technical question - breaker bar on torque wrench?

[spicy]

i'm about to adjust/clean/lube my chain, and i was wondering if there is any reason for me not to use a super long breaker bar on my torque wrench for tightening the rear axle nut? (only reason i'm asking anyway is i'm weak/lazy).

as far as my rudimentary grasp of physics goes, and my understanding of torque wrenches, there shouldn't be any problems because the force is measured at the head anyways, which should be exclusive of whatever torque multiplier i'm using, which would mean it doesn't matter if i had a 2mi long breaker bar, it'd just be absurdly easy to exceed the torque required.

i just don't want to way overtighten it and clamp my swingarm or do any other damage to it...

anyone have any thoughts?

[OreoGaborio]

Here's my thought:

[Doc]

I wouldn't use any kinda handle extension on a torque wrench.

[BMFR6]

depends upon the type of torque wrench. if you are using one of the bar style torque wrenchs i would say no breaker bar. if you look at one of these wrenches the bar pivots in the handle. the correct way to ue this wrench is to keep that pivot centered, meaning the bar is not resting against either side of the handle, it is just supported by the pivot. you would have a very tough time pulling that off with a breaker bar.

if you are using a digi torque or something similar, i would think you would be okay.

in all honesty, it doesn't take 9,000 punds of torque so you should be able to pull it off without the bar.

[keeena]

If its a clicker or beam type of torque wrench, a change in leverage (changing hand position or adding offset square-drive attachments) will result in a different torque value applied to the fastener.

Dial-type torque wrenches are not susceptible to changes in handle length.

[spicy]

sounds good. thanks guys. i'll just suck it up and do it with the naked torque wrench

[Doc]

Dial-type torque wrenches are not susceptible to changes in handle length.

I did not know that.

[SSearchVT]

How tight are you making the axle nut??? I weigh all of 135 and have never had a problem getting enough torque from a simple beam scale wrench. Let gravity work in your favor - line the wrench up so you're pushing down instead of pulling up at torque.

As for a helper handle on a torque wrench - It's not the best idea. a long enough handle will give you such a mechanical advantage you can turn a nice torque wrench into scrap without knowing it. Save the helper handle for the 18" breaker bar for taking big stuff apart.

[ZX-12R]

If its a clicker or beam type of torque wrench, a change in leverage (changing hand position or adding offset square-drive attachments) will result in a different torque value applied to the fastener.

Dial-type torque wrenches are not susceptible to changes in handle length.

I'm with you on beam type wrenches but can you explain to me how a clicker type is susceptible to changes in handle length? The internal mechanism works independently of where you apply force with your hands or a cheater bar.

[keeena]

I'm with you on beam type wrenches but can you explain to me how a clicker type is susceptible to changes in handle length? The internal mechanism works independently of where you apply force with your hands or a cheater bar.

Just what I've heard when using both beam and clickers. You're definitely right as far as doubling the length will allow you to apply same amount of fastener torque w/ 1/2 the effort.

My *guess* would be that the clicker mechanism is not exactly at the head of the wrench (meaning its not directly measuring torque at the center of the fastener). The calibration of the wrench takes this offset into account relative to the handle position. If you look at a clicker (the kind I have anyways), the pivot and clicker mechanism is behind the head a bit.

I have 2 clicker wrenches and both specifically mention to apply force @ the handle and at 90*. And my dial torque wrenches highlight the fact that they aren't affected by handle length (perhaps because they measure torque directly at the head of fastener).

[loridin64]

you shouldnt need a breaker bar with additional mechanical advantage to take anything apart on a bike.

eat your damn wheaties in the morning

[seth399]

huh? whether you are applying force 3 inches from the head or 15 inches from the head the same torque is being applied at the head as long as you don't go past the max torque (hear it click). It will just be easier to get it to that value as the moment about the head is changing.
I think people are confusing extensions (off of the head) which can change the torque output.

[seth399]

you shouldnt need a breaker bar with additional mechanical advantage to take anything apart on a bike.

eat your damn wheaties in the morning

this is true, but I put a 1/2" drive socket and slid a steel pipe over it (as a breaker bar) to get my front sprocket bolt off and it didnt budge...I need to find an impact wrench I guess.
This is also a good reason to buy new and never let anyone work on your shit

[TimD]

It should be fine as long as you don't exceed the max torque of the wrench. Most of the torque wrenches I've seen don't have a torque range higher than what you can apply by hand though.

[keeena]

this is true, but I put a 1/2" drive socket and slid a steel pipe over it (as a breaker bar) to get my front sprocket bolt off and it didnt budge...

Are you using your torque wrench to bust the counter sproket nut loose? I've heard thats a no-no too.

But any reason to get more tools is a good reason in my book.

[edit] This article has some good info re: torque wrenches. It does indicate that clicker wrenches do come w/ instructions to use grip location and not use extensions. "[extension] use will result in erroneous torque readings, and may damage the grip or adjusting screw.” If you look at the construction of the clicker you can see how my comment may make sense (the linkage is well behind the drive). But OTOH the author does try a very simple test w/ an extension and didn't see any noticeable torque difference. <shrug>

Up Tight With Torque Wrenches

[seth399]

Are you using your torque wrench to bust the counter sproket nut loose? I've heard thats a no-no too.

But any reason to get more tools is a good reason in my book.

O noway haha, I just meant a regular 1/2" drive socket and socket wrench setup...but was still suprised i couldn't get the damn thing off.

[ZX-12R]

[edit] This article has some good info re: torque wrenches. It does indicate that clicker wrenches do come w/ instructions to use grip location and not use extensions. "[extension] use will result in erroneous torque readings, and may damage the grip or adjusting screw.” If you look at the construction of the clicker you can see how my comment may make sense (the linkage is well behind the drive). But OTOH the author does try a very simple test w/ an extension and didn't see any noticeable torque difference. <shrug>

I think they tell you not to use a cheater bar is because on most clicker types the adjustment is in the handle which could possibly be damaged by the bar. The internal mechanism still works regardless of where you apply force but if you kink something in the handle with a cheater bar, you just destroyed an expensive tool.

[keeena]

O noway haha, I just meant a regular 1/2" drive socket and socket wrench setup...but was still suprised i couldn't get the damn thing off.

OT - but make sure you bend the tabs back on the washer behind the nut first (some folks miss this step).

[seth399]

OT - but make sure you bend the tabs back on the washer behind the nut first (some folks miss this step).

ya I agree, I did check that...but thanks for looking out anyhow.

[SSearchVT]

ya I agree, I did check that...but thanks for looking out anyhow.

Next thing to make sure of - the transmission is in neutral. It can go from a routine PITA job to a real expensive bitch if you bend the shift forks...

[seth399]

Next thing to make sure of - the transmission is in neutral. It can go from a routine PITA job to a real expensive bitch if you bend the shift forks...

ya good point, I was wondering what to do in this case...as I was basically over the bike with my foot on the rear brake and it felt like I was going to snap the caliper off or something before it came loose haha