Calibrated Fingers

[TimeMachine]

Being a regular XS650 site reader there is a subject which periodically brings up a question concerning home mechanic technique. Often torque values on components are addressed by specific torque values from service manuals in this forum. Torque wrenches of a variety of design are at times compared to others and technique is also described in detail. Precision use of tools is a great concern for all of us to achieve best results working on our XS's , as well as our other machines ! My own question is, Who is actually using precision torque wrenches and who is actually using ratchets and combo wrenches by "feel" ? I am confessing that after decades of wrenching on my own machines, trucks, motorcycles etc. I rarely ever actually use a torque wrench. This is not to shock anyone . I am a long time machinist by trade and precision is instilled in my every thought much of the time. Being a regular "hands on" kind of person for many years, I simply have extremely good feel because of my life style and many years of practice. At home working on my own motorcycles, I prefer "feel" of my calibrated fingers over a torque wrench. I cannot even remember stripping a thread. My bikes and machines generally do not leak. I know many of you are also well aged and experienced with your tools. This is not at all to dismiss the importance of proper tightness. This is to hear whether others believe they are so familiar with their finger calibration that they "skip" the effort of setting the torque wrench.. lets chime in on whos doing this ? I hope its not just me -RT

 

[TwoManyXS1Bs]

No, it's not just you, RT. Just like a child learns to walk by falling down, developing the deft touch with threaded fasteners involves experience and a history of *oops*.

For normal fastening, there's a happy zone between too loose and too tight, vibrates off or cracks parts, leaks or warps.

For those in the learning stage, a torque wrench is invaluable. Saves a lot of time and hair-pulling. But, it isn't necessarily the end-all, as strictly following torque specs can still get you into trouble if you haven't developed the feel for imminent failure. Helps to know the materials and fastener grades here.

Then, there's those mystery areas, where the torque value is not just to hold things together. Like lug nuts, conrod end caps, suspension bridge tension components, shear loads, threaded foundation rebar, ...etc. You have to get into the engineering department to understand those callouts. This is a strictly calibrated torque wrench neighborhood.

For the simple attachments, I'll usually go with my deft touch: finger pain, wrist crackling, elbow pop, passing gas.

May I recommend this torque limiting wrench set:

 

[Bob Kelly III]

Nope it's not just you.... the only place I use a torque wrench ( if I had one all 4 of my torque wrenches burnt up in the ranch fire)
is on the cylinder head the rest I do by feel..... and I usually stop before I sheer a bolt, but I admit.... not always ! LOL
if it takes a 10mm 12mm or 14mm end wrench to torque it down I use the wrench if it's recessed and have to use a socket and extension i use the socket and extension..... its no problem though I tend to get them a tad too tight with the ratchet
I have a 12" 3/8" extension that I use allot that flexes and it's perfect for cinching down the bolts....I can feel the bolt allot better with it than I can other extensions....dunno why ....
moving to the 1/2" drive sockets is no problem the technique is in the feeling of the bolt flexing....bigger bolts don't flex as much so you
have to be more careful,... they snap easier... I use cheater bars all the time for things like the rear axle and head bolts, or my foot like last time adjusting the chain tension good and tight is good enough for me !
....side plate screws are different and sort'a new to me I am used to using a air impact on them but have learned to flex the allen wrench about that far and no more......if you know what I mean....<grin>
......
Bob......

 

[Bob Kelly III]

Hay I need a set of those in 14mm !!!!! my long 9/16" box end wrench has caused more sheared bolts than any wrench I own and with that sharp edge in your hand it would definitely cure that problem completely....or end wrench turning completely ! one or the other !!! LOL
.....
....Bob......

 

[retiredgentleman]

In certain industries, calibrated torque wrenches are mandatory. Aircraft and nuclear power plants are examples. Many people's lives are at stake, if a bolt comes loose or is over torqued and breaks. Now for our motorcycles, if a bolt is torqued wrong, death is not likely, but it could occur. More common would be oil leaks or a stripped thread, leading to the need to do a helicoil.

If someone is an accountant, a stock broker, or a nurse, and likes old bikes as a hobby, then they are very wise to use torque wrenches. They just don't have the experience in turning wrenches. However, if your whole life has been using tools in various trades, then you probably have a good feel for the correct torque.

So, each person has to decide for themselves, if they need to use torque wrenches. Personally, I always use a torque wrench. I have never stripped a thread in a car,truck or bike. I think its dumb to not use torque wrenches, even for experienced mechanical
lads.

What if an aircraft mechanic, with 25 years experience, thinks its too much trouble to bother going for a calibrated torque wrench in the next building. Besides he has installed the jet engine mounting bolts, hundreds of times. So, he just installs the bolts, by "feel", because his fingers are "calibrated". What if your family goes on vacation, and that engine falls off the plane.

 

[TwoManyXS1Bs]

This reminds me of a little science experiment I conducted with my cousin. The difference in tensile strength between equal diameters of cotton string and Spider Wire.

I tied each end of a 4 foot piece of string to two wooden rods. Stand on one rod, pull upward on the second rod, like 'curling' weights, until it broke.

He easily broke the first, cotton string. A bit more effort, but he broke the 2nd, Spider Wire string. He claimed that they felt the same, and that my claim of Spider Wire being stronger was false. Dunno if he was just showing off (he's a strong fellow), or if he really couldn't tell the difference.

Ok, science experiment stage 2.

Repeat the experiment, but while standing on a bathroom scale. I'll stand on the bottom rod, he'll be on the scale and pull until breakage, and we'll note the scale readings.

The cotton string broke at 10 lbs, the Spider Wire at about 42 lbs.

He honestly couldn't tell the difference.

I wouldn't trust him to torque anything without a torque wrench.
He *does* have a history of snapping fasteners...

 

[Paul Sutton]

I have always used a torque wrench on engines and any critical components. I also use them where strippiing the threads or breaking a bolt will cause major headaches to repair. On the XS engine I sometimes use them on the valve covers because I do not trust 6mm threads. Drilled bolts like bangos I check but not those in the indicator stems. I take great care if the bolt goes into aluminum because I once stripped an alloy head with a spark plug using my calibrated elbow. I always set the torque on spark plugs even though it never seems tight enough at 15ftlb..

On my car the manual refers to setting the torque in steps using a torque wrench with a degree indicator. I have never used this technique but instead tighten the XS head studs in steps of 7/15/20/30 ftlbs. I assume there must be something very important/advantageous in setting torque in steps and degrees but have never looked this up.

 

[Max Midnight]

On my car the manual refers to setting the torque in steps using a torque wrench with a degree indicator. I assume there must be something very important/advantageous in setting torque in steps and degrees

Here is why you would use torque and angle.

And for those who should probably get out more something else to play with.

 

[gggGary]

Mostly dig the old beam wrenchs out for cylinder heads, brake rotors, calipers, any critical assembly I'm not familiar with. I kinda hate torque to yield bolt up technique. I feel that's a cludge around poor assembler proficiency. Like the XS head method I have "fixed" leaky cylinder head gaskets on several old beater OHC 4 cylinder cars by the release and retorque method even though they have torque to yield bolts. Shrug. Probably more important than torque wrench but seldom mentioned is CLEAN threads I keep a 6mm bottoming tap on the work bench rack. Torquing a bolt to "spec" in a dirty corroded cast aluminum bolt hole is worse than pointless. If you didn't chase every thread with lube and compressed air on castings that have been "media" blasted you are an idiot.

 

[weekendrider]

Not always. But it isn't the security of experience, mostly sheer laziness, hoping it doesn't become shear laziness.

 

[YamadudeXS650C]

Not always. But it isn't the security of experience, mostly sheer laziness, hoping it doesn't become shear laziness.

I appreciate your honesty, WR. The variable "laziness" probably is involved in more of our mechanical decisions than we are willing to admit at a given moment.

 

[YamadudeXS650C]

Like most mechanics who have multiple decades of experience with wrenching , I have developed good confidence in my "feel" for torque, bolstered by my knowledge of metallurgy, metal fatigue, the influence of lubricants, and direct experience with "the limits" (actually snapping off bolts).

However, I never let myself lose track of the fact that a mechanic's "feel" is very much a subjective phenomenon. We are not robots, although when we are wrenching it is convenient to imagine that we are. Subjective means existing in the mind;
> Belonging to the thinking subject rather than to the object of thought.
> Relating to properties or specific conditions of the mind as distinguished from direct experience.
> Pertaining to characteristics of an individual; personal, emotional, influenced by attitude.

Therefore, I have 4 torque wrenches of various types and application ranges.

But, honestly, I don't always use them.

 

[xjwmx]

I don't use a torque wrench except in cases where there's weirdness that keeps feel from working. Examples would be very low or very high values or where things flex and stuff; things like the fork clamps, head bolts, front axle clamp.

I don't see the point of torque wrench + feel, unless you're trying to salvage bad parts, which is a legitimate thing to do. In an ideal world if you have to rely on feel to stop you before you reach the spec'd torque, the part is no good. But I think that philosophy would have you stripping old motorcycle threads all over the place.

 

[Bob Kelly III]

Well, gggGary's links provide very interesting info.... and insight into bolt fastening.
although I very rarely "chase out threads" with a tap ...I do believe i will take up the practice as stretching the bolt is actually what your trying to achieve on every installation to get that hold that your after.... and if you don't have clean threads you get hung up on torque but not stretch
this is why heads leak even though they were torqued to the proper values all the torque went into turning the nut and not stretching the bolt
..... I knew it was important to have clean threads that turn easy but never gave it much thought before....
no doubt I will be applying lube to the threads more often and getting me another torque wrench again.
.... an interesting note on one of those links was when torqueing something like a head down that taking it down to say 7 ft lbs doing all of them in their sequence and then increasing to say 20 ft pounds and doing all of them then doing the final 30 ft pounds virtually eliminates the possibility of the torque going into twisting the bolt but puts it into stretching the bolt .... which is what you want !
Cool stuff Gary ! thanks !
Bob......

 

[retiredgentleman]

Gary's quote:
"Probably more important than torque wrench but seldom mentioned is CLEAN threads I keep a 6mm bottoming tap on the work bench rack. "

Yes I agree. Its very important to have clean threads. Yes, the 6 mm bolts/threads are more likely to be over torqued than the larger sizes. Using a 6 mm bottoming tap is a fine idea. Also for 6 mm bolts, if you don't have an in-lb torque wrench, you should buy one.
Regardless of how much skill you think you have, its very hard to judge torque in the 72 to 84 in-lb range.

Another tip for the young, inexperienced lads.........................always install the spark plugs using your fingers, until they are fully seated, and only then use a torque wrench.

 

[TimeMachine]

Great variety of responses on this thread, from a great variety of members ! Now Im going to volunteer a specific XS related situation in which I've gone beyond the torque wrench usage. One item which I have found difficult to properly tighten to specs is the countershaft sprocket nut. Many of us have experienced the darn nuts loosening with use. There are assembly procedures used which include cleanliness, loctite, washer condition , etc but above all I found it difficult to "torque" the nut to the high setting which has a range. I kinda remember going for 75+ lbs torque. My thinking of this followed remembering disassembly of a too tight one. How did I loosen a too tight sprocket nut ? Reluctantly, an impact driver and 36mm socket. Common practice Im not sure ? So after attempting to torque the nut on installation, I decided to "seat" it in using the same 36mm socket and impact driver. At this time I am completely leaving the accuracy (or inaccuracy) of the torque wrench and opting for my own "feel" of a good smack of my old trusty impact driver and rubber dead blow. Cringe and a big bump and its all over ! That nut did not loosen again. So that example is the kind of choice made by a guy who is working on his own motorcycle ! Which I often make... but I have wondered about the possibility of damage by that impact ? Opinions ? -RT

 

[weekendrider]

I can think of one fixture where you would probably over torque without a tool giving that gives you some indication of force.
You will not strip threads out. You will probably not deform it or the engine. You will cause yourself an hour or so of aggravation and extra work.
Wadami referring to? Go.

 

[weekendrider]

TM I tend towards the rattle gun for removal. For install a torque wrench to the upper end of the range. 85#'s.

 

[TimeMachine]

Good riddle WER, Im thinking ... Face shield pivot screws ?

 

[weekendrider]

No. That would be top down. I'm talking bottom up.
Excellent guess though.