Torque Multiplier

mmranch · Jun 23, 2011

I've got some bolts that need tightening to about 400 ft lbs. My torque wrench only goes to 250 ft lbs.

I've seen some torque wrenches that go higher and I guess I need one of those... but they are a bit pricey.

I've seen torque multipliers and am wondering if that would make torquing these bolts easier. Not quite sure I understand how these work. I guess I need to attach the torque wrench to the torque multiplier. Does it make torquing process easier to turn the wrench?

Thanks for any ideas!

Mace Canute · Jun 23, 2011

Yes it does. If the torque multiplier is 4 to one, you only need 100 lbs/ft of torque on the torque wrench to get 400lbs/ft of torque at the bolt.

5030 · Jun 23, 2011

However, a quality torque multiplier is also expensive. I'd suggest renting a 3/4" drive hi torque wrench or a multiplier from a local tool rental place.

Hardon Fright sells a multiplier for cheap, but it's a one, possibly 2 time use tool and it breaks. Why add to the landfill, go rent one.

You can (with caution) use a 1/2" drive and quality breaker bar. Measure from the center point of the rotational axis (center of the socket drive when the drive head is at 90 degrees to the breaker bar handle) back 2 feet on the breaker bar (you might have to add a short cheater pipe. 2 foot back is 200 pounds of force applied to the bar, 3 foot back is 133 pounds of force and 4 feet back is 100 pounds of force applied to the breaker bar at that point. All axis must be at 90 degrees relative to rotatoional motion and don't forget to stay away from the socket and the end of the breaker bar. Things break and become missles.

mmranch · Jun 23, 2011

Thanks very much for the ideas! Renting may be the best option. But for the future, having the torque multiplier might be handy too... but I would need some adapters to make it work as it's a 3/4" female and 1" male and my wrench and socket sets are 1/2".

Thanks again!

5030 · Jun 23, 2011

Snap-On, MAC and Proto all sell multipliers. I have a Snap-On myself. It's 3/4" drive on the output and 1/2" on the input and it's capable of just under 1000 foot pounds with a 1/2" drive ratchet and it was costly but useful at times.

I use it on 10 hole Bud style truck rims in the field.

I always use alloy, impact sockets on the output (for safety) but again, you can probably get away with a common chrome vanadium socket, but then again, it might shatter.

You don't want to reduce the drive square to `1/2". That's not enough meat at the moment of truth.

Start saving. My Snap-on was over 1300 bucks 10 years ago.

Snaker · Jun 26, 2011

You can also go with extensions as a torque multiplier. Here's a website that gives some good info on the subject.

AKO Inc. Torque Specialties Division
click on Torque Data

You can make or have made an extension to increase the range of a single wrench. You want to make it pretty stout and with snug fittings so you can keep control of it. Keep the lines of axis as square as possible.

Go through the calculations to get an approximate length, build the extension, then get as accurate as measurement as possible between axis for the permanent calculation data.

Then whenever you use it, run the formula to determine the setting for the wrench.

I made an extension to get 200 ft/lb on a 150 ft/lb wrench to tighten snowmobile clutches.

I have troubles with pictures but I'll try on a separate post.

Snaker · Jun 26, 2011

Snaker said:
You can also go with extensions as a torque multiplier. Here's a website that gives some good info on the subject.

AKO Inc. Torque Specialties Division
click on Torque Data

You can make or have made an extension to increase the range of a single wrench. You want to make it pretty stout and with snug fittings so you can keep control of it. Keep the lines of axis as square as possible.

Go through the calculations to get an approximate length, build the extension, then get as accurate as measurement as possible between axis for the permanent calculation data.

Then whenever you use it, run the formula to determine the setting for the wrench.

I made an extension to get 200 ft/lb on a 150 ft/lb wrench to tighten snowmobile clutches.

I have troubles with pictures but I'll try on a separate post.

Uploaded with ImageShack.us

crazyal · Jun 26, 2011

If you only plan on using it once then this might be one of those times you try the horrible freight version. You can try to make one like Snaker said but when you heat up the steel you loose it's strength, 400lbs is a lot of force. I'm sorry but $1300 (10 years ago) for a one time/ rarely used tool is just nuts. For that kind of money you would be better off just hiring someone to come out and do it for you (maybe a tire dealer that deals with semi tires).

5030 · Jun 27, 2011

crazyal said:
If you only plan on using it once then this might be one of those times you try the horrible freight version. You can try to make one like Snaker said but when you heat up the steel you loose it's strength, 400lbs is a lot of force. I'm sorry but $1300 (10 years ago) for a one time/ rarely used tool is just nuts. For that kind of money you would be better off just hiring someone to come out and do it for you (maybe a tire dealer that deals with semi tires).

1300 for me was a good investment. I use mine regularly but then I deal with large nuts (me included

).

I also have a 500 foot pound clicker wrench and a couple Snap On dial torque wrenches in inch and foot pounds.... for little nuts too.:laughing:

MikeD74T · Jun 27, 2011

A torque multiplier is handy for lots of things. Check out item number 360375569838 on EB.. & buy the correct socket for your job. 400 ftlbs on a 1/2" socket is looking for trouble. Otherwise get a 48" ratchet or breaker bar in 3/4" drive & the right socket, both of which can also be routinely found on EB.. . MikeD74T