Ironhead Removing primary engine sprocket nut with heat gun, special caution needed?

[The Doctor71]

DR DICK..... understood, I get it now. I hadn't run across the term "reaction tool" before. Thank you for educating me.

[mikethebike61]

Originally Posted by andy2175m4

I'd try it cold first with a breaker bar, I dont think that red loctite has a ghost of a chance against a breaker bar.

You would be WRONG on that....when the manufacturer tells you to heat to 125F....heed what he says

[andy2175m4]

OK so I use an impact to break free the primary nut on the crank and the clutch, so I guess I am ok then ?

[Ferrous Head]

Yup. Now worries with either of them.

[DDDDylan]

It can be argued that using an impact tool to LOOSEN most fasteners is SAFER than using a wrench.

An impact delivers only pure torque (aka a couple or a moment) to the fastener, in the axis of the fastener. That moment is what you need to get things unscrewed.

A wrench applies a moment AND a force to the fastener. Say you have a 1 foot long wrench. To generate a 100 lb-ft moment on the fastener you have to apply 100 lbs 1 foot away from the axis of the fastener. However, your 100 lbs of force on the wrench has to have an equal and opposite force from somewhere so the fastener now has 100 lbs of force directed at it perpendicular to its axis.

That side-force on the fastener can sometimes spell the difference between the torque/moment loosening the fastener vs. the fastener just getting sheared off. Think about getting your rusty lug nuts off your car with the crummy OE "L" shaped lug wrench/tire iron vs. using a 4-way wrench. The L wrench is basically designed to shear studs off. Two hands on a 4-way create pure torque, like an impact.

Bonus round: The longer your wrench (moment arm), the less force you have to apply to achieve any given torque, and the LESS likely you are to shear off a fastener. To use the earlier example, move to a 3 foot wrench with 33 lbs force and your fastener will still see 100 lb-ft, but now it only sees 33 lbs side force. Use an infinitely long wrench and you'll apply no side force.

[rejeanprimeau]

The impact wrench is not recommended because of some left threaded bolt. With a bar, you'll figure it out but with the impact you'll just shear the bolt.