Torque spec for weathered bolts

[noid]

When was the last time you heard a story about someone putting steering rack (or whatever) back on, re-using all the bolts, and then all the bolts falling out because they weren't tight enough?

Better yet, how many professional mechanics do you know who, when putting a customer's car back together, grease every fastener and recalculate all their own torque values? Bet its zero.

I fully agree that the average north american mechanic is both under educated and over incentivized to go fast (flat rate).

Come backs are unfortunately way too common. I've seen countless mistakes and oversights made by mechanics.

Lets not confuse redundancy with proficiency though.

I never said I didn't agree with that.

What I said was that lubricating fasteners which don't call for lubrication is a bad idea. Which it is.

Based on the above it sounds like you think manual torque specs do cover all (most?) conditions and factors.

If that is so, lets agree to disagree.

 

[Fcvapor05]

I fully agree that the average north american mechanic is both under educated and over incentivized to go fast (flat rate).

Come backs are unfortunately way too common. I've seen countless mistakes and oversights made by mechanics.

Lets not confuse redundancy with proficiency though.

LOL. K dude.

 

[Blickus]

Hate to interrupt the ******* contest that usually arise here. A little engineering information has crept in, but the basis of the engineering is as follows:

The torque required for a bolted joint design comes from a long string of calculations, but boils down to a simple equation.

T = Wp x K x dn
Where T=torque; Wp=fastener preload; K=torque coeff; dn=diameter

The factor that changes with dry vs lubricated fasteners is the "torque coefficient" and is published for a variety of cases. These values are taken from DuPont Engineering Specification (10 pages of calcs). Examples:

Dry steel fasteners: K=0.20
Lightly oiled steel: K=0.15
Cad Plated: K=0.14
Anti Seize on steel: K=0.13 (as published by Bostik for their Never Seez products)
Graphite & mineral oil: K=0.10

Solving the equation for the fastener preload using the original torque (specified by the engineer that designed the joint). The preload remains constant as the k factor is changed, then solve again for resultant torque. It is a ratio of the original fastener k factor to the new k factor with lubrication.

Example: Using Never Seize versus dry uncoated steel, multiply the dry steel torque by 0.65.

 

[noid]

Hate to interrupt the ******* contest that usually arise here. A little engineering information has crept in, but the basis of the engineering is as follows:

The torque required for a bolted joint design comes from a long string of calculations, but boils down to a simple equation.

T = Wp x K x dn
Where T=torque; Wp=fastener preload; K=torque coeff; dn=diameter

The factor that changes with dry vs lubricated fasteners is the "torque coefficient" and is published for a variety of cases. These values are taken from DuPont Engineering Specification (10 pages of calcs). Examples:

Dry steel fasteners: K=0.20
Lightly oiled steel: K=0.15
Cad Plated: K=0.14
Anti Seize on steel: K=0.13 (as published by Bostik for their Never Seez products)
Graphite & mineral oil: K=0.10

Solving the equation for the fastener preload using the original torque (specified by the engineer that designed the joint). The preload remains constant as the k factor is changed, then solve again for resultant torque. It is a ratio of the original fastener k factor to the new k factor with lubrication.

Example: Using Never Seize versus dry uncoated steel, multiply the dry steel torque by 0.65.

We're not allowed to play with lubricants though.

 

[Cgw1984]

Ya, ANY suspect bolt gets replaced, and the thread chased.

 

[noid]

A couple <strike>fun</strike> prohibition charts:

 

[Fcvapor05]

A couple <strike>fun</strike> prohibition charts

If you're going to post like a petulant child, at least snipe at what I actually said.

I never said to never use anti-seize. I have like 5 half empty bottles in my shop cabinet right now. I use it all the time.

Where it's called for.

 

[noid]

If you're going to post like a petulant child, at least snipe at what I actually said.

I never said to never use anti-seize. I have like 5 half empty bottles in my shop cabinet right now. I use it all the time.

Where it's called for.

Perhaps this will suit your needs: