Noisy NuVinci

[Rassy]

For the last couple of hundred miles my 171B NuVinci CVT (Developers Kit) has been making a rattleing noise in the higher gears. It sounds sort of like a jack-hammer except not so loud. The noise is there only under power, motor or pedal, and goes away when coasting. The noise can even be heard when running in the shop with the wheel up. Everything is working properly, except for the noise.

Since I had another NuVinci CVT on the shelf I swapped the noisy one out for the new one. Noise gone, as expected. The only change is the NuVinci hub, i.e., the same wheel and spokes, track cog, chain, electronics, actuator, etc. were used.

Now my question. What happened to my original NuVinci CVT? It probably had over 1000 miles on it. The 500 Watt electric assist mid drive hub tops out just over 1000 Watts draw from the battery. Could it be internal damage because I use a track cog instead of an external freewheel? (This means the internal NuVinci frequently freewheels.)

I would like to hear about any similar problems and causes. Even though there was no warranty on the developer kits, I am going to see what Fallbrook might think caused the problem.

Thanks,

 

[dnmun]

pictures when you get it open!!!

it may be that the CVT pulley/gear inside is riding out on one end of the shaft and there is so much play in the bearing on that end that it flops around on the shaft or the shaft it self is moving around as the load rotates

 

[StudEbiker]

Bummer. Hope you get it sorted out.

 

[amberwolf]

it may be that the CVT pulley/gear inside is riding out on one end of the shaft and there is so much play in the bearing on that end that it flops around on the shaft or the shaft it self is moving around as the load rotates

There isn't exactly a pulley or gear in there. It uses two rings and a set of ellipsoidal "balls", and a traction-transfer-fluid to move the power from the input ring to the balls and back to the output ring. THen there is a shifter mechanism to tilt the balls to change the ratios.


I am not sure what would cause the noise itself, among those parts. I would suspect a bad bearing, though, as that general type of noise I have heard from various powered devices when bearings fail or get a splinter of metal debris in them. I have a bike with broken crank bearing races that clicks on every passing of a ball during the downstroke.


It might also be possible that something is wrong with one of the balls, so that when it is oriented in certain positions (ratios) it makes a noise as it rotates past the damaged area.

 

[Rassy]

Thanks for the comments. I am currently waiting to hear from NuVinci Support before looking inside the NuVinci. But if/when I do I'll post some of my poor quality pitures. If I'm lucky NuVinci will want to take a look at it and perhaps repair it.

 

[Rassy]

I didn't get any warantee service on my noisy CVP, but their Marketing Rep from Portland that took an interest in both the problem and my trike set me up to purchase another $150 developers kits if I wanted it. Apparently the ones they have left are being saved for warantee service and not for direct sale. I did get another spare kit.

He also got a reply from one of their engineers (or whatever):

He also said that we have never seen an issue with a direct cog into the CVP and that freewheeling internally has never shown to cause any issues. The external freewheel is more of a safety redundancy. Hopefully that can put to rest some potential fears.

So maybe by the time I've used up all my spare parts, if I don't just die of old age first, there will be an even better auto shifting IGH available.

In addition to what's being used on the trike, the shelf currently contains one new developers kit, one used developers kits, another new actuator, another new controller, a "noisy" hub that still works, and one manual shift hub that may have some compatible internal parts.

 

[StudEbiker]

Dang dude, I know who I'm coming to if I ever have any problems with mine. Cool to know that they have some kits held back for when things happen to the ones already sold.