbs. Given the well known fragility of the 11 mm blocks, I don't want to risk over-torquing yet again!
I realize the lube they send with the kit is supposed to reduce the thread friction which will result in a lower clamping force for a given torque, but I'm on the time-sert / studs path because I've already had (block) thread failures and don't want any more. The engine is normally aspirated, bone stock. If I do anything special, it would be a Giles pump, and only if the stud thing works.
Anyone out there do the 11 mm studs? On time-serts? Any wisdom will be deeply appreciated.
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If using ARP you cannot go by what VW / bentley/ oem specs. ARP are not stretch bolts like OEM. With 11 block, I don't know if I would go with arp - no give if you over do it. At least oem will stretch or yeild. ARP will not.
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My 11mn block has those studs??? studs. Use arps torque numbers.
The first there threads see the most force. Normally tapping is 1.5x threads diameter.
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If using ARP you cannot go by what VW / bentley/ oem specs. ARP are not stretch bolts like OEM. With 11 block, I don't know if I would go with arp - no give if you over do it. At least oem will stretch or yeild. ARP will not.
ARPs will just pull right out of the block..
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What's confusing is the torque spec that came with the studs. ARP sez to torque to 80 ft lbs (in 3 equal steps). My Bentley only gets to 66 ft lbs. Given the well known fragility of the 11 mm blocks, I don't want to risk over-torquing yet again!
I realize the lube they send with the kit is supposed to reduce the thread friction which will result in a lower clamping force for a given torque,
With super slippy lube, you will have less friction on the threads, providing more clamping force at a given torque value.
If the top threads are a different pitch, that would also change things.
Don't 11MM bolts come in stretch and non-stretch flavor? 66 sounds like a non-stretch spec.
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What's confusing is the torque spec that came with the studs. ARP sez to torque to 80 ft lbs (in 3 equal steps). My Bentley only gets to 66 ft lbs. Given the well known fragility of the 11 mm blocks, I don't want to risk over-torquing yet again!
I realize the lube they send with the kit is supposed to reduce the thread friction which will result in a lower clamping force for a given torque,
With super slippy lube, you will have less friction on the threads, providing more clamping force at a given torque value.
If the top threads are a different pitch, that would also change things.
Don't 11MM bolts come in stretch and non-stretch flavor? 66 sounds like a non-stretch spec.
the 6pt bolts have a straight up torque value..
the 12pt bolts have a torque value, plus a yield value..
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I should have mentioned I have the earlier 11 mm head bolts, hex head, which do not give. At all. I have some cute cast iron curly-cues that used to be threads to prove it.
The ARP studs in this kit are undercut, intended to provide some stretch. How much compared to the later 11 mm head bolts, I don't know.
I won't pull the studs out of the block if I know what the appropriate torque level is to clamp down the head, for this type of fastener using this type of lube. Sounds like I'm on virgin territory here. The lube ARP provides alters the relationship between the torque (part of which is thread-to-thread friction) and the resulting clamping force. Their thread pitch on the nut side is finer as well. Guess I'll have to chat up the ARP boys some more...
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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
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Hey RustyCaddy, thanks for your reply.
Are the numbers you quoted Newton-Meters, or foot-pounds? Your ultimate torque of 100, if in N-M, is reasonably close to ARP's recommendation of 80 ft-lbs, (which is ~108 NM).
BTW, I stated earlier that using a thread lube lowers the clamping force for a given torque spec, that is BACKWARDS; the slicker the thread, the more turn you get till you hit a given torque, thus a HIGHER clamping force (and thread shear stress). Which is why I posted this thread to begin with.
I have a query in to ARP's tech support, stay tuned...
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It was ft/lbs.
Check the search when you can. some folks have torqued ARP studs really high...i think up to 120 ft/lbs in a sound block, but that might have been 12mm.
Raceware studs seem to give people problems past 80 IIRC
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It was ft/lbs.
Check the search when you can. some folks have torqued ARP studs really high...i think up to 120 ft/lbs in a sound block, but that might have been 12mm.
Raceware studs seem to give people problems past 80 IIRC
you can go to 125+ with the real diesel studs..
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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...
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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..
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R.O.R, what do you mean by "the real diesel stud"???
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I thought R.O.R was referrin to himself? ;)
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R.O.R, what do you mean by "the real diesel stud"???
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I thought R.O.R was referrin to himself? ;)
LMFAO!!!
just about fell out of my chair from laughing!!
thats pretty hilarious btw..
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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?
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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.
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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..
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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.
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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!!!!
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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.
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http://www.vwdiesel.net/forum/index.php?topic=7919.0 (http://www.vwdiesel.net/forum/index.php?topic=7919.0)
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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.
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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)