Torque arms for my odd shaped swingarm

[cheetor]

Hi ESers
I'm rebuilding my electric bike at the moment, somehow 12S of LiFePO4 just isnt enough for me anymore, so I'm repacking my 12S2P Headway pack to 24S and buying a Leyn 12FET for it. Somehow I think my poor alloy dropouts just wont handle it. I've had a look at the available torque arms and I dont think any will fit my odd shaped swingarm, I'd make some myself however I'm pretty bad with making things. I was curious if anyone had any suggestions to help me out?

[MadRhino]

You have enough axle left on both side, to add thick torque plates. They could be bolted or glued, or both. Easy job.

[cheetor]

looks like custom ones may be the only choice, I knew I should have done metalworking at school

[John in CR]

You have enough axle left on both side, to add thick torque plates. They could be bolted or glued, or both. Easy job.

Glued??? Please don't tell me you're part of the "let's get someone killed" crew. Would you ride a glued together bike?...Of course not, and neither would the guy profiting on that ridiculous idea.

[wesnewell]

There's 2 holes in each dropout where they could be bolted down, so epoxy and then bolt down. If the holes aren't treaded the tap them. Or bolt and weld.

[dogman]

It's actually pretty easy to cut some 3/16 thick steel with a drill and a dremel or small file, to get the axle hole right. After that, any welding shop could easily shape the plate of steel to match your bikes droputs.

They are a bit like those on my longtail. I had some cheapie torque arms around, and ended up shaving them to shape to fit the funny swingarm .

Funky%20torque%20arms_.jpg (96.41 KiB) Viewed 278 times

Maybe some modified front hub torque arms will fit your rear end better than you think.

[icecube57]

Here are some modified amped bikes torque arms chopped and modified to the disc brake bracket. I also had several holes in my drop out where i could have bolted it on also. I have aluminum drop outs.

[cheetor]

Don't worry fellas, I prettymuch ignored the glue suggestion, sounded terribly dangerous, I do have 2 holes on one side.. but not the other.

[d8veh]

You have enough axle left on both side, to add thick torque plates. They could be bolted or glued, or both. Easy job.

Glued??? Please don't tell me you're part of the "let's get someone killed" crew. Would you ride a glued together bike?...Of course not, and neither would the guy profiting on that ridiculous idea.

Aeroplane and car manufactirers are using glue(adhesives) more and more to hold their main structures together!

[d8veh]

I'd make something like this out of 1/4" steel plate. It should rest on the underside of the swinging arm, so that you wouldn't even need to bolt it. The torque will be pushing it upwards. You only need a hacksaw and a couple of files to make them, although an angle grinder would help to make them more accurate. Ideally you should weld in a little bit to stop the slot fom spreading, but it should be enough without it.

[MadRhino]

You have enough axle left on both side, to add thick torque plates. They could be bolted or glued, or both. Easy job.

Glued??? Please don't tell me you're part of the "let's get someone killed" crew. Would you ride a glued together bike?...Of course not, and neither would the guy profiting on that ridiculous idea.

My dropout torque plates are glued and bolted. I wouldn't trust glue alone, and bolts get loose some day, Both is safe and lasting.
Yet, many are riding high power with torque plates that are glued only. Properly done, it can be made safe.

[icecube57]

[dogman]

Not such a bad dropout to do something like this either.

Since the frame is not steel, spreading out the forces on the piece bolted to the frame by using high strength epoxy glue and bolts would be a good idea.

[John in CR]

You have enough axle left on both side, to add thick torque plates. They could be bolted or glued, or both. Easy job.

Glued??? Please don't tell me you're part of the "let's get someone killed" crew. Would you ride a glued together bike?...Of course not, and neither would the guy profiting on that ridiculous idea.

Aeroplane and car manufactirers are using glue(adhesives) more and more to hold their main structures together!

Car and plane manufacturers wouldn't even sign off on the size axles on ebike hubmotors and they're steel, so the idea that it's ok to use an adhesive for such a small surface area that is effectively a motor mount is absurd. There have already been glued torque arm failures, some due to improper prep which is guaranteed a significant percentage of the time, and some with proper prep, and the excuse offered is that it must be fake DP420 instead of the obvious, that it's simply a bad idea.

icecube,
Easing heavy weight on a glued connection is about as useful an experiment as the old Crazyglue commercials. Take a big hammer and beat on it while hanging some weight and watch what happens. That would be far closer to real world use.

How many of the epoxied torque arm advocates realize that the shear strength of DP420 is about half as strong when bonded to some steels? Did you know that it loses about 90% of its strength at only 82°C? The stated limit is 121°, but it has less than 5% of its strength at that point. As hot as some guys run their motors there's little doubt that their axles, which have a direct metal-to-metal connection with the stator, get above 80°C. A little research is warranted before following something that doesn't sound right.

I love using epoxies and taking shortcuts whenever I can, but not when it comes to dropouts and torque arms. The main reason there haven't been tons of failures is that the thick aluminum dropouts are quite strong, I'm sure a lot stronger than the DP420 in this application. If the axle is well fitted to the dropouts then the torque arm doesn't come into play unless the dropouts snap. Another reason is that those who use regen is still in the minority, and it's regen that's the real torture for dropouts and torque arms.

John

[hjns]

Hi all,

Just wanted to chime in here.

I had fixated the steel DrBass TAs with only DP420 to my alu frame, both sides. Both surfaces were completely filed, then made rough, then cleaned with alcohol, left to dry. I had painstaikingly made sure to have the correct ratio of raisin and hardener, and after application it had cured in my wintergarten for 48h at an average temp of 25oC.

Yesterday, during a test ride with low speed - average power (3-4kW), they both came off. I will try and properly document it, but the main message is that - despite the nice vids from DrBass - DP420
ALONE is not strong enough for a high power motor.

[icecube57]

Hi all,

Just wanted to chime in here.

I had fixated the steel DrBass TAs with only DP420 to my alu frame, both sides. Both surfaces were completely filed, then made rough, then cleaned with alcohol, left to dry. I had painstaikingly made sure to have the correct ratio of raisin and hardener, and after application it had cured in my wintergarten for 48h at an average temp of 25oC.

Yesterday, during a test ride with low speed - average power (3-4kW), they both came off. I will try and properly document it, but the main message is that - despite the nice vids from DrBass - DP420
ALONE is not strong enough for a high power motor.

Did you cure it properly in a makeshift oven like doctorbass did....

Dont get me wrong I agree with you john. I was sold on jb weld until it got hot one day and something i had used it on failed and it was gummy to the touch this was 2=3 months after the initial application. Held like a champ for those first couple months and then damn and it was in the hot sun at prob 60-80C.

I will feed people the information they want to hear or request. Doesnt mean I support it. Just passing it along. I personally dont use it and dont plan to. I have some multi angle torque arms bolted in my buil in tidal force torque arm slot that suit me just fine at 4-5kw.

[John in CR]

...I will feed people the information they want to hear or request....

I'll feed people the information I believe to be true whether they want to hear it or not.

[John in CR]

Did you cure it properly in a makeshift oven like doctorbass did....

DP420 cures to essentially the same strength at room temperature. It just takes longer. http://multimedia.3m.com/mws/mediawebserver?mwsId=66666UF6EVsSyXTtnxf258s6EVtQEVs6EVs6EVs6E666666--&fn=78690097106.PDF

[Spacey]

Ran my greyborg with glued torque arms with heavy regen use, no probs at all.

[John in CR]

Ran my greyborg with glued torque arms with heavy regen use, no probs at all.

DC10's flew around for quite a while with crack engine mounts before an engine fell off and they discovered the problem.

In the case of glued on torque arms the weakness was obvious the first time it was suggested. Failures have proven the weakness to be real. Successes prove nothing other than it hasn't failed...yet.

[hjns]

Ran my greyborg with glued torque arms with heavy regen use, no probs at all.

DC10's flew around for quite a while with crack engine mounts before an engine fell off and they discovered the problem.

In the case of glued on torque arms the weakness was obvious the first time it was suggested. Failures have proven the weakness to be real. Successes prove nothing other than it hasn't failed...yet.

well, I feel like I have proven that I still need to learn a LOT about building powerful e-bikes....

[MadRhino]

Double protection has proved safer on the long run.
I would have a few kids less if I had known that when I was young

[John in CR]

Double protection has proved safer on the long run.
I would have a few kids less if I had known that when I was young

Glue and a bolt is a winner. Too bad he makes them out of unnecessarily hard steel making drilling so difficult. Once it gets harder than the axle anything more is overkill. Personally I'd rather the torque arm give than the axle, so I'd prefer softer than the axle if given a choice, but that's not a safety issue. That's an issue of I'd rather fix/replace a torque arm or homemade dropout than replace a motor axle. With the clamping type I use, all greater than .5" wide, there's been no notable deformation of the ones I used mild steel, and some of those are a couple of years old now.. My new favorite material for clamping dropouts and torque arms is leaf spring steel. It's cheap and readily available, welds well, drills fairly easily as long as you stay away from work hardened areas, and it's strong tough steel inherently made to flex instead of break.

well, I feel like I have proven that I still need to learn a LOT about building powerful e-bikes....

Why the sad face? We're all still learning. That's what's so cool about it. I thought I knew a bit about controller/motor tuning and performance until I racheted my Super V up from 10kw to 30kw, learning a ton in the process. Every day I learn something new is a good day, and we're out there on the frontier of what's never been done, so every day's a good day.

[hjns]

Why the sad face? We're all still learning. That's what's so cool about it. I thought I knew a bit about controller/motor tuning and performance until I racheted my Super V up from 10kw to 30kw, learning a ton in the process. Every day I learn something new is a good day, and we're out there on the frontier of what's never been done, so every day's a good day.

Ha, you are right, that needed correction. The sad face is because the way I needed to learn this lesson, not because that I need to learn in the first place. I agree that every day I learn something new is a good day. And I am fortunate that I can learn new things not only as a hobby, but also in my professional life and in my family life. Life has been good to me, and I try to give something back as well....

[Punx0r]

Too bad he makes them out of unnecessarily hard steel making drilling so difficult.

Just heat it up and drill it hot. You should be able to get it hot enough to drill more easily without affecting the temper.

If you really don't like how hard it is, you can probably anneal it and then drill it cold.