steelbikeguy

I've spent some time in glamorous NAS Millington! It's been more than a few years, though.
I was there for avionics school, so we learned how to use a Simpson 260 meter, how to set the trigger on the oscilloscope, and many things about electronics (i.e. transistors can be considered Magic Rocks).

A couple/few photos of the era...







This was Sept '77 to March '78.
I'm pretty sure that our friend Robbie Tunes was there for ATC school at a later time.

Steve in Peoria
(using Fluke digital meters now instead of Simpsons, but the Simpson was the Campy Gran Sport of meters... not sexy, but reliable and durable)

Nemosengineer 

I was there for AD "A" school at about the same time, small world.
: Mike

steelbikeguy

I had to use the internet to learn that "AD" is an Aviation Machinists Mate, and that AD's work on engines and propellers. The Marines just call them Powerplants techs, perhaps so it is easier to remember.
As a Marine, life on a naval base was full of confusion (especially when wondering if I needed to salute that guy with the shiny stuff on his collar and was rapidly approaching).

Steve in Peoria, former A-4 Skyhawk avionics guy
(saluted more than a few Chiefs in my day!)

Mad Honk 

I have yet to over torque a crank arm when installing it. And that includes my days of working in a beer store and being able to throw a keg across the room. ( But that is some long ago history!) Nonetheless I have been using a small Makita impact driver to attach fixing bolts, which provides enough torque. However on auto wheels I have spent the $300 for torque bars that prevent me from over tightening wheel bolts which will warp rotors for disc brakes. As a lot of old mechanics here have attested you pretty quickly find out just how tight the right feel is for torque. I had a guy once test my "feel" against his torque wrench on twelve head bolts for a Toyota. I was within 1 ft /lb for the entire set. Smiles, MH

Nemosengineer 

I did a few one man detachments at MCAS Yuma in support of playing fleet adversary the desert, It was no more than a fuel coffee and rest stop for the pilots. I must have been told "GET A HAIRCUT" about 5 times a day every day.
Somehow during one of the detachments I also ended up supporting two FA-18's out of MCAS El Toro in addition to the two F-4S Phantom's I was responsible for as a favor to someone... I was given a FA-18 NATOPS manual about an hour before the first one showed up, at least I knew where the fuel filler door was, the first FA-18 pilot had to show me how to pin the seat!!! I got a nice thank you letter from the CO of the Marine squadron. Lots of fun, Semper Fi my friend.



: Mike

Road Fan

Yes, I've had that on my Trek with the stretched-out seat lug. I also think overtightening was the root cause of my seat lug opening up. But I was specificaly talking about Campy seat bolts on a frame that was made for them and fit its post pretty well. But all of those are several decades behind me since I started using a torque wrench.

Road Fan

Was not in the service, but I learned early on that transistors work based on FM. After engineering school, it still seemed like FM!

Road Fan

Love those Phantoms!

abshipp 

So those of you who do use torque wrenches, how tight do you go?

A cursory Google search shows 25-30 ft/lbs.

I use your standard ~10" ratchet most of the time and typically tighten it up until it starts to get quite snug, and then maybe a teeny bit more. Haven't had an arm come loose or broken a crank yet.

I almost always use torque wrenches when I know the required torque value, but I've gotten experienced enough to know what's tight enough on vintage bikes, most of the time.

Salamandrine 

It depends on the crank. 25 ft/lb is typical for higher end cranks and good if you don't have factory specs. I'll often give the left crank a couple pounds more, since those are more likely to loosen. Some softer and/or cheaper cranks will start to deform and slide up the spindle if tightened to 30.

There are factory specs available for most cranks.

Phil_gretz

I'm in the camp that says, "just buy a torque wrench". There must be an obscure internet game entitled "who can live the longest while getting by without the right tools." I suspect on the dark web somewhere...

SJX426 

I would rather be oft torqued than torquedoff!

beicster 

I lucked into a Snap On torque wrench. I usually shoot for 30 Ft/lbs. That has always worked for me.

ThermionicScott 

Guys, I'm worried that this thread might reach a peaceful end if we're not careful.

I use a thin film of oil/grease on the tapers, and torque to 25 ft-lbs, checking again after the first ride.

Piff 

Even though my cranks aren't exactly high end (swaged), I probably still will be fine using the pb wrench, right? Since I will be unlikely to boost it onto there with a severe amount of torque.

As for why I'm resisting buying a torque wrench...I dunno, I guess I probably should at some point. I've been alright so far, except for these cranks.
​​

steelbikeguy

The electronics classes at Millington did teach me a lot, and certainly developed a curiosity in the subject. It left a lot of questions unanswered too, which may be why I went on to get an electrical engineering education. It did teach me about doping of the silicon, charge carrier gradients, bandgaps, etc. I was able to describe in detail how the stuff behaved, but the underlying physics... it's still a bit magical. Why should two electrons repel each other? Why should a changing magnetic field cause electrons to flow? How is it possible that radiant heat, radio waves, x-rays, and light are all the same thing, differing only in their frequency??
Definitely a bit of "Fargin' Magic", for sure!

Steve in Peoria

Phil_gretz

I took Electromagnetic Field Theory from Charney himself. Crouched in the front of the room, cupping a Lucky Strike and exhaling out a window. He could go 45 minutes without notes, filling three large chalk boards with derivations of field equations. Pausing to hack and cough periodically, he'd ask if we had any questions. It was mesmerizing...

steelbikeguy

Just a note to discuss times when I've had a crank lose a bit of bolt tension....

Case #1 :
As a treat for myself, I bought a Phil BB with titanium axle for the Campy Record cranks on my Raleigh Team. I had been using the cranks with a Campy bottom bracket axle. Phil said the taper on their axle was compatible, so I really didn't think there would be any issue. Well, I did find the crank bolts became loose a week or two later! I checked them regularly for a few weeks afterwards, and it required less and less retorquing each time. Haven't had any issue with it since.

Case #2 :
I wanted a classic bike with some low gears, so I bought a SunXCD clone of the Cyclotouriste crank to put on my Hetchins. I had a nice Sugino cup & cone BB in the parts box that looked like it would work. Since they were both Japanese, I figured the tapers should be compatible.
Well... they were probably close. It did take frequent checks of the torque, but after a few weeks or so, the bolts no longer lost tension and things have stable and tight since.

My guess is that the difference of tapers was the culprit in both cases. The aluminum of the crank arms ended up deforming slightly to match the taper of the axle, I'm guessing. They have been fine ever since, and have seen hundreds or thousands of miles of use w/o incident.
In the old days, I always used Stronglight cranks with Stronglight axles, Campy cranks with Campy axles, etc. There was no mention of standard tapers, so I never mixed brands. Nowadays, most of the parts we use have been around for a while and might have been used with some other taper standard, so the issue of allowing the aluminum to deform slightly might have to be considered even if using a Campy crank with a Campy axle.
My personal recommendation is to use a torque wrench, but also check again periodically until you know that it will not lose tension.

Steve in Peoria

ltokuno

A cheater bar and some weights could have the PB wrench apply a measured amount of torque. The calculations are easy enough.

Dwillems26

Replaced my BB all proper like. Clean, dry tapers, greased bolt, torqued to spec. Feeling good I tried it out, and my chain wouldn't shift to the big crank gear. My cranks weren't fully seated and the derailleur couldn't reach my gear.

Took them off, greased the tapers and bolts, and torqued that bolt down as snug as I could get with a half inch breaker bar. Backed off the bolt, torqued to a good amount (no torque wrench this time), and I'm back in business.

after years of breaking bolts I can mostly foresee when I'll break one off and I stop before then. Is it right? Probably not. Have I had issues? Not yet.

Road Fan

Anathema and sacreledge! Happy now?

Ferrouscious 

I torque to 25-30 lb-ft. dry* depending on assumed use and quality of crank. I always use a torque wrench. Why?
1-I work on cars a bit in my spare time, so I have a couple torque wrenches around.
2-I work at the LBS, and we have torque wrenches there. That said, I have a pretty decent idea of what various torques feel like.
3-I'm obsessive. I do my best to taper match with modern cartridge BBs. I also usually polish the spindle. *Dry fit is my default unless the crank needs to sit further in, then I use grease.

Bottom line is, if you have a torque wrench, why not use it? Some things can be deadly if they slip or break (bar/stem interface, wheels on a car, brake cable pinch bolts, etc.).