A real concern or noobie paranoia?
Discussion
Hello
So I'm putting a engine back together first time and I overtightened the rod bolts to 70lb meant to be 50lb, I've loosened them and retorgued to the correct value my concern is have I ruined the bolts? Are the bearings crushed? I have too many thoughts going through my head like I'll spin a bearing as soon as I start it
Ps they are Arp bolts
Thanks for reading
So I'm putting a engine back together first time and I overtightened the rod bolts to 70lb meant to be 50lb, I've loosened them and retorgued to the correct value my concern is have I ruined the bolts? Are the bearings crushed? I have too many thoughts going through my head like I'll spin a bearing as soon as I start it
Ps they are Arp bolts
Thanks for reading
40% over tightening has to be a lot!
It all depends on the metallurgy of the bolt metal, have they reached their yeild point?
Only ARP themselves could answer, and they have an obvious bias to to saying you have ruined them, but the obvious answer is yes, you need to buy another set.
John
It all depends on the metallurgy of the bolt metal, have they reached their yeild point?
Only ARP themselves could answer, and they have an obvious bias to to saying you have ruined them, but the obvious answer is yes, you need to buy another set.
John
As above, you need to speak to ARP, but my guess is that those bolts are probably meant to fir many different engines & some of those will have torque figures higher than yours, so you may well be OK, but only ARP can confirm that unless they have an "online catalogue" and from your part number you can find the same bolts on an engine with a torque figure relating to what you did them up to.
The likelihood is that you have done zero damage to the engine internals as you have just stretched the bolts a bit more than you should have done, not compressed incompressible metal parts.
The likelihood is that you have done zero damage to the engine internals as you have just stretched the bolts a bit more than you should have done, not compressed incompressible metal parts.
ThermalDog said:
Hello
So I'm putting a engine back together first time and I overtightened the rod bolts to 70lb meant to be 50lb, I've loosened them and retorgued to the correct value my concern is have I ruined the bolts? Are the bearings crushed? I have too many thoughts going through my head like I'll spin a bearing as soon as I start it
Ps they are Arp bolts
Thanks for reading
Depends how you torqued, them, what lube, how accurate your torque wrench is..what material the bolts are etc etc.So I'm putting a engine back together first time and I overtightened the rod bolts to 70lb meant to be 50lb, I've loosened them and retorgued to the correct value my concern is have I ruined the bolts? Are the bearings crushed? I have too many thoughts going through my head like I'll spin a bearing as soon as I start it
Ps they are Arp bolts
Thanks for reading
No the bearings will not be crushed though.
There is every likelihood the bolts are fine though, as often their quoted torques are far below what is need to achieve stretch targets....but it does still depend on all of the above.
ARP's own site says:
"As a rule of thumb, if you measure a fastener and it is .0005˝ (or more) longer than its original length it has been compromised and must be replaced."
https://arp-bolts.com/p/technical.php 'Installation' sub-heading.
Do you have measuring equipment accurate enough to do that?
What engine are the bolts in?
ARP are telling you that the bolts should be replaced & if you don't it's always going to be worrying you so you're probably going to need to replace the bolts just for peace of mind.
"As a rule of thumb, if you measure a fastener and it is .0005˝ (or more) longer than its original length it has been compromised and must be replaced."
https://arp-bolts.com/p/technical.php 'Installation' sub-heading.
Do you have measuring equipment accurate enough to do that?
What engine are the bolts in?
ARP are telling you that the bolts should be replaced & if you don't it's always going to be worrying you so you're probably going to need to replace the bolts just for peace of mind.
How much do the bolts cost? How much is your peace of mind worth?
What is the strength grade of the bolts? What is the maximum tightening torque for that grade and size? Did you follow advice on preparing the threads and bolt head?
It's often the case that we worry a lot more about achieving the correct torque than using bolts of sufficient/correct strength. In some applications, thread and head friction can vary by almost a factor of two giving a factor of two uncertainty in the bolt tension. Tightening torque can be a bit of a lottery!
What is the strength grade of the bolts? What is the maximum tightening torque for that grade and size? Did you follow advice on preparing the threads and bolt head?
It's often the case that we worry a lot more about achieving the correct torque than using bolts of sufficient/correct strength. In some applications, thread and head friction can vary by almost a factor of two giving a factor of two uncertainty in the bolt tension. Tightening torque can be a bit of a lottery!
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