Air impact gun question

[PandaWill]

Hi all,

Just recently I have had 2 jobs where I thought my expensive half inch ingersoll rand air gun would be the perfect tool (set to 90psi as recommended and run from a fairly meaty compressor)

First one was a crank bolt on a Peugeot xud engine. These are notorious for being incredibly tight but I was confident in the tool. To cut a long story short it wouldn't touch it and I had to remove it via the starter motor method.

Second one were the 27mm wheelnuts on a Land Rover rebuild I am doing. I could tell by looking at them that these hadn't been off for a long time. Again, the gun wouldn't touch them. They were tight and it took my full body weight on a long breaker bar to shift them.

However, given the cost, I feel a little disappointed. The gun is rated to 800NM +.

Does it sound like something is wrong or is this normal?

Many thanks
Will

 

[PandaWill]

To add I have done 3 crank bolts on Land Rover engines with it so it does work - just maybe doesn't have the grunt I was expecting....

 

[rikrobson]

I've only had the cheapo ones and an old CP one. They work upto a point, but i've always found that a ploe on a breaker bat always gets the job done.

 

[brightspark]

I have a rather large cp 3/4 drive gun-and it struggles to undo some nuts and bolts so I wouldn't worry about it. as long as your airlines-are half decent 10mm or larger bore and your using a bit larger bore than the standard pcl u will have no loss there

 

[grim_d]

Impact guns are great but sometimes things are just too tight/seized for them. That's why we have breaker bars. I often view the impact gun as a strong nut runner.

Also remember that 1/2 inch drive is only the middle size!

Don't try it on the rear hub bolts of a mk5 golf then or you will be disappointed! 5ft scaf bar on a 3/4 breaker and I still turned beetroot!

 

[NickyEng]

If they were so tight that it took your entire body weight on a breaker bar no way an 800nm gun will slacken them mate. That is normal. My nitrocat is rated at 1100FT Ibs and doubt it would slacken that amount of required torque

 

[colnerov]

Hi, As has been said the fixings were done up tighter than the guns capacity. I've found that new guns are lacking a little but get better with some service behind them.

Colin

 

[PhillipM]

Are your air lines and fittings high enough flow for the gun? And when was the last time it was stripped and serviced? As colnerov says, a good clean and service works wonders on air tools.

 

[NickyEng]

I have had years working with air guns and still reckon if the nuts were untouched and seized up as tight as OP suggested there is no danger an 800nm torque from an airgun will slacken it.
It's totally different where you just done the nut up with the gun and held it on for a while then try to slacken it. The gun in these circumstances will usually slacken it since heat from friction has been applied to the fastener, also you may have lubricated the fastener.

 

[Cobbler]

I have come to the conclusion that the manufactures are somewhat optimistic with the figures. You read what their supposed to do & its "will remove the propellor of the Titanic" I've got a Metabo one, it will remove Landy wheel nuts nearly always, but every so often it stalls. I don't run it with a regulator, I run it direct from the tank as I find the reg cuts the flow enough to make a big difference, I keep it well oiled as it then runs without a water trap.

Also I bought a 10mm air line instead of the more usual 8mm this made quite a difference. There could be quite a pressure drop if using a long airline. I think 10mm is recommended for them anyway.

 

[MoreWellie]

land rover wheel nuts are often on stupid tight, I had one discovery that most of the alloy wheel nuts failed both with an air gun then a mains electric gun.

I then used a decent half inch breaker bar which broke and finally succeeded with a 3 quarter breaker bar and an indecent pole

when they finally came off I found no rust inside them just grease

who the heck is doing these things up????

 

[NickyEng]

land rover wheel nuts are often on stupid tight, I had one discovery that most of the alloy wheel nuts failed both with an air gun then a mains electric gun.

I then used a decent half inch breaker bar which broke and finally succeeded with a 3 quarter breaker bar and an indecent pole

when they finally came off I found no rust inside them just grease

who the heck is doing these things up????

They can blast them up in the garage with the air gun and due to the speed generated and subsequent torque applied they can be very tightly done up if the mechanic holds the impact wrench on too long, once the cone touches the seat especially when's it's a quality powerful gun

 

[MoreWellie]

and all done without any thought for the poor owner who gets a puncture and tries to change a wheel with the tiny wrench the manufacturers supply

 

[NickyEng]

Can be a nightmare mate.
I always use the torque wrench to finally torque, I am fussy about that for the very reason you state.

 

[PandaWill]

All very interesting and thanks for your help guys! You can always rely on this forum for a speedy and informed response

I will double check the air line but pretty sure it's 10 mil.

I do like the gun having done about a dozen jobs with it since I bought it and no probs until the last two. To be fair the wheel nuts were very tight and had a good coating of rust at the end and the crank bolt was literally covered in threadlocker so....

Just, like @Cobbler states, when I bought it I was given the impression from the IR website that I would be able to strip down a Caterpillar dump truck, if one should happen to break down near by

Thanks again!

 

[PhillipM]

I have come to the conclusion that the manufactures are somewhat optimistic with the figures. You read what their supposed to do & its "will remove the propellor of the Titanic" I've got a Metabo one, it will remove Landy wheel nuts nearly always, but every so often it stalls.

The air ones seem worse for it than the electric these days, it used to be the other way around, but the Makita a mate of mine has will undo anything we throw at it, there was a siezed M16 bolt on a Dozer the other day that the nut had welded itself to - it didn't shift the nut, but it did just shear the bolt clean off instead.

I suppose technically the nut came off...

 

[Bill Edwards]

To be honest, although that impact wrench may have been expensive and they're a good brand, it isn't close to being top of the 1/2 range at 800nm so you can't expect it to do everything.
By comparison, my 1/2" is rated to double that and will remove a wheelnut tightened by me bouncing on the end of a 5' pipe and it even managed it off a 6mm hose.

 

[pedrobedro]

Mine is a cheap Aldi 1/2" rattle gun and I was trying to get some flywheel bolts out of an engine and it was not having it. I didn't want to mess about locking a piston and the flywheel kept turning when I tried a bar and so I turned the air up to 125 psi. It flew them off and now it gets used on full pressure all the time. It only cost about £15 so I don't mind if it breaks.

 

[blenkie1]

Cordless ones are getting better. Mine has 800nm and some are even better

http://uk.milwaukeetool.eu/power-tools/cordless/m18-chiwp12/

No starting the compressor, no hoses, and you can use it just about anywhere. Lot of the service lads swear by them. I never use an air one even though the workshop is swamped by air lines. We have an 1" impact gun when it gets really tough. Some bolts though you need to use the forklift to loosen and tighten them.

 

[NickyEng]

Cordless ones are getting better. Mine has 800nm and some are even better

http://uk.milwaukeetool.eu/power-tools/cordless/m18-chiwp12/

No starting the compressor, no hoses, and you can use it just about anywhere. Lot of the service lads swear by them. I never use an air one even though the workshop is swamped by air lines. We have an 1" impact gun when it gets really tough. Some bolts though you need to use the forklift to loosen and tighten them.

That's the milwaukee cordless one I got pal, it's a beast of a thing, it's got about 1000 nm of slackening torque I think