Okay, first a digression: buy a set of torque wrenches, and use them. Don't gimme that crap about how you have been wrenchin' fer forty years and you know the right torque by "feel". It's bullshit. I can "feel" the right torque if I just used a torque wrench on a bolt and torqued it to the exact same torque from the same moment arm, otherwise I'm like every other wrench on this planet -- I overtorque small bolts, and undertorque big'uns. My use of torque wrenches tends to bear that out -- my torque wrench always clicks long before I think the bolt is "tight enough" on small bolts, and on large bolts I'm always sayin', "is this damned torque wrench gonna ever friggin' click? Is it broken or somethin'?" Of course it ain't. I just haven't torqued the big bolt enough yet.
My recommendations for torque wrenches: Sears "click" types. First of all, you can get'em calibrated by Sears Roebuck & Company, though if you properly care for them by putting them away in their cases with the dial set to zero between uses, they generally don't need calibrating more than every five years or so. These make a little "click" noise when you reach the set torque. You may not be able to see a dial or lever when your ass is buried deep under a car hood, but you can damn well hear the "click". Furthermore, get a set. I got a little inch pounds one, a medium-sized one that goes to about 50 foot-pounds, then a big'un that goes all the way to 150 ft/lbs. Deal is that big torque wrenches are no good at the low end of their scale, they're just not very accurate down there, so you need small torque wrenches to handle those. But when you're torquing lug nuts to 100 ft/lbs (gotta do it evenly so that you don't warp the brake rotor)1, you damn well need that big friggin' wrench. And yeah, they're expensive. So what. Don't buy cheap tools, that's how ya get busted knuckles. (Sorry, Ornery Bastard, had to steal yer tag line there).
Anyhow, back to the thread repair. What kind of thread repair you use depends on what you're fixing. Me, I'm going to take that cross-member that I broke a bolt off in the other day, drill that bolt out of there, and then put a thread repair coil in there. If it was a spark plug hole or a brake cylinder bleeder hole I'd use something different -- a Timesert, which is a solid repair that won't leak like a Heli-coil or its clones. But for a general frame tube that's expensive overkill. Anyhow, here's a Heli-coil kit, a Makita drill, a bench vise, and a left-handed drill bit for drilling out a bolt broke off in a hole:
Now, one thing you'll find out, pricing thread repair kits, is that they're expensive. The good part is that you can re-use them and just buy coils. That particular Heli-coil kit is so old that the packaging has yellowed, but the tap and insert in it work just fine. As for the Makita drill, a word of advice -- have a second fully-charged battery available if you're using a battery-powered drill. This is my only drill that will hold a 31/64 drill bit (needed for the Heli-coil kit), so that's what I gotta use. Finally, it's a lot easier to work on a piece if you can get it up on your bench. Obviously that won't work if you're working on the frame of a car, but here I took a bit of inner tube and stuck that frame tube on my bench and started drilling, first punching a small indention with a punch then drilling like my life depended on it:
Until finally, I drilled all the way through:
Once through, I moved up one drill bit size at a time until I was up to the size specified on the Heli-coil packaging, then tapped new threads into it to wind the Heli-coil into. Note: I used the can of cutting oil in the pump can below the bench to lubricate the tap, those things are expensive ($55 for a Helicoil kit nowdays, and most of that is for the tap!). Said cutting oil actually being 80w gear oil :-). Note that I'm using a high-tech tap wrench on this tap, but you'll see a "real" tap wrench later:
Once the hole is threaded, then you put the coil on its inserter so that the tang is resting against its end:
And then screw it into the hole using the inserter and a tap wrench (from my tap and die set, duh).
Until finally it's all the way in!
And then you have to break off the tang on the bottom using a punch and a hammer. Luckily I have a punch set from Cheap Chinese Tool Company in the second drawer from the top of my rightmost tool chest-of-drawers (which used to be a bedroom chest-of-drawers before I retired its ugly ass to the garage). One whack with the hammer, and the tang was history. And now the end result:
Yay, my (replacement) bolt screws in! And now I'm ready to put this cross-member back on the bike until its replacement gets here. Beats bein' out of commission for a week!
-- Badtux the Wrenchin' Penguin
12 comments:
How cool, someone actually used my line!
Thanks Badtux.
As for torque wrenches, you are so right on when you say on big bolts it feels like they are never going to click!
Some of the stuff I work on uses insane torque specs, 1600 Foot pounds, lots of 3-400 foot pund stuff.
On the really big stuff we rent a hydraulic powered torque wrench, yhat thing is bad assed!
The other stuff we use a 4 to 1 torque multiplier and a 250 ft pound wrench.
Snap On, of course.
Craftsman makes some quality tools and their ergonomics and finish have improved dramatically over the last few years.Perfect for Do It yourselfers!
Good post. I have installed hundreds of Heli-coils and I think they're an excellent repair. Sometimes they're the only repair. I keep many sizes in stock, which means I needed a particular size once and still have the rest of the kit.
I'll disagree slightly with you (!!?? Heh.) on using them in spark plug holes. I think they work fine, and they're the only thread repair you can install with the head on. I have a technique to keep the chips from falling into the cylinder and a small needle-nose pliers to bust off the tang. I have heard that they alter heat transfer so you should run one heat range colder plug, but I've never experienced that.
The worst thing when extracting broken screws is to bust the EZ-Out or whatever you're using. Those things are harder than Chinese arithmetic and you can't drill them. You can get them out, but sometimes it's difficult. Heat, penetrating oil, and the shock of setting the extractor is usually enough to loosen the screw somewhat, and you develop a 'feel' for how much manly arm or wrist torque is about to be too much.
Torque wrenches are good where you have to get a buncha bolts tightened exactly the same at just the right torque value, like cylinder heads, but they might be even more important on small screws that can easily be overtightened and break, or pull the threads they're going into.
Back when the, er, metric bikes used cheesehead Phillips screws on cases and covers, ya just whacked 'em once with a hammer on an impact driver and they were fine, but the modern bikes use a lot more Allen bolts which are way stronger and can be easily overtightened by big strong men like us.
I have noticed over the years that motorcycle repair is largely about missing, broken, stripped, stuck, rusted, incorrect, and rounded-off fasteners.
Went to 'publish' this and it didn't take, so I saw Nucks. comment and thought I'd add a little. Harley-Davidson used to use (I'm not very current on them) 450ftlbs on the nuts that held the axle shafts and crankpin into the flywheels. They were only about 3/16" thick, so first you had to take a perfectly good socket, 2 1/2" if I remember right, and grind the chamfer off the end to make it flat so it would stay on the nut. Then you put the flywheel in the hydraulic press to hold it steady. Then you attached a very large torque wrench that was supposed to light up at torque but never did (made for noisy factories. It clicked too.) and had an assistant lever the head of the wrench against the flywheel with a 2x4 and then you leaned on the wrench for all you were worth. It was kinda funny to watch, but that's the way we had to it. I'm sure they have fixtures these days that make that unnecessary.
Sometime I'll tell ya about The Boring Bar That Beat The Kaiser.
Addenda
...you develop a 'feel' for how much manly arm or wrist torque is about to be too much.
After you've broken enough screw extractors and had to deal with the result, you learn how not to.
The worst thing when extracting broken screws is to bust the EZ-Out or whatever you're using. Those things are harder than Chinese arithmetic and you can't drill them.
Indeed. That's why I decided I wasn't going to use the extractor on it. I'd already busted a damned strong bolt in the thing 'cause the threads were jammed tighter than a neo-con's wallet in an orphanage ("dratted kids ought to get jobs and quit feeding off of my money!"), so I figured that a) the threads were toast anyhow, and b) I might as well just drill it out and forget using the extractor part of the extractor kit, maybe the left-handed drill bit would break the bolt loose, maybe not, but I wasn't going to risk breaking the extractor in that hole. Since it was going to need new threads anyhow (the old ones were obviously AWOL and FUBAR and especially would be once I drilled the bolt outta there), there wasn't a damned thing I could do by drilling it out that was gonna make things worse, while having the extractor broken in that hole... (shrug). You know *that* story!
So anyhow, having already done something that made things worse, I was determined to not do something again that made things worse. And accomplished my mission :-).
-Badtux the Wrenchin' Penguin
One more thing. Cheap tools have their place, particularly wrenches. Sometimes you have to modify wrenches by grinding or by heating and bending, to suit an application. I'm not about to mess up a $20 Snap-on wrench forever just for one seldom-used purpose, and Craftsman wrenches, which are my preferred choice, are so thick they're hard to bend.
Also, I use a lot of Cheap Chinese Tool Co. electric & air tools, and other kinds as well. I'm a DIY (read 'cheapskate') homeowner and a retired mechanic who doesn't do too much actual pay work anymore, so they suffice for the occasional use I put them to. If I had to make a living with them, I'd buy the good stuff.
I have rollaway upon rollaway full of good quality tools I've had for years along with the cheap stuff, and I still use all of them from time to time.
Ha! 'Publish' didn't take again.
tighter than a neo-con's wallet in an orphanage
(Many laughing smiley faces)
Yer home today! We're in real-time mode! Way cool.
I feel obliged to go do some work at the Brain, but I'll be back. Hangin' out over here is too much fun.
Oh, I have the ULTIMATE broken headbolt on a motorcycle story but it's a very long story. Weeks long. Maybe later.
Lemme guess - it was on the rear cylinder of a Shovelhead and you had to hacksaw a section out of the frame to get the head off...;)
Not quite real-time, sometimes I gotta do the job they pay me to do :-).
I have a fair amount of stuff from Cheap Chinese Tool Company. That shop vise came from there, as did the punch set I used to punch out the tang, a set of *big* allen wrenches (including the 12mm that I need to take off the front wheel of the new motorbike), that big drillbit set that you saw in the pics above, and so forth. For occasional use they're fine. But don't get any precision tools from there, they just aren't precise. I bought one of their torque wrenches to fit between the little one and the big one. I discarded it after discovering that it just wasn't as accurate as my Craftsman torque wrenches, as well as being a pain to set and use. And I wouldn't trust any sockets or wrenches from there, I've broken too many cheap ones and rounded off too many bolts with cheap ones. That's where I use my good Craftsman stuff (alas, all the Snap-on stuff I inherited from my father, a professional mechanic, got stolen about 10 years ago when some low-life who's now in jail broke into my storage room and sold'em for meth).
Anyhow, question for Gordon: what's your secret technique to handle a stripped spark plug hole without taking the head off? And why will it work for Helicoils and not for Timeserts? Curious penguins want to know! (Post it over at Fixer'n'Gordon if it's more than a few lines though, 'cause we all know how badly the Blogger comments editor works, though at least it's workin' better this morning than Hellscan!).
- Badtux the Wrenchin' Penguin
Yeah, Haloscan's slurping product from the hind end of a diseased yak today. Seems to be better now.
I'll do something at F&G. I learned the secret technique in college.
Huh. I didn't know they taught that sorta thing at Clown College. Was that before or after they taught yous guys about the red binky noses?
- Badtux the Snarky Penguin
I went to L.A. Trade-Tech. They taught all kindsa shit there. The Clown Dept. was next door, but sometimes it was hard to tell the difference.
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