Empowering car owners right across the globe in the fight against weapons of mass prosecution, slippery car sales tactics (new & used), extortionate motoring expences, road rage...

Posts & Solutions

Back to Discussion Summary Page
Discussion Title:  Torque conversion 1/2" drive to 3/8" socket

cbolt1967

2005-05-30 20:18:00

Torque conversion 1/2" drive to 3/8" socket

I have never used a torque wrench with an adapter. I have a 1/2" drive wrench and 3/8" drive sockets and an adapter. Do I have to convert the amount of torque applied in this situation?



DRW1000

2005-05-30 21:47:00

Re: Torque conversion 1/2" drive to 3/8" socket

No. Just like you do not need to worry about what socket size you use either. The force only "enters" the wrench at the 1/2" drive point. It also does not matter where you grip the wrench along the shaft It may make it harder for your arm but the reading or click will be accurate.



curtis73

2005-05-31 00:52:00

Re: Torque conversion 1/2" drive to 3/8" socket

Agreed. Using a long socket extension can throw you off by as much as 5% from twist, but I should think a short little adapter should keep you very accurate. I've used them with no ill effects *knock on wood*



CraigFL

2005-05-31 06:59:00

Re: Re: Torque conversion 1/2

Quote:
Originally Posted by curtis73
Agreed. Using a long socket extension can throw you off by as much as 5% from twist, but I should think a short little adapter should keep you very accurate. I've used them with no ill effects *knock on wood*
I'm not sure why you would say a long extension would affect the torque reading??? Although the extension is twisting, the torque at the wrench end still equals the torque at the socket(applied) end.

__________________


curtis73

2005-05-31 11:31:00

Re: Torque conversion 1/2" drive to 3/8" socket

That would be true if there were no friction at the bolt. Lets say you're torquing to 100 ft lbs. Its quite possible that the bolt will get to 90 ft lbs and then the friction of the bolt turning is greater than the rigidity of the extension. The last 10 ft lbs in that case would be twist on the extension.

Try it sometime. For the sake of exaggeration, use an impact extension. They are softer which will exaggerate your results. Torque something to 100 with the extension, then put a socket directly on the bolt and retorque it. You'll get more turn out of the bolt before it truly reaches 100.



eckoman_pdx

2005-06-01 06:15:00

The instructions included with every singal torque wrench I've ever owned (I've had a few) state an extention/adaptor between the torque wrench and the socket will not throw off torque or change it. It does not change the force applied. Now putting an extention on the shaft handle would effect the reading, since you would be lengthing it and thereby changing leverage, which changes the force applied. If you do this there is a math formula that you can do to compinsate for this and figure out the torque setting you need the wrench to read to end up with the correct torque.

__________________
"You shouldn't throw stones if you live in a glass house"


Empty Pockets Racing Member #6
EPR Member 4 Life


DRW1000

2005-06-01 06:36:00

Re: Torque conversion 1/2" drive to 3/8" socket

I am of the opinion that putting an extension on the end of a torque wrench will change the force you have to use to apply a certain torque to the bolt but the torque wrench itself measures at the socket end and not at your arm.



curtis73

2005-06-01 13:46:00

Re: Torque conversion 1/2" drive to 3/8" socket

Oh, I see. I don't think we're talking about the same thing. I'm not talking about a pipe on the wrench for leverage, I'm talking about a socket extension between the wrench and the socket. I agree with you though, adding an extension to the handle of the wrench just makes your work easier but doesn't change the click point of the wrench.



curtis73

2005-06-01 13:56:00

Re: Torque conversion 1/2

Quote:
Originally Posted by eckoman_pdx
The instructions included with every singal torque wrench I've ever owned (I've had a few) state an extention/adaptor between the torque wrench and the socket will not throw off torque or change it.

Mine said that too. But if you actually try it, it throws it off. I tried it once with a huge 24" extension and at 100 ft lbs it was off by about 15. It torqued the bolt to about 85, but the wrench clicked at 100. I'm sure that short extensions are a neglegible amount which is why they probably say it won't throw it off, but when it comes to accuracy, I need all the help I can get

The other frustrating point for me coming from a physics background is that it shouldn't affect it! You are right on that, too. Even if the extension does twist (provided it doesn't break) it should still transfer the load, just with more movement. I don't understand it, but it happens.

It would be interesting to see how much its affected by extension rigidity. I wonder if a really beefy extension would do better than my wimpy Craftsman extensions



DRW1000

2005-06-01 14:58:00

Re: Torque conversion 1/2" drive to 3/8" socket

Actually I was the one that digressed. I think your explanation in regards to flexing (or twisting) may explain the socket extention variations and probably is only noticeable at high torque settings.



curtis73

2005-06-01 18:27:00

Re: Torque conversion 1/2" drive to 3/8" socket

Quite possible. It makes sense that the extension would only twist after a certain force is applied.



Autoinfozone is an established Trade Mark owned by Internet Unlimited LLC
Autoinfozone.com is owned and operated by Internet Unlimited LLC
Copyright 2003 - All Rights Reserved Internet Unlimited LLC

Website: Terms of Use
Stock Trading Site