When was the last time you checked calibration on the wrench? Just for fun, set it at 4.4 lb-ft and see how much torque it actually needs to click.
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Special KTM butter bolts + ****** torque wrench = beer o clock.
- Thread starter jc100
- Start date
Every start of the season I usually get the pair of wrenches out and go over every bolt on the bike to snug them up. I did that last year, but haven’t done it this year yet. Was going to do it after the oil change. Last year all seemed fine and there were loud clicks from the pair, I don’t recall hearing that when the bolt snapped.
I've had a MC Maximum torque wrench out by 30% when I checked it using a weight and distance (in that case, click when set at 100 gave you 70 on the nut).
Can you explain the logic? I believe you,of course, but can't figure the real difference.
For given torque, stud has more clamping force than bolt. The bolt has a long spring connecting the threads to the clamping surface. There is also issue of friction between bolt head and clamping surface prior to torque traveling through a spring to the threads. Studs effectively remove the spring from the equation and put all the forces close to each other. Consistent clamping is also why so many bolts have gone to torque plus angle and stretch bolts.
If this is a contest here goes. As young kid I worked at a shop that built large presses. I was on a ladder tapping a large bolt hole - maybe 1 1/2" with a tap handle at least 2 feet across. SNAP!Amateur...
Backed the tap out and to my amazement the tap had broke at such an angle that the broken half was spun out by the half still in the handle.
Didn't realize that was a sign to go buy lotto tickets.
I don't get it. Where is the spring? If that's unthreaded bolt stretching how is it different from unthreaded stud? Also isn't friction between bolt head and clamping surface similar to nut and clamping surface?
If you trace the force vector, a bolt adds a moment equal to the length of the bolt.
A bolt twists as you add torque to the end. The twist shortens the bolt (metal plasticity), when you release the torque, the bolt un-twists and goes back to it's original length (almost), releasing clamping pressure.
The bolt is the spring, a stud twists less, mostly because you are introducing torque at the thread plane, not at the other end of a moment, so you can add more torque for a given diameter fastener.
A torque wrench is a lousy way of measuring clamping forces.
A bolt twists as you add torque to the end. The twist shortens the bolt (metal plasticity), when you release the torque, the bolt un-twists and goes back to it's original length (almost), releasing clamping pressure.
The bolt is the spring, a stud twists less, mostly because you are introducing torque at the thread plane, not at the other end of a moment, so you can add more torque for a given diameter fastener.
A torque wrench is a lousy way of measuring clamping forces.
Priller
Well-known member
I stole this pic of a caliper bolt from the RC51 forum:
Torque wrenches may not be perfect (oil/lubricants or corrosion also throw torque values way off) , but they're better than some shadetree mechanic elbow gauges. I'm blown away by the ability of the steel to both elongate and withstand twisting forces, both for the overtorquing and the removal. Honda's supplier deserves a lot of credit...
Torque wrenches may not be perfect (oil/lubricants or corrosion also throw torque values way off) , but they're better than some shadetree mechanic elbow gauges. I'm blown away by the ability of the steel to both elongate and withstand twisting forces, both for the overtorquing and the removal. Honda's supplier deserves a lot of credit...
That must be one of those new elastomer bolts.
Mad Mike
Well-known member
I’m no expert on drill technology, I have a machine shop at work that gives me a drill when I need it - I think we pay a couple of bucks for a a drill that will bore lots of stainless 1/2 bolts.
I’m pretty good at getting them out, I have never left handed drills.
I normally do a very small pilot hole followed by a drill 2mm smaller than the bolt size. If the bolt is m10 or bigger, I’ll use an easy out. Smaller and I’ll broach it by tapping in a hardened torx bit. If the bolt gas locktite, apply liberal heat to soften up the grip.
To remove, I use a 12v impact driver. Just enough torque to break free, not enough to tear out the torx bit.
I learned a long time ago to check one size up and down from what seems to fit.
So the stud doesn't twist (spring) because you twist the nut onto it instead of the twist being passed thru the whole length of the bolt. Is that it? That now makes sense to me.
Are we still talking about motorcycles here...?
Dirty Frank
Well-known member
Proper nomenclature would be TTY JS.
Roadghost
Well-known member
Hey folks, if you're installing a small bolt (under 3/8" or 12mm) into aluminum and you have applied lubricant (oil, anti-seize, etc.) don't tighten it to the specified torque setting. Those settings are for dry bolts and you risk stripping the aluminum threads. Cut the torque specs in half for lubed bolts, and use a BEAM type inch/lb wrench for the best accuracy.
If I'm replacing stripped bolts I like to use SAE grade 8 for allens and torx or for my metric bikes I use ISO class 10.9 (the black ones). I buy them at Brafasco or Bolts Plus. Stainless and grade 5 (usually what the factory uses) are too soft.
If I'm replacing stripped bolts I like to use SAE grade 8 for allens and torx or for my metric bikes I use ISO class 10.9 (the black ones). I buy them at Brafasco or Bolts Plus. Stainless and grade 5 (usually what the factory uses) are too soft.
Quiet, you. We're learning physics now.
Now...carry on with the lesson (seriously, I love this stuff).
...but I see what you did there...
Digital and click torque wrenches scare me a bit. With the beam type you can watch the torque increase and decide when to stop.
The click type ones (I used to service them) have a pawl that does the click thing when the spring pressure meets the setting. On the cheap ones (Mine) if you back the setting off too far the pawl can drop out of position and the torque wrench becomes a power bar.
Before you go to the needed setting do a test at a very low setting. If it doesn't click you have a problem.
Get to know the weights of common items like dumbbell weights, bags of potatoes. Does the pressure on your hand feel like doing curls with a 5 pound bag of potatoes, a 20 pound dumbbell etc. The curl torque will feel heavier because the moment arm of your arm is greater by about 50%.
The curse of motorcycles is that unlike heavy equipment so many parts are aluminum. Busting a bolt hurts but stripping a hole is an introduction to the world of Helicoils or worse still major part replacements.
The click type ones (I used to service them) have a pawl that does the click thing when the spring pressure meets the setting. On the cheap ones (Mine) if you back the setting off too far the pawl can drop out of position and the torque wrench becomes a power bar.
Before you go to the needed setting do a test at a very low setting. If it doesn't click you have a problem.
Get to know the weights of common items like dumbbell weights, bags of potatoes. Does the pressure on your hand feel like doing curls with a 5 pound bag of potatoes, a 20 pound dumbbell etc. The curl torque will feel heavier because the moment arm of your arm is greater by about 50%.
The curse of motorcycles is that unlike heavy equipment so many parts are aluminum. Busting a bolt hurts but stripping a hole is an introduction to the world of Helicoils or worse still major part replacements.
Irwin extractors are the best, and are what companies like SnapOn rebrand. Brafasco sells them as a set with a good drill bit.
But once you slam it into a couple of drilled holes, throw the thing out. Or use it for something you don't care about. That is why they break, reuse of what's really a disposable tool.
As for torque, on Aluminium, you almost never torque to yield (the female threads will fail before the bolt or screw gets to yield depending on thread engagement), but any steel on steel bolts, screws or studs that need to be torqued. Should be replaced every time.
But once you slam it into a couple of drilled holes, throw the thing out. Or use it for something you don't care about. That is why they break, reuse of what's really a disposable tool.
As for torque, on Aluminium, you almost never torque to yield (the female threads will fail before the bolt or screw gets to yield depending on thread engagement), but any steel on steel bolts, screws or studs that need to be torqued. Should be replaced every time.
When they get dull, sharpen them. Its easy. And you can tailor the angles to match the material you are drilling for optimal performance.
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