Air impact torque figures. Rant/question.

[BobMelroe]

I've been looking to replace my 20+ year old 1/2" drive impact. Bought one from Autozone for $80 that stated 450ft lbs on the box, but when I got it home it wasn't any better than my old one, so I took it back and told them it was a POS (verbatim). Mine is a Taiwanese one I bought for $20 new in 198?(something). It still works ok, but it won't take off a lug nut anymore. Anywho, was looking at Sears, Harbor Freight, and so on, and one thing that keeps irking me is the rated torque. For example they boast 750ft lbs of torque, but when you look at the description it reads "250-400lbs of torque. Maximum torque 750ft lbs.". WTF?? I'm not going to spend a couple hundred dollars on an impact, and probably not near a hundred either. I don't use one that often anymore. I just don't understand how they rate these things at 750, then tell you its range is 250-400. Maybe you lock the anvil and put a 5' cheater on the handle of it? Working pressure is clearly stated at 90PSI, so I doubt its higher pressure. Anyone have an idea on how they arrive at the inflated numbers, or how "maximum torque" is achieved?? Imagine looking at a car that has 450HP in huge letters, getting all excited, then reading the owners manual and finding "HP 100-190, maximum HP 450". Or maybe I'm missing something........ Maybe I'll just get a cheapy 3/4" drive that has a range I'm looking for.

 

[coreya3212]

http://www.toolsofthetrade.net/industry-news.asp?sectionID=1520&articleID=501481

I hear your anger and have been bitten in similar ways. This link is sort of addressing this issue. Manufacturers seem to have a fairly wide berth when it comes to what they can write on a package. Its sort of like all the parts are made in china and is assembled in Canada, so its "made in Canada".... as to specifically with Impact wrenches, I say the 20 dollar model and anything else gets the breaker bar with a snipe.... My 2 cents

 

[OldMachinist]

http://www.toolsofthetrade.net/industry-news.asp?sectionID=1520&articleID=501481

I hear your anger and have been bitten in similar ways. This link is sort of addressing this issue. Manufacturers seem to have a fairly wide berth when it comes to what they can write on a package. Its sort of like all the parts are made in china and is assembled in Canada, so its "made in Canada".... as to specifically with Impact wrenches, I say the 20 dollar model and anything else gets the breaker bar with a snipe.... My 2 cents

I just want add to your rant a little. Impact wrenches should never be used to put the lugs back on. I don't know how many times I've been asked to come out on the side of the road where somebody had a flat and can't get the lugs off because the gearhead down at the local tire shop used his high torque impact to put the lugs on. Lugs should always be torqued using a torque wrench or torque limiting device. Everytime I have tires put on a vehicle I come home and loosen and retorque the lugs properly and if thats done you should never have a problem with even the cheap impacts to taking them off.

 

[Tazza]

I just want add to your rant a little. Impact wrenches should never be used to put the lugs back on. I don't know how many times I've been asked to come out on the side of the road where somebody had a flat and can't get the lugs off because the gearhead down at the local tire shop used his high torque impact to put the lugs on. Lugs should always be torqued using a torque wrench or torque limiting device. Everytime I have tires put on a vehicle I come home and loosen and retorque the lugs properly and if thats done you should never have a problem with even the cheap impacts to taking them off.

Agreed there OldMachinist. When my cousin did work on my brakes he said never use that gun to put the nuts on, its too powerful. He has one that isn't as strong and you can still get them off if required with a bar.
The rattle guns i have, i never relied on their numbers. I have a few good Shinano and IR ones. If the bolt is too tight i grab a long breaker bar, crack it then rattle it off. Some bolts will simply be too tight for any standard shop air rattler. It could also be how much air you can suply. feed it with 3/4" hose and i bet you will notice a big difference.
Over time the hammer and anvil will wear, and you won't get as much power to the socket, but you can't do anything about that.

 

[BobMelroe]

Agreed there OldMachinist. When my cousin did work on my brakes he said never use that gun to put the nuts on, its too powerful. He has one that isn't as strong and you can still get them off if required with a bar.
The rattle guns i have, i never relied on their numbers. I have a few good Shinano and IR ones. If the bolt is too tight i grab a long breaker bar, crack it then rattle it off. Some bolts will simply be too tight for any standard shop air rattler. It could also be how much air you can suply. feed it with 3/4" hose and i bet you will notice a big difference.
Over time the hammer and anvil will wear, and you won't get as much power to the socket, but you can't do anything about that.

Thanks for the feedback everyone. Good info coreya3212. DeWalt seems to get it. Whether or not others will follow remains to be seen. The majors like Milwaukee, and Makita most likely will. I do have the 1/2" drive 18V DeWalt impact, and it WILL break a lugnut loose. Not sure what it's rated at, I never bothered to look. My old air impact is just plain worn out. I don't use impacts to put wheels on, just to take them off or zip up the lugnuts while the vehicle is in the air. I always use a breaker bar for final tightening and go by feel. Have done it for years with no problems. I always check them after about 50 miles or so. The impact I bought from Autozone was brand spankin new, and it wouldn't take off even 1 nut at 125PSI. Put the breaker bar on them and broke 'em all loose with very little effort. It was just plain junk. I rechecked the descriptions of some online, seems "working torque" is the lower range. I just don't get "maximum" torque, or how one achieves it. They don't tell you that. I guess inflating the numbers makes them look more attractive or something. I don't want to go the Sears store and ask as I'd probably just be more irritated by their response. I'm just like anyone else, trying to get the best value for what I'm spending. Just wish they would call a spade a spade. Like the ol' man used to say "It is what it is, and it ain't nothin' BUT what it is."

 

[coreya3212]

Thanks for the feedback everyone. Good info coreya3212. DeWalt seems to get it. Whether or not others will follow remains to be seen. The majors like Milwaukee, and Makita most likely will. I do have the 1/2" drive 18V DeWalt impact, and it WILL break a lugnut loose. Not sure what it's rated at, I never bothered to look. My old air impact is just plain worn out. I don't use impacts to put wheels on, just to take them off or zip up the lugnuts while the vehicle is in the air. I always use a breaker bar for final tightening and go by feel. Have done it for years with no problems. I always check them after about 50 miles or so. The impact I bought from Autozone was brand spankin new, and it wouldn't take off even 1 nut at 125PSI. Put the breaker bar on them and broke 'em all loose with very little effort. It was just plain junk. I rechecked the descriptions of some online, seems "working torque" is the lower range. I just don't get "maximum" torque, or how one achieves it. They don't tell you that. I guess inflating the numbers makes them look more attractive or something. I don't want to go the Sears store and ask as I'd probably just be more irritated by their response. I'm just like anyone else, trying to get the best value for what I'm spending. Just wish they would call a spade a spade. Like the ol' man used to say "It is what it is, and it ain't nothin' BUT what it is."

OM has rattled my cage now.... 2 weeks ago my GF's jeep had a vibration like crazy so I was moving tires around to see if I could isolate a unbalanced wheel. ( turned out to be a broken sway bar link). Any way, he is right, some jackarse must have put the lugs on with a 11/4 impact cause my impact wood not take them off and I almost popped a hole in my dirt shoot trying to get them off with a breaker bar. Ended up breaking a stud which really frosted my apricots...know how much dodge wants for one wheel stud and one lug nut??? 40bucks. Bastards....

Ok I am done too... thanks for listening fellas!

 

[jerry]

Thanks for the feedback everyone. Good info coreya3212. DeWalt seems to get it. Whether or not others will follow remains to be seen. The majors like Milwaukee, and Makita most likely will. I do have the 1/2" drive 18V DeWalt impact, and it WILL break a lugnut loose. Not sure what it's rated at, I never bothered to look. My old air impact is just plain worn out. I don't use impacts to put wheels on, just to take them off or zip up the lugnuts while the vehicle is in the air. I always use a breaker bar for final tightening and go by feel. Have done it for years with no problems. I always check them after about 50 miles or so. The impact I bought from Autozone was brand spankin new, and it wouldn't take off even 1 nut at 125PSI. Put the breaker bar on them and broke 'em all loose with very little effort. It was just plain junk. I rechecked the descriptions of some online, seems "working torque" is the lower range. I just don't get "maximum" torque, or how one achieves it. They don't tell you that. I guess inflating the numbers makes them look more attractive or something. I don't want to go the Sears store and ask as I'd probably just be more irritated by their response. I'm just like anyone else, trying to get the best value for what I'm spending. Just wish they would call a spade a spade. Like the ol' man used to say "It is what it is, and it ain't nothin' BUT what it is."

A few years ago I finally got tired of the cheap air impacts and bought a makita electric, have not used the air ones since. A lot of times I am doing something and don't need air or haven't the compressor and I like it better.

 

[skidsteer.ca]

A few years ago I finally got tired of the cheap air impacts and bought a makita electric, have not used the air ones since. A lot of times I am doing something and don't need air or haven't the compressor and I like it better.

The last electric I used was 15 years ago, forget the brand but it was not over blessed. I have a 1/2 cambell hausfeld rated at 380 ft lb, the 230 ft lb one are useless. And a old Rodac 1/2"
Failing that I have a 3/4 CP and 1" IR. All of which I run at tank pressure. between 150 and 175. maybe thats nuts but have been doing it for years. Figure there is no point in letting them hammer and hammer. I'm guilty too of not using the torque wrench, but have developed a decent feel for it over the years.
Ken

 

[BobMelroe]

The last electric I used was 15 years ago, forget the brand but it was not over blessed. I have a 1/2 cambell hausfeld rated at 380 ft lb, the 230 ft lb one are useless. And a old Rodac 1/2"
Failing that I have a 3/4 CP and 1" IR. All of which I run at tank pressure. between 150 and 175. maybe thats nuts but have been doing it for years. Figure there is no point in letting them hammer and hammer. I'm guilty too of not using the torque wrench, but have developed a decent feel for it over the years.
Ken

Well I did an autopsy on my old 1/2" drive. Bore was scored up pretty bad and the vanes were too. I used a bore cleaner (flap wheel made specifically for bores) and cleaned up the bore till it was smooth. Took a flat plate and a piece of sandpaper and took the grooves off the vanes, then knocked the sharp corners off left from sanding. Oiled everything, as I reassembled it. Added a bit more oil in the coupler and ran it at free speed for a minute or two, then put it on an old 3/8 bolt to try it out......twisted the bolt off!! I'm happy now. It's about 20 years old,and hopefully it'll last another 20. Didn't take any pictures of the process cuz I had no idea what I was doing. Of course if I did and then ruined it, I could have titled it "Here's how to wreck a 1/2" drive impact".

 

[metalmeltr]

Well I did an autopsy on my old 1/2" drive. Bore was scored up pretty bad and the vanes were too. I used a bore cleaner (flap wheel made specifically for bores) and cleaned up the bore till it was smooth. Took a flat plate and a piece of sandpaper and took the grooves off the vanes, then knocked the sharp corners off left from sanding. Oiled everything, as I reassembled it. Added a bit more oil in the coupler and ran it at free speed for a minute or two, then put it on an old 3/8 bolt to try it out......twisted the bolt off!! I'm happy now. It's about 20 years old,and hopefully it'll last another 20. Didn't take any pictures of the process cuz I had no idea what I was doing. Of course if I did and then ruined it, I could have titled it "Here's how to wreck a 1/2" drive impact".

To answer the origonal question I am going to use a made up but totaly posible set of specifications 1/2" drive 90 psi working pressure 50-350 ft lbs working torque 400 ft lbs maximum torque the 50-350lbs of torqre refers to torque of the wrench turning the blot or nut clockwize 400 ft lbs is torque generated in reverse a good impact will have a reverse torque a consirable amount higher than torque in forward.