Help: torquing converter bolts

[maine04max]

the only way i seem to be able to get to the converter bolts is with extensions. there seems to be alot of twist in the extensions and I dont think they will torque correctly . How do you guys do it and what ft /lbs do you guys use?
Thanks Craig

 

[Mike L.]

the only way i seem to be able to get to the converter bolts is with extensions. there seems to be alot of twist in the extensions and I dont think they will torque correctly . How do you guys do it and what ft /lbs do you guys use?
Thanks Craig

Must use 1/2 extension. 3/8 won't cut it. Remember you will lose 2lb tq for every 1" of extension length. If you use multiple 3/8 extensions connected, all bets are off. Do it right the first time.

 

[SIKDMAX]

Remember you will lose 2lb tq for every 1" of extension length.

Cool! Didnt know that.

 

[maine04max]

Thank you very much Mike , you are a life saver :hug:

 

[mainer]

Must use 1/2 extension. 3/8 won't cut it. Remember you will lose 2lb tq for every 1" of extension length. If you use multiple 3/8 extensions connected, all bets are off. Do it right the first time.

maybe i'm wrong here but from my engineering background and knowledge of torque over a distance etc....

if the extension flexes your just pulling the wrench farther.


It is simple laws of physics, whatever force you input into one end of that extension is what is going to be exerted on the other end period. If you were getting less energy out of it than you put into it where on earth does that energy go?


The only way i see the desired torque being altered is if the extension is to not be perfectly perpendicular from the fastener.

now i'm certainly not encouraging you use 4ft of 1/4" extensions to torque your lug nuts down.... but i think its fine to use 2ft of 1/2 extension etc when needed and if you are twisting off the fastener (not perpendicular to it) your going to end up stripping it anyways so the torque being low is not going to be your issue the stripped fastener is.

 

[duratothemax]

as long as extension doesnt snap off, it is still transmitting all of the torque through the extension to the bolt.

Even if the extension DOES start to twist (yeild) and passes its elastic region, IF the torque wrench "clicks" before the thing actually breaks, you still transmitted the desired amount of torque to the bolt.

Where extensions DO make a difference is if they are loose fitting, you are less likely to keep the extensions perfectly in-line, as foster said. Or if you use a u-joint socket, that will mess with the torque reading/transmitted as well........

ben

 

[Mike L.]

maybe i'm wrong here but from my engineering background and knowledge of torque over a distance etc....

if the extension flexes your just pulling the wrench farther.


It is simple laws of physics, whatever force you input into one end of that extension is what is going to be exerted on the other end period. If you were getting less energy out of it than you put into it where on earth does that energy go?


The only way i see the desired torque being altered is if the extension is to not be perfectly perpendicular from the fastener.

now i'm certainly not encouraging you use 4ft of 1/4" extensions to torque your lug nuts down.... but i think its fine to use 2ft of 1/2 extension etc when needed and if you are twisting off the fastener (not perpendicular to it) your going to end up stripping it anyways so the torque being low is not going to be your issue the stripped fastener is.

If you read what you just posted you will answer your own question. You lose the tq in the twist of the extension. Simple test; tq a bolt with a 2ft extension and then remove extension and retq with socket only.
Are you an engineer ?

 

[Mike L.]

as long as extension doesnt snap off, it is still transmitting all of the torque through the extension to the bolt.

Even if the extension DOES start to twist (yeild) and passes its elastic region, IF the torque wrench "clicks" before the thing actually breaks, you still transmitted the desired amount of torque to the bolt.

Where extensions DO make a difference is if they are loose fitting, you are less likely to keep the extensions perfectly in-line, as foster said. Or if you use a u-joint socket, that will mess with the torque reading/transmitted as well........

ben

This could be true if all extensions were the same, but they are not. Tire shops have special extensions to tq wheels.

 

[TrentNell]

This could be true if all extensions were the same, but they are not. Tire shops have special extensions to tq wheels.

i was just going to post that Mike about "torque sticks " . the diameter of the stick usually determines the amount it torque's the fastener .

 

[mainer]

yes but torque sticks are used with an impact gun. not a torque wrench or ratchet (not their intended use). They have a certain elasticity and flex that allows them to flex in sync with the blows of the Impact wrench once a certain amount of torque is reached. The flexing at its torque limit prevents the stick from exerting any more force on the nut and overtightening it.

this is completely different than whats being debated above


and no i guess i'm not an engineer.... not yet, give me one more semester

where do you get the 2lbs loss of torque per inch?

 

[duratothemax]

This could be true if all extensions were the same, but they are not. Tire shops have special extensions to tq wheels.

but the way an impact wrench works though is much different than the way a torque wrench works as far as how the bolt sees the force applied, when you use a torque wrench its obviously a constant smooth force, where as the impact wrench hits it with little bangs.

Because an impact "hits" so fast, the force is absorbed by the twisting of the extension and the torque doesnt have enough time to transition smoothly to the bolt head. When an impact wrench "hits", its always hitting with the same force each time. When you put leverage on a bolt/tighten a bolt with a torque wrench or ratchet, you are constantly increasing the force exerted on the extension/bolt. I guess when an impact wrench says its capable of "500 ft lbs", all that means is it hits the bolt with enough force to get it tightened to the rough "equivilant" of if you ACTUALLY applied 500 ft lbs of smooth steady static (not dynamic) force to the bolt with a breaker bar/torque wrench.

Thats why the torque sticks work; they are only compatible/work when used with impact wrenches because of the way an impact wrench exerts force as a moment arm. If you apply a smooth constant force to a torque stick, its not going to work properly. Say you have 2 bolts and a single torque wrench set to 100 ft lbs. One of the bolts you tighten directly with the torque wrench....pull the wrench until it clicks. Then put say a "50 ft lbs" torque stick on (but kept the torque wrench set on 100 ft lbs), and repeat until the wrench clicks. If you then measured each bolt I guarantee both would be roughly the same torque. HOWEVER, if you use an impact wrench in that situation, all bets are off and they will NOT be torqued equally.

Thats why it is especially important when you use a torque wrench to tighten in a smooth steady pull...dont bounce on the torque wrench because in that case if you are bouncing on the torque wrench to get it to click, yes, twist in the extensions WILL affect it.

I cant really explain it though??

ben


EDIT: foster beat me to it...nvmind

 

[sweetdiesel]

I am not a engineer....But just cause it clicks doesnt mean its right?
If there is twist in the extensions we are actually TQ all of this. When your done tqing and release the tension that is absorbed in the extions is released and the bolt isnt as tight... ,Maybe not?

Crows foot for example having at a 90* or a 45* makes a differrence

 

[durallymax]

I took mikes dvice and did it by feel.

I know that personally 45lb-ft is a tight as i can get the bolt with the ratchet i use.

I use a 15mm deep well and a 3" extension, then an 8" 3/8" ratchet and tighten it right there.

My first time i guess i didnt get them tight enough, they worked loose.

Since then i havent had one work loose. This method works for me. However I may be overtoqueing. I do know the motor turns nd then i turn the bolt probably another 10 degrees.

 

[duratothemax]

I am not a engineer....But just cause it clicks doesnt mean its right?

why not??? Simon think about it. The wrench clicks when it sees X amount of torque/resistance. If one end of the extension is seeing 45 ft lbs of resistance, the other end is going to see the same damn thing.

think about it like a torsion bar on your truck. They twist a lot dont they? So by your theory, I could probably hold one end of the bar in my hand and it would "work"....because even though the suspension might be putting 300 ft lbs on one end, the bar is twisting a lot and absorbing a lot of torque, so the other end might only see 50 ft lbs. NO. The mount on one end of the torsion bar needs to be just as strong as the other end because they both see the same forces.

heres another example. Axle shafts and driveshafts. They can twist and are theoretically directly equivilant to a socket extension. By your theory, we could gain a lot of rear wheel torque by shortening the driveshafts and narrowing the rear axle. NO. Doesnt work that way.

As I said before, AS LONG AS THE EXTENSION IN QUESTION DOESNT SNAP OFF its transmitting 100% of the torque from one end to the other.

the only situation where transmitted torque is affected is if you dont keep the extension perfectly perpendicular/inline with the bolt head, and at a perfect right angle to the torque arm (read: your socket wrench or torque wrench).

We need Guy to see this so he can give the definitive answer...

ben

 

[hondarider552]

I just torque my lug nuts to 140 ft lbs and go drive...

:rofl:

 

[GMC_2002_Dmax]

Can't we all just get along..........

Mike tries to help, he has R&R'd more Allison's that anyone I know except maybe Big Dipper.

If you want to argue with him that is your prerogative, arguing over how much TQ is lost is fine if your sending a man into space, but a few lbs on TC bolts when they are Loctited anyway is splitting hairs.

I used to deal with engineers on a daily basis, no offense to any here, but you guys always look at things in Black and White, the world is full of many shades of gray !!!

 

[sweetdiesel]

um why not??? Simon think about it. The wrench clicks when it sees X amount of torque/resistance.
ben

Im thinking of it as when you let off on the tq wrench and extensions that there is absorb tq in the extension ( only if they are loose extension )

Im not thinking its a big deal, but i think there is still a difference

 

[Mike L.]

I dissagree Ben. You can realy see this well using a 3/8 extension and trying to take off a lug nut. Watch the extension twist and absorb all the tq and the nut never moves.

 

[WolfLMM]

Take a shaft apply 20ft/lbs to one end, now measure the tq at the other end it WILL equal 20ft/lbs. The only way it will not is if the shaft is yielding or has broke.

A crows foot affects the geometry, thus throwing the tq reading off a little.

 

[duratothemax]

Yes, the extension does twist, but the bolt is still seeing the same amount of torque applied, because when the bolt twists, you just swing the torque wrench further to account for the twist in the extension.

This is only relevant when using a torque wrench or breaker bar. If you use an impact, yes, you "lose" the amount of torque able to be applied to the bolt with an extension that twists. Here is the mathematical equation to determine how angle and length affects a torque artm.

Torque = L * F * sin(A)

where

L = length of lever (from where you hold the wrench to where it rotates about an axis (bolt)
F = force applied to lever
A = angle at which the force is applied in relation to the lever arm (the ideal angle is 90* if you keep the extension perpendicular on the bolt and dont try to bend it to one side along the "X" or "y" axis. I put those in quotes because they arent technical engineering terms, but its a basic way to grasp concepts and think of things as)

there is no part of the equation that refers to length of an extension, because its still perpendicular to the bolt....if you look at it from a "two dimensional" point of view, nothing has changed in the force legver...you've only added something to I guess what you could refer to as a "z-axis", which doesnt change the way torque is transmitted in physics.s I think thats the right equation, I read it in a physics/engineering book a while ago because I was wondering the same thing, so I might have it wrong??


http://www.jeepforum.com/forum/showthread.php?t=616139

http://home.jtan.com/~joe/KIAT/kiat_3.htm

I think the main thing is people are confusing/not realizing that the way an impact wrench "torques" a bolt is much different than the way a torque wrench or breaker bar "torques" a bolt.

ben