favorite way to put heads down for FI
#24
Originally Posted by MIGHTYMOUSE
ok so update:
i did the cold retorque yesterday on the big bolts one at a time loosened and then pulled back to 90# i was surprised by how much some of them moved... hopefully that is a good thing.
i did the cold retorque yesterday on the big bolts one at a time loosened and then pulled back to 90# i was surprised by how much some of them moved... hopefully that is a good thing.
I torqued teh heads up to 80lbft yesterday in 2 stages, ARP Moly, ARP studs, GM MLS.
Then left for circa 24hours, and tonight I decided to undo each nut 180degress in turn, and re-torque.
Id say most of them went an additional 45degrees over where they had been previously.
Im only doing it once though.
#25
Studs - Good! (Bolts - bad)
Originally Posted by MIGHTYMOUSE
just had a conversation about cold retorqing with greg at fel pro
said a few interesting things, hope he's ok with spreading the knowledge.
-remove black coating from arp studs, says it decreases friction
-prefers to use cmd#3 lube as compared to arp lube or oil, says it is more stable
-prefers 3 rounds of tqing.. second and third round to loosen the bolts in sequence one at a time, and then go back to the tq you want to click in one motion.. said you should see it geting further around each time.
-prefers a head surface roughness of 30RA or better, i have to read up on what RA is.
-also wants me to check to see if any of the nuts are bottoming out on the stud and locking as opposed to locking from clamping force.. said he has heard of that before.
anybody have tricks up their sleeve similar?
i think with all of this it is worth seeing if i can retorque mine.. at least the big nuts
said a few interesting things, hope he's ok with spreading the knowledge.
-remove black coating from arp studs, says it decreases friction
-prefers to use cmd#3 lube as compared to arp lube or oil, says it is more stable
-prefers 3 rounds of tqing.. second and third round to loosen the bolts in sequence one at a time, and then go back to the tq you want to click in one motion.. said you should see it geting further around each time.
-prefers a head surface roughness of 30RA or better, i have to read up on what RA is.
-also wants me to check to see if any of the nuts are bottoming out on the stud and locking as opposed to locking from clamping force.. said he has heard of that before.
anybody have tricks up their sleeve similar?
i think with all of this it is worth seeing if i can retorque mine.. at least the big nuts
Here it is in a nut-shell:
The use of studs (vs. bolts) allows a significant increase in the torque used to be applied as a clamping force vs. a force used to rotate the fastener into the material.
(Ever notice when a bolt brakes, it almost always brakes flush with the surface, this is because of the amount of force being used to twist the bolt into the material; that percentage used is about 45% of the total torque.)
With bolts, typically only 5% of the torque applied actually gets used to create the clamping force (Yeah, I know sounds VERY low, but every SAE document available confirmed this!); however, when using studs about 50% of the torque is used for clamping! That is a 1000% increase - reason enough to change from bolts to studs - if you (like MM) are pushing 96 PSI!!!
Oh, the guy who mentioned the accuracy of the typical torque wrench - Right on the Money! (Even directly after calibration, the design is simply flawed, that's why the big money guys measure bolt strech not torque when dealing with connecting rod bolts - much more accurate!)
Torque in stages??? Yep! It help equalize the torque across the material.
Heat cycles / retorque??? Sure! But it is just as effective to torque the nut to the correct amount / wait 30 minutes then retorque - the reason? "Stress relaxation" and microscopic ridges in the "flat / smooth" surfaces of the stud and nut.
Oh, the final word on how much torque is enough? In six words I can sum up EVERY paper on this topic ever published; ALL SAE docs, and even the 200+ page German Holy Grail on this topic:
"If in doubt, tighten it more!"
Oh, I don't know if these things ever became available in the US, but a company called "Nord-Lock" makes some amazing matched-pair washer products which ensure a nut / bolt will NEVER loosen. They are very cool indeed.
MIKE
OK, let the flaming from un-informed know-it-alls (who are faster than me and therefore more knowledgable in ALL automotive areas) begin!
Last edited by great421; 07-19-2007 at 10:39 PM. Reason: spelling
#27
I torque my heads in stages, 15-30-45-60-75- and the final 85 ft-lb stages. and I let it sit overnight, recheck in the morning at 85, usually a fwe of them will torque more.
Never had head lifting problems yet.
Never had head lifting problems yet.
#28
Originally Posted by great421
OK, I actually wrote a book on this topic (Threaded Fastner / Threaded Joint Design and Usage) with two other engineers back in 2004 while working for one of the Big Two.
Here it is in a nut-shell:
The use of studs (vs. bolts) allows a significant increase in the torque used to be applied as a clamping force vs. a force used to rotate the fastener into the material.
(Ever notice when a bolt brakes, it almost always brakes flush with the surface, this is because of the amount of force being used to twist the bolt into the material; that percentage used is about 45% of the total torque.)
With bolts, typically only 5% of the torque applied actually gets used to create the clamping force (Yeah, I know sounds VERY low, but every SAE document available confirmed this!); however, when using studs about 50% of the torque is used for clamping! That is a 1000% increase - reason enough to change from bolts to studs - if you (like MM) are pushing 96 PSI!!!
Oh, the guy who mentioned the accuracy of the typical torque wrench - Right on the Money! (Even directly after calibration, the design is simply flawed, that's why the big money guys measure bolt strech not torque when dealing with connecting rod bolts - much more accurate!)
Torque in stages??? Yep! It help equalize the torque across the material.
Heat cycles / retorque??? Sure! But it is just as effective to torque the nut to the correct amount / wait 30 minutes then retorque - the reason? "Stress relaxation" and microscopic ridges in the "flat / smooth" surfaces of the stud and nut.
Oh, the final word on how much torque is enough? In six words I can sum up EVERY paper on this topic ever published; ALL SAE docs, and even the 200+ page German Holy Grail on this topic:
"If in doubt, tighten it more!"
Oh, I don't know if these things ever became available in the US, but a company called "Nord-Lock" makes some amazing matched-pair washer products which ensure a nut / bolt will NEVER loosen. They are very cool indeed.
MIKE
OK, let the flaming from un-informed know-it-alls (who are faster than me and therefore more knowledgable in ALL automotive areas) begin!
Here it is in a nut-shell:
The use of studs (vs. bolts) allows a significant increase in the torque used to be applied as a clamping force vs. a force used to rotate the fastener into the material.
(Ever notice when a bolt brakes, it almost always brakes flush with the surface, this is because of the amount of force being used to twist the bolt into the material; that percentage used is about 45% of the total torque.)
With bolts, typically only 5% of the torque applied actually gets used to create the clamping force (Yeah, I know sounds VERY low, but every SAE document available confirmed this!); however, when using studs about 50% of the torque is used for clamping! That is a 1000% increase - reason enough to change from bolts to studs - if you (like MM) are pushing 96 PSI!!!
Oh, the guy who mentioned the accuracy of the typical torque wrench - Right on the Money! (Even directly after calibration, the design is simply flawed, that's why the big money guys measure bolt strech not torque when dealing with connecting rod bolts - much more accurate!)
Torque in stages??? Yep! It help equalize the torque across the material.
Heat cycles / retorque??? Sure! But it is just as effective to torque the nut to the correct amount / wait 30 minutes then retorque - the reason? "Stress relaxation" and microscopic ridges in the "flat / smooth" surfaces of the stud and nut.
Oh, the final word on how much torque is enough? In six words I can sum up EVERY paper on this topic ever published; ALL SAE docs, and even the 200+ page German Holy Grail on this topic:
"If in doubt, tighten it more!"
Oh, I don't know if these things ever became available in the US, but a company called "Nord-Lock" makes some amazing matched-pair washer products which ensure a nut / bolt will NEVER loosen. They are very cool indeed.
MIKE
OK, let the flaming from un-informed know-it-alls (who are faster than me and therefore more knowledgable in ALL automotive areas) begin!
So with a lack of facilities to measure bolt stretch, would using a lower initial torque, and then angular tightening be better ? as many OE seem to do now.
Or for the more DIY based people, what is the best way to go about it ?
You say, if in doubt, tighten it more !!
For our typical M11 studs on an alloy LSx motor, at what point should we fear ripping the threads from the block ?
Again, assuming our torque wrenches or torquing methods are accurate enough to use here ?
Any reccomendations as to the best torque wrench out there ( within sensible price limits )
Any thoughts on ARP Moly, different thread lubes ?
#29
Originally Posted by great421
"If in doubt, tighten it more!"
At some point thread shear comes into play, and the stud material yield strength comes into play as well, past that, you're just in plastic deformation and you loose all the clamping force.
#33
Originally Posted by cablebandit
i got an old ls1 block and old arp stud (hex hole in top is worn)...want me to see what it takes to break the stud or threads with arp moly lube?
This would be a fun experiment but you do need something to simulate the head deck thickness to make it relatable.
#36
I TRIPLE DOG DARE YOU !!!!!!
Seriously, it will be interesting to see the results.
If this is done on a production head, I would bet that the head will
deform WAY before the stud or threads let go.
There is not a realistic way to measure the head deforming without
running an engine hard and examining the head gasket afterwards.
Keep us posted Cablebandit!
Seriously, it will be interesting to see the results.
If this is done on a production head, I would bet that the head will
deform WAY before the stud or threads let go.
There is not a realistic way to measure the head deforming without
running an engine hard and examining the head gasket afterwards.
Keep us posted Cablebandit!
#37
Torque 2 Yield at home?
I'll try to address each topic / question below:
It depends on the materials used to create the actual fastener. The harder / stronger the material, the less the fastener needs to ‘twist’ to achieve the same clamping force. Because that material specification is a known, specified quantity with OEMs, they can use angular measurements vs. torque.
Another issue to consider is percentage error; which is why the specs for angular tightening procedures are somewhat complex (e.g. - t1, t2, t3, wait 30 minutes, twist fastener X degrees, wait 30 minutes, twist another Y degrees). If a wrench is only 80% accurate, then 80% of a lower # is still (with respect to the actual amount of error, not % error) better than 80% of a higher torque value; that’s the logic anyway of T2Y fastener tightening specs.
Use a calibrated torque wrench and use the best quality fasteners you can afford!
I simply quoted all the engineer papers on the topic, but if the fasteners can accept a higher torque value, and that value is still in their elastic deformation range, then SURE!
With Aluminum, you need a depth of 4X the diameter of the fastener is avoid that issue, with Steel 2X. This is one reason I like studs – You just bottom them out! That (almost) always gives lots of extra thread depth.
In this area, price does indeed strongly correlate to quality / accuracy. Whatever you can afford, German, English, US, Swiss – all good; China / Taiwan – well, you already know… junk. Don’t buy precision tools from Harbor Freight!
Clean, lightly lubricated treads are fine, the oil will prevent the damage to the treads / block / fastener / nut. Of the research I did, no fastener manufacturers recommended anything other than a very light weight oil though.
Originally Posted by stevieturbo
So with a lack of facilities to measure bolt stretch, would using a lower initial torque, and then angular tightening be better as many OE seem to do now?
Another issue to consider is percentage error; which is why the specs for angular tightening procedures are somewhat complex (e.g. - t1, t2, t3, wait 30 minutes, twist fastener X degrees, wait 30 minutes, twist another Y degrees). If a wrench is only 80% accurate, then 80% of a lower # is still (with respect to the actual amount of error, not % error) better than 80% of a higher torque value; that’s the logic anyway of T2Y fastener tightening specs.
Originally Posted by stevieturbo
Or for the more DIY based people, what is the best way to go about it?
Originally Posted by stevieturbo
You say, if in doubt, tighten it more!!
Originally Posted by stevieturbo
For our typical M11 studs on an alloy LSx motor, at what point should we fear ripping the threads from the block? Again, assuming our torque wrenches or torquing methods are accurate enough to use here?
Originally Posted by stevieturbo
Any recommendations as to the best torque wrench out there (within sensible price limits)?
Originally Posted by stevieturbo
Any thoughts on ARP Moly, different thread lubes?
#39
am i the only one who has broken a stud?
i was once putting the heads back on cranking down for the final pass on a bolt, cranking, cranking, cranking, the torque wrench wasnt clicking, i thought i was getting weak from all that cranking, when snap------------- broke one of the big studs.
thankfully reckless helped me out and extracted the broken stud.
i was once putting the heads back on cranking down for the final pass on a bolt, cranking, cranking, cranking, the torque wrench wasnt clicking, i thought i was getting weak from all that cranking, when snap------------- broke one of the big studs.
thankfully reckless helped me out and extracted the broken stud.
#40
am i the only one who has broken a stud?
i was once putting the heads back on cranking down for the final pass on a bolt, cranking, cranking, cranking, the torque wrench wasnt clicking, i thought i was getting weak from all that cranking, when snap------------- broke one of the big studs.
thankfully reckless helped me out and extracted the broken stud.
i was once putting the heads back on cranking down for the final pass on a bolt, cranking, cranking, cranking, the torque wrench wasnt clicking, i thought i was getting weak from all that cranking, when snap------------- broke one of the big studs.
thankfully reckless helped me out and extracted the broken stud.