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Long story short, I have to purchase a torque wrench which I will use to torque things like brake calipers, wheels and the like. To make things interesting, I will have to buy it a different size ratchet than all of the sockets I already own. I am therefore thinking of getting a ratchet adapter so that I can avoid purchasing more sockets and accessories.

Below is a picture of a 1/2" ratchet torque wrench next to a 1/2" to 3/8" step-down adapter as an example:

1/2 torque wrench 1/2 to 3/8 adapter

Does using a ratchet adaptor (say 1/2" to 3/8") on a wrench reduce the applied torque? How about using 2 adapters in series (say 1/2" to 3/8" to 1/4")?

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    A couple notes on reducers. Be sure to use quality reducers or you have a high likelihood of snapping them. Impact reducers are stronger. You should not be using a 1/2" torque wrench with a 1/4" socket. That torque wrench will not be accurate in the range needed for bolts that small.
    – rpmerf
    Apr 28, 2016 at 14:41

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No, it won't reduce the torque. Torque is equivalent to radius x force. As long as A, the force is applied at the same distance from the nut/bolt that you're tightening and B, it's applied in the same direction then you'll be applying the same torque. An adapter (especially so short) shouldn't have a noticeable effect on the direction that you're applying the force. Luckily, you don't have to measure your radius(foot) x force(lbs) because the torque wrench will do that for you.

The one concern with using more than a couple of adapters is that the possibility of introducing a significant change in the angle between the torque wrench and bolt/nut face becomes more plausible. The torque wrench should be parallel to the face of whatever you're torquing for the measurement to be accurate. See the image below.

enter image description here

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  • +1 Could you please explain this statement The torque wrench should be parallel to the face of whatever you're torquing for the measurement to be accurate. and also the image?
    – JoErNanO
    Apr 28, 2016 at 13:58
  • In the picture you can see what's supposed to be a bolt pointing downward and left. By face I mean the top of the bolt which the green line is supposed to illustrate. The face is perpendicular to the shaft of the bolt. The two green lines should be parallel and there shouldn't be such a large angle (if any) between them. I don't know that I'm using the proper terminology, sorry about that.
    – Craig Lafferty
    Apr 28, 2016 at 14:03
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I would strongly advise against using a 1/2" torque wrench with 1/2->3/8 and 3/8->1/4 adaptors, particularly in the range you are suggesting. 1/4" drive adaptors are weak, and I think you'll struggle to find any that can take 200NM of torque without twisting (or failing completely).

I would recommend picking up a rail of 1/2" drive sockets when you get the Torque wrench - in my local store they are about 1/4 the price of the wrench, so it won't add too much to your outlay, and will be much more accurate, and stronger!

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    200Nm of torque with a 1/4" socket? Damn, what are you tightening that is so small and needs so much force?
    – I have no idea what I'm doing
    Apr 28, 2016 at 16:00
  • @IhavenoideawhatI'mdoing 1/4" drivers come into various not so small sizes including 17mm hex key.
    – JoErNanO
    Apr 28, 2016 at 18:16
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Torque is twisting force, if the adapter has some flex to it then torque would be reduced, similar to the torque you loose on a long ratchet extension bar. A short adapter like in your question would have little or no twist or reduce the torque.

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    In a quasi-static case, even if the adapter has some flex, the torque is not reduced, as moments have to be balanced.
    – Tristan
    Apr 28, 2016 at 14:46
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    This is only true in the case of an impact wrench, not conventional use of a torque wrench. The same is true for extensions. You only lose torque from a constant force in that case if the extension fails... or you're bouncing on it.
    – Lathejockey81
    Apr 28, 2016 at 18:41

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