School me on wimpy impact gun

[Runamuk13]

For years, I have hated my Craftsman (Model 875.168820) impact wrench/gun that won't loosen a lug nut torqued to 90 lbs. Why?

When I'm changing tires on the car, I try to loosen the lugs nuts and it chugs and chugs, but won't break them loose. Very frustrating. I end up using a breaker bar to loosen the lug nuts. Then use the impact gun as a glorified "nut spinner" to turn the nuts off the studs.

It shouldn't be this difficult. Why won't the impact wrench develop enough torque to loosen the lug nuts?

Some details ....

• The impact wrench is rated at 400 ft/lbs of torque, 5.2 scfm.
• 25 gallon air compressor is rated at 7 scfm at 90 psi
• 25 feet of 1/4" air hose.
• Air pressure at the gun is 110 psi
• I'm using 1/2" drive "impact-rated" sockets and no extensions
• There is no significant rust or crud on the studs.

Please help restore my respect for this impact gun (cause the other option is to throw it as far I can).
Thanks for any insight and advise you can provide.

Bill

 

[The Cobbler]

......
[*] 25 feet of 1/4" air hose.
[*] Air pressure at the gun is 110 psi
......

110 psi with the trigger pulled or with the tool not running?
1/4 hose is part of your problem

 

[CJM8515]

1/4 air hose, too small a compressor, not enough regulated PSI. ditch it and buy a battery powered gun and never have to worry about hoses or a compressor again.


I watched a guy with one of those HF 30 gallon oil lubed jobs try and remove lugnuts off a 1 ton truck. It wouldnt do it and he was using 3/8 air hose too. I walked over with my old pos snap on nicad gun and zipped them right off lol.

 

[79firebird]

my boss had the same prob with his and air grinder bogging down was his 1/4 hose use min 3/8 or 1/2 and it will work perfect

 

[Mr_B]

Size of compressor not an issue in short trigger on times of like 10 seconds .
You need a 3/8 hose minimum and keep length short as can .
Also the 90psi tool rating is dynamic (tool running)
You want give gun everything your tank got, I run mine at 140 to 150psi static and get about 105 to 115 dynamic which gives you full plus power from the gun .
Other issue is the impact itself, on poorer air system you want some of best modern hard hitting low cfm impacts you can get and that craftmans ain't one of them (craftsman is a gutless large lump) .
Modern gun from Astro, Aircat, Facom, Kuani, DR, M7 will blow it away with power .
I run a Facom nano 1/2", Astro 1823, DR 126 & 127 and can take farm equipment lugs off with a precharged mobile air tank. The modern guns hit hard, are small and more air efficient and also not too expensive .

 

[iamrfixit]

Yup, simply not enough air.

Single stage compressor with that small 25 gal tank is only going to have enough air for the first few seconds, then the tank psi drops off, you lose pressure at the tool and the tool's power falls off quick. Went through it for years when I had single stage compressors. The last one was a 60 gallon and it was better but still not very good. You'll need a constant 120-130 psi at the regulator to even get close to having 90 psi at the tool, with the trigger is pulled.

Larger hose and a high flow regulator will help but with a small tank it will only be a few seconds worth. Most single stage compressors will cycle on at 90psi and cut off at 125psi, so you never actually have enough air even at full pressure.

Two stage compressors will cycle on at 150psi and cut off at 175 psi, the tank pressure will be regulated down from storage to the desired pressure on the hose. I run my regulator set at about 130, if I run into something really tight I can crank up the pressure and it will almost always bust it loose.

 

[Leaflessshadetree]

I have a 1/2" and a 3/8" Craftsman impact wrenches that came with my compressor. Neither was ever any good. IMO most of the Craftsman ratings (HP, CFM, ft/lbs) were the result of some marketing formula rather than testing, engineering calculations or physics.

 

[oldschool59]

I don't use air impacts much anymore. My 3/8 drive Milwaukee 12v impact will remove truck lug nuts at 140 lbs. My snap on 1/2 cordless is strong. Cordless is hard to beat.

 

[CJ7VFR]

The owners manual for your Craftsman impact says to use, at a minimum, a 3/8 inch airline for up to 25 feet, and to use a larger air line when going over 25 feet in length. It says not following this recommendation will cause the tool to loose torque.

If you are using a 1/4 airline at 25 feet long, you are loosing almost half the torque the impact can give.

Also, do you have the Forward/Reverse switch turned all the way over in the Forward direction? It states in the manual that the farther you turn the switch in the Forward direction, the more torque the impact will produce.

Jim

 

[DieselNut88]

Buy a battery gun and never look back. My DeWalt 20v will break the lugnuts loose on my truck that are torqued to 170 ft/lbs. The best part is no hose to drag around. I recently replaced the front ball joints and u joints and used this gun with the press and it had no problem.

 

[Kev442]

Mostly the 1/4" hose, partially the gun. Not the compressor. I routinely take 5 lug nuts off using my ancient Bluepoint gun with 3/8 hose on an even older 11 gallon portable compressor I have. Even 90 psi will take a clean lugnut off.
Those "included with purchase" $20 impact guns are a joke, although I have used them in situations where I did not want tons of torque.

 

[oldmxracer]

I too would ditch the 1/4" air hose for this purpose ! If it still will not work, ditch the gun !

 

[mattbal]

I have seen noticeable improvement with my air guns with a squirt (or two) of some Mobil 1 10W30. (I am pretty sure any oil would work) but with just a shot of oil and no other changes I was able to remove fasteners that seconds before were stuck.

Matt

 

[The Cobbler]

^^^ proper tool lubrication is crucial to good performance

 

[ChrisLS8]

You'd be better off with a cordless nowadays. Ridgid, Ryobi, Milwaukee or whatever brand you're invested into

 

[OHMS LAW]

When I was a green new lube tech, sears used to sell combo kit that came with a 1/2 impact, 3/8 air rat and a 25 ft hose. First set out the box hooked to shop air, nothing. Air blew right through it. A second and a third had the same issue. The next time
The snap on guy came to the tech school, ordered the mg325 and that carried me until I got my Matco air impact. Moral of the story craftsman impacts ****

 

[RKA]

I have a 20 gal compressor and even my little impact has no problem spinning off a properly torqued lug nut. 3/8” air line is the norm for these tool. I only use 1/4” for nailers, blow guns and filling tires.

If that doesn’t fix your problem, get a new impact gun. It’s entirely doable with your compressor.

 

[Wamsutta]

The first thing I'd do is take the exhaust screen off the handle and see if there's something that looks like steel wool stuffed up in there; that's the silencer packing. Take it out and keep it out.

 

[setfocus]

the 1/4" hose is definitely a problem, I've never seen a 1/2 drive impact not call for 3/8" hose in the specs, most 3/4 drive need 1/2" hose. As far as the compressor goes, my only experience is with shop air which currently is from 2 kaeser screw compressors on one big tank, set at 125psi. From what I've heard, a small compressor should be enough to run an impact for the short time it takes to remove a few lugs but I don't think a pancake size compressor would do it.

The impact could be a problem. Most craftsman impacts are likely on the gutless side except maybe the highest end models, craftsman was never known for their impacts, but 400 ft/lbs should be enough for the average lug. If the lugs were over torqued and it's been long time since they were off, even my IR 2235 (rated 900ft/lbs working torque at 90psi) has failed once or twice and the big *** breaker bar was needed.

An IR 231 should take normal lugs off no problem and last over a life time of home use, but wont break the bank around $120 or get a midgrade HF earthquake impact for a cheaper option. The good cordless are $$$ if you don't have the battery line already but are hard to beat for home use

 

[plinker]

The impact isnt the best per say, but it should do the job. The hose really needs to be a 3/8 as it is a problem. A new Flexzilla hose is only about 20$. Some air tool oil isnt a bad idea.

That size compressor will work though it may need to catch up at times. I've found if the compressor kicks off at 125psi or so, it doesnt pay to use a regulator, just straight air & it'll be about where you want it to be with running psi at the tool.

 

[81turbota]

Rig up a gauge to see what the pressure is at the gun with the trigger pulled. My 5HP 60 gallon IR wouldn’t run my MG725 until I diagnosed 65psi at the gun running. My garage has hard lines to a 50ft 3/8 reel. I cranked the regulator and upgraded to high flow fittings. It now runs fine.

Apologies, I see you already measured pressure at the gun. At 110 PSI with the trigger pulled, it’s either a flow issue or a gun issue. Was it 110 psi trigger pulled or not pulled? Before I condemned my new to me MG725 I took it to a friends shop and hooked it up to their air. That pointed me to the shortcomings in my system noted above.

 

[Citation]

Yup, the 1/4" hose is the issue. I have both 1/4" and 3/8" hose. Even though I know better sometimes I will use the 1/4" hose on with my 1/2" impact. It can barely pull lug nuts off a small car. With the 3/8" hose it's no problem.

 

[joshmodelskidoo]

I had a water hose barb vs an air hose barb in my hose reel and changed that out and noticed a big difference but i also fixed it at the same time I upgraded compressors. But yes 1/4in hose is good for a nailer and that’s about it. Seems like they slow down with an air chuck to

 

[ItsNemo]

Hose and fittings is the problem. A 25 gallon compressor is plenty to run an impact wrench. I had no problem with my 26 gallon tank for years, could almost do all 4 wheels in full without it cycling when using 50' of 3/8" hose with milton V fittings with an IR 2135TiMax.

 

[Squankum]

High flow fittings. This is the 10 pack, for the kind of fiend who hangs around here and keeps buying more air tools:

Milton 760-1 1/4" MNPT V Style High Flow Steel Plug - Box of 10
https://www.amazon.com/dp/B001O2ZID2/?tag=atomicindus08-20

 

[Squankum]

Now, I assume these lug nuts were torqued properly when they were installed? That helps.

You know what also helps? Antiseize on your lug bolts or studs.


(Hops on pony, rides like hell to the horizon.)

 

[setfocus]

You know what also helps? Antiseize on your lug bolts or studs.

Careful with antisieze on fasteners, a little on rusty studs is fine but you're lubricating the stud and could over torque it if not careful. Studs stretch a little when torqued and spring back when loosed. If over torqued, they'll stretch past their limits and could snap thousands of miles down the road, especially on an old car where the studs are already nearing the end of their life. Only designed to go through so many cycles of stretching and springing back. If under torqued, the lubed up lugs could more easily back off on their own

Sent from my SM-G920V using The Garage Journal mobile app

 

[M635_Guy]

Not a fan of anti-seize on lugs or anything bearing active load. If they're properly torqued and aren't incredibly rusty, a decent impact should break them.

 

[Runamuk13]

Original Thread Starter here.
Thanks for all you input. I appreciate dipping into your fast knowledge.

First - a correction to my original post - I'm using 25 feet of 3/8" hose (not 1/4" hose as originally stated).

As per normal, the 3/8" hose has 1/4 in-18 NPT quick-disconnect couplers at the ends. And the air inlet on the gun is 1/4".

It seems to me that if I went with a larger 1/2" hose, these couplers would still restrict the air flow. Basically negating the advantage of the larger hose. Am I thinking right?

Are there 1/4 in-18 NPT quick-disconnect couplers that allow more air flow than other couplers of the same size?

 

[RKA]

The Milton V style couplers squankum linked above have a larger bore. But your gun should be able to develop sufficient power with the standard 1/4" coupler, so I would follow another poster's suggestion to add a few drops of oil to the gun and try again. If that doesn't work (probably won't), time for a new gun.

 

[Runamuk13]

Apologies!
I was just re-reading the posts. I see that Squankum recommends upgrading to High-flow connectors.

I'm gonna do 2 things and I'll post my results:
1) I will measure air pressure at the gun with trigger pulled.
2) I will upgrade to high-flow connectors
3) I'll measure air pressure at the gun with trigger pulled again.

okay, 3 things.

This may take me a week or 2 but I'll let you know what I find out.

Responding to RKA - I have tried the few drops of oil. That didn't seem to make a difference. But I think you may be right - "time for a new gun".

Thanks again to all of your responses.

Bill

 

[Jagmandave]

I bought the HF 400lb ft rated impact gun and it would not remove clean lug nuts torqued to 100, took it back and got their 600 lb ft rated gun and it takes off anything and everything with no issues. I think it's the gun.

 

[Jazz1]

Milton High Flow connections may improve CFM to gun. Check to see gun not leaking.,,tighten any screws.. I'm not familiar with that model, I have IR but the final tool purchase I intend to make is a cordless 1/2" impact.

 

[sberry]

I agree that the hose is undersized for a 1/2 gun. The older 400# Sears gun probably lacks too. Whoops, I see 3/8 now. There is likely about 10# or so loss from the hose in the small gun. The 1/4 connectors on the end don't hurt much, crappy connectors a little but guys have used them for decades.

 

[sberry]

At gun with 70 cfm connectors. On 50 ft need to be 135 to see 90, 15 ft it zooms to 110 or 115

 

[GTO]

I don't use air impacts much anymore. My 3/8 drive Milwaukee 12v impact will remove truck lug nuts at 140 lbs. My snap on 1/2 cordless is strong. Cordless is hard to beat.

This

 

[sberry]

I like air with wheel work but,,,, I don't own a new generation of bat impacts either. I might if I was under the car all day.

 

[sberry]

Now, I assume these lug nuts were torqued properly when they were installed? That helps.

You know what also helps? Antiseize on your lug bolts or studs.


(Hops on pony, rides like hell to the horizon.)

I used to be real smooth about putting them on air gun but the advent of aluminum wheels really makes a need to do them by hand. Impacts just hammer them on too tight especially with a little oil. Dry isn't really better though due to the fact they stick like that too. A pinch tight from oil isn't squat, what is bad is so tight they wont reverse,, 3 or 4x what they go on at. The hammer of the gun squashes and deforms the aluminum seat, can do it on some steel if its done hard enough but alum is easy.
Could use a heavy air ratchet for install but final with a tq wrench or by hand so they are not seized tight is the right way.

 

[Mr_B]

while battery impacts improving hard beat quality compact modern impacts for power to size, throttle control and durability .
OP can easily improve with 3/8 hose and could get a much better impact for 80 to 120 bucks that take things to a new level . those craftman windy guns are pretty weak air guzzlers .

 

[creativecars]

I agree with much that has been said, 3/8 hose & even the HF Earthquake impacts are a huge step up from a Craftsman.

But don't forget a air flow system is only as strong as its weakest link. If you have a 1/4 fitting inline some where, especially close to the tank, a 1/2" hose and a $300 impact won't fix the real problem.