I’m currently in the process of rebuilding a Pontiac 400 v8. The process has led me to buy a lot of new tools. Most of these new tools aren’t too expensive, such as a dead blow hammer and piston ring compressor. The one tool for this project that is quite an investment is a good torque wrench.
I already own Craftsman beam type torque wrenches and a Harbor Freight 1/2″ drive torque wrench. They worked well for the little things I’ve needed to torque down, but decided that they are not up to par for an engine rebuild. Thus my torque wrench research started.
Around Christmas I got an Alltrade 940759 Powerbuilt Digital Torque Adaptor. It comes with what they call a calibration cube, it’s a square chunk of metal for your vice that has a 1/2″ square hole machined into it to plug your torque adapter into. The Adaptor can be used as a torque wrench, but it is better used as a way to test the calibration of your torque wrenches. I took it over to a buddies place and we tested his torque wrenches (he had a small click-stop that measures in inches and a larger click-stop that measures in pounds, I believe both are from AutoZone). We found that placement where you held your hand on the torque wrench effected the measured torque as much as +/- 10 pounds depending on where you had your hand on the handle. Essentially we learned that you want your hand exactly where the manufacturer tells you to hold it, and you want most of the force to be applied along your index finger and thumb so the force you apply is placed exactly where the torque wrench expects it.
The following weekend I tested my torque wrenches (I have a 1/2″ 0-150 ft. lb beam style Craftsman, a 3/8″ 0-75 ft. lb beam style Craftsman, and a 20-150 ft. lb. click-stop Harbor Freight) and found them all to be very accurate. With the beam wrenches, you need to be able to read it straight on, any angle and you were reading 5-10lb over/under. The beam style wrenches have special handles that pivot exactly where you want all the force to be applied, so there was no issue of hand misplacement like the click-stop type. The click-stop from Harbor Freight however, was not as accurate counter clockwise as it was clockwise. The Harbor Freight, though accurate, was not precise and would click anywhere between +/- 3 ft. lb. when torquing tests of 75, 100 and 125 ft. lbs. This is within the advertised +/- 4%.
Precision and Accuracy
There is a difference between precision and accuracy. Accuracy is when you’re within a certain range consistently. Precision is when you hit the same measurement every time. You can be precise without being accurate, e.g. you set your torque wrench for 100 ft lb and it constantly stops at 110 ft. lbs, your precise, but it’s not accurate. To be both precise and accurate is the end goal.
What to Look For
When buying torque wrenches, there are details you need to look for.
- Does it meet industry standards? (e.g. ASME B107.14M-1994, ISO 6789)
- What do other folks say about the wrench
- Type of torque wrench (beam, click-stop, split-beam, dial, digital)
- What is the accuracy +/- in what percent of the range
The type of torque wrench is important based on how you plan on using the tool. I prefer the beam style simply because they are very reliable, you can rely on the beam to be accurate every time and they typically never need calibrated. The only down side is you need to be able to read the wrench straight on. The click-stop are the most popular, but their accuracy and precision is heavily focused on the manufacturer of the wrench. The split-beam are excellent wrenches as well that will not need calibration as often as a click-stop, but they only torque clockwise, which could be a problem depending on what you want to do. Dial type wrenches are expensive. Digital torque wrenches are great, but most are priced beyond what we can afford.
The accuracy in what percent of the range was one item that took me a while to put my head around. Basically, a torque wrench will have a range e.g. 10-100 ft. lbs, and in most of that range it is accurate. Typically the torque wrench makers call this it’s accuracy percent range. All the wrenches I narrowed my results down to have upper 80% range accuracy. What this means is that the first 20% of the range of the torque wrench may not be within the advertised +/- accuracy. In the case of a 10-100 ft. lbs torque wrench, this would mean that from 10lb to 28lb the wrench may not be as effective. I suspect the lower range is not as accurate because of the low tension being applied to internal springs. With this accuracy range in mind, it may be ideal to have multiple torque wrenches to cover specific ranges.
Narrowed the Results Down
In January, I discovered there are quality wrenches under $150 if you know where to look. Here’s a quick outline.
- CDI Torque Wrenches (Maker of the Snap-on torque wrenches) can be purchased online for a great deal less than their Snap-On counterparts. The Best thing is, they don’t hide the fact that they are a division of Snap-on. Wrenches are made in USA.
- Precision Instruments Split Beam (maker of the Snap-on Split-Beam specific wrenches) wrenches can be purchased online for a great price as well. Split-beam are less likely to ever need calibration, but one downside is they only torque clockwise. Wrenches are made in USA.
- GearWrench and KD Tools (divisions of Danaher Tool Group, who also make torque wrenches for Sears Craftsman) have well made torque wrenches for the money. Torque wrenches
arewere made in USA.
- Brown Line Metal Works BLD0212 Digital Torque Wrench is a new torque wrench that is the only digital wrench that fits within the budget. It is a new wrench from a new company, regardless I believe they have a pretty reliable design. I talk further about this torque wrench at the bottom of this post. Wrench made in Malaysia.
What I Purchased
Based on all the different ranges each torque wrench advertises, I decided to purchase two wrenches.
CDI 1002MFRMH 3/8″ drive 10-100 ft. lbs: I would say this is the best designed torque wrench I’ve had in my hands to date. Changing the torque amount is easy and the wrench definitely feels like a precision tool. I plan on using this for torquing bolts between 30-100 ft. lbs.
GearWrench 85054 1/2″ drive 25-250 ft. lbs: Also well designed torque wrench, adjusting the torque setting is just as easy as the CDI model, but it doesn’t quite feel as precise as the CDI, though still in the same quality class as the CDI. The long length of the wrench makes it easier to apply torque. I plan on using this for torquing bolts between 75-250 ft. lbs.
Both the GearWrench and the CDI are both accurate and precise when I tested with my Digital Torque Adapter, both clockwise and counter clockwise. I was unable to test the GearWrench beyond 147 ft lbs due to the limitation of the Digital Torque Adapter. They are both excellent torque wrenches.
The BrownLine Digital Torque Wrench
This wrench really interests me. I tried to contact the manufacturer to see if someone sells the wrench locally and received no response. I did do some research and found the patent they filed for the wrench. I also found from an Ebay seller that the wrench is made in Malaysia.
When I reviewed the patent, I quickly figured out what they did. Essentially the BrownLine torque wrench is a beam-style wrench with a microprocessor that translates the beam measurement to digital. This essentially solves the issue with reading beam wrenches at an angle. Remember the beam style wrenches don’t go out of calibration unless the actual beam itself is broken. By reason, this wrench should last a very long time. Aside from the microprocessor, there’s not much with this wrench to go wrong. Had I been able to see one of these wrenches in person, I may have purchased one.
If you have the money, the Snap-on torque wrench is definitely a quality tool. If you are on a budget like me, the CDI torque wrenches (which are essentially Snap-on torque wrenches without the logo on them) are a real bargain. If you want a torque wrench you never have to worry about calibrating or torquing counter clockwise, the Precision Instruments will fit the bill nicely. If you’re on a really tight budget, The GearWrench torque wrenches are the best value priced on the market.
If you have a Brown Line digital torque wrench, please leave a comment and tell me what you think of it.
Update on July 4, 2016
My collection of torque wrenches has grown since I wrote this post.
Park Tool TW-1 Torque Wrench 1/4″ drive, 0-60 inch lbs: – I had a need to torque between 16-20 inch pounds for adjusting a Saginaw steering box. This is a beam style torque wrench which, in my opinion, is appropriate for this kind of usage. Park Tool is a tool manufacturer specifically for the bicycle industry.
CDI 2502MRMH 3/8″ drive 30 to 250 inch lbs: I purchased this for the 5-20 lb torque range. Most common usage example would be valve cover bolts.
I now am a big advocate for click-stop type torque wrenches. Both GearWrench and CDI torque wrenches provide a confident click as well as a stop that you feel when you hit the selected torque. A friend was using a generic torque wrench from Harbor Freight and had the situation where he was over torquing because he did not hear or feel the torque being reached.
If I could design a torque wrench, I would take the best of the GearWrench and CDI together. It is easier to read the numbers on the GearWrench and I prefer the GearWrench handle. I prefer the locking mechanism of the CDI and I think the click stop of the CDI is superior.