Use impact wrenches at their limit? Need more torque? Use extensions? How much torque do you lose with them? Here are some numbers...

[e9999]

First time I've seen numbers on this. Very interesting. Didn't expect the effect to be quite that dramatic. Good to know I think, if you ever struggle with a bolt or nut. Well, assuming you have a choice as to how long an extension to use, that is.

 

[Snafu13F]

Can’t believe no ones commented on this. Very informative video. One more thing to remember when I’m wrenching. Thanks for sharing.

 

[e9999]

I have since found some other interesting videos on that channel. They do measure a bunch of stuff.

Although to be fair, I have to say that I was curious about how they calibrated their "torque" measurement system; and it turns out that they what they did is to measure the pressure obtained by one specific impact wrench (from memory I think an IR air one) and use the corresponding published torque spec for that specific tool as the reference/calibration factor for all their displayed numbers. Which admittedly is not exactly very accurate probably. But still useful to see the numbers on a relative basis.

Of course, none of this extension effect is that surprising given that I assume this is a similar principle to that used intentionally by torque stick limiters.

 

[e9999]

if you're interested in maximizing torque, I just saw a new vid they made where they showed that a smaller Ah OEM battery did give significantly less torque than a bigger Ah one. Not surprising, we know that, but they had some numbers, from memory I think it was increasing the torque by something like 10 or 15% by going from a 4Ah to a 5Ah (Dewalt) battery. Not inconsequential if you are fighting with that last bolt. It could be even more noticeable relatively speaking if you move to a battery that has 21700 cells instead of the 18650s since the former should be able to give more current, IIANM.
Also they showed that a clone generic battery gave significantly (20%?) less torque than a same stated capacity - 5Ah- OEM battery. Interesting.

 

[PAToyota]

I have a DeWalt DCF899 1/2" 20V Impact and there is a definite difference between using a 5ah 20V battery and a 9ah 60V Flexvolt battery.

 

[alia176]

I learned something new today, thanks for sharing.

 

[e9999]

I recently looked again at some vids about the difference in torque with different batteries and those differences are really large between smaller and larger batteries. 30% and up more torque with impact wrenches and drivers with run of the mill battery sizes. However, IIRC, they also mentioned a limit when the battery would become very large, in that the torque no longer increased, suggesting that the tool just simply can't suck in any more amps at some point with larger batteries, whereas the battery iself is the limiting factor for small batteries. But of course, all of this only matters if you can't remove the bolt you so desperately need to. If you can remove all the nuts and bolts you want with the small battery, all the better for it.

 

[ntsqd]

Those truly tight/stuck bolts & nuts are why I have a Snap-On 24" breaker bar. Back in the dune buggy days to get at the rear brakes you needed 275 ft-lbs or more. Standing on the breaker bar (why I bought Snap-On) almost generated that. One good bounce always broke those nuts loose. With smaller bolts it either breaks them loose or it merely breaks them. Either way they're loose!

 

[NCFJ]

Interesting video for sure. I never really worried about it for an impact gun but have been aware to not use extensions on a torque wrench for the same reasoning.

I work on a lot of LCs that are rusted up, to say the very least. I rarely use an impact gun for anything other than speed. I break all nuts and bolts with breaker bars, by hand. Old rusted bolts break far to easy with an impact for my taste. Bigger stuff I use the gun, like the large suspension bolts.

 

[ntsqd]

I don't worry about extensions when using a torque wrench. The torque at both ends of the extension is the same because it is basically a static torque. This not true with an impact.

If you're using an torque-angle meter then the extension obviously needs to be above that meter.