PAS sensor (KT-V12L) install issues

[James Torr]

Folks - my first post here, so be gentle!

I started a eBike conversion (Yosepower back wheel kit) about a month ago, and have learnt a considerable amount about bikes and ebikes in the ensuing afternoons working on this project.

Finally, I'm a bit stumped about how to install the PAS sensor. I'm keen to get this on as it saves me fingering the throttle if I'm wanting some juice. The sensor works, but initially the pedal crank was too tight. I've filed off enough of the pedal to give about a mm clearance - although it's a little uneven (1mm on one side, 3mm on the other). The sensor pushes into the slot on the frame fine, but with a small amount of pedalling it quickly comes loose. There doesn't really seem to be anything holding it in there aside from the teeth, and you can pull it quite easily out. Is this thing designed to sit in the frame with just a snug push in? Seems a bit unlikely, but I can't rule out my uneven filing is the cause of the sensor popping out.

I've heard mention here that some people have used cable ties to secure the PAS sensor, but the ties are pulling at an angle (they'll just fall off otherwise) and seem to affect the function of the PAS sensor.

Am I missing something here, or is the design of this thing not exactly brilliant? Any other people have any methods of securing the sensor that aren't going to come loose after a few miles?

If I have to get another PAS sensor - with a better design, any recommendations for julet plug fitted PAS sensors that'll work with the Yose kit?

 

[James Torr]

Briefly spoke to Pete (I think) at Wooshbikes today and he recommended putting in a rubber washer between the PAS (or should I say POS) and the crank. Got some rubber sheeting at work so I'll give that a try cutting it out and mounting it.

 

[wheeliepete]

When you say slot in frame, do you mean the splines on the bottom bracket? A cable tie around the wire and the chainstay should hold it fine. If you put a rubber washer in there, make sure it is only just big enough to touch the inner part of the sensor or it will make the whole thing spin with the crank and you will damage the wire.

 

[James Torr]

So this is the PAS sensor in it's place. Tried the cable tie option but it was sitting in there so loosely that it didn't hold it in place. I may have made the fit a bit looser by pedaling against the sensor when there wasn't enough clearance and the PAS got a little damaged.

https://photos.app.goo.gl/HzXH8iaDgFHoN63n7

I got the impression that if it was just a little bit of clearance between the crank and the sensor that was holding it in place, it would come out quite easily and also rubbing against the sensor would quickly damage it.

https://photos.app.goo.gl/8tKG4PRLaGx3MFWL6

In the end, I got the pedal crank a bit flatter than it was before so it wasn't rubbing against the PAS sensor and pushing it out. Then I cut out a bit of rubber from some sheeting I had, and placed it between the crank and the sensor. Seems to be working ok now. I might need to replace it after a bit, but it's pretty tough stuff and should be ok for the while.

the sheeting

https://photos.app.goo.gl/z4MUqM3V2YPYC8jC9

the "washer" in place. It ain't too pretty but seems to do the job.

 

[James Torr]

 

[Millard]

I can’t get my KT-V12 to work with my LCD3 any ideas

 

[Nealh]

Have you tried C1 setting with value 05,06 or 07 ?
And C11/0.

 

[Millard]

Yeah tried it and it didn’t work. This lcd3 is very difficult to program

 

[jeff St.Clair]

James , on my rockhopper the magnetic disc was too thick to fit between the crank and the bottom bracket ...so I fixed it to the granny gog with epoxy glue on the other side then mounted the pas sensor underneath the bottom bracket glued on a strip of metal screwed on with the plastic gear cable guide thingy...The red thing is the sensor and there is about 1mm gap between it and the magnet disc ...I hope this helps ...click on the thumbnail and a bigger photo should pop up

 

[Ken Kesler]

Like James, I have a PAS (KT-V12L) issue. Mine has worked fine for a year, but now only works consistently if I aggressively tighten the crank. Even with lock washers the crank loosens enough so that the PAS doesn't work. I've tightened so much now that the PAS is worn and if tightened even more the crank is difficult to turn. Is there a better technology without moving to a completely new system? Thank you in advance for your time.

 

[Nealh]

Like James, I have a PAS (KT-V12L) issue. Mine has worked fine for a year, but now only works consistently if I aggressively tighten the crank. Even with lock washers the crank loosens enough so that the PAS doesn't work. I've tightened so much now that the PAS is worn and if tightened even more the crank is difficult to turn. Is there a better technology without moving to a completely new system? Thank you in advance for your time.

The fact the crank doesn't/can't tighten up is because it isn't able to locate on the Sq taper enough, have a look on ebay for thinner PAS disc/sensor of about 2.5mm - 3mm thick. Usually with Sq taper BB you have to either buy the next size up BB for the V12L.
First off you need to measure the available gap on the axle with the crank tightened up without the sensor attached.

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[Kwozzymodo]

I have always found the integrated PAS to be a bit of a pain. Too tight and the unit internals will wear out in short order. Too loose and the unit won’t work properly. Get hold of a two-piece PAS, much easier to install and pretty much bulletproof.

 

[Nealh]

Quite a few have bemoaned the one piece V12L in previous years.

 

[Ken Kesler]

I have always found the integrated PAS to be a bit of a pain. Too tight and the unit internals will wear out in short order. Too loose and the unit won’t work properly. Get hold of a two-piece PAS, much easier to install and pretty much bulletproof.

Thank you for the advice. This is most helpful!!! I thought that I had done something wrong. You have done your good deed for the day.

 

[Ken Kesler]

I have always found the integrated PAS to be a bit of a pain. Too tight and the unit internals will wear out in short order. Too loose and the unit won’t work properly. Get hold of a two-piece PAS, much easier to install and pretty much bulletproof.

Is there a particular two-piece PAS you would recommend?

 

[Woosh]

I beg to differ. The left side PAS is much easier to install and replace.
You need a BB axle of 122mm if your BB shell is 68mm, 127mm if your BB shell is 73mm.
Check also the diameter of the BB axle, it should be 16mm. If yours has 17mm dia axle, replace it.
If it's too short, replace the BB, it's £10 well spent.
The right hand PAS is good but so last decade. The magnet disc can be easily knocked, the sensor is exposed to surface water and some bottom brackets are a pain to remove before you can fit a right side PAS to it.
The reason why some people may have problems with fitting a left side PAS is because they don't pay attention to the way the crenellations on the PAS slot into slots on the bottom bracket side. When they force the PAS in, the crenellations don't match, causing friction inside the PAS unit, leading to premature death of the PAS.
Before refitting the left side PAS, you should match the left BB cup with the PAS to get a feel for how it fits first.

 

[Kwozzymodo]

Something like this - an 8-pole PAS . Available on a well-known auction site for a few quid. Check connector compatibility with your controller.

You do have to remove the bottom bracket to locate the sensor collar. The magnet disc should slide onto a square-taper bottom bracket. These sensors are reversible, so you can put them on the left or right side of the crank (I prefer the right side, as the disc is hidden behind the chainring and relatively well protected from accidental knocks, etc.). You can get away with a gap between the magnet and sensor of 5mm or so, so you have some 'wiggle room'.

If the disc interferes with the sensor, you may need to remove some of the centre for the disc and epoxy it to the inner chain ring. In some cases, the disc fits without any fettling and the magnets hold it in place. Otherwise, some cable ties around the chainring spider keep the disc in place.

Hope this helps!

 

[Ken Kesler]

I beg to differ. The left side PAS is much easier to install and replace.
You need a BB axle of 122mm if your BB shell is 68mm, 127mm if your BB shell is 73mm.
Check also the diameter of the BB axle, it should be 16mm. If yours has 17mm dia axle, replace it.
If it's too short, replace the BB, it's £10 well spent.
The right hand PAS is good but so last decade. The magnet disc can be easily knocked, the sensor is exposed to surface water and some bottom brackets are a pain to remove before you can fit a right side PAS to it.
The reason why some people may have problems with fitting a left side PAS is because they don't pay attention to the way the crenellations on the PAS slot into slots on the bottom bracket side. When they force the PAS in, the crenellations don't match, causing friction inside the PAS unit, leading to premature death of the PAS.
Before refitting the left side PAS, you should match the left BB cup with the PAS to get a feel for how it fits first.

Thank you for your reply about the left side PAS. That being said, it's clear I'm in over my head. I'll have to look up "BB shell." Crenellations? Sensor seems seated well. The problem seems to be how to tighten the crank without it being too loose (PAS doesn't work) or too tight (excessive rubbing on PAS).

 

[Ken Kesler]

View attachment 34338

Something like this - an 8-pole PAS . Available on a well-known auction site for a few quid. Check connector compatibility with your controller.

You do have to remove the bottom bracket to locate the sensor collar. The magnet disc should slide onto a square-taper bottom bracket. These sensors are reversible, so you can put them on the left or right side of the crank (I prefer the right side, as the disc is hidden behind the chainring and relatively well protected from accidental knocks, etc.). You can get away with a gap between the magnet and sensor of 5mm or so, so you have some 'wiggle room'.

If the disc interferes with the sensor, you may need to remove some of the centre for the disc and epoxy it to the inner chain ring. In some cases, the disc fits without any fettling and the magnets hold it in place. Otherwise, some cable ties around the chainring spider keep the disc in place.

Hope this helps!

Thank you for your reply. You wrote that I should remove the bottom bracket to locate the senor collar. Got to admit I'm clueless here. The bottom bracket of what? The PAS is a sealed unit. ???

 

[Woosh]

The problem seems to be how to tighten the crank without it being too loose (PAS doesn't work) or too tight (excessive rubbing on PAS).

That is why I suggest fitting a BB (bottom bracket) with the correct axle length and diameter.
make sure that there is 1mm air gap between the crank and the left side sensor and the cranks rotate freely after installation.
The problem with kits sold on amazon and ebay is they don't come with installation manual and backup, just in cases like this.