Torque-to-yield bolts are better than standard bolts for clamping because they provide more consistent torque over varying conditions and are designed to match the gasket and prevent failures. The bolts stretch into the plastic deformation region when tightened, meaning they will not loosen on their own. However, overtightening the bolts can cause them to snap, so it is important to follow the shop manual's instructions for the correct torque and tightening procedure.

1. TORQUE TO YIELD
TYPE FASTENERS

2. Why are Torque-to-Yield bolts
a better choice for clamping?
 More consistent torque over wider range of
operating conditions.
 Matched to gasket and engine
 Head gasket failures are very rare now

3. Torque-to-Yield Angle Gauge

4. How to use gauge

5. So…what is happening?

6. Twist a little too far and…
BANG!!!

7. So…what is happening?
 As a bolt begins to
tighten, it enters the
area known as the
“Elastic
Deformation”
Region where the
bolt stretches, but
will return to original
length when
loosened.

8. Example: Connecting Rod Bolt
 This special tool will
actually measure
the amount that a
bolt will stretch
when tightened.

10. Let’s tighten the bolt some
more!
 As the bolt is
tightened further, it
reaches the “Plastic
Deformation” region.
At this point, the bolt
will not return to its
original length when
loosened. But it will
be a better “Bolt”!

11. But, we can over do it!
 It just got real easy
to turn all of a
sudden! At this
point, you can’t back
it off a quarter turn
and save it!

12. Hey! It got real easy to turn
 Ok, dumb-bunny.
You didn’t follow the
special “Torque-to-
Yield” directions in
the shop
manual…and now
you have a real
problem!

13. What this looks like-Real World!
1st Step: Base Torque, Mark
Bolts

14. What this looks like-Real World!
2nd Step: 90 deg. Turn

15. What this looks like-Real World!
3rd Step: 45 deg. Turn

16. What this looks like-Real World!
4th Step: 45 deg. Turn Center
Bolts

17. Remember!
 Always check the shop manual for instructions
for:
 Bolt length
 Lubrication requirements
 Special torque values and procedures
 Mark bolts when finished with final torque angle