n.m setting for headbolts
Moderators: daewoomofo, Moderators Group
n.m setting for headbolts
hi can anyone tell me the required torque for 1.6 nubira headbolts (without using a angular torque gauge) cheers
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PrecisionBoost
- Super Moderator
- Posts: 4437
- Joined: Thu Jun 19, 2003 5:59 am
- Location: Edmonton, Alberta, Canada
They are "Torque-to-yield" bolts so the initial torque is desiged to load the bolt to just before it starts to stretch.
Then the angular movments create the stretching (and thus clamping force)
90% of the torque is spent overcoming friction.... only 10% of the force/torque is used in clamping/stretching.
This is also why your not supposed to reuse TTY bolts.... they are stretched past their elastic deformation point into plastic deformation.
If your not sure what that means.... it's like a spring.... if you pull on it with a certain amount of force the spring will allways go back to the original shape (elastic deformation) but at a certain point when you pass a particular level of force pulling on the spring it will elongate further so that when you release the force you will find the spring does not look the same and is stretched longer than it was when you started.
What happens with TTY bolts if you re-use them?
Simple... they've allready been stretched so your torque and angular values required to bring them back to the "standard" clamping force has changed.
That is to say they might produce 5000lb of clamping force per bolt using the standard bolt tightening technique.
If you re-use them you might only get 3750 lbs of clamping force which could result in a head gasket leak
Additionally the bolts will snap at a lower force because you've stretched them twice.
In short, you absolutely must use the angular gauge to get the correct amount of stretch on your TTY bolts.
Daniel.... that's a great tip with respect to using a CD and protractor for those who are having a hard time finding a gauge.
Then the angular movments create the stretching (and thus clamping force)
90% of the torque is spent overcoming friction.... only 10% of the force/torque is used in clamping/stretching.
This is also why your not supposed to reuse TTY bolts.... they are stretched past their elastic deformation point into plastic deformation.
If your not sure what that means.... it's like a spring.... if you pull on it with a certain amount of force the spring will allways go back to the original shape (elastic deformation) but at a certain point when you pass a particular level of force pulling on the spring it will elongate further so that when you release the force you will find the spring does not look the same and is stretched longer than it was when you started.
What happens with TTY bolts if you re-use them?
Simple... they've allready been stretched so your torque and angular values required to bring them back to the "standard" clamping force has changed.
That is to say they might produce 5000lb of clamping force per bolt using the standard bolt tightening technique.
If you re-use them you might only get 3750 lbs of clamping force which could result in a head gasket leak
Additionally the bolts will snap at a lower force because you've stretched them twice.
In short, you absolutely must use the angular gauge to get the correct amount of stretch on your TTY bolts.
Daniel.... that's a great tip with respect to using a CD and protractor for those who are having a hard time finding a gauge.
2010 BMW 335D
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos
re
hey yeah i reused my headbolts as i have done with everyother car i have had i have had mixed emotions about the isssue with the bolts yes and no from all different places at $80 for the set im going to risk this one but if i have issues then i will replace them my car is very simple to perform tasks on so im not too scared about failure on this. thanks to daniel for the makeshift gauge. i just ended up buying one $36 wasnt to bad after all i would have used the teqnique u provided but i wanted acuracy and the tool will come in handy later on all went well with the retorque of the headbolts anyhow was just starting to fight with the cambelt wen the sun went down later date lol figured out the previous owners mechanic had set it a notch out it (seems) with his white markers possible why the pistons and valves were so carbonised oh well all fresh now heres a little sheet on what everything has costed so far $80 VRS (cheapest on the market will soon find out if its the nastiest pmsl) $70 waterpump (not bad has 3yr warranty) dayco T.belt and idlers $95 (popular tbelts in aus) $246.30 (16 valves best to do them all i think) cleaning products oil and glycol around $30 $5 for 5 lts of fuel car would have cost around $1500 after its registered as i paid $400 for it didnt pay for tow as it was like around the corner not bad for a car that sells between 4 and 5 grand here plus had awesome stereo did they put factory amps in woos or is it my kenwood headeck cuz it sounds pretty neat (well for my commuting needs im no racer pmsl) cheers stevie
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PrecisionBoost
- Super Moderator
- Posts: 4437
- Joined: Thu Jun 19, 2003 5:59 am
- Location: Edmonton, Alberta, Canada
many of the older engines did not use torque to yield bolts.... they usually didn't have angular torque requirements.
Perhaps you should consider an ARP stud conversion for the cylinder head.... makes things easier in the long run.
I'm pretty sure the stock deck was a Sony... so if it's a Kenwood it's probably a decent aftermarket.
Perhaps you should consider an ARP stud conversion for the cylinder head.... makes things easier in the long run.
I'm pretty sure the stock deck was a Sony... so if it's a Kenwood it's probably a decent aftermarket.
2010 BMW 335D
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos