Torque Wrench question

[cgv69]

I want a new 1/2 torque wrench to be used for working on cars and building AR's (rifles).

I want a quality US made tool that will last and can be trusted but not break the bank. This will be a low use, non-production tool so top of the line is not needed.

I was\am seriously leaning towards a CDI model 1503MFRMH which is a micrometer\click style wrench with a 20-150ft-lbs range. I did some reading around here and it seems like a board favorite is the Precision Instruments C3FR250F model. It does seem like a good deal and the dual beam style does have the nice advantage of not needing to be turned back to zero after each use and the Flex Head could be nice to. The only down side to it for me is it's range of 40-250ft-lbs. When installing an AR barrel, the minimum torque spec is 30ft-lbs so I'd really like a tool that can go at least that low.

I guess my real question is this, I've noticed the most common 1/2 torque wrenches go up to 250ft-lbs but I've never needed to torque anything that high. Is there anything on the typical car that needs to be torqued that high (or even over 150ft-lbs)? I'm just wanting to make sure which ever model I get has the best range for my uses so I'm not left hanging on a job because of a tool limitation.

 

[Buckgnarly]

Why are you set on a 1/2?

Not sure what on an AR would need anything that high, it sounds like you need a 3/8 for that stuff and a 1/2 for auto. You generally sacrifice accuracy for bigger range or being further from you most used range.

As for "heavy" stuff, I've run mainly into CV shaft nuts, and unit bearing bolts as well as suspension stuff that can require high torque numbers. There's other, but that's the two main spots I can think of.

 

[trboxman]

Serious answer: Buy the 3/8" torque wrench from Harbor Freight for working on your AR's and buy the Precision Instruments C3FR250F for working on cars where the 3/8's doesn't go high enough. The ranges overlap enough that you should be covered from 5 ftlbs up to 250ftlbs.

There are lots of suspension and brake parts that require torque above 150ftlbs.

 

[pipsters]

For working on cars you'll probably find you'll need two:

A 3/8" in the 10-50 ft-lbs range
A 1/2" in the 30-150 or 50-250 ft-lbs range

If working on a personal car look thru your service manual to find some torques for things. I originally had a 20-100 ft-lbs (torque wrenches tend to only be accurate 20% to 100% of scale) as I tried to cover everything with that one but I found you really need two on most things you work on these days.

 

[Butters]

Generally speaking, aren't the calibrations off more in the upper and lower 10 or 20% of the range? So you wouldn't really want to use the 1/2" at the very low end of the scale anyway. I would think for something like an AR, you might even want something down lower, like in the inch pound range.

Based upon reviews here, I bought two US made Gearwrench clickers. They run about $100.

 

[cgv69]

All AR barrel wrenches I've seen (and I have a few of them) are designed to work with 1/2" wrenches so 3/8" is not an option unless I use an adapter (which I believe introduces some sort of variable in the torque setting?)

Can any of you tell me the last time you had to torque something over 150ft-lbs and what it was?

 

[trboxman]

Axel nut at 177ft-lbs
Caliper mounting bolts at 221ft-lbs

 

[Buckgnarly]

All AR barrel wrenches I've seen (and I have a few of them) are designed to work with 1/2" wrenches so 3/8" is not an option unless I use an adapter (which I believe introduces some sort of variable in the torque setting?)

Can any of you tell me the last time you had to torque something over 150ft-lbs and what it was?

That type of adaptor will have no effect on torque. Only one that adds length to the wrench will change readings.

 

[cgv69]

Axel nut at 177ft-lbs
Caliper mounting bolts at 221ft-lbs

Thanks - what kind of vehicle may I ask?

I have to admit, I've never pulled an axle apart and as many brake jobs as I've done, I've never re-torqued the caliper bolts although I probably should.

On the other hand, the torque range on an AR barrel is anywhere from 30 to 70ft-lbs. That's a pretty wide range and I know others who don't even bother using a torque wrench at all when installing an AR barrels. I've done a few that way myself and it's not a critical as you may think.

 

[cgv69]

That type of adaptor will have no effect on torque. Only one that adds length to the wrench will change readings.

Thank you for the clarification.

 

[pipsters]

Reading thru the procedure you go to 35 ft-lbs, loosen, 35 ft-lbs, loosen, then tighten but no to exceed 80 ft-lbs. You might be able to do the same thing by setting 80 ft-lbs on a clicker, tightening but no exceeding the click but on that pic they are using a beam torque wrench.


Craftsman 1/2" beam torque wrench $27

 

[trboxman]

That's the exact same armorers tool that I use for AR builds and I use a clicker as pipsters describes...I've used both a 3/8's and a 1/2.

As for vehicle with the torques I quoted, it's a 3/4 ton pickup truck but there are lots of cars that have fasteners with similar torque requirements.

 

[Major Ramifications]

Get two nice USA Craftsman beam type torque wrenches that NEVER need to be calibrated and you always KNOW that they are reading the correct torque. They are cheap and will last longer than you.
If you can swing the fancy Precision Instruments model, that would be nice but for the amount it sounds like you will be using one the good old Craftsman beam type will serve you well.

The engineering department at Chrysler will not allow any clicker types in the building, they use beams only because the clickers can get out of whack and you have no way of knowing.

 

[plung]

For working on cars you'll probably find you'll need two:

A 3/8" in the 10-50 ft-lbs range
A 1/2" in the 30-150 or 50-250 ft-lbs range

Anyone have any recommendations for 3/8" for auto use?

These were all the ones on tooltopia that fit the requirements.

Sunex Tools (SUN9702A)
$38.33
+/- 3% accuracy
10-80 ft. lbs
3/8" Drive
http://www.tooltopia.com/sunex-tools-9702a.aspx

KD Tools (KDT85052B)
$107.99
+/- 3% accuracy
10-100 ft.-lbs., 17.8” Length.
3/8" Drive
http://www.tooltopia.com/kd-tools-85052b.aspx

Snap-on Industrial Brand CDI Torque 752MFRMH
$116.78
+/- 4% accuracy
5-75 ft.-lbs.
http://www.amazon.com/gp/product/B002L9Z27E/?tag=atomicindus08-20

Armstrong (ARM64146)
$158.99.
+/- 3% accuracy
5-75 ft./lb
3/8" Drive Micrometer Flex Head
http://www.tooltopia.com/armstrong-64-146.aspx

K-Tool International (KTI72130)
$168.99
+/- 1% accuracy
10-100 ft./lb
3/8" Drive Digital Torque Wrench
http://www.tooltopia.com/k-tool-international-72130.aspx

 

[CJKaz]

Chrysler's Delaware plant (shutdown several years ago) used these wrenches. Each one was tested daily with Mountz's PTT test stand:

http://www.mountztorque.com/products/torque-wrenches/titan-click-wrench

Very reliable, repeatable, and expensive. Lots of good tech papers on that site

 

[junkscouts]

I swear some of the axle tube to spring u-bolts go in the 175 range, most everything else is 80-110 or so. I've found the torque wrenches (clickers) that max at 150 wear out too quickly when working on cars, too many torques near the max of the tool. I switched to a max 250 ft lb wrench (Craftsman) and it has lasted 15 years without a problem. The other ones were Craftsmans too, but they didn’t hold up.