I have a question for all you pro mechanics out there. Listed throughout my FSM, there are torque specs listed for every little bolt on my engine. Do professional mechanics really torque every single bolt? Sometimes I'm lucky if I can get a socket or wrench on a bolt, much less a tourque wrench. I understand torquing the important things like headbolts etc., but what about little things like your thermostat cover bolts that are a PIA to get to? Just wondering.
I use a torque wrench on every bolt I can get a socket on. With an aluminum block engine, it is too easy to strip the threads out by overtightening. Of course, certain ones are critical to tighten correctly, like head bolts, rod bolts, and cam bracket bolts (which seem to snap rather easily).
Well, it depends. I've seen my dad work on engines (owns his own shop, has been a technician for almost 20 years), he uses a torque wrench on every engine bolt that is absolutetly critical to have to spec. The one's that don't he usually senses when it's tight enough. I guess after 20 years or wrenching you can do somethings by feel.
Head bolt torque is very important, as is intake manifold bolt torque, and most all internal engine things ....Otherwise, I tend to do everything else (outside the engine) by feel. Feel can get you in trouble too though, especially with bolts that have been heat stressed, like exhaust manifold bolts. They tend to break rather easily if reused or even slightly over tightened. Same thing with bolts smaller than 10 mm. And like Ish said, you don't really want to mess around on an aluminum block. Some places are impossible to fit a torque wrench into, so I usually limit the torque I can put on a small bolt by using a "shorty" wrench, or even 1/4 drive on the really small stuff.
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1992 Yamaha FZR 1000. 145 Hp, all stock..
I use a torque wrench on every bolt I can get a socket on. With an aluminum block engine, it is too easy to strip the threads out by overtightening. Of course, certain ones are critical to tighten correctly, like head bolts, rod bolts, and cam bracket bolts (which seem to snap rather easily).
Lew
When using a torque wrench does it matter if you are using an extension or a u-joint connection? And if does, how are you supposed to allow for these factors? Sometimes I wind up with some pretty strange ratchet/extension/u-joint combinations to tighten some of my bolts. I can't help but think it would effect your torque wrench reading with all the stuff hooked onto it. Of course, I'm sure there are better ways of going at bolts than I do, but sometimes, it just seem no matter what, you gotta put some pretty strange stuff together to get the bolt tight.
When using a torque wrench does it matter if you are using an extension or a u-joint connection? And if does, how are you supposed to allow for these factors? Sometimes I wind up with some pretty strange ratchet/extension/u-joint combinations to tighten some of my bolts. I can't help but think it would effect your torque wrench reading with all the stuff hooked onto it. Of course, I'm sure there are better ways of going at bolts than I do, but sometimes, it just seem no matter what, you gotta put some pretty strange stuff together to get the bolt tight.
im more than sure extensions dont affect it, not sure about u-joints, but i doubt they do
Some places are impossible to fit a torque wrench into, so I usually limit the torque I can put on a small bolt by using a "shorty" wrench, or even 1/4 drive on the really small stuff.
I like that thinking. I've been looking for an excuse to buy a 1/4 drive set and a shorty set. Now I can explain to my wife why it's so important that I have those tools in my box.
im more than sure extensions dont affect it, not sure about u-joints, but i doubt they do
Seems like back in my Army days, we had a tech-bulletin of some sort that covered allowances for extensions on torque wrenches. Of course I wasn't a mechanic and didn't actally work on vehicles (I just kept up with the parts) so I don't remember for sure. Then again, those were 52-ton tracks and not little Nissan cars so that might have had something to do with it.
i dont torque anything to spec. unless its something to do with the engine its self (like you all said before head bolts etc.) i havent use a torque wrench on any bolt on my car.
and i think youre going a little overboard if you torque down your lugnuts
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91 sentra 2dr E 4 spd......getting stripped and junked...mission aborted
91 NX2k auto eggshell white :cool:
mods: uh...prothanes for when the motor goes in...otherwise stock
When using a torque wrench does it matter if you are using an extension or a u-joint connection? And if does, how are you supposed to allow for these factors? Sometimes I wind up with some pretty strange ratchet/extension/u-joint combinations to tighten some of my bolts. I can't help but think it would effect your torque wrench reading with all the stuff hooked onto it. Of course, I'm sure there are better ways of going at bolts than I do, but sometimes, it just seem no matter what, you gotta put some pretty strange stuff together to get the bolt tight.
For extensions it doesn't matter. For u-joints, it won't matter either unless you're trying to make some extreme angle and it ends up binding. Where you can run into trouble is if you do anything to lengthen the wrench (i.e. use crow's feet, etc)
I torque every drivetrain and chassis bolt to spec. I have many different torque wrenches in my tool box. It is also important to have the torque wrench calibrated periodically to insure accuracy. For critical engine fasteners like the headbolts and rod bolts, I use the torque angle method or stretch gauge with a dial indicator which is much more accurate than a digital torque wrench. ARP bolts has a good tech article on why each of these tension methods are better or worse than the others. http://www.arp-bolts.com/pages/tech/fastener.html
I don't do the "feel" torque because after replacing your 2000th broken stud or bolt especially the M6 or M8 bolts in the car because someone before you had an "off day" or several people did, then you start to torque more fasteners as a regular practice. I always torque suspension fasteners because if one of those pieces fails it could mean an accident or worse. The wheels are an ALWAYS torque item because not only is it a way to double check your work but it saves the rotors from warpage because of uneven preload from the different torque values on each lugnut.
It maybe "overkill" to some but it makes for a safer more reliable vehicle after it leaves the shop because the job was done properly.
An extension on either side changes the torque values. Like the extension on a torque wrench multiplies the torque because the leverage changes. The correct torque measurement is going to be with your hand on the hand grip. The torque measurement changes when a socket extension is used as well but it is decreased. Also no reliable torque value can be obtained with a u-joint because the fulcrum angles change thus it is no longer measuring with any physical constant.
Troy
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1992 S13 240SX SE Fastback KA24DE 5 spd - Type X Aero & Seibon Carbon Hood & Hatch -soon GT28RS
1993 U13 Altima SE KA24DET 5 spd w/ Nismo LSD - A high hp FWD can be fun (GT30R Turbo inside)
1990 Z32 300ZX VG30DETT 5 spd - 600HP & Very Civilized (working on twin GT28RS turbos)
Still trying to import a 1988 R31 Skyline GTS-R w/ RB20DET-R - only 800 produced (legal under show/display regs)
Last edited by KA24Tech : Feb 10th, 2005 at 04:06 PM.
....Otherwise, I tend to do everything else (outside the engine) by feel. Feel can get you in trouble too though, especially with bolts that have been heat stressed, like exhaust manifold bolts. They tend to break rather easily if reused or even slightly over tightened. Same thing with bolts smaller than 10 mm. And like Ish said, you don't really want to mess around on an aluminum block. Some places are impossible to fit a torque wrench into, so I usually limit the torque I can put on a small bolt by using a "shorty" wrench, or even 1/4 drive on the really small stuff.
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