School Me on Torque vs Torque + Degrees

[XraytecH]

Why two different kinds of Torque Values?

Doing YouTube research on the Steer Smarts Sector Shaft Brace and I'm getting Torque Values from NorthRidge and Torque + Angle from JL Life.

Also, Steer Smarts go by Torque + Angle on some of their bolts.

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[bleda2002]

Torque + angle is the way the factory does it as its a very precise way to measure bolt stretch. For my sector shaft brace I ended up using the synergy torque spec on the steel steering bolts of 99 ftlbs (even though i used a steer smarts brace the bolts are in the steering box so it should be the same). Thats probably where northridge got their numbers

 

[spectre6000]

It's a spec for TTY fasteners. Torque is torque a la torque wrench like usual. Torque + angle, you torque to the spec, then turn the fastener however many additional degrees. The torque seats the fastener, the "+ angle" stretches it to plastic deformation (you only get to use them once for the spec). TTY (torque to yeild) fasteners are, as previously mentioned, more precise than simple torque because your clamping strength is dictated by the plasticity of the alloy of the fastener, and can be more carefully controlled by the manufacturer.

 

[ShadowsPapa]

It's pretty simple. There are 360 degrees in a circle. There are 6 sides to a hex bolt or nut. That means corner to corner of a bolt head is 60 degrees (6 x 70)
You torque the bolt to the torque setting and then turn it the number of degrees stated. If that's 150 pound feet plus 30 degrees, that's half of the flat side of a hex bolt.
360 is a full turn, 180 degrees would be another half turn, 90 would be another quarter turn of the bolt and so on.........

Like already said - it's an accurate way to set a bolt because you can be precise with bolt stretch.
The pitch of the bolt thread determines how much the bolt stretches with each full turn.
For a bolt that had 32 threads per inch, one half turn would mean 1/64th inch. That's an exaggeration but explains how it's figured.

When building performance engines, you may actually measure the length of the rod bolt at a certain point and torque it until the bolt is stretched a certain amount.

 

[ShadowsPapa]

It's a spec for TTY fasteners. Torque is torque a la torque wrench like usual. Torque + angle, you torque to the spec, then turn the fastener however many additional degrees. The torque seats the fastener, the "+ angle" stretches it to plastic deformation (you only get to use them once for the spec). TTY (torque to yeild) fasteners are, as previously mentioned, more precise than simple torque because your clamping strength is dictated by the plasticity of the alloy of the fastener, and can be more carefully controlled by the manufacturer.

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And it's that clamping force that holds things in place, not the sheer strength or the body of the bolt keeping things from moving. When properly "clamped", the items being held act as one.

 

[XraytecH]

It's a spec for TTY fasteners. Torque is torque a la torque wrench like usual. Torque + angle, you torque to the spec, then turn the fastener however many additional degrees. The torque seats the fastener, the "+ angle" stretches it to plastic deformation (you only get to use them once for the spec). TTY (torque to yeild) fasteners are, as previously mentioned, more precise than simple torque because your clamping strength is dictated by the plasticity of the alloy of the fastener, and can be more carefully controlled by the manufacturer.

Now this is interesting. So when a manufacturer says torque this bolt to 70lbs + 90. That means that bolt is a single use bolt?

 

[spectre6000]

Now this is interesting. So when a manufacturer says torque this bolt to 70lbs + 90. That means that bolt is a single use bolt?

That is correct. Also, if you get cheap ones, they can be a bit fickle. I did head gaskets and timing chain on a Dodge 4.7L V8 with TTY head bolts a few years back. Single use, and not cheap (~$75 a set, from memory). As I was going through the torque sequence, one of the bolts went plastic much sooner and much more than the others, and I had no confidence in it. I had to buy a whole new set for a single bolt.

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