torque arm picture thread

[John in CR]

My homemade foolproof stainless steel arms...

At only 4mm thick you're jinxing yourself calling them foolproof. My very first torque arms were 3mm thick and they didn't last 10ft of the first ride before cutting into the axle like butter and letting it spin. What many miss, including the good Doctor, who uses that ridiculously hard steel for torque arms, is that hard steel is unnecessary. You actually want it to be softer than the axle, so if something gives, you damage the easily replaced/repaired part, not the motor axle. Width and a good tight fit to the axle flats are what count. My current set is 20mm wide on each side.

You've got all the tools, so adding some real thickness and making your dropouts clamping type would have been much much easier. A clamping dropout can eliminate the need for nuts at all, so there's always room to go plenty wide.

Still good work and it looks great. I hope your axle holds up, but starting with loose dropouts and using through-hole type torque arms which can never get a perfect fit without precision machining, I wouldn't run regen on the motor. Without regen they will probably be fine.

 

[DVDRW]

As you can see on that picture. On red ebike I welded 2x4mm sheets together from sides. So actually it is 8mm thick.
And the other green bike 3x4mm welded together from sides so actually it is 12mm thick.
Found 4mm sheet pieces just laying around in my garage.
I think thats more than enough for 1000W motor :wink:

 

[Doctorbass]

Say what you want John :lol: But people love them because it's the community that helped to improove the desing with the average of their best request i followed :wink:

none of them ever break.. NONE..a and NONE ever had an axel that break too because they use them on both side!... Hard steel is the key and it has prooven that it work for years.

Anyway it is normal to have various opinion about anything and you are one of the guy that proove that, wich is normal... I still appreciate your comments John 8)

Doc

 

[John in CR]

Say what you want John :lol: But people love them because it's the community that helped to improove the desing with the average of their best request i followed :wink:

none of them ever break.. NONE..a and NONE ever had an axel that break too because they use them on both side!... Hard steel is the key and it has prooven that it work for years.

Anyway it is normal to have various opinion about anything and you are one of the guy that proove that, wich is normal... I still appreciate your comments John 8)

Doc

Hard steel isn't the key to anything but increasing the cost of drill bits burned up trying to drill a hole in it. At least you make them nice and wide, because that along with a good fit are the true keys....fact not opinion. Make a pair too thin with your hard steel and watch what happens. OTOH make a pair of proper width that are no harder than the axle and they'll be fine as long as they fit properly.

John

 

[amberwolf]

My very first torque arms were 3mm thick and they didn't last 10ft of the first ride before cutting into the axle like butter and letting it spin. What many miss, including the good Doctor, who uses that ridiculously hard steel for torque arms, is that hard steel is unnecessary. You actually want it to be softer than the axle, so if something gives, you damage the easily replaced/repaired part, not the motor axle.

No argument there:
http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=22720&p=721954#p721954

 

[bowlofsalad]

I understand the logic, about the concept that softer torque arms acting as a potential sacrificial surface if the axle starts spinning. But that argument or concept is complete bunk. Why bother having torque arms at all? The problem is, if the torque arm does end up getting destroyed, there is no question that the dropouts will be splayed in the process, there is no such thing as sacrificial drop outs. If your torque arm fails, your drop outs will go with it. The only way torque arms will protect dropouts is if the torque arms never fail.

I am sure material strength or hardness is important, but I think surface area, fit, and tension are also critical components when concerned with a good torque arm. The idea of gluing or welding very wide, hard torque arms to drop outs sounds like a very solid win.

 

[John in CR]

I understand the logic, about the concept that softer torque arms acting as a potential sacrificial surface if the axle starts spinning. But that argument or concept is complete bunk. Why bother having torque arms at all? The problem is, if the torque arm does end up getting destroyed, there is no question that the dropouts will be splayed in the process, there is no such thing as sacrificial drop outs. If your torque arm fails, your drop outs will go with it. The only way torque arms will protect dropouts is if the torque arms never fail.

I am sure material strength or hardness is important, but I think surface area, fit, and tension are also critical components when concerned with a good torque arm. The idea of gluing or welding very wide, hard torque arms to drop outs sounds like a very solid win.

No, you don't understand the logic and it's not bunk. If something changes and deforms over time, which is quite common with torque arms, you want the change to be in something that is easily replaced or repaired, not the axle. Having a torque arm made of a material harder than the axle serves no useful purpose at all, and the end result doesn't mean a spun axle. Having a harder torque arm doesn't make up for inadequate width. If it's not thick enough then a very hard torque arm material will result in axle damage. If the torque arm/dropout is adequately thick then even cheap soft mild steel can be sufficient and neither the axle nor torque arm will deform, especially clamping type.

Width and a tight fit are what really matter, and if either are inadequate then failure is guaranteed over time regardless of how good the steel is used for the torque arms. That's before even considering the practical problems in working with some extremely hard steels.

The problem is that most people use aluminum bikes, so they can't simply weld on adequately wide steel dropouts. That means torque arms are required and the axle nuts are still necessary, which commonly leaves limited width.

 

[Bluefang]

I would think the best middle ground is nice soft cheap 5-6mm steel plate they sell at the local hardware store for foundation brackets, drills easy and very easy to cut out a slot the right width to fit over the hub axle and then bolt into place a inch or so away from the axle to resiste the torque.

In terms of going wide/thick and clamping i think its heading into negative impacts. No dropout i have ever put a hub motor in has been perfectly lined up with the other side, clamping the axle with a really thick torque stop is more likely to cause stress on the axle by trying to deform/bend it even before you have applied power or hit large pot holes.

 

[John in CR]

In terms of going wide/thick and clamping i think its heading into negative impacts. No dropout i have ever put a hub motor in has been perfectly lined up with the other side, clamping the axle with a really thick torque stop is more likely to cause stress on the axle by trying to deform/bend it even before you have applied power or hit large pot holes.

That's why I make my dropouts, clamp them to the axle, align the wheel perfectly, clamp dropouts to frame, check alignment, tack weld, check alignment, tack weld some more, check alignment, and then remove motor for full welding.

 

[bowlofsalad]

Maybe I did a poor job of explaining it. If the dropouts would bend under the stress of ebike use alone, wouldn't it make sense that the moment that the torque arms loose their effectiveness the drop outs would go with it?

Lets pretend invaders are trying to breach your gate/walls and torque you, those darn torquonians. The moment those torquonians breach the gate/walls, they are going to torque you.

 

[John in CR]

Maybe I did a poor job of explaining it. If the dropouts would bend under the stress of ebike use alone, wouldn't it make sense that the moment that the torque arms loose their effectiveness the drop outs would go with it?

Lets pretend invaders are trying to breach your gate/walls and torque you, those darn torquonians. The moment those torquonians breach the gate/walls, they are going to torque you.

Pretend whatever you want, but with reasonable torque arms and dropouts there is always warning. It's when you have totally inadequate torque arms, or you ignore the warning signs, that spinouts occur. Most torque arms are cheap soft steel that's too thin, and those that came with used motors I've purchased were all deformed to some extent, some quite deformed, however, none of the axles had spun and none of the axles showed much, if any, deformation, just the torque arms.

OTOH on my first ebike I had hard stainless steel torque arms that were too thin. Within 10ft of the first ride the front fork dropouts snapped, and because the torque arms were too thin, the axle spun cutting into the axle like it was butter ruining the axle. If my torque arms were say 1/4" (6mm) mild steel that wouldn't have happened. While that's not thick enough for long term durability, it's thick enough that deformation occurs over time, and you notice the rocking axle and/or constantly loosening axle nuts. At 8-12mm and a clamping tight fit, then cheap easy to work mild steel becomes a long-term solution. My dropouts are my torque arms, and mine are retaining an excessively powerful motor, so they are 20mm wide on each side.

John

 

[bowlofsalad]

I guess at best, it sounds like a self fulfilling prophesy.

 

[migueralliart]

After all this is a torque arm thread

here ya go

 

[Skedgy Sky]

Cool stuff. Here's mine!

Piece of steel welded to bike frame with hole in it.
Another piece of steel with notch and hole in it which slides onto the axle.
The holes of the steel plates line up in which a 7/8ths inch (I think) bolt and lock nut (on other side) go through.

 

[cal3thousand]

Here's my most recent creation which includes a built-in hitch for a bike trailer. There's another TA on the opposite side. They are made from 5/16" (~8mm) thick high carbon steel.

I sanded the dropouts and used DP420 to affix them. For extra strength against shearing, 2 M5 screws were also used. With washers and Nord-Locks added, I managed to use the whole length of the MAC 7T axle exactly.

 

[spinningmagnets]

From German builder "izeman":

http://endless-sphere.com/forums/viewtopic.php?f=3&t=38848&start=50#p703564

 

[dan974]

from my thread for the GIANT DH teams =) 15mm thick ones

files ready to lasercut...

 

[thewmatusmoloki]

20mm thick clampers, welded on

 

[Kingfish]

^+1 That's exacory wot I want to do - except it will also have an additional attachment point for the trailer. Been tinkering with the CAD layout for the last few days; still needs twiddling. With the horizontal dropout design I also had to move the brake mount to the backside; no other place for it with full-suspension.

Nice job, KF 8)

 

[D-Man]

Oh no! The hub motor has NOT broken my suspension fork.

 

[dr_lulz]

just want to show you my new torque arms, im running heavily modded magic pie @ 5kW -> 140Nm

i had 2 wrenches 4mm thick before, they are ok but i cant use regen braking with them, also this was caused by them




i dont have much machinery so im using 10mm thick aluminium, which should be stronger than 5mm steel?

the screw that holds the brake adapter also holds the torque, you can also see oil running of the motor >_>

other side currently in progress

 

[spinningmagnets]

laser cut for the A2B E-bike (chrome-plated soft steel on the bottom, hard and thicker stainless-steel on top:
http://endless-sphere.com/forums/viewtopic.php?f=31&t=47855

 

[Spicerack]

Simple clamping type on a Norco shore2 with 9C 8x8. Threads were stuffed anyway so needed to do this. Base plate is a 4mm torque arm from when it had a mac on it. This clamping one is made from an off cut of thick mild steel. Easy enough to make with an angle grinder, drill press and die grinder. Works beautifully.

 

[isd88]

Hi guys! i forget to post last evolution of my torque arms!



After 3 monts there is not any slip/deformation of the torque arm and the brake disk works perfect! i just changed it to hydraulic one , i will post the picture soon!

 

[adam333]

KMX Typhoon dropout:


I cutted the KMX Typhoon dropout in order to fit a new set made out of 7075-T7 aluminum.

brake adaptor, 7075-T6 aluminum

A few pic of the assembled rear wheel with the brake:

Norco A-Line 2009 dropout:

I made a pocket in the original dropout and press fit a Stainless Steel insert each side.

Press fit result:

Assembly part 1:

Assembly part 2 with nut, washer and lock washer:

Assembly part 3: