What is a torque-to-yield bolt? It is a one-time-use fastener that is designed to stretch during the torquing process (installation). Because of this stretching, the integrity of the bolt is compromised. These bolts cannot and should not be reused due to the stress caused to the bolt during its first installation.
Why do they use torque to yield bolts?
First, it overcomes friction between the threads in the block and the bolt as well as friction between the cylinder head the underside of the bolt head. Secondly, the torque stretches the fastener slightly to establish and maintain the desired clamp load on the gasket.
Are ARP bolts torque-to-yield?
No, ARP bolts are not torque to yield (TTY). TTY fasteners, when being torqued, actually stretch because of the elastic properties of the material. This gives them the needed clamping force, but the downside it that they aren’t reusable (well, at least they shouldn’t be reused).
How does a torque-to-yield bolt differ from a standard bolt?
With a standard bolt, a technician could torque the bolt to its yield point, and it would return to its original form and length when removed. It has elasticity; it can stretch and then return to its original form. This is not so with torque to yield bolts.
Can you reuse bolts that have been torqued?
Reusing nuts, bolts, washers, and other mechanical fasteners is generally never a good idea. If you have any doubts about a fastener’s condition, it is best to discard it in favor of new fasteners as that will always result in a stronger, more durable joint.
How much does a bolt stretch when torqued?
To appropriately answer this question, it helps to first consider that only approximately 10-15% of the input torque actually stretches the bolt; the remaining 85-90% of input torque is primarily used to overcome friction between the mating threads and friction under the bolt head or nut.
What is a common application for torque to yield type fasteners?
Today, TTY fasteners are employed for bolted joints in a variety of automotive components, such as ball joints, knuckles and tie rods. Traditional fasteners are torqued to a load that will slightly stretch the bolt but won’t over-stretch it past its yield point.
Are flywheel bolts torque to yield?
All of the documentation that I found indicated the flywheel bolts are torque to yield, and not reusable.
What is the torque angle method?
The torque angle method is a more precise way of torquing a standard fastener to a predetermined tension. When using this method, the bolts are torqued to a minimal specification, say 20 foot-pounds and then tightened a further specified number of degrees, say 90 degrees.
What is torque turn method?
Torque-Turn. The torque-turn method is used when precise control over clamping force is required. There is an initial torque and an additional turn. The initial torque is required to bring all parts of the joint into contact. The additional turn provides the desired clamping force.
What will happen if you overtighten screws?
One of the most damaging ways to do that is by over-tightening, or over torquing the fastener. This can result in stripping screws, snapping screw heads and damaging pre-tapped threading.
What happens if you don’t torque to spec?
In the case of insufficient torque, it’s the stud or the bolt itself that suffers all the impact, causing it to shear. Alternatively, the engine’s vibrations can cause the bolt or nut to come undone, displacing the tensioner.
What happens if bolts are over torqued?
Typically, an under torqued bolt will deform and be unable to provide as much clamping force as needed. An over torqued bolt will break.
What’s so good about ARP bolts?
ARP’s fasteners are built to withstand serious racing and have higher tensile strengths and can survive higher stresses than most aircraft fasteners will ever see.
Is it OK to reuse ARP head studs?
Are ARP bolts and studs re-usable? Yes. As long as the fasteners have been installed and torqued correctly, and show no visible signs of damage, they can be re-used. If they show any signs of thread galling or corrosion, they should be replaced.
Why are head studs better than bolts?
Studs provide the ability to obtain much more accurate torque values because the studs don’t twist during tightening as do bolts. Because the studs remain stationary during nut tightening, the studs stretch in one axis alone, providing much more even and accurate clamping forces.
