Torque question

[Admiral Nelson]

Its always tricky isn't it. I asked about a torque value on a Vrod forum - had I followed it, I would have sheared the bolt. I managed to obtain a manual for my Vrod and I tended to follow it..

 

[Dr.Evil]

On our products we recommend sealent because tape will shread on can contaminate solenoids etc..

We have used this with great results.

 

[bc45]

I found that when torqueing fasteners to use the right size torque wrench. If you try to torque Derby cover bolts to 8ft lbs with a 1/2 drive 2foot long or3/8 drive 1 1/2 foot long torque wrench you will probly stripp or break the bolts if you use a small 1/4 drive tourque wrench you will be able to correctly torque them.

 

[R_W_B]

I found that when torqueing fasteners to use the right size torque wrench. If you try to torque Derby cover bolts to 8ft lbs with a 1/2 drive 2foot long or3/8 drive 1 1/2 foot long torque wrench you will probly stripp or break the bolts if you use a small 1/4 drive tourque wrench you will be able to correctly torque them.

Well I don't doubt your word, but I would think the torque wrench needs recalibrated or a new one bought if it doesn't click (or read) what it should no matter what size drive or length the wrench is. Foot lbs of force is what it is, if a wrench doesn't respond the set ft. lbs (or inch lbs) then it is useless.
Or are you saying to make sure you get a wrench within the torque "range" of the specs ? If so then yes I totally agree that would be necessary.
Additionally some click type torque wrenches I have used are of the cheaper version, some worked good others were a little off. I tend to always test them with the "physical needle type" before doing anything important. The reason I don't use needle types all the time is they are hard to read upside down and sideways.

 

[Dr.Evil]

RWB makes a good point. If a wrench has a 1% tollerance full scale and is 200ftlbs that 2 ftlbs could be off at 8ftlbs, but that should not be enough to overtighten and brake or strip. You should try to use a wrench rated closer to the spec for accuracys sake.

 

[Admiral Nelson]

My torque wrench came with a calibration certificate.

In the Navy, we had to send all of the torque wrenches away for annual calibration.

 

[bobwire]

look at the torque specs. for origional question. 33% hummmm................bw

 

[Elmosac]

In some cases Yes!. Do you actually believe because the "factory" said so, it is 100% absolutely correct.? I can not tell you the number of times I have found the manufacture to be INcorrect. Even though they developed the product, it does Not mean an improvement or a mistake can not be found.

I won't argue that the engineers don't make mistakes, recalls happen all the time because of them. However ignoring torque specs is not something that you do in my world. I have seen torque specs get changed when it was discovered that there in fact was a problem, but don't ever recall something having a torque spec removed.

Your argument for ignoring the torque spec was only supported with "I've done it that way for years and never had a problem"

Not to many people get caught drinking and driving the first time they do it, but if you keep on doing it, it will catch up with you sooner or later. Either way it doesn't make it right.

I am open minded and able to accept other peoples points when they can support them with something more than "I did it and it worked out for me"

If I get hosed by a bad product I can go after the manufacture. If I get hosed by bad advise on a forum, I'm all on my own.

Don't take that personally, I see people offer their opinions as fact on forms all the time. Most don't mean any harm.

No need to respond to this as I'm not looking to pick a fight, so I won't respond to any replies anyway.

[ Elmosac wrote : First, why would you not follow the torque specs in the manual? ]

Well that was the question, my thoughts were since the teflon tape (or any pipe dope) lubricates the threads so as to allow easily tightening to a leak proof state, the "torque" or twisting resistance you feel would not be the same as raw metal. Which I would have to assume the torque values are based on raw metal. So you could actually tighten it past the recommended point if you kept going to the documented resistance on the wrench.
It is not leaking and it's tight enough that I don't think it's going to vibrate loose so I figure I'm in much better shape than a stripped thread on my crankcase. I don't have them accessible right now but some Harley manuals (and printed sheets that come with parts) have different torque values for the same parts, it's rare but I have seen it. But of course that last statement is deviating a bit from the point of my question. I have done a bit of house plumbing and the whole reason for pipe dope is to make the tightening of pipe thread easier since in some tight places it can be pretty darn hard to get copper, brass or galvanized to tighten enough not to leak, it tends to bind without pipe wrap or dope and you will keep getting those slow drips without it.

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Oh and by the way the reason natural gas codes don't allow teflon tape is because pieces of it can clog the gas fiittings if they get loose in the pipe. I think that is to protect against sloppy work since if you leave it away from the first threads in that won't happen. But most plumbers in my area use teflon on everything but gas since it stops leaks better. I'm not a plumber, (I did work in construction most of my life) but the side plumbing I have done, I have had pipe dope keep having a slow drip leak. I would pull the joint apart clean it up and wrap it with teflon and it would not leak. But again the point is, it changes the torque resistance on the wrench.

I follow what you are saying but don't follow you logic. 100 ft/lbs of torque is just that. It doesn't matter if you use thread tape or pipe dope or nothing. You are not trying to get a certain number of threads screwed in, you are making it tight enough so that it holds and does not leak. If they threads could not hold the pressure they would strip out with or without thread tape, dope or anything else. Thread lube actually allows you to get a more accurate torque on the fitting as your reducing thread friction. But even with thread friction, 100 ft/lbs of torque doesn't change at the wrench.

I have always found the tape to clog up the threads and make it harder not easier to tighten things up. That is why I tend to stay away from it.

Wow…..your reply is quite a bit condescending to me. If you think someone should stick to the manual you should probably just say “hey my friend I’ve been a professional mechanic for years and would recommend you stick with the manual.”

See how much nicer that sound!!!!

I guess that I just don't know when to keep my mouth shut (or hands off the key board)

Your right though, it would have taken less time and been far less controversial.

 

[Hoople]

Elmosac, I understand your point 100% but also realize you are coming from an aircraft world as a Jet engine mechanic. Your everyday principals and practices are 10 times more precise than what we are doing here. Your carrying over upstanding practices to our everyday consumer grade products (a Chevy Astro Van for example) and we need to not mix those up..

The products you are working have FAR greater detail and quality than the average consumer grade product.

I am sure a final jet aircraft product & it's service manuals have been tested, proof-read, tested, proof-read and tested once again...before they are sent to market. Do you think that really happens to the Chevy Astro Van sold down on the corner.?

Correct me if I am wrong,,, but isn't it true that an owner of a jet plane, by law can Not "tune up" his own engine? Even if he has an engineering degree and a Manual, he is not allowed by law to "change the plugs" on his own Jet plane. I only say that because your everyday practices are 10X in precision than what the average wrench performs.

Lets take for example the "Fall Away" adjustment on the neck bearings that we all have on our bikes. The service manual goes something like this..."Lift the front wheel off the ground and make the bike level with the bars straight ahead. Tap on the bars left or right. Adjust the bearing crush nut until the "bind" allows the bars to "fall away" at 2" from either center"

I really wonder what a company like Timken would think of this procedure. I wonder which HD "engineer" came up with that method to adjust & set preload on a set of taper roller bearings?

I agree with everything you say regarding following specifications of torque. I also realize the precision your profession demands & how the product drives the need to be accurate.

 

[Dr.Evil]

Two mechanics service the same aircraft pump. The plug torque spec is 50-60 in lbs, they both misread the spec as 50-60 ft lbs. One technician believes everything he reads, and torques the plug to 55 ft lbs and cracks the housing, but he is not aware of it. The second tech is tightening the plug and notices that at 12 ft lbs it should be tight, he stops, ignoring the spec. When he checks the spec, he realizes the mistake. I will take the technician who knows when to question information, weather it is written wrong or just misinterpreted.