Picked up a Milwaukee 2754-20 impact wrench. What a great tool!

It has three speeds: 900, 1500, and 2500 rpm. Maximum torque is 210 ft-lb.

Am I correct that the relationship between speed and torque is roughly linear? That, if I get 210 ft-lb at 2500 rpm, at 900 rpm it would max out around 75 ft-lb?

If this is the way it works, then I can fasten lug bolts without fear of over-torquing.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 157k miles
06 E320 CDI "Rutherford", Black on Tan, 175k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 144k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 70k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Don't guess it. You run the risk of really screwing something up and making the job much harder for yourself. Get these instead:

https://www.harborfreight.com/10-piece-12-in-torque-limiting-extension-bar-set-69870.html

These bend at a certain torque when the actual torque has been applied. Always recheck your torque with an actual torque wrench.


Never rely on torque sticks alone!

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-Typos courtesy of my mobile phone.

Yes torque sticks actually work, they save time when hammering down wheels.

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1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.

I'd contact Milwaukee directly, this isn't something that can be guessed with limited data. Also the specs say the tool stops after impacting for 1 second for repeatable torque.

When using an impact, I zip the bolt down with a quick burst of the throttle then feel / watch the socket rotation for final tightening.

Talked to Milwaukee. Apparently the problem with Mode 4 (where it stops after a second) is that overtorquing could occur during that one second. But, if I use Mode 1 (900 rpm), the max torque output will only be about 75 ft lb. So it's perfectly safe to drive bolts until there's resistance and then torque by hand to spec. And I just confirmed that that's the case...when I drove a lug bolt there was still some tightening to do to get it to 82 ft-lb.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 157k miles
06 E320 CDI "Rutherford", Black on Tan, 175k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 144k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 70k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

If you are torqueing by hand after, you will know if they have been overtorqued...

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I dunno about that.

I worked as an Assistant Service Manager at PepBoys for awhile and we ended up banning their use due to numerous wheel offs (a wheel leaving the hub while someone is driving). It is not just possible but probable that someone will over torque a wheel nut/bolt regardless of the torque stick being used.

Granted, even when we switched to manual torque wrenches idiots still existed. After training for two days on the proper procedure for using a manual torque wrench (the clicking type), I walked out the shop to ask someone a question and saw one of the tire techs torquing a few wheel nuts. He tightened the nut, heard the click and then continued to torque each nut a further 180 degrees.

I'll use my impact to drive the bolts/nuts in, but I'll seat/torque them using a manual wrench. Usually I'll use a spare Mercedes lug wrench I keep around just for that purpose. I figure that if I need to get a wheel off on the side of the road I don't want it tightened more than I can physically loosen.

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Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]

The RPMs are with zero load, nothing attached to the impact gun. You will never see that RPM with a socket attached.

I have a 2860. Milwaukee impacts are ****ing awesome but I still torque down my wheel bolts by hand.

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CENSORED due to not family friendly words

I'm betting it was due to not seating the wheel with at least 2 opposing lug nuts before installing the others and torquing all.

If only one nut is tightened, the wheel can cock on the center bore and the other nuts can appear to be tight. Once the car is driven, the wheel seats against the hub but now the nuts are loose.