Broken CVT :(

[alexanderfoti]

I seem to have broken something in my driven pulley.

I was gave it a lot of acceleration as I was about to join a slip road and something went crack and I felt a lot of vibration from the drive size of the bike.

Turned around and came home, found this:



This piece has a crack mark all the way around so it used to be attached to something. The expanded diagrams don't help me understand where its broken off from though:



not sure if its an inside casting of 2...

With it off nothing feels loose etc, but it certainly was not happy.

[gilburton]

Use a vice, valve spring compressor or ratchet strap to compress it and remove the circlip(7) It's not difficult to compress and you will then find out.
It's an Aixam diesel microcar pulley if you need another. You might get away with a petrol version pulley if you swap the spring over.
There are usually a few being advertised on ebay.

[alexanderfoti]

Thanks!

I took it apart, and the piece is a plastic collar/bush that is pressed into the center of number 2. I will try and get a picture.

[alexanderfoti]

Thanks!

I took it apart, and the piece is a plastic collar/bush that is pressed into the center of number 2. I will try and get a picture.

Looks to be possibly a plastic bush. Not listed in the bits, here it is pressed back into place again:

[gilburton]

Looks like you have some damage in there. It needs the collar to centre the outer pulley.
You might get away with sticking it back in with some sort of adhesive but the whole thing relies on a good fit to operate smoothly so I would advise getting another complete pulley. It might get you mobile but the only answer is another one.
There are no specific driven pulleys on ebay although there are a few ads for aixams being broken so you'll have to email around.
https://www.evergreenautos.co.uk/

[alexanderfoti]

I agree, does look like its been designed to be replaceable but alas, not available seperately.

I have bought another whole pulley from evergreen, so will see how that goes. Many thanks!

[gilburton]

Another thought came to me is number 5 a key ?
If so has it sheared off causing the outer half and 6 to rotate and ruin the plastic bush at the same time?
I think the key engages with 6 so check it out.

[alexanderfoti]

Number 5 is a key, but it appears to be fully intact. Its only about an inch long, and can be pushed all the way into the bore.

In my picture of the plastic bush, there is a metal ring/shim that was loose when I opened it up, I have pressed it back into the bore, and I suspect its job is to keep the plastic bush in place. I think the shim was loose and then caused the bush to come loose.

I wonder if it can be replaced with an oillite bush or something similar

[gilburton]

Put 1 and 6 together with the key in place but without the spring and the moving pulley half.
Does it engage all ok and stops 6 rotating?
Going by the scores in the outer pulley half where the spring sits it looks like something has been rotating when it shouldn't.

[alexanderfoti]

Will attempt it tomorrow.

I have been trying to track down an odd thing.

When accelerating hard from a stop, something grumbles/rumbles from the driven pulley area. I initially thought it was the chain jumping teeth but observing it whilst moving proved it was coming from the secondary pulley.

I thought it was coming from the belt slipping on the pulley but not so much now...

[alexanderfoti]

There is a thin metal shim that presses into the housing after the plastic bush goes in, and on mine it had come out, allowing the bush to come out.

On the replacement CVT this is very well pressed into place.

I have not tried putting 1-6 together with the key yet, will do that today.

[gilburton]

Is it sorted now?

[alexanderfoti]

CVT working well, have changed my front sprocket at the same time, so now waiting on a longer chain before I can test the ruddy thing!

[alexanderfoti]

All back together with the new CVT and working well.

I took it all apart and cleaned it up before fitting.

[alexanderfoti]

Longer ride today with the new secondary and it does the acceleration slip thing much more than the old one.

Took it off, removed 2 shims from the centre and moved the spring one click round on one end to increase the clamping force. Much better now, only slips/jumps if I am very aggressive with the acceleration.