Cheap torque arm solution from Mcmaster

[migueralliart]

I was looking for a cheap torque arm solution for a low power setup and mcmaster has thick slotted washers out of hardened steel for 5$ each. I'll install these on the I drive with the dp420 and report back. I took the cad drawing and did a quick fea analysis and they should withstand 100-150 lbs of torque each.

[mrdavies]

nice find, what item # are these?
thanks

[migueralliart]

nice find, what item # are these?
thanks

Well I got the 1-1/4" diameter version because the idrive has a really small flat dropout region. But for my other bike I'll order the 1-1/2" version

The 1-1/4 item 90339A034 is 4.39$ each and they are .36"-.39" Thickness I haven't measure the thickness on the ones I got but will do as soon as I get home.

The 1-1/2" is item 90339A035 and costs 5.64$ and the same thickness.

Total was 14.26$ shipped in the US for 2 of the 1.25" diameter ones.

[teklektik]

The catalog page is here for 11/32" 'Easy-Install Slotted Washers':

slot = 13/32 = 0.40625" = 10.31875mm
interesting find but needs a bit of shimming... (.31875mm = .0125")

The next size down is 11/32 = 0.34375 = 8.73125mm which might be opened up to avoid shims, but it will probably be tough going.

EDIT - just noticed these are case hardened - probably not the best idea to enlarge the slot, but for low power the exposed softer steel is probably okay... (these appear similar to, but are not made of uniformly hard steel like Doc's handiwork)

90339A034L.gif (13.42 KiB) Viewed 2443 times

[migueralliart]

Thanks for posting the drawing!

[joe tomten]

"Made from black-oxide case-hardened steel, they offer mild rust resistance and have a minimum surface hardness of Rockwell C40"

Seems like I could weld an arm onto it to resist twisting forces.

[neptronix]

Nice find.
This would be very suitable as a 'weld it on' type of affair.
With such a small surface area, i would not consider this a replacement for doc's torque arms. Looks like there is literally half the surface area to glue up. Considering that some people have had a difficult time getting the DP420 to work now, i would think the case would be even worse with these.

These would be fantastic for speeding up the process of making a steel swingarm or really powerful cromoly / steel bike.

[migueralliart]

I'm pretty sure these will do a good job for my demands even with the DP420. After all not all of us are hauling school buses to work everyday LMAO.

like I said I'll test them at 36V 1000 watts and some regen if they hold up pretty good I see no reason to upgrade to another torque arm.

* EDIT - DP-420 has a 4500psi shear strength if you are able to glue these in perfectly you will probably have ~3500 psi of shear limit. I think that is quite simply enough for low power setups.

On a side note if this was good enough for an overvolted setup on one side only I see no reason why these won't even overvoltaged plud REGEN. I'll put em to the test.

http://endless-sphere.com/forums/viewtopic.php?f=6&t=14842&hilit=gt+i+drive&start=15#p224658

[migueralliart]

The catalog page is here for 11/32" 'Easy-Install Slotted Washers':

slot = 13/32 = 0.40625" = 10.31875mm
interesting find but needs a bit of shimming... (.31875mm = .0125")

The next size down is 11/32 = 0.34375 = 8.73125mm which might be opened up to avoid shims, but it will probably be tough going.

I slided these to the axle of my yescomusa kit and there is not significant wiggle when you try to move them sideways. By reading doc's thread people always notice a bit of a wiggle on the torque arms so no shimming will be required.

[teklektik]

some people have had a difficult time getting the DP420 to work now.

Hmm - I missed those. Except for the bizarre attempt to glue down a pinch dropout, can you supply links to any other failures? I'm about to go down this path, so this would would be useful.

[migueralliart]

Got one of these arms installed with the dp420... let's see how it goes. Ended up putting them on the inside because there is more flat area. The I-drive frame has a really bad dropout design to install torque arms.

[teklektik]

That's a powerful looking spring clamp there. Be careful when clamping to avoid a starved joint - you need to hold the TA in place but not squeeze the bonding agent too thin...

As you say - see how it goes, but if it does separate, take a look at the surfaces. If the epoxy is barely present, it might be worth another go with less squish

[migueralliart]

I sanded both surface areas with 120 grit paper and cleaned with paint thinner. The clamp is not as strong as a vise grip so it won't squeeze the epoxy too much. I used the motor to align it first.

[999zip999]

Doc I think said it will cure stronger if in a heat box ? If not faster.

[migueralliart]

Left it in my garage which is 80F plus during the day... will install motor tomorrow

[migueralliart]

Wanted to update people on this

Been running this setup on ONE SIDE ONLY with a 36V 800 watt yescomusa kit with 12S lipo and regen ... so far no problems

For a higher power setup i think the 1.5" diameter one will be a better fit on both sides and it will be good enough.

I sanded the surfaces on both ends and cleaned them let them dry up and it is still working like day 1.

[BikeFanatic]

Thank you migueralliart for sharing this! And thanks to Dr B for the glue suggestion.

I damaged my dropout with a spin out on one side, so I glued the McMaster torque plate on one side only as you did migueralliart.
Sanded, cleaned well with alcohol, let dry for 7 days ( overkill), then I rode the bike with 12 series lipo, off road, on road, regen, and it has been stable since July 4th.
I

[migueralliart]

Thank you migueralliart for sharing this! And thanks to Dr B for the glue suggestion.

I damaged my dropout with a spin out on one side, so I glued the McMaster torque plate on one side only as you did migueralliart.
Sanded, cleaned well with alcohol, let dry for 7 days ( overkill), then I rode the bike with 12 series lipo, off road, on road, regen, and it has been stable since July 4th.
I

I also let the thing dry up for a couple of days. Definitely a really cheap and good solution to this whole torque problem. Also McMaster has an EXCELLENT shipping service.

[HypnoToad]

Thank you migueralliart for sharing this! And thanks to Dr B for the glue suggestion.

I damaged my dropout with a spin out on one side, so I glued the McMaster torque plate on one side only as you did migueralliart.
Sanded, cleaned well with alcohol, let dry for 7 days ( overkill), then I rode the bike with 12 series lipo, off road, on road, regen, and it has been stable since July 4th.
I

I also let the thing dry up for a couple of days. Definitely a really cheap and good solution to this whole torque problem. Also McMaster has an EXCELLENT shipping service.

Do you know if they ship to the UK at all? I tried to find out on their site but it wouldn't let me browse the site without signing up.

[migueralliart]

Thank you migueralliart for sharing this! And thanks to Dr B for the glue suggestion.

I damaged my dropout with a spin out on one side, so I glued the McMaster torque plate on one side only as you did migueralliart.
Sanded, cleaned well with alcohol, let dry for 7 days ( overkill), then I rode the bike with 12 series lipo, off road, on road, regen, and it has been stable since July 4th.
I

I also let the thing dry up for a couple of days. Definitely a really cheap and good solution to this whole torque problem. Also McMaster has an EXCELLENT shipping service.

Do you know if they ship to the UK at all? I tried to find out on their site but it wouldn't let me browse the site without signing up.

Sorry for the late reply. I don't know if they ship to the UK but if you need me I can relay a pair towards your way!


Wanted to give you guys an update... so far having the torque arm attached to only one side with dp420 a yescomusa kit DD with lots of regen and 12S lipo pushing 30 amps thru it so far no problems whatsoever and it is holding strong.