Air tool question - PeachParts Mercedes-Benz Forum

kerry · #1 09-25-2008, 11:05 PM

The lug nuts on my Mitsubishi FG are overtightened. I tried a 3/4"x40" breaker bar with a 3' cheater with no luck. I have a 1" impact wrench. It's designed for use with 1/2" air hose and 12cfm. I have a small compressor (5cfm?) with 3/8" hose. What kind of performance will I get out of the impact wrench if I hook it up to that small compressor? It is rated at 1400 ft lbs under normal operation.
Will it harm the impact?
I actually have 2 small compressors. Could I T the lines together to get enough ooomph?

Wodnek · #2 09-25-2008, 11:16 PM

The compressor will work fine. It will peter out after about 2 - 4 seconds and you will have to wait for it to recover.

Brian Carlton · #3 09-25-2008, 11:24 PM

The real question is whether the compressor has a tank. If so, the requirement of the impact wrench can be met without the capability of the compressor via the use of the air in the tank. Naturally, the tank pressure will drop, but, you'll only need full pressure for two seconds to break the nut loose.

The 3/8" hose will limit the airflow somewhat and the wrench won't develop the rated torque.........not much you can do about that.

I might heat the studs if the ends are exposed. They'll lengthen slightly and the clamping force from the nuts will drop dramatically.

kerry · #4 09-25-2008, 11:31 PM

Yes, compressor has a tank. The larger one is 10 gallons I think. Smaller one is a pancake.

Brian Carlton · #5 09-25-2008, 11:37 PM

Quote:

Originally Posted by kerry

Yes, compressor has a tank. The larger one is 10 gallons I think. Smaller one is a pancake.

Naturally, the larger tank is preferable.

Emmerich · #6 09-26-2008, 12:03 AM

The impact won't help if a 3 foot cheater bar didn't break it, you get way more torque than a 1/2 impact generates. It is possible you can beat on it with the impact and then try again with the big bar and see if that helped.

The power the impact generates is only due to air pressure, the air volume it puts out determines how long that pressure can be maintained.

Thread dope will help in the future, but I think torque specs are listed as dry. I am not sure how you measure torque with dope. Is you use dope put some on the face of the lug nuts, when nuts get stuck it is usually not because they are bound up on the threads, but because they are bound up on the face of the wheel.

cmac2012 · #7 06-08-2009, 04:04 PM

Quote:

Originally Posted by Brian Carlton

The real question is whether the compressor has a tank. If so, the requirement of the impact wrench can be met without the capability of the compressor via the use of the air in the tank. Naturally, the tank pressure will drop, but, you'll only need full pressure for two seconds to break the nut loose.

The 3/8" hose will limit the airflow somewhat and the wrench won't develop the rated torque.........not much you can do about that.

I might heat the studs if the ends are exposed. They'll lengthen slightly and the clamping force from the nuts will drop dramatically.

These days I always carry a blowtorch in my car. Might need it for quick plumbing duty and heat has worked very well for me on stuck nuts.

kerry · #8 06-08-2009, 06:45 PM

I did try heating the lug bolt with a Mapp gas torch and using a 6' bar. Kept the heat on for 3 minutes. Did not break them free. They were REALLY tight.

cmac2012 · #9 06-08-2009, 10:06 PM

Quote:

Originally Posted by kerry

I did try heating the lug bolt with a Mapp gas torch and using a 6' bar. Kept the heat on for 3 minutes. Did not break them free. They were REALLY tight.

Whoa, and Mapp gas is pretty dang hot.

FWIW, I felt pretty sure that you had used heat already, based on your remarks on other DIY topics.

I dunno, if a 6' bar and heat won't do it, I'm not sure an impact gun will either.

mgburg · #10 06-08-2009, 02:40 PM

T'ing two compressors together will work if BOTH compressors are rated to handle the same P.S.I. compressing capacity and their holding tanks are similiarly rated...that also includes the T'ing components and related materials...the weakest item in all of this plumbing BETTER BE the pop-off values...

And, T'ing everything together will only get you more reserve pressure to last longer, not more pressure overall...two tanks of 200#s of pressure don't add up to 400#s of pressure...it just adds up to just two tanks of 200#s of pressure...period. Your tool will work about twice the time before it quits or the compressors kick back in to re-pressurize...

I use the anti-seize on the bolts and nuts...then the t-bar lug wrench...when the the t-bar quits spinning, I'm done torqueing...I've never had a tire fly off the car, a nut come loose or a nut seize on me while taking a tire off...

Now, the only other thing I could add is this...

Some tire shops have a set of "torque-wrenches" that they use on their air-guns in their shops...each one is marked on the perimeter of the torque-wrench head with a series of black "slashes" that "stop moving" when the proper torque level is reached...(sort of like the "strobe-lines" on the phonograph platters of record players back in the 70s and early 80s).

The "strobe-marks" on the torque-wrenches are aligned with the shop's flourescent lighting so if the mechanic is USING the flourescent lighting, those torque-wrenches are useful in getting you in the ball-park for the proper torque...but if they are using a shoplight (an incadescent bulb) and torqueing your nuts with that...you don't know for sure what the actual torque value is...

Better invest in a manual torque wrench and double-check their work...otherwise, you'll be loosening more than your tire's NUTS...

catmandoo62 · #11 09-26-2008, 08:46 AM

your mitsu does'nt by chance have air brakes!!if so the air reservoir tank usually has a couple extra plugs you can remove for a line.i did this on my freightliner.its not an 80 gallon tank but enough to at least crack the lugs loose,and thats the main mission.

kerry · #12 09-26-2008, 09:03 AM

It's a medium duty truck but it doesn't have air brakes. I have a torque multiplier but it is missing its original handle and I was using a piece of 3/4 steel rod as a handle. I only succeeded in bending the rod when I started putting pressure on the breaker bar. Perhaps with a better handle, the torque multiplier might work but I think I really need the hammering of an impact wrench as Brian noted.

kerry · #13 09-26-2008, 03:05 PM

Well, I ended up using the pancake compressor because it was putting out around 110-115psi whereas the larger tanked compressor only had around 100psi. The extra psi seemed to make a substantial difference in power. I could get about a 5-10 second burst out of the compressor until it weakened. I worked on one wheel. Most nuts took about 5 attempts to loosen. One took 10-12 attempts but all nuts on that wheel eventually loosed. I retightened them with my 40" breaker bar.
One set of rear duals had been off recently when I had a flat on the way home from NC about a month ago. Those immediately loosened with the 1" impact. Don't know if I could have loosened those by hand since I don't have long enough 3/4 extensions at the moment to reach inside the dual wheel.

Mike D · #14 09-26-2008, 03:17 PM

Glad you got them free. Now do yourself a favor. Take them all off, dab a small bit of Permatex Anti-seize lubricant, part # 80078, onto each lug and re-tighten. Not the nuts but the lugs themselves. You will NEVER have the problem again.