cracked axle housing

[scruffy]

While I can agree with some of what TomG says, I cannot agree with other parts. Lug nuts? Well, lets use that vet for example. You have a wheel that will run out at 2G to replace (computerized air pressure in tire). Would you use the impact and let it go, or would you torque it down to prescribed specs? If you ruined a wheel, and the business had to replace it, how long would you have a job? Spark plugs? Depends on the heads...a cast or steel head will support over torquing much better than an aluminum one. Customers get cranky when they come in with a dent in the hood from a spark plug blowing out the threads and hitting the underside of the hood. Ever replace a thermostat housing that had an ear broken off from being tightened down too tightly? True, the experienced mechanic can run the bolts in and be pretty much on the money, BUT your customer is NOT paying for 'pretty much on the money', he/she IS paying for the professional job being done. Shop rates are pretty much done on a flat rate manual, which is allowing time for you to do a PROFESSIONAL job, and you can normally beat the manual rather easily. Occasionally, due to oddities occuring, you catch the balance wheel and run behind, then you philosophically cross off the clean up time, and count that as your time.
Would I do differently on my own hardware? Truethfully, I have, but when time is available, I will still do the job in the proper manner, as I am my own customer, and do not like possibly wasting my own time and money.

 

[Anonymous Poster]

Tomg, I don't think that everyone is implying that you must torque every bolt to be professional, if that were the case, Me and everyone I ever worked with would be classified as unprofessional. I've been a professional mechanic for 20 years, the first 9 as an air force aircraft mechanic.
After leaving the service I pursued getting an A+P(airframe and powerplant) license. In the meantime I took a job at a local tractor dealership and fell in love with it. I had my chance to work on cival aviation aircraft working part time with an A+P mechanic at a local FBO gaining the necessary
practical experience I would need to pass the A+P test(A+P's must be familiar with all aircraft from DC-10's to cessna 150's) And believe me while working on aircraft (in the military) you were expected to torque EVERY bolt according to the T.O. (maint. manual) and for the most part we did, Esp. if QA was giving you an evaluation. While working with the A+P, torquing was always an issue. Critical parts and assemblies such as cyl. heads, manifolds, valve covers, flight control systems, transmission parts and housings, wear even tightening and bolt stretch are a big factor should ALWAYS be torqued to the proper spec and sequence. A jet engine can/will grow 6 inches when at full operating temperature, if fasteners are not properly tightened you could see where that could cause some problems. Now while I've never heard a case where a tractor fell out of the sky because of an improperly torqued bolt I believe the customer deserves the same attention to detail I have applied to all the work I've done throughout my career as a mechanic. Do I torque dash board screws? no way, would I if you asked me to? absolutely. No I do not torque every bolt and neither does any mechanic Ive ever worked with and yes you do develop a good feel. And yes you can tell that the backlash is good on that ring and pinion or that clutch freeplay is good or that fan belt tension is ok by feel, but only after you've done enough of it with the proper measuring devices to develop "The Feel" You also have to screw up a time or two
to develop "The Feel". Aviation is a very interesting and exciting field (esp. military aviation, afterburners and bombs, pulling g's, flying at high speed 300 ft off the deck
etc.) I found civil aviation to be somewhat lacking in the fun dept. due to restrictions on "creativity" that MUST be in place for obvious reasons. Tractors are just plain fun to work on. And the $$ aint too bad either.....

 

[paccorti]

I hope that I didn't give everyone the impression that I'm some torque wrench nut /w3tcompact/icons/smile.gif! The big things for me are lug nuts and any brake caliper bolts (about the only repairs I perform myself, oil changes etc.). Since my life may depend on it, I want those torqued to spec. Plus, I'm suspicious that I've suffered many warped brake discs due to over-torque. In fact, without a torque wrench I'm probably as guilty as anyone. When in doubt I just pull harder. Since I perform these repairs so infrequently, it's hard to image that I would ever develop a "feel" for the proper torque.

Bird,

With regards to your calibration question my manual says that it should be done after abnormal use. In my case I would expect that to mean exceeding the 250 ft lb max capacity. Actually that reminds me of something. My father has an older style torque wrench, the kind where there is a long pointer to the handle. My friends and I used to play in the garage and pretend that it was a depth sensor on a submarine (or something). So we pulled that needle all over the place as we played /w3tcompact/icons/smile.gif. Hmm, I guess I should go make sure that my father's wheels don't come off.

Peter

 

[Rowski]

Scruffy,

I agree that one should use their judgement on when to use a torque wrench. I know I do. As far as getting a professional job or a pretty much on the money job, well. I feel that if the end result is that the "fix' is fixed and doesn't come back to be refixed then it is professional. If the fix requires a torque spec and it is not torqued with a torque wrench and it never bothers, does it really matter. Also alot of repairs done on todays modern car the quarters are so cramped you could can't see what one is working on half the time. Flat rate labor is a very touchy subject for me. The only flat rate that pays well is Toyota.

A note about lugs and warped brake rotors. Most of the time this is due to the uneven torque, add some heating and cooling and WARPAGE.

For the record, I use a torque wrench when I feel it is needed for the application. If i don't used one and the fix comes back, I take care of my customers.

Derek

 

[Bird]

Peter, I've still got one of those old torque wrenches with the long pointer to the handle; bought it 20 years ago to use when I replaced a blown head gasket on my aunt's old Ford. How accurate do you reckon it would be now?/w3tcompact/icons/laugh.gif/w3tcompact/icons/laugh.gif

Bird

 

[scruffy]

I suppose I've given everyone the wrong impression. Many things that have a torque setting listed, I agree they don't get torqued. Head bolts? Sorry, I will torque them in the proper sequence due to the possibility of warping. I also have required rebuilds to come back into the shop after a couple hundred miles or so, so that the head bolts and intake/exhaust manafold bolts can all be retorqued. Not always necessary, but a percentage always seem to need to be tightened. Wheels? Only those little jewels that cost an arm and a couple legs will get a full torque sequence run on them, the rest get a tighten down with impact (lightly run into snug) and a final torque run done on them.
I had a dodge omni (wife's) that I lost a head gasquet on, no biggy, easy job to do. Called for 90lbs torque plus 1/4 turn (???). While running the head bolts to 90lbs, one corner head bolt gave a 'snick', causing me to start looking. Cracked right down the corner of the block. Specs Not always correct! Time I got done with that thing, I had a new engine in it, and rebuilt the transaxle, plus rebuilt the cvc joints. (It had a 1700 cc VW engine in it, and I dislike VW's)

 

[Rowski]

Scruffy

I have had an instance were the torque spec was not enough. It was a crank bolt for the crank pulley (timing belt engine). The original bolt had no lock tight on it so upon assembly the bolt didn't get any. The bolt threaded in by hand to snug. Apply the 65 ft lbs torque as per Subaru spec.. Well customer called back a couple days later with a problem. Went to tow the car in and took a look. The pulley came of and put a hole in the radiator! Well I had to swallow the repair. The bolt in question lossened up did not break and not damage to the crank shaft. So got a new bolt from the dealer and asked about the situation. They said the crank them down to 95 to 110 ft lbs. due to pulley coming loose but not TSBs. The bolt was a 14mm diamter bolt, after the fact, 65 ft lbs seems a little low. Customer is some what happy a little disturbed by his down time. So As you mentioned torque specs are not always right either way, high or low.

Derek

 

[TomG]

The old pointer type is what I've got too. I used it about a year ago and also wondered about the accuracy. I used it after recalling that the deflection of steel shafts is pretty stable unless they've been bent. Maybe Peter has got a better answer. I used it on a steering knuckle. The linkage fell apart the day after I got my tractor. Somebody probably had it apart and didn't know the knuckle will just spin around inside the socket when it's tightened. The steering arm has to be twisted to bind the knuckle shaft. Then the nut can be tightened and brought up to torque. Sure hope nobody got paid for that one.

Overall, I did knowingly overstate my case and was somewhat cranky. Everybody's comments since yesterday seem balanced, informed and useful. A casual reader is likely to come away with some pretty good ideas about this stuff. I learned a few things as well. If my crankiness bought some of that, then I think it's a good result.

Maybe my crankiness can be somewhat excused. For the past several weeks my wife & I were dealing with government (enough to make anybody cranky). A highway engineer wants to redo a highway intersection and expropriate some of our neighbours land and run the new road between our camps. Ouch! In a place surrounded by bush, the engineer threads the needle and runs a right of way within 50' of each of our front doors. Ours are the only two places still on the highway. Getting jerked around by government just seems to be part of living in the country I guess, but maybe this belongs in rural life.

Regarding torquing in the military: I spent 4 years working on ground aircraft guidance systems in the USAF. Military SOPS are procedure happy. Everything in sight is measured. Well, planes do navigate and land by these signals. Most experienced techs could adjust the equipment as well without the sophisticated test gear provided, at least most times, but you know when you can't. However, if there was an accident, aside from legal liability issues, I wouldn't want to spend the rest of my life wondering if a plane fell out of the sky because my feel was off. You better bet us techs did all the measurements. Besides, if you didn't, you just end up mopping floors instead. I imagine the same is true with aircraft mechanics, and I think that torque wrenches are shop, rather than personal, tools. That's probably why my father and friends didn't have them. They had become flyers by the time I was looking for tools.

 

[Bird]

In '85, I decided to use that pointer type torque wrench to put the head bolts back in my daughter's motorscooter. Of course, the manual only called for 9 ft./lbs. The pointer got to about 7 before I twisted the bolt in two./w3tcompact/icons/frown.gif

Bird

 

[scruffy]

Bird,
Are you sure it called for 9 FOOT pounds? Could it have been 9 inch pounds? Big difference. At any rate, that small of a torque setting would call for using a 3/8 or 1/4 inch drive torque wrench. The 1/2 inch drive would be too large, and when working at the bottom end of a torque wrenches scale...I've found them to be inaccurate. I've got them up through 3/4 inch in my toolbox, never had a call for a 1" drive torque wrench, and at the cost of one, I hope I never do!!!
P.S. - They're all 'clickers'.
<P ID="edit"><FONT SIZE=-1>Edited by scruffy on 12/8/00 01:54 PM.</FONT></P>