Drilling out easy out

[JFP in PA]

Originally Posted by B6T

Standard practice, at least in automotive assembly, is NOT to lubricate threads and or washers. In specific applications, lubricant may be called out, but those are the anomaly. ARP might claim to lubricant "ALL" threads because in their world of specialty high strength fasteners, this is the standard they can expect from the users of the product since they have a specific attention to that detail. But I'd wager that you wouldn't find a single lubricant near any fastener in an automotive assembly plant.

A specified level of torque applied to a fastener head will result in more clamping force when the fastener is lubricated than when it is not lubricated. The reason is because you are reducing the friction between the thread flanks and thereby increasing the tension in the bolt. Hence, if you lubricate the threads and apply the specified torque value, you run the risk of breaking the bolt or the mating parts since you are applying a greater clamping load than intended. Bolted connection design takes into account all these factors and the design engineers follow proprietary tables when they size a bolt for an application, which for the most part, is a dry fastener that has a reducing clamping load than the same fastener when lubricated.

VW/Audi/Porsche flywheel bolts have a thread locking compound that will not work properly if you lubricate the threads with oil.

I don't know what the hell ARP is talking about, and I don't have time to read it, because I own a Boxster which is waiting for me in the garage.

You would lose your wager. First of all, engines and transmissions are not assembled in the same plant the car is, they are shipped in from a facility the is setup specifically to assemble them, and they do use specialized lubricants on the fasteners. I've watched them do it. Secondly, the torque spec to reach the design clamping force is set with lubricated fasteners because dry fasteners will reach that torque spec level due to friction in the treads and at the bolt head before actually achieving the desired clamping load level, leaving the parts with less clamping load than expected.

You really ought to take the time to read the ARP paper, you might actually learn something.

[B6T]

Originally Posted by JFP in PA

You would lose your wager. First of all, engines and transmissions are not assembled in the same plant the car is, they are shipped in from a facility the is setup specifically to assemble them, and they do use specialized lubricants on the fasteners. I've watched them do it.

Not entirely true. There have been plants that house both engine assembly and vehicle assembly under the same roof. Except in this context we're not talking about assembling engines, we're talking about some random M6 bolt that goes into a caliper. So my comment was regarding vehicle assembly, not engine assembly. Even still, only rotating assembly bolts are lubricated within an engine at assembly. Bolts that hold on accessories like the starter and alternator are not.

Originally Posted by JFP in PA

Secondly, the torque spec to reach the design clamping force is set with lubricated fasteners because dry fasteners will reach that torque spec level due to friction in the treads and at the bolt head before actually achieving the desired clamping load level, leaving the parts with less clamping load than expected.

You really ought to take the time to read the ARP paper, you might actually learn something.

I understand how bolting friction works, since that's exactly what I explained in my previous post, and what you explained as well. But if you're saying that a torque specification like those in a service manual require lubrication on thread to achieve that spec, I think that is where our opinions differ.

The designers for a vehicle understand what clamping force they are looking for, and to achieve that force they will specify a dry torque... which is much higher than a lubricated torque to overcome that friction, but still achieves the same clamping load in the end. I'm sure they do base it on a lubricated torque at some point, but the torque value you will see is for a dry fastener.

Why dry? Because when they're building the vehicle, lubrication on assembly lines is a) messy, b) an added expense, and c) from a torque calibration perspective, lubrication is an additional control point that can cause process variation since lubrication amounts, lubrication type, and even location on the fastener are hard to keep consistent. Way too many variables to control.

It is much easier to specify a dry fastener torque since the characteristics of a dry fastener are much much much more consistent and well established in proprietary design standards.

[JFP in PA]

Originally Posted by B6T

Not entirely true. There have been plants that house both engine assembly and vehicle assembly under the same roof. Except in this context we're not talking about assembling engines, we're talking about some random M6 bolt that goes into a caliper. So my comment was regarding vehicle assembly, not engine assembly. Even still, only rotating assembly bolts are lubricated within an engine at assembly. Bolts that hold on accessories like the starter and alternator are not.



I understand how bolting friction works, since that's exactly what I explained in my previous post, and what you explained as well. But if you're saying that a torque specification like those in a service manual require lubrication on thread to achieve that spec, I think that is where our opinions differ.

The designers for a vehicle understand what clamping force they are looking for, and to achieve that force they will specify a dry torque... which is much higher than a lubricated torque to overcome that friction, but still achieves the same clamping load in the end. I'm sure they do base it on a lubricated torque at some point, but the torque value you will see is for a dry fastener.

Why dry? Because when they're building the vehicle, lubrication on assembly lines is a) messy, b) an added expense, and c) from a torque calibration perspective, lubrication is an additional control point that can cause process variation since lubrication amounts, lubrication type, and even location on the fastener are hard to keep consistent. Way too many variables to control.

It is much easier to specify a dry fastener torque since the characteristics of a dry fastener are much much much more consistent and well established in proprietary design standards.

You are correct on one point: We disagree.

[Xpit77]

Originally Posted by B6T

Not entirely true. There have been plants that house both engine assembly and vehicle assembly under the same roof. Except in this context we're not talking about assembling engines, we're talking about some random M6 bolt that goes into a caliper. So my comment was regarding vehicle assembly, not engine assembly. Even still, only rotating assembly bolts are lubricated within an engine at assembly. Bolts that hold on accessories like the starter and alternator are not.



I understand how bolting friction works, since that's exactly what I explained in my previous post, and what you explained as well. But if you're saying that a torque specification like those in a service manual require lubrication on thread to achieve that spec, I think that is where our opinions differ.

The designers for a vehicle understand what clamping force they are looking for, and to achieve that force they will specify a dry torque... which is much higher than a lubricated torque to overcome that friction, but still achieves the same clamping load in the end. I'm sure they do base it on a lubricated torque at some point, but the torque value you will see is for a dry fastener.

Why dry? Because when they're building the vehicle, lubrication on assembly lines is a) messy, b) an added expense, and c) from a torque calibration perspective, lubrication is an additional control point that can cause process variation since lubrication amounts, lubrication type, and even location on the fastener are hard to keep consistent. Way too many variables to control.

It is much easier to specify a dry fastener torque since the characteristics of a dry fastener are much much much more consistent and well established in proprietary design standards.

I agree. In the 21 yrs that I worked in the Mass Transit industry we never used anti-seize on a torqued fastener that required a specific torque. But,all these fasteners were brand new .In this case a heli-coiled wanked out hole? I be putting a whole lot of locktite not anti.