Getto Torque Wrench

[Slideways]

I'll be replacing the belt on a Brose 1.2S motor soon and am seeking specific advice. The folks at Brose are quite firm that the torque on the set screw that sets the tension of the belt tension pulley he set to their spec. That torque value is 0.2Nm (1.77in/pds). My inch pound torque wrenches start at 40 in/pds and some quick searching for a tool that reads that low turned up nothing but really expensive options. I have no interest in spending lots for a tool that will likely be used only two or three times. Reaching back to my school days and recalling basic physics class lead me to a cheap way to solve this twisting problem. My hope is someone truely knowledgeable in these things will confirm if my idea will work and if my calculations are correct.

Here goes. In layman terms torque is force on a moment arm. An inch pound, if I understand, is a pound acting perpendicular to a lever at one inch out from a center of rotation. With this in mind I figure a 200gm weight hung 4 inches from center of the set screw will do the trick. I cut an Allen wrench so it extended out from the set screw just enough to clear the motor case. Next at 4 inches out from center of the short end of the wrench a small groove was made. Now a 200gm weight (a small bag with pennies) is hung from the wrench. I can pick up the motor and rotate it until the tension on the set screw causes the Allen to rotate up to a horizontal position and stay there. All right smart people is this going to work? Thanks in advance.

 

[Rusty]

Y'all should have a small Torque Wrench - I use mine at least a couple times a month.
Cheapie

 

[Webike]

Y'all should have a small Torque Wrench - I use mine at least a couple times a month.
Cheapie

Not sensitive enough. Best if the specified value falls midrange on the tools torque range...especially on something as finicky as this. There are some torque screwdrivers out there in the $50 range but would you trust them? Capri tools sells a quality looking driver on Amazon for $114 with a perfect torque range...from .5 to 6 inch pounds.
BTW, I seem to recall the belt setting was 0.25 to 0.3 Nm...I need to review "Bearing Man" video on Brose rebuild.
Sorry, I can't answer the ghetto question but it is interesting.
The math looks right...I think.
Check this post:
Brose S and T overhaul video done at last!

 

[Zimmerframe]

Not sensitive enough. Best if the specified value falls midrange on the tools torque range...especially on something as finicky as this. There are some torque screwdrivers out there in the $50 range but would you trust them? Capri tools sells a quality looking driver on Amazon for $114 with a perfect torque range...from .5 to 6 inch pounds.
BTW, I seem to recall the belt setting was 0.25 to 0.3 Nm...I need to review "Bearing Man" video on Brose rebuild.
Sorry, I can't answer the ghetto question but it is interesting.
The math looks right...I think.
Check this post:
Brose S and T overhaul video done at last!

I think your link edit went funny .... the link again :

Brose S and T overhaul video done at last! - EMTB Forums

 

[steve_sordy]

I worked it out and got 0.1994Nm.
Close enough for government work I guess.

 

[Slideways]

I worked it out and got 0.1994Nm.
Close enough for government work I guess.

Well there is the weight of the long arm of the Allen wrench which I imagine factors in somehow but that calculation is above my pay grade. I weighed the wire I used to hang the pennies as well as the little bag and the pennies. I used pennies because I could get really cost to the desired weight.

 

[Zimmerframe]

Well there is the weight of the long arm of the Allen wrench which I imagine factors in somehow but that calculation is above my pay grade. I weighed the wire I used to hang the pennies as well as the little bag and the pennies. I used pennies because I could get really cost to the desired weight.

I'm getting the feeling that beneath all this, your subconscious just isn't happy with the idea of spending Supermarket Bicycle money on a tiny spanner/screwdriver which clicks

 

[steve_sordy]

I'm getting the feeling that beneath all this, your subconscious just isn't happy with the idea of spending Supermarket Bicycle money on a tiny spanner/screwdriver which clicks

Trouble is that 0.2Nm or 1.77 inch pounds is just a tiny bit more than finger tight!
But whose fingers? And when? (before or after a good night out?). And how much is "a tiny bit more"?

If it is crucial, I would have more faith in Slideways method than a torque wrench working accurately enough at that level. It would need to be kept in a clean grease proof bag and not left knocking about in my toolbox to be sure of retaining its accuracy.

 

[Webike]

It seems to me that this setting, if finite, would require readjustment very soon after the belt is broken in and stretched out via stress & temperature but what do I know??
My Levo emits a whine noise when the motor is above 105 degrees F and climbing but my wife's Levo can barely be heard even with my 205 lbs aboard.

 

[Zimmerframe]

My Levo emits a whine noise when the motor is above 105 degrees F and climbing but my wife's Levo can barely be heard

....... Over her own whining ???

 

[steve_sordy]

Y'all should have a small Torque Wrench - I use mine at least a couple times a month.
Cheapie

Like many riders, I have a torque wrench with a similar range to the one your link points to. The problem is that its lowest setting is 2Nm. The OP (Slidways) needs something that is one tenth of that! (ie 0.2Nm)

 

[R120]

Can you borrow one?

 

[Zimmerframe]

Here's one for £60 ..


In case that doesn't work ..

www.amazon.co.uk/FIRSTINFO-6-35mm-Adjustable-Torque-Screwdriver/dp/B073B1FG9K/ref=pd_sbs_263_5/280-7103305-2958166?_encoding=UTF8&pd_rd_i=B073B1FG9K&pd_rd_r=d9403c5e-bf12-43ac-8f75-7d0bc2dc1852&pd_rd_w=Ptv3Z&pd_rd_wg=dKjOZ&pf_rd_p=f4a31d1d-8f61-48f5-b6f4-a22ba06df575&pf_rd_r=5A03W54QYKT2AVQPCZNC&psc=1&refRID=5A03W54QYKT2AVQPCZNC

 

[steve_sordy]

That looks good, and unlike every other torque wrench I've seen it works in both directions.
Pricey though!

 

[Binhill1]

I'll be replacing the belt on a Brose 1.2S motor soon and am seeking specific advice. The folks at Brose are quite firm that the torque on the set screw that sets the tension of the belt tension pulley he set to their spec. That torque value is 0.2Nm (1.77in/pds). My inch pound torque wrenches start at 40 in/pds and some quick searching for a tool that reads that low turned up nothing but really expensive options. I have no interest in spending lots for a tool that will likely be used only two or three times. Reaching back to my school days and recalling basic physics class lead me to a cheap way to solve this twisting problem. My hope is someone truely knowledgeable in these things will confirm if my idea will work and if my calculations are correct.

Here goes. In layman terms torque is force on a moment arm. An inch pound, if I understand, is a pound acting perpendicular to a lever at one inch out from a center of rotation. With this in mind I figure a 200gm weight hung 4 inches from center of the set screw will do the trick. I cut an Allen wrench so it extended out from the set screw just enough to clear the motor case. Next at 4 inches out from center of the short end of the wrench a small groove was made. Now a 200gm weight (a small bag with pennies) is hung from the wrench. I can pick up the motor and rotate it until the tension on the set screw causes the Allen to rotate up to a horizontal position and stay there. All right smart people is this going to work? Thanks in advance.

Think you need to recount that one mate ???

 

[Mikerb]

Personally I think torque settings that low are a nonsense. Few torque wrenches are accurate to within those small margins...or stay accurate over time with use and with temperature variation and most fixings take extra torque to initiate movement. Brose would be better merely stating how many turns on the screw ( better still how much deflection on the belt except the belt is hidden when the torque is applied!). Most belts drives in cars for example are tensioned just sufficient to remove free play and prevent it jumping...…..these days that is done by hydraulic pressure rather than a manual adjustment. If there is a way to do it I would be inclined to tension by eye/feel.

 

[steve_sordy]

My mechanical engineering apprenticeship calibrated me on steel, cast iron and aluminium alloy. It helps that the relevant hand tools are sized to help with the application of the correct torque. I gave up when I bought my first carbon fibre component (bars). The torque required was smaller than that for anything I was used to and the consequences of getting it wrong were unpleasant. So I bought a torque wrench. The problem is that the wrench handles are so big that they remove all the feel from what I'm doing. I just have to trust the wrench!

And why aren't they all made so that they can go clockwise or anticlockwise. The first wrench I bought even had that little lever to switch the ratchet over. The first time I worked on my pedals, I used the lever to tighten a left-hand thread and irretrievably damaged the torque wrench. (Rant over!)

Edit: It was only when I broke it that I discovered that the small print said right hand threads only. So why make it capable of winding anticlockwise, with a reversible ratchet?

 

[Webike]

Here's one for £60 ..


In case that doesn't work ..

www.amazon.co.uk/FIRSTINFO-6-35mm-Adjustable-Torque-Screwdriver/dp/B073B1FG9K/ref=pd_sbs_263_5/280-7103305-2958166?_encoding=UTF8&pd_rd_i=B073B1FG9K&pd_rd_r=d9403c5e-bf12-43ac-8f75-7d0bc2dc1852&pd_rd_w=Ptv3Z&pd_rd_wg=dKjOZ&pf_rd_p=f4a31d1d-8f61-48f5-b6f4-a22ba06df575&pf_rd_r=5A03W54QYKT2AVQPCZNC&psc=1&refRID=5A03W54QYKT2AVQPCZNC

Potentially great find Zimmer!
Looks almost exactly like the one I referenced in post #3 above at 60% of the cost...which one is the "knock-off" or is it a private labeling arrangement? Nice looking tool and with "free returns" could be the less risky investment. I'll risk it when the time comes for a new belt out of warranty.

CAPRI TOOLS: Model # CP21075S via Amazon USA (Link will not copy/paste to UK site??)

 

[Zimmerframe]

Potentially great find Zimmer!
Looks almost exactly like the one I referenced in post #3 above at 60% of the cost...which one is the "knock-off" or is it a private labeling arrangement? Nice looking tool and with "free returns" could be the less risky investment. I'll risk it when the time comes for a new belt out of warranty.

CAPRI TOOLS: Model # CP21075S via Amazon USA (Link will not copy/paste to UK site??)

www.amazon.com/Capri-Tools-Screwdriver-inch-pounds-inch-pound/dp/B07C3HW56N/ref=sr_1_fkmr0_1?keywords=CAPRI+TOOLS%3A+Model+%23+CP21075S&qid=1574965536&sr=8-1-fkmr0

You need to remove the "https://" or it tries to be clever lately, for some reason, and screws up some of the links ...

 

[Mcharza]

I use this for smaller torques, I have been satisfied.
Lezyne Torque Drive

 

[Zimmerframe]

I use this for smaller torques, I have been satisfied.
Lezyne Torque Drive

Nice, looks pretty too .... but sadly rated at 2-10 Nm , so a bit like a sledgehammer in this search for a delicate toothpick freshly treated with liquid nitrogen.

 

[Binhill1]

Yes need 3 different wrenches great big one for the crank . I've managed with out since 86 so unless I get one for Xmas not be bothering. I've got my helmet on for the onslaught.

 

[Binhill1]

Yes need 3 different wrenches great big one for the crank . I've managed with out since 86 so unless I get one for Xmas not be bothering. I've got my helmet on for the onslaught.

 

[Slideways]

The best torque spec I ever heard of came to me from a customer care rep at SRAM. She was someone whose advice was always spot on so it was with some surprise when she answered my question about the torque spec of a certain crank. Her answer was RFT... There was a pregnant pause while my slow brain figured it out then I couldn’t stop laughing. Been using it ever since.

 

[Rusty]

The OP (Slidways) needs something that is one tenth of that! (ie 0.2Nm)

Yup - didn't have my glasses on and thought it was 2.0

 

[wepn]

How bout this:

www.amazon.com/Gedore-PGNS-1-5-FS-Screwdriver/dp/B06XPXH8GH/ref=sr_1_12?keywords=0.2+nm+torque+wrench&qid=1575001871&s=power-hand-tools&sr=1-12

 

[Zimmerframe]

How bout this:

Tried to post the link but it doesn't appear if not altered. Is Amazon banned here???

You'll need to replace *AMAZON* with amazon.

https://www.*AMAZON*.com/Gedore-PGNS-1-5-FS-Screwdriver/dp/B06XPXH8GH/ref=sr_1_12?keywords=0.2+nm+torque+wrench&qid=1575001871&s=power-hand-tools&sr=1-12
View attachment 22259

Nope .. for some reason the forum keeps trying to be clever and change the hyperlinks into media, so you have to delete the "https://" and then it works as a link.

 

[Binhill1]

The best torque spec I ever heard of came to me from a customer care rep at SRAM. She was someone whose advice was always spot on so it was with some surprise when she answered my question about the torque spec of a certain crank. Her answer was RFT... There was a pregnant pause while my slow brain figured it out then I couldn’t stop laughing. Been using it ever since.

Exactly touch wood never had one come off yet. You know as soon as you take one off that it was RFT ?

 

[steve_sordy]

When you know that it is going the be RFT, then you have to be CERTAIN that you also know which way to RFL!
Writing as someone who has twisted a 10 mm Allen key!

 

[Binhill1]

When you know that it is going the be RFT, then you have to be CERTAIN that you also know which way to RFL!
Writing as someone who has twisted a 10 mm Allen key!

I could break an anvil Steve not even aloud to hammer a nail in at home.