Amount of Torque

[trek7000]

Hi all,

Have a rear 408 going on a new aluminum frame (i plan on using torque arms) ... how much torque should I use to put on each axle bolt when bolting the wheel into the dropouts?? I guess what i'm asking is how many pounds of torque do I tighten it to using a torque wrench?

Thanks!

[kbarrett]

If you are using torque arms, don't sweat it. Just tighten them normally.

[lazarus2405]

You need to be careful. If you use more than a 6" long wrench, don't tighten them as tight as you possibly can; you'll strip the threads right off the axle. Just get them darn tight (not insanely tight), and use some sort of locking washer/loctite/double nut to keep the nut from loosening.

[fechter]

I wish there was a known torque specification for these nuts.
As Laz points out, you want them as tight as possible without risking stripping the threads.

[TylerDurden]

I wish there was a known torque specification for these nuts.
As Laz points out, you want them as tight as possible without risking stripping the threads.

Well............ you have a hub motor....... find out how far you can go.......

[lazarus2405]

Just to be sure we're on the same page, the threads on the axle will fail before those of the bolt. With stainless bolts and a 14" long wrench, I stripped a small portion of my x5's axle. If it happens to you, just add a washer and don't tighten so hard.

The lever arm you use will limit your torque. Now I only use a 6" wrench, which gets it plenty tight but won't let me do damage with my rather average biceps.

[methods]

I stripped one side of my 5305 bad.
Unfortunately I listened to people who kept using the phrase "as tight as you can" (lol)
I wrench on cars and 90 ft lbs is easy for me. Maybe as tight as I can with a 6" monkey wrench!

I happened to have a very long wrench in my hand. . . Maybe 16" (slaps head)
Spun the nut right around without even trying.
Right in the middle of the axle.

I chose to remove the washer and lock washer to move the nut inboard on a few good threads.
Now it is just "tightish". . . I need to space out the dead part of the axle and put on a second nut on the end.

On the other side I got out my torque wrench (after the fact) and it clicked at 60 ft lbs so. . . It is probably at like 70.

DO NOT OVER TIGHTEN! CRYSTALYTE AXLES ARE WEAK SAUCE.

Just do them as tight as you would for a normal bike. I should not have listened to "all the hype". . . I think guys must be trying to tighten these things with a tool set they got for free at McDonalds =) Real tools in the wrong hands will destroy the axle.

Anyhow, it runs fine now.

I am running 100V @ 90A with a 5305 on a 26" wheel
Electra Cruiser with 6mm mild steel drops
I hammer on it and it is rock solid.

now to rethread it. . . I think I will just turn it down to a smaller nut size. Something metric with a lot of threads.

-methods

[recumbent]

Yep, a 6" wrench is the safest size to use on these motors. Thanks for reminding us how easy to strip these threads.

[Dee Jay]

If you are using torque arms, don't sweat it. Just tighten them normally.

DO NOT OVER TIGHTEN! CRYSTALYTE AXLES ARE WEAK SAUCE.

LuLz

Words of wisdom, Lloyd. Words of wisdom...

When over-tightening the axle nut, not only you risk stripping the axle thread, you'll also risk turning the axle *whilst turning the nut* damaging your drop-outs.

J

EDIT:
I think another solution is to use a weaker nut so that you'd strip the nut before you can strip the axle. Stainless Steel nut?

[John in CR]

Soft steel on the axle of a very powerful hub motor. That has class action suit written all over it. When are we going to stop accepting such a poorly engineered connection to the bike? Why don't any quality US motor manufacturers start building hub motors? It's just silly that you can pick up a well made 50lb golf cart motor for less than a lot of these poorly constructed hub motors.

John

[Jeremy Harris]

Soft steel on the axle of a very powerful hub motor. That has class action suit written all over it. When are we going to stop accepting such a poorly engineered connection to the bike? Why don't any quality US motor manufacturers start building hub motors? It's just silly that you can pick up a well made 50lb golf cart motor for less than a lot of these poorly constructed hub motors.

John

Soft steel may well be much better suited to this job than a hardened shaft for a couple of good engineering reasons. The shaft is subjected to pretty high cyclic loads from bumps in the road. Hardening can lead to surface crack formation during high cyclic loads and the shaft would be more likely to break then bend if overloaded - pretty dodgy for a bike axle, I'd rather bend it than break it. A good analogy would be aircraft steel bolts, these are deliberately made from relatively low tensile steel and left soft, rather than hardened, so that they bend rather than break if overloaded. I chuckle when I see people spending a fortune on aircraft steel bolts, thinking they are getting some sort of super strong bolt, when the reality is that their strength is similar to a mid grade hardware store bolt.

The issue of nut torque is really a symptom of the real problem here. The problem is that bicycle dropouts were never designed to take torque loads at all, so we tighten up the axle to try and bodge around the problem by increasing the amount of friction in the bolted joint. This is a bad idea from an engineering viewpoint, as all it does is increase the static load in the joint, so increasing the local stress in the most stressed part of the axle, the ends. Add in the fact that the torque will be trying to undo the nut on one side anyway and this whole idea of just using tight nuts to hold a really powerful motor starts to look increasingly dodgy.

With decent torque arms, that closely fit the flats on the axle, there is no need for excessive torque on the nuts at all, just enough to keep them tight as you would on an ordinary bike axle.

Jeremy

[Dee Jay]

Soft steel on the axle of a very powerful hub motor. That has class action suit written all over it. When are we going to stop accepting such a poorly engineered connection to the bike? Why don't any quality US motor manufacturers start building hub motors? It's just silly that you can pick up a well made 50lb golf cart motor for less than a lot of these poorly constructed hub motors.

John

Ah! More words of wisdom... and these are some of the reasons why I'm gearing towards RC motors (or cylindrical motors?)

The shaft is subjected to pretty high cyclic loads from bumps in the road.

Something that I've been observing during my ride on non-shock-absorbing no-name BMX tires and it's been eating me up since I ride with my son and I have yet to fab my fabulous torque arm solution...

I still see the potential in hub motors but the weight and engineering is sadly lacking.

Engineers were capable of churning out high precision products long before CAD. Were now in what? *looking at watch* 2008? Something like that? . .. and were still getting wobbly hubs and wheels? I don't know what's so hard about keeping things straight?


?

[dogman]

I have about 600 miles now since I stripped a WE axle and re threaded it. It seems to be no problem, but I also now back off a bit on the tightening. It would be nice it the nut was softer than the axle.

[Eric G]

Interesting read!
~ 25km's after installing my new rear Brushed C-lyte it had loosened up on the left (freewheel) side.It utterly scared the crap out of me when it happened.The other side had remained nice and tight.After realigning the wheel and retightening it's been fine ever since (2249km's.)

Someone had mentioned to me that after first tightening the nuts I should have loosened them and retightened again to seat them.Anything to that statement or...???

Eric

[Drunkskunk]

Its not that the axles are all that soft. they are plenty hard enough for the job. its that the threads are cut instead of rolled. Rolled threads are far superior to cut, but the technology to do it on a shaft with flat sides is something that may not exsist in China.

The other thing to remember is with the 2 flat sides, you only have 50% of your threads there. So it might look like a big 14mm nut, it's only got the streingth of a 10mm

[pwbset]

I am running 100V @ 90A with a 5305 on a 26" wheel

OMG you are my hero. That's probably my ultimate setup right there... I'd be just fine with even half the amps.

[Microbatman]

I am running 100V @ 90A with a 5305 on a 26" wheel
Electra Cruiser with 6mm mild steel drops
I hammer on it and it is rock solid.

-methods

Nice!!

What controller are you using to get 90 Amps?
What device are you using to measure current and amps? Eagle Tree? Watts up meter? Something else

[methods]

I guess I forgot to subscribe to this thread. . .

(Quick threadjack =)

The Bike - I have to admit that the bike is actually a little more than I can handle some times. The front wheel will lift off the ground at 25mph for the entire pack so when I start to become complacent I sometimes scare myself. I tend to agree with the Doc's thinking on over-volting a low kv motor. All the good with none of the bad. I have already hit 41MPH so speed certainly is not an issue. . . The higher the voltage the lower the current for the same power.

Controller - I bought the standard 72V 40A electric rider version 2. White board. First thing I did was make sure it worked. (always do this)

- Soldered in 4110 fets and got as much solder on the tracks as they could take. This version already has copper wire on the main tracks so this was easy.

*IMPORTANT* 100V is up into the arch territory so the spacing between tracks becomes critical. After beefing up pads they get closer together together. It is imperative to go over the board with a jewelers loop to inspect each leg of the fets to make sure that there are no tiny little traces of solder or specs of metal. I have 10-20 vision (better than perfect) and I cant see it with my naked eye so it is a must to use a good magnifier. I found 3 places where potential shorts would have occurred. SEE MY PICTURES for how clean I got the board.

I did not solder over the "hidden trace" as I determined that it was fat enough.

- Shunt - I soldered over half the shunt to take it from about 1.1m ohm to around 0.5m ohm.

- Data aq - I have a Watts up, an Eagle Tree, and several other do-dads. I used a CA to take all my measurements. Here is how I calibrated it:

* The shunt on the board does not pick up the 40ma of current for the "other half" of the board, so when calibrating the shunt it is important to run high enough current to mask that.
* I put a current meeter inline with my pack. Ran at .5A, 1A, and 10A to "tune in" the CA. At every point I was off by under 150mA so I am confident in the reading
* I calibrated my speed first by measuring the wheel, then by running past 3 different radar signs, then by riding to 3 separate locations that I had mapped via Google Maps. I was off by less than 1/10th of a mile after 5 miles so I have confidence in those readings.

Um. . . I am babbling. Here are some pictures.

Oh wait -- To get 90A

Most of the time I have the constant current set to around 60A which will get me "burst current" to around 86 amps. I have set the steady state as high as 70A to see bursts up around triple digits but that is almost too much. Setting the current on the CA up to 90 would be a big risk. Too much onset current. (overshoot)

Electric bikes are like turbocharged 4 cyl engines. . . You can make 400hp real easy but ** you can not ** expect to run them like that steady state. Keep the constant current down to like 60 or 70 amps and just use 90A for bursts to ensure a non-melt down situation. I would not try (at this point) to pull 90A continuous though I could if I wanted to take on the risk.

Electra001.jpg

Removing the old FETS.

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Electra008.jpg

Start Clean!

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Electra014.jpg

Nice and new!

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Electra017.jpg

4110 installed. KEEP IT CLEAN!

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Here I took pictures through the jewelers loop. . . See that there is not even a spec of solder? This is important at 100V !!!

The rest of the pictures are still in the camera somewhere. . .

[methods]

lol. . .

http://www.deviantmethods.com/PostHold/Electric/Bikes/Methods_5305_lipo_bike.wmv

lean forward =)

*** Save to disk, please dont stream from my server for best performance ***

*

[pwbset]

[lazarus2405]

The front wheel will lift off the ground at 25mph for the entire pack so when I start to become complacent I sometimes scare myself.

Heh, I had that issue too with the Clyte v2 controller. Since there's no armature current limiting, you can generate a stupid amount of stall torque. Do you have pics of your build? I'm interested in what you did to keep you front wheel on the ground when accelerating from 0. With my ~65a Clyte v2 controller, 5303 in a 20", at 84v, and batteries above the rear wheel, I couldn't safely accelerate from stoplights!

[methods]

I documented everything =)

I did something very sweet just today. . .
I moved the packs from hanging over the rear wheel
To right in the middle.

You are going to love this!

So start with one of these from Walfart:
http://www.walmart.com/catalog/product. ... id=9207799

I used to run it like this:

The LAME way to use a post rack

The seat post is at an angle, so the bracket for that rack is at that same angle.
Before I had my batteries hanging out as above. . . sucked. Weight was high and back and it vibrated.
Then I thought. . . "hmmm... What if I turn that rack upside down and face it forward?"

ElectraMore007.jpg

Now that is better!

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Procedure:

* Remove the two screws that hold the plastic rack to the metal post
* Turn post upside down
* Attach to frame BELOW seat, facing forward
* Reattach rack

Now the batteries are perfectly level, in the middle of the bike, forward and low.
The plastic rack is not attached to the metal arm so I can remove the pack as a unit
The rack swivels in and out but will not come out or move under load (tested for 50 miles)
Check these pictures out:

ElectraMore001.jpg

Mount in

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ElectraMore003.jpg

Swivel out

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ElectraMore004.jpg

Remove

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ElectraMore005.jpg

Add packs

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ElectraMore006.jpg

Replace

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ElectraMore007.jpg

Now that is better!

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ElectraMore002.jpg

Easy control!

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RESULT:

* Tire only lofts when I peddle and **try** to make it loft
* Bike rides MUCH better and feels better
* Handles bumps better
* Feels slower since it is more predictable and smooth
* Looks better
* Less vibration on the packs

I just did this today so of course I will modify the procedure.

Attached are just 24S1P Lipo 4150mah.
Next I will put my 24S2P Lipo 9000mah stack.
Will probably build a case around them with fan to protect from the sun, crashes, and people.

-methods

[methods]

P.S. Please consider that I believe in function first and then form!
Once I get the design worked out I will clean up the wiring and make things look "nice" (as my wife would say)

P.S.S.

Those with an eye for detail will notice that I converted my electra single speed cruiser over to a 7 speed (which I just leave on the fastest sprocket). I have a 54 waiting for the front to allow me to peddle at over 30 mph.

I also had to use a drum brake in the front since the only brakes were the coasters

Note the way the front tire is laced up. Stout!

I hit 41mph today on the flat with the current capped at 60A and only a 4150mah pack
I am going to up it to 80 tonight and see if I can pop some traces =)

P.S.S.S

Absolutely no interference with the peddles or my legs. The bike is much easier to ride with human power now since the weight is balanced but. . . That 5305 drags like a mother! Too many turns!

-Patrick

[shinyballs]

ingenious! You can also mount more batteries at the bottom rack. More the merrier other end of the rack needs a clamping bracket to make it really sturdy.

[Doctorbass]

That's a nice and simple setup you have!

Welcome to the 5305 small club

Now you should try 24" wheel!.. same top speed but more acceleration!!!

My 5305 run on a 24" wheel, 90A too.. but peak often at 102A and use 23Ah 100.8V li-manganese DIY pack.

I reached 72kph on flat and get 0-20kph in 0.53sec, 0.40kph in 2.78sec.. alot of fun!!

I calibrated my CA current reading with an external DALE 0.1ohm 250W 1% resistor. It give 1V every 10A

I can pull my car and my wife's car (integra and Matrix) at the same time!!


5305 are the most powerfull torque hub motor for ebike in the planet!

It could be nice to drag race our ebike!

Oh.. and i forget.. i torque both nut to the maximum "safe mental feeling".. ad never got any problem.. but the solution i think with a 5305 is not to overthighten the nut... but more to keep it in a fixed position.. see my torque arm pics:

I replaced 2 tire since i choosed this installation and never had any problem even if i desinstalled-installed it 3 times...