Torque Arms

[TricycleMichael]

Have had some issues with the commonly available two piece torque arms. I prefer single piece like the photo.
Can't find them, can anyone help?

 

[markz]

Make your own, I just head to Home Depot to buy the steel and use your angle grinder then use a thick and thin wheel, do the thin first to get the sides perfect, constantly measure constantly with a digital caliper you can buy for $15 from Harbor Freight.
Then use the thick to get the bulk out.

My next t.a.'s are going to be much harder steel, and a more refined design. Havent decided what that is yet, probably 2 pc, might be a bolted end to clamp the axle.
I want to see how much a shop can precisely cut the axle slots.

 

[motomech]

Have had some issues with the commonly available two piece torque arms. I prefer single piece like the photo.
Can't find them, can anyone help?Torque Arm right.JPG

I bought a pair like you pictured and they were junk. Very sloppy on a 12 mm axle and they wouldn't fit on a 14 mm axle. A waste of money.
If the way genaric TA's fit on the axle is the prob, these are the best fit for low-cost TA's;
https://www.pswpower.com/products/electric-bike-torque-arm-dropout-amplifier-for-electric-bike-hub-motor-left-or-right-side-74
A higher cost solution are the TA's from Grin. There is no ebike fitment that one of their TA's won't work.
90 % of the time, prob.s with TA's are because of way they are installed.
Show us a pic of YOUR bike and tell us what the prob. is.

 

[markz]

BMS Battery also sells 2pc torque arms.
You could also check out Greentime EVFitting on Aliexpress/Alibaba if they sell same.

 

[TricycleMichael]

This is the photo of the second fork. The clamp has been pulled and the arm seems to twist against the drop-out.
The first fork was worse, threw it away.
I'm using two torque arms.

 

[TricycleMichael]

This has worked best for me, over 700 miles and it still looks perfect.
Nice and strait.

 

[motomech]

Ok, I looked at the one piece TA's that I have and they have a different shape than yours, they are more of a J-shape, so they are different.
I also looked around for one piece TA's and couldn't find any either, so no help on your original question.
And although I don't know if this applies to your install, but I might take this opportunity to comment on 2-piece TA install techniques that I have found to work.
I have never used a rubber bushed clamp on those and I think part of their strength is the hose clamp holding snugly and flat against the fork leg. If I am worried about scratching the leg, I wrap it a thin strip of rubber that comes with handlebar mounted accessories.
I do not use the commonly supplied "castle" washer that has a tab as I have had that tab break off. I always use the C-washers.
I also install the torque arm so it "pushes" against the leg rather than pulls away. that would be the force that is applied opposite the direction the whl. rotates.
These "tips" are not meant to lecture you, but for the benefit of any other readers approaching a hub motor install.
The one piece install that is working for you looks very neat.

 

[TricycleMichael]

Thank you Motomech, I'll post my progress. Second most important thing for me after functional simplicity is the aesthetic. Got to look good.

 

[TricycleMichael]

Yup - Hard to see, tried the front location on one of my earlier builds. Liked the look a lot, some said it was backwards. Actually I liked both.

 

[99t4]

This is the photo of the second fork. The clamp has been pulled and the arm seems to twist against the drop-out.
The first fork was worse, threw it away.
I'm using two torque arms.

That looks like the (obsoleted since 2010) Grin torque arm rev 1 (or a common unimproved knockoff)
"TorqArm_V1

We developed our first such 'universal' torque arm design in late 2009. In this model, the arm part was attached to the fork with a single hose clamp, and the the axle plate could pivot to fit different dropout slot angles. When the motor is powered, it tends to rotate the plate clockwise, and with the pivot point on the back this causes it to further 'push' the axle up deeper in the dropout. Notice that if the torque arm is mounted backwards, on the front side of the fork, then it would have the opposite effect and axle torque would tend to pop the wheel out of the dropout. While this design did work, we did run into several instances of failure from the hose clamp in cases where a motor controller had shorted mosfets. The curved hose clamp slot in this design put stress concentration points on the clamp which facilitated the hose clamp tearing in half. As a result we discontinued manufacturing this model in 2010 and do not recommend its usage. "

Look at some of their newer improved TAs; better engineered, better materials, better results.
https://ebikes.ca/product-info/grin-products/torque-arms.html

 

[markz]

Unless you use e-brake low/high then the nut comes loose, I just tighten mine up everyday.
I might look into how to make it not rotate back and forth, "castle nut" or "Nylocks" or a thin lock nut to double the nuts up as I dont have lots of axle length
https://www.bearingshopuk.co.uk/km-18-lock-nut/ in the right size and pitch same with this, its interesting because its thin and has a locking nut to bite into the threads
https://uk.misumi-ec.com/vona2/mech/M0800000000/M0810000000/M0810010000/#
might wreck the threads on the axle though but its 35 euros

Ok, I looked at the one piece TA's that I have and they have a different shape than yours, they are more of a J-shape, so they are different.
I also looked around for one piece TA's and couldn't find any either, so no help on your original question.
And although I don't know if this applies to your install, but I might take this opportunity to comment on 2-piece TA install techniques that I have found to work.
I have never used a rubber bushed clamp on those and I think part of their strength is the hose clamp holding snugly and flat against the fork leg. If I am worried about scratching the leg, I wrap it a thin strip of rubber that comes with handlebar mounted accessories.
I do not use the commonly supplied "castle" washer that has a tab as I have had that tab break off. I always use the C-washers.
I also install the torque arm so it "pushes" against the leg rather than pulls away. that would be the force that is applied opposite the direction the whl. rotates.
These "tips" are not meant to lecture you, but for the benefit of any other readers approaching a hub motor install.
The one piece install that is working for you looks very neat.

 

[DMC]

Cut the slot a little to small with a 1mm angle grinder disc and then file to size using the stock of a drill bit to measure, usually 10mm. I make mine from 5mm steel. Would like to find we some stainless , maybe have to buy some.