crystalyte 3540 axle failure

[wojtek]

it just broke during riding my velomobile Go-one Evo... it lasted for 2 months - how sad

the motor was modified by Farfle. In order to accomodate the larger wires, he must have drilled out too much from the axle and made it too weak..

Just a warning not to overdo it...

[Farfle]

Ouch... My hypothesis is that the new crystallite axles are a very poor steel. I had to make a new one for another sphere member who had a similar problem. His is made of stressproof rod in the exact same shape, and AFAIK has worked fine so far. If you have access to a press, I can send you a new axle for the cost of shipping.

[NeilP]

Farfle...are the splines on these motors the same as the 53xx series motors or are they smaller?
Can that 53xx series shafts also bee pressed out?

Do you know if that particular size / design of splines is an off the shelf size of splined shaft that can be purchased as stock splined steel shaft or do you have to machine the splines your self?

I want to make myself a new axle, for my 5304 and do not like the idea of using a keyway/woodruff key. I do not have the ability to create a splined shaft, but if I can get the stock splined steel, I can turn the axle down as I require

If it is available, do you perhaps have a supplier and or part number for that type shaft.

Thanks

Neil

[Farfle]

No, the X5's are not the same size as the hx axles but yes, they can be pressed out. They are not a splined shaft, you use a linear knurling tool with coarse teeth, I bought this one: http://www.grizzly.com/products/2-pc-Kn ... -Set/H5936
and it held up for about a month until it wore out, but it's 1/10th the cost of a good one.

[rojitor]

Just a warning not to overdo it...

I was thinking about dremeling mine... I will keep in mind your advice

[wojtek]

thanks a lot for your offer and sharing your experience, Farfle!

a new axle would be fantastic, im happy also to pay for the material and your time..

[NeilP]

No, the X5's are not the same size as the hx axles but yes, they can be pressed out. They are not a splined shaft, you use a linear knurling tool with coarse teeth, I bought this one: http://www.grizzly.com/products/2-pc-Kn ... -Set/H5936
and it held up for about a month until it wore out, but it's 1/10th the cost of a good one.

Not come across that before. so how does that work? I imagine you stick the workpiece in teh lather, rotate very slowly and apply the tool against the workpiece with pressure to create the 'splines' on the shaft...but then what...you just press the shaft into a slightly under sized hole I guess?
maybe you heat the rotor a bit first to expand the metal? before pressing the shaft in,

So it is almost just a friction fit with a bit of knurling on the shaft as opposed to a proper keyed fitting. Would not have thought it would have been enough..

[neptronix]

On the plus side, you did a great job on preventing the axle from rounding out the dropouts

[NeilP]

That is a scarely thin axle...what remains of it after it was drilled out. Hardly any axle left, surprised it lasted for more than one or two runs down the road
Looking closely at the fracture surface, looks like it has two fractures in it. Older one initially cracked but axle hung on for a while, started rusting then it cracked again failing totally at a later date.

[MadRhino]

I had an X5 axle failure, and it wasn't even modded. The H series axle seem stronger to me, but its smaller size doesn't let a lot of room to enlarge the channel. I dremeled mines, and they are holding well riding hard off road.

[NeilP]

I have been considering a torque plate with a 'metalastic' type fitting, you know what I mean? something to still prevent axle rotation but with enough give in it to take out these shock loadings that are probably a contributing factor on these failures..or just thicker axles I suppose

[The Mighty Volt]

the more and more I read about the "new" Crystalytes the less impressed I am.

[MadRhino]

I have been considering a torque plate with a 'metalastic' type fitting, you know what I mean? something to still prevent axle rotation but with enough give in it to take out these shock loadings that are probably a contributing factor on these failures..or just thicker axles I suppose

I've been thinking about torque absorber axle mounts to replace the dropouts, but this would make servicing longer and I like to swap the motor wheel on my bikes. So far, I found that thick and tight fit dropouts are safe for the axle.

[sn0wchyld]

FFS. just another issue with these motors to worry about. Granted though, looks like there was allot of material taken out, to close to the point that the axle narrows to the 12x10mm threaded part. where you doing anything in particular when the failure occored? I'm worried now since with the MX rim/tire ive started riding much harder off-road than before

send you a pm farfle, i'd be interested in a new axle too, obviously happy to pay for your time etc etc.

[wojtek]

i was just riding on a road ..

[Spicerack]

I reckon the only way to go is a bigger axle but if not, then rifle drill the whole xle and run wires through each side.

The axle needs to be drilled in a lathe so it's perfectly central- looks like this one may have been drilled offset. Looking at Farfle's 2Pi effort I don't imagine a new 3540 axle will be much of a challenge....

[miro13car]

This axle is dangerously thin was asking for trouble

[electricwheels.de]

Here's a model of an axle for the H-series motors

Modified H Serie Motor Achse ISO NO.JPG

H motor new axle

(80.49 KiB) Downloaded 4 times

and a top view on to the assembled gear...

Modified H Serie Motor Stator mit Achse Frontal.JPG

Top view of assembly

(97.72 KiB) Downloaded 4 times

Runs with larger bearings dia 42 x 20 x 12 mm, so sidecovers would need machining.

Take a close look at the axle. The thread is M14 x 1.5 mm. Where it sits in the dropouts, its been machined out to 10 mm width, with one side being a radius of 5 mm. That way it sits centrally in the original dropout slot, has a 'flag' but would need a torque arm fitted.

I've got the whole motor, original and modified, as models on my computer. Production drawings are made. Shame it's too expensive to have them made.
If anyone is willing to produce the parts, I give the drawings away for the cost of 2 sample sets

[miro13car]

Wondering what would be the cost of such rebuilding of HS/HT motor presuming you don't pay for drawings, charging US$50 labour rate and and material easy US$ 1000 I would say but I think much more maybe 1500.
Only taking such motor apart with Chinese using thread locker compond is a challange and time consuming and their choice of Philips screws for cover is complete ignorance , because standard screw for such application is Allen bolts , well but they cost cents each more.
Machining new axle is only beginning of mods, reboring and replacing bearings is another mod, next replacing halls with quality ones, after that what else
China manufacturing is obssesed with cost savings?

Such modified HT/HS is not exactely cheap anymore,

[wojtek]

Wondering what would be the cost of such rebuilding of HS/HT motor presuming you don't pay for drawings, charging US$50 labour rate and and material easy US$ 1000 I would say but I think much more maybe 1500.
Only taking such motor apart with Chinese using thread locker compond is a challange and time consuming and their choice of Philips screws for cover is complete ignorance , because standard screw for such application is Allen bolts , well but they cost cents each more.
Machining new axle is only beginning of mods, reboring and replacing bearings is another mod, next replacing halls with quality ones, after that what else
China manufacturing is obssesed with cost savings?

Such modified HT/HS is not exactely cheap anymore,

IF done correctly in first place in chinese factory, the price would rise insignificantly..

This is exactly the case we were raising with Kenny re 54xx order. He promised to do upgrades and raised the price but not much at all.
The labour normally is the same, it is only about using higher quality materials..

China may be great to produce cheap products IF you tell them exactly how, and run strict QC, but if they come up with their own products, they build and design, they are normally not impressive.

[John in CR]

It just goes to show that there's no shortcut that enables big power and low weight in a truly reliable hubmotor. If you cyclist weight guys are breaking axles, imagine what it requires to power fat ole me, and to make matters worse in hardtail.

[Spicerack]

Why do you comment John, got a better motor to offer or something?

[wojtek]

i still think heat is the main problem for hub motors..

but there are geniuses out here in ES already doing the liquid cooling and pulling huge A with no overheating issue.. so the weight to power ratio with cooling system is getting quite impressive..

[miro13car]

you forgot cooling system with liquid weights also , right?
There something wrong with hub motor needing cooling at even 2000W.
There is something wrong with the motor which simply needs to draw so much power, to much power to reach say 35mph comparing with other motors .
So the question should be why it needs to draw so much to produce?

[wojtek]

you forgot cooling system with liquid weights also , right?
There something wrong with hub motor needing cooling at even 2000W.
There is something wrong with the motor which simply needs to draw so much power, to much power to reach say 35mph comparing with other motors .
So the question should be why it needs to draw so much to produce?

the weight penalty for adding cooling system is nothing comparing to the results it gives !!! Look here

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