Hi Art and all!

I think you have already given the ONE best answer Art, for not using an impact driver!

I will put in my best, if anyone thinks, what you say, holds water for me BEING ABLE TOO!

Couple thoughts to keep in mind, An impact driver has no feelings!

Second, they are not intended to be used as an assembly tool!
Some mechcanics want disclaimers! Because they use them anyway.
Ok, here is the only one!
That is, unless you know for sure it's not capable of exceeding the fasteners stretch limit!

Example: The was only time I trusted an impact driver! A brute force young man's sport!

I have used 1 & 1/2" air impacts with two inch air lines, to run down 2 & 1/2" diameter studs or about 5" nuts, as tight as they would go. This with gobs of high temperature anti-seize on the threads.

Then I measured, from a hole depth in the center, the amount of stretch obtained overall from the normal relaxed reading.

Then, the bolts were heated up with electric heating rods poked down the center.
After the expansion occurred, the bolt got turned "X" amount of degrees.

This turning was calculated on the helix. The amount of the pitch in the thread would pull the stud into the nuts to get a certain amount stretch to meet yield requirements.

We use what is called "slugging" wrench and 30 lb. sledge hammers to drive the head around those few more degrees of rotation. You got to be careful not to let hit your ankles while swinging it between your legs.

All of this was to get the high torque values, that are above the "realm of rotational torquing" and will avoid Galding! Remember you want to take it back apart someday!
The reverse of that above is used to take it apart too!

You wonder what was this was on! Power plant Steam turbine cases. All along their split line. It holds their halves together.


Now think about, go ask or work inside a tire shop and you will find out how dangerous impacts are toward wheel studs!
Don't let your tire shop use them to install anything! Look and watch! If they do go somewhere else!

They can break or strip studs in a blink.
The impact driver has no feelings and does not transmit any notice to the user of one. It's too momentary. The stud stretches and later the nut falls into the hub cap or street!

Sledge hammers and Impact drivers are brute force tools, period!


You ask, what does this have to do with the Volvo tool and bushings?
Well, Its operating up at the maximum range of mechanical stresses of metal.
The diameter of the bushings and tabs have their surface areas chemically bonded by by nature let alone a fit.
As the length of the tool shortens, the angles of distortion change slightly. This draws energy into different parts of the tab of which release unevenly.
Relaxing the pressure actually releases in all directions and redistributes the next application of energy. You gain on some force from the part that was binding the rings on the diameter, to moving the bushing along.
Like I said, the first half inch is a toughest. The thickness of the tabs.

This is With any material! Plastic even has structural limits but they are in chains, instead of a lattice frames though.

There is a limit at the molecular level that you can move molecules against molecules.

It is worse when there are two materials with molecular structures the same or have like crystalline lattice structures.
Not all molecules are perfectly round or smooth since they are grains of a crystal nature. A different material lattice may have openings and will make it more compatible against galding. In wear bushings for example that are sacrificial! In Caterpillar equipment for example.

Deformation or galding occurs when some don't slide but try to roll and slide to another place of less pressure. No room, then an ouch is heard! Not a good sound!


This is how I think it works for me and my wrenches.

Imagine a farmer and a shear plow with a horse in a dirt field. As long as the dirt can move away from the plow the horse moves. If there is a hard crusty chunk getting hit it and cannot be pushed up the horse will stall!
The farmer has to relax the plow and let things shift. The plow shifts, the crust flops or he backs up and tries ramming the loosen chunk again and it crumbles or shifts!

This I called a "relax or rest" technique! Give a little, to Get a little!
There are many things that this method work well on! (:-)

When two surface planes are together under pressure there is no room. Like a lid dragging on top of the plow and next to the ground.
The extra energy being used to get movement, while compacting, now transfers into more heat from friction.

A release of pressure or force is due, it's R &R time! If not, the excessive heat starts sticking molecules together. A result is a stacking of molecules. It is the Welding or is molecular fusion that starts the galding!

An impact driver just keep on ripping!
No feelings for the horse or the plow until something becomes breaks down to a stop and then it probably unrepairable.
Unrepairable, Because, it cannot be taken apart and used easy again!
YOU JUST BOUGHT THE FARM!
In these cases, a rental tool!

Now if using the same plowing idea, think about a threading tap.

The sheared metal chips or even dirt in a thread has to go someplace.
If not, it binds and if you keep turning it, the extra energy goes to work against you and you break it.

Now the work doubles or triples. You got to remove the old one and buy a new threading tap with new money you have to earn!

Now Look, into a stuck spark plug situation.

Corrosion or coked carbon has filled in clearances between the surfaces planes.
You start wangling on it and it does not move. Keep imparting energy and what happens, the crystals crunch and fuse. Crunch is ok, but don't let them fuse!

Now is the time for finesse!
A strategy of using some knowledge, of what is going on and applying techniques as needed.

I work with what I discussed above, as they are almost identical!

Lots of tightening, relaxing and even backing up to a tight spot, relax it and tighten the other way again. Over and over patiently.

This is the technique I use with my favorite penetrate Maltby. It talks molecular to me.
But any fluid that you can get to go in there helps. I have several brands in my cupboards. I'm always looking for that other miracle stuff!

I use the relax portion of my technique to apply my coolant or lubricant in this particular case.
The lubricant allows slippage of the crusty carbon and aluminum particles, to shift or dissolve.

Working the spark plug back and forth, with lots of finessed patience, gives time for the particles to become smaller and smaller! Finding space that was not there!

It's like a box of corn flakes. It starts out full at the factory full, but looks like the "Mikey Eats Anything" syndrome struck it and snitched some out, but it was from settling. (:-)

So far, for me, no spark plug has been too tough to get out of an engine.

I did have one real tough one though inside my junkyard engine find.
Like, it took a very long time to get it to move around that first crackling.

All by hand. Strained it incrementally, both ways, with a torque wrench!
Like excerise, stretch and relax! The liquid needs to be there and ready to creep in.
Some say to tap things for vibration to set up. I guess? I use anything including heat if I can or absolutely have too!

I would work on it a little, let it set a few days and let time be on my side! Soaking and softening.

The threads in that hole may have been abused a little bit before, in its life time!
Another inner thought was, it probably was never changed out of there because it was so very stuck!

I did worry, that it did suffer some galding and a HeliCoil was coming at me! But I got it out fine and cleaned the threads.

Galding and Balding are two things that can get to most men, one time or another!

I hope I gave up some good advice to all! (:-).

Phil