NuVinci hub slipping and making grinding noise.

[Jdevon]

Hi all,

I have tried searching but can't seem to find anything on the issue I'm having. We have a Yokler T pedicab that has a nuvinci optimised hub. Recently it has started slipping and making a grinding sound that is very loud when moving through the lower range, when this happens if you shift to full over drive this goes away.
We had a bike mechanic come and take a look and he adjusted the cable lengths but the problem is still there. Another issue that came at the same time is when in full overdrive it feels like there is less resistance than before, as if some of the range has gone.
Any ideas what this might be? Or would I be better off to just replace the unit?

Many thanks

 

[PaPaSteve]

The orange planetary "balls" can wear down causing slippage.

How it works video here

 

[Jdevon]

The orange planetary "balls" can wear down causing slippage.

How it works video here

This could well be what it is, the part that confuses me is why it only seems to have issues in the lower ranges.

 

[PaPaSteve]

This could well be what it is, the part that confuses me is why it only seems to have issues in the lower ranges.

The orange planets can wear differently across their shape.
The NuVinci I ruined slipped in the higher range and had a flattened groove on a portion of the ball.

 

[Superb_Raccoon]

The orange planets can wear differently across their shape.
The NuVinci I ruined slipped in the higher range and had a flattened groove on a portion of the ball.

Is it repairable? Or is it a "Ship to Enviolo" kinda thing?

 

[gromike]

As I have read it is a "Ship to Enviolo" situation. I imagine that the compression on the tilting balls is quite high, so the thing might be dangerous to disassemble yourself, providing you have the tools, let alone replacement parts. That said, it would be cool to open one up and have a look inside.

 

[Chalo]

This could well be what it is, the part that confuses me is why it only seems to have issues in the lower ranges.

The difference between the input and output radii on the spherical rollers is greatest in the low ratio, so if it's going to slip, that's where it will happen.

Note that there's a specified maximum input torque for that hub (though I don't know offhand what that value is), and if you exceed that torque you can expect to have the symptoms you describe. If you run the numbers and find you're overcooking your hub, you may have to raise your overall gearing to get the peak primary drive torque under its limit.

 

[PaPaSteve]

Is it repairable? Or is it a "Ship to Enviolo" kinda thing?

This was some time ago so as I remember ...
We removed the covers on the damaged hub to see what the issue was and then replaced the entire unit.
The experimental bike was powered by a ETEK brushed motor capable of 15hp continuous and 25hp peak.
Motor controller was an AXE Alltrax 48V 400A
So, in our case the hub was being severely abused.

 

[Chalo]

This was some time ago so as I remember ...
We removed the covers on the damaged hub to see what the issue was and then replaced the entire unit.
The experimental bike was powered by a ETEK brushed motor capable of 15hp continuous and 25hp peak.
Motor controller was an AXE Alltrax 48V 400A
So, in our case the hub was being severely abused.

I remember chatting up the NuVinci guys at Maker Faire, where they had an off-road kart with a 10kW (I think) motor. The engineer more or less characterized that as their upper range of power through the N171 hub, contingent on staying under the torque limit.

 

[Superb_Raccoon]

This was some time ago so as I remember ...
We removed the covers on the damaged hub to see what the issue was and then replaced the entire unit.
The experimental bike was powered by a ETEK brushed motor capable of 15hp continuous and 25hp peak.
Motor controller was an AXE Alltrax 48V 400A
So, in our case the hub was being severely abused.

Yeesh!

I am using the HD with a CYC Photon driving it. I have capped it to 95Nm

 

[Chalo]

Yeesh!

I am using the HD with a CYC Photon driving it. I have capped it to 95Nm

Note that you have to divide that value by your external gear ratio (F/R), and then add maximum muscle powered pedal torque divided by the same ratio. The resulting sum should be compared against the hub's rated torque limit.

 

[amberwolf]

As I have read it is a "Ship to Enviolo" situation. I imagine that the compression on the tilting balls is quite high, so the thing might be dangerous to disassemble yourself, providing you have the tools, let alone replacement parts. That said, it would be cool to open one up and have a look inside.

Unless the Enviolo is designed differently than the NuVinci versions before them, there is a special fluid that fills the hub to make the system operate correctly. AFAIK NuVinci (Enviolo) is the source for that fluid.

If you just want to see inside, there are a few pages with videos or pictures, like this one at the top of a google search

 

[PaPaSteve]

I remember chatting up the NuVinci guys at Maker Faire, where they had an off-road kart with a 10kW (I think) motor. The engineer more or less characterized that as their upper range of power through the N171 hub, contingent on staying under the torque limit.

10kw = 13.4hp
The 25hp peak no doubt is what damaged the hub.
2007 is when the bike was built which makes the hub the N171 model.
N171 production ran 2007 to 2010
The bike was dangerously powerful and fast.

 

[amberwolf]

Given those power limits, it's funny that their warranty was voided by powering it with a motor. :/

I'd wanted to use one in my original ebike design way way back when, probably crazybike2, and in a cargo / passenger trike design I had wanted to make and sell locally, but Fallbrook told me that any motor usage would void the warranty on the hub, regardless of torque/etc levels...which would make it pointless to build. I'd also wanted to use it outside the wheel so I could use regular wheels (stronger, easier to work on, etc), but they said that it must be used as the rear wheel hub of a bike, and can't be used as a non-wheel transmission somewhere, or again the warranty would be voided. (couldn't even use it as a front drive wheel).

I found it especially frustrating because *they* had contacted *me* about using their hub, even knowing what I was intending, but wouldn't make exceptions for this usage.

Since then I've collected a couple of them for reasonably cheap, including a full N171 developer's kit. Just before the housefire a decade ago I was working on a replacement for CrazyBike2 that would have used that as the transmission in the frame, but the fire and subsequent events put that on hold for so long that needs changed, so I never got that past the built-frame stage.

I may well use one in the (pedal) drivetrain of the future SB Cruiser Mk II, possibly even in the motor drivetrain...but that is still in the idea / planning stages. (had a plan, life went south again, don't need that plan anymore, so still working out best ways to do what I want with what I already have).

 

[gromike]

Wow, there was a lot in there. I didn't see the spring compression in the hub that I thought would be in there. But those CVT hubs are heavy and rob a fair bit of power. I put one on a 36v TSDZ2b bike and, to say the least, I was underwhelmed.

 

[amberwolf]

Some people using motors on them have reported something around 2/3 efficiency (less than 70%).

Per this article it's between that and 89%.

NuVinci continuously variable transmission - Wikipedia

en.wikipedia.org

per this it's around 80%

NuVinci Efficiency | Rattleak NuVinci

Don't know what it *actually* is for a specific scenario, but I expect that the higher the torque is the lower it's efficiency (greater potential slipping?).

 

[Superb_Raccoon]

Unless the Enviolo is designed differently than the NuVinci versions before them, there is a special fluid that fills the hub to make the system operate correctly. AFAIK NuVinci (Enviolo) is the source for that fluid.

If you just want to see inside, there are a few pages with videos or pictures, like this one at the top of a google search

OMG, he moved the camera so much I thought I was gonna barf. didn't get past 2 minute mark.

The fluid might be "proprietary" and the only source is them, but that does not mean they won't sell you some. Curious how that runs or does not run afoul of Moss-Magneson. Act

Unless the hub has to be sent to them only for service.

 

[Superb_Raccoon]

Some people using motors on them have reported something around 2/3 efficiency (less than 70%).

Per this article it's between that and 89%.

NuVinci continuously variable transmission - Wikipedia

en.wikipedia.org

per this it's around 80%

NuVinci Efficiency | Rattleak NuVinci

Don't know what it *actually* is for a specific scenario, but I expect that the higher the torque is the lower it's efficiency (greater potential slipping?).

Well, that is for the reference Kopp design, which the Enviolo is a variation on that.

Also in the article:

"In general because of the way the CVT is set up, it is more efficient at a 1:1 ratio compared to maximum overdrive or underdrive positions. Independent test results have shown that at 1:1 it is actually more efficient than comparable bicycle internal gear hubs, while at the ratio extremes it is slightly lower"

"comparable" is not defined, could be Rollf, or more likely Shimano.

 

[amberwolf]

I'm pretty sure they will sell the fluid, or at least did at one time; I am not certain but I think one of the hubs I was looking to buy once upon a time came with some, as it needed repair. A quick search shows Calfeedesign used to stock it, but is sold out. Another thread here Need NuVinci Invaritorc 638 Fluid please :) says it that at that time Fallbrook wasn't even "allowing" it to be sold (though it had been before), but I don't know what Enviolo does.

Sorry about the video; I don't watch them so I don't know what they're like. I prefer to read articles and see schematics and pictures, instead of suffering thru minutes to hours of someone else's presentation of something, when instead could spend a few seconds searching text or images and get the info I need.

 

[Superb_Raccoon]

I'm pretty sure they will sell the fluid, or at least did at one time; I am not certain but I think one of the hubs I was looking to buy once upon a time came with some, as it needed repair. A quick search shows Calfeedesign used to stock it, but is sold out. Another thread here Need NuVinci Invaritorc 638 Fluid please :) says it that at that time Fallbrook wasn't even "allowing" it to be sold (though it had been before), but I don't know what Enviolo does.

Sorry about the video; I don't watch them so I don't know what they're like. I prefer to read articles and see schematics and pictures, instead of suffering thru minutes to hours of someone else's presentation of something, when instead could spend a few seconds searching text or images and get the info I need.

Same.

Just... watch some of it, make sure it is not a vomit comet.