In the ongoing saga of “What were they thinking?” I had to scratch my head on a recent repair.
The torque specs called for 89 in/lbs on the valve cover bolts. Why such an oddball number?
Like using a round number of 90 in/lbs is suddenly going to result in the destruction of the bolt or hole by increasing it 1 in/lb? It can’t be that critical so what compels the engineer to specify something like that?
During another repair, I was loosening numerous fasteners that were the ubiquitous 10mm. Then, for whatever reason unknown to normal humans, there are two that are 13mm. Same bolt length, diameter, thread pitch and same type of clamping force so why change head size?
This seems to be a throwback to the olden days where there was a lot of mixed hardware. Then they discovered the benefits of using same sized and type of fasteners throughout. Maybe this was a geriatric engineer…?
Because you’re using an antiquated and outdated measuring system that few other people use. I mean you weren’t using a 3/8" socket on that bolt, right? You were using a 10mm.
Try 10 Nm for the torque spec. That’s the correct value, an easy round number to remember.
As mentioned they are typically both specified. And that was the actual point. If the intent is to set the torque at 10 Nm, then that is not an integer value in in-lbs. So why not list it is a “round number” for the conversion? 0.6 in-lbs additional is not going to result in snapping off the bolt…
Because converting from one measuring system to another requires being faithful to the original value. I wouldn’t trust a service manual that rounds off numbers for convenience. I want accurate numbers.
The people who designed and built the engine decided the torque should be 10 Nm. A round, easy to remember whole number in a system that the whole world uses. That’s 7.376 ft/lbs. Not as easy to remember and not as widely used.
Some years ago, on a UseNet group called rec.autos.tech, I was next to being run out of town for allegedly improperly expressing the phrase for English torque values:
“ft-lb” I stated in a sentence , after which I was just about tied to a stake and burned alive..!
So I’d like us to settle it right here: Which is the correct way to state it: “ft-lb”, “ft/lb”, or “lb-ft”?
Personally, I couldn’t give a rat’s ■■■ how it is worded, I’m not an English major…
As long as I get the correct torque spec, all I look for is the ft, in, or Nm… I really don’t care if the lb is in front or behind it…
That being said, lb-ft is the technically preferred way to state rotational force (torque), for example, “torque the lug nuts to 100 lb-ft”…
In everyday speech and automotive manuals (IIRC), ft-lb and lb-ft are often used interchangeably… You’ll see ft-lb used for torque all the time, even though lb-ft is technically more precise…
ft/lb is the incorrect notation for torque, because the “/” means division. lb-ft and ft-lb are both expressing a force multiplied by a distance: force × distance = torque…
But again, I don’t pay attention to how or what order it is written as long as the “lb” or “in” is correct… Or another way of saying it, I don’t care what you call me, as long as you call me for supper…
I’m sure the more smarter members on here can explain it mo better…
