Cracked side casing on Crystalyte 408motor - Strange Failure

[dnmun]

you should contact justin or zev so they know this problem is out there. before they order more motors, and they are the ones who can help you get replacement parts, and maybe for free under a warranty, but it is curious that both you and the sacman have such similar problems with new 400 series castings.

 

[Sacman]

do you pedal hard a lot with the chain on the 11 tooth end of the freewheel?

I actually use the smallest outermost wheel on the freewheel almost all the time when biking around. I normally use the two highest gears at the front when riding on the plain. I switch to lighter gears both at front and at rear when I meet hills.

Yeah I too pretty much ride on the highest/smallest gear most of the time myself. I believe that gear places the least ammount of torque on that threaded shoulder on the motor casing. And yet ... it still cracked. Unbelievable!

 

[Zoot Katz]

do you pedal hard a lot with the chain on the 11 tooth end of the freewheel?

I actually use the smallest outermost wheel on the freewheel almost all the time when biking around. I normally use the two highest gears at the front when riding on the plain. I switch to lighter gears both at front and at rear when I meet hills.

Yeah I too pretty much ride on the highest/smallest gear most of the time myself. I believe that gear places the least ammount of torque on that threaded shoulder on the motor casing. And yet ... it still cracked. Unbelievable!

According to the troubleshooting page on ebikes.ca they attribute the failure, in part, to the sharp break at the shoulder of the casting.
A fillet bead might take care of it.
Has anyone tried welding that stuff?

 

[dnmun]

it's an aluminum casting, welding is not an option, and it would never be as strong as a casting.

but i would like to see justin get a chance to look at the parts, even send them back to the source so they can stop the problem. this sounds like it could be poor casting and machining techniques, and maybe some fatigue cracking starting at the base of the freewheel threads. aluminum is very sensitive to stress cracking, ypedal actually lost the stud on one of his headway cells from metal fatigue with just a few tightenings of the nuts on the stud. so maybe the freewheel loading the hub at the junction between the stub for the freewheel and the face causes it to flex just a hair. that's why i wondered if loading the freewheel on the other end could be torquing the stub at the base where it comes out of the face of the side plate. it could be the freewheel itself. not fitting properly, or stressing the bottom threads the most because the die that cut the threads is worn, you never know, but the only way the factory will learn is if somebody tells them to fix it. justin may be able to do that.

 

[Zoot Katz]

it's an aluminum casting, welding is not an option, and it would never be as strong as a casting. . . .

There are techniques for welding aluminium castings, but you're right, they usually can't be welded after heat treating or machining.
I was thinking of a weld fillet as a prophylactic measure more rather than a repair. Maybe a bead of JB Weld could help distribute the load.

I'm not doubting that there are different batches of motors with parts from different suppliers that contributes to quality control issues leading to the failure.

For all the 400 series Crystalytes in service, how frequently does this problem occur?
Anyway, it's probably cheaper to keep shipping out replacement cover plates for those that fail than to re tool.

I'm not even sure you could get enough personal injury suits going in the USofA to change things in China. The failure seems to rarely cause anyone bodily harm.

 

[dnmun]

that's not what i meant. the manufacturer needs to know that they have this failure mode since they may not be aware of it. as a manufacturing engineer, you always want feedback to your manufacturing process and most people establish statistical quality control over known issues, but they could have made a recent change in alloy source for the aluminum or the molds are different and so the flange strength could be different if they now have a lighter plate because it is cast thinner and goes beyond some critical strength level at that point in the casting. i doubt if they have testing regimes in the final product stream either.

but as a former manufacturing engineer myself, this coincidence stands out, which is why i mentioned it. not sure what liability in the court has to do with it. but if justin got the motors through kenny, or whoever runs C'lyte, he likely can talk directly to the source and see if there are others with the same problems appearing. he doesn't want them on his shelf if they will fail, even if they can get replacement parts. if this is a manufacturing problem and they don't fix it at the source, they will go out of business. their reputation could be ruined in weeks or months if suddenly a bunch of these motors is sold out there and a lotta people complain. but i thought if he could look at the parts he could make that decision himself. same is true with all those who sell the motors.

 

[Ypedal]

...ypedal actually lost the stud on one of his headway cells from metal fatigue with just a few tightenings of the nuts on the stud. .

Actually.. it was a PSI cell, and i was not aware that the threaded stud was hollow, entirely my own fault for overtightening it, had i known it was hollow aluminum i would not have broken it..

And as far as the clyte hubs go...

http://clevercycles.com/?p=97

Read that for a reality check.

 

[Mathurin]

From cleverchimp blog


Incredibly awesome trike is incredibly awesome, but I can't see a throttle?