New OEM hv battery post stud snapped

If there's a rebuilder out there publishing a PDF that says 60 instead of 48, those guys might be throwing in a 60 in lb T handle instead, and we'd still have mishaps....

 

the prices they are selling and the marketing they are using...... smh.....

 

Harbor Freight retail $19.95

1/4 in. Drive Click Type Torque Wrench

 

Yeah, 60 inch pounds did not snap the battery studs. It's really hard to measure the difference the difference between 48 and 60 inch pounds. Here's a cheap 60 inch pound t handle with a 5/16" socket. A 5/16" and 8mm sockets are interchangeable. The difference is in thousandths of an inch. It is preset and freewheels once 60 inch pounds is met. It could be a good option for a DIY build. The wrench is designed to tighten hose clamps.

https://www.lowes.com/pd/AMERICAN-VALVE-Torque-Wrench/1244081

 

With a good T handle set for the specified torque of 48 in lb, you could probably call it right ten times out of ten.

 

By any chance is your new 1/4 inch in*lbs torque wrench dual calibrated with in*lbs on one side and in N*m (metric) on the other? I've been caught out with this once. Fortunately, I felt something was not right and checked it before I did anything disastrous.

 

The OP had a 48 in lb wrench and goofed up 2 out of four times.

 

The OP wrote:

 

You went way past 60 inch pounds to break the posts. Maybe it was a faulty wrench but there was operator error. With experience you can tell when you are way past the safe limits of a 5mm stud.

 

HF user review for the the torque wrench

No more stripping fasteners!
I've ALWAYS stripped fasteners because I am very heavy handed. Per new electrical codes, every fastener on equipment must now be torqued to proper values. Since I needed torque wrenches, I figured I try Harbor Freight. Now these wrenches are heavy and the "lock" that keeps the handle from moving off of the value you set isn't the most user friendly. You have to really tighten the knurled set screw to keep the handle from twisting hence moving your setting. With that said, you can't get a less expensive torque wrench that has 4% +- accuracy. It also comes with a calibration certification. In my business, you MUST have a calibration certificate and the Plant I just worked at accepted it with no issues. However, it will cost you more to recertify this wrench than to just buy a new one so I'll be giving the expired ones away.

 

The experience has to involve knowing the material of the M5 stud too. If you've got an M5 stud made from property class 5.6 steel, you're going for not quite 24 inch pounds. If it's property class 8.8 steel, you're going for not quite 55 inch pounds. (Quite a difference!)



If it's a specialty stud made from unidentified electrical terminal material as part of a battery, there's probably no generic table to look up the safe torque in, so you're kind of reliant on the manufacturer to say what it is.

 

hmmmmm....one thing you have to recognize is the HF torque wrenches, regardless of what they say, are NOT 'click' style wrenches. They do not make a firm click and release. What happens, is the handle makes a very slight pivot near the head. If you're torqueing and waiting for a click, that may be the problem. The handle will perform the 'pivot' and if not recognized, will easily allow the operator to continue cranking on it.

 

The "click" of a Harbor Freight 1/4" torque wrench is very subtle. It's easy to miss and keep going past the set value. Also the 12" long handle is complete overkill for 48 inch pounds. The math shows that only 4 pounds of force is needed at the end of the wrench. A four inch long wrench would be more appropriate for tightening 5mm studs by hand.