Agni 95R overhaul help - noob here

[sdeluca]

I have a 2010 Zero DS with the Agni 95R motor. I was having issues with a grinding/rubbing sound and eventually a burning smell (you can read a longer description of symptoms below) that resulted in sending the motor to Zero for them to check the brushes, as they suspected that was the problem. They inspected them and determined they were fine and shipped the motor back to me with the explanation that the "magnets were weak, the only option is a whole new motor" which makes no sense based on the symptoms I experienced.

I managed to remove half of the motor casing to inspect the armature myself. I inserted a shim between the magnets and the armature and moved it around the armature to check the distance. There was certainly a difference in the spacing towards one side. I imagine this means one of two things. The shaft is very slightly bent, such a minor amount that I could not determine it by measuring - or - the shims have shifted out of place and the armature is not level. The only other observation I noted was that the edge of some of blades on the armature were ground away. This was on both sides of the armature, on the same outer edge; not opposing edges as one would expect if the rotation of the armature was tilted and it was rubbing - very strange.

Before I bother to remove the armature and continue inspection I wanted to start a thread and ask some more experienced folks out there what their ideas may be on my problem. I have no experience working with these motors so this overhaul is a also an education for me. Below are pictures I took when I cracked open the motor case. Obviously the magnets, the commutator, and just about everything else needs cleaning, but I know the problem is much more complicated than that.

A section of an email I sent to Zero describing my experience, after hearing a grinding/rubbing sound for a couple days and thinking initially it was my rear brake pads as I had just replaced them:
'In the evening when I went to go home, I started the bike, sat down and rolled the throttle. The warning indicator flashed three times. This, according to the manual indicated something was wrong with the throttle connection or the throttle was "ON". I investigated what I could in my company parking garage, but ultimately after turning the bike on and off a few times, it lurched to life. I drove the bike slowly and stopped periodically to check the brush less motor as now my suspicion was something was wrong there. The bike seemed to function fine on the drive, but at the end the cooling fan was running higher than I had ever experienced and something smelled burnt. I had also read in the manual that if the warning light flashes while driving it could mean the brush less motor is overheating and that I should pull over. I never got an such warning/flashing on the ride yesterday evening."




dirty communtator

View attachment 2
some black gunk against the side of the case


the ground away edge of the blades described above


another angle of the ground blades

Thanks in advance everyone.

 

[major]

Avoid cleaning (or even touching) the commutator surface. The dark color is the film (sometimes called patina) which develops from the copper-carbon interaction and is an important component of the commutation process. Clean it only if there is contamination or mechanical damage to the copper like burrs, high spots, burns, etc. Do not let any grease or oil (even from your fingers) get on the comm surface. If it is contaminated with greasy or oily dirt wash it with water/mild detergent and thoroughly dry it.

The blades on the armature as you call them are the armature coil ends. My guess is that these were ground down at the motor factory to balance the armature.

Magnets can weaken for several reasons like excessive heat, excessive field (from too high armature current) or mechanical shock. The motor controller should prevent excessive current and heat or shock should have left telltale signs which I didn't see in the photos. The result of weak magnets will be less torque from the motor which will cause higher current and a hotter running motor.

You're probably screwed and need a new motor. A shame an original motor only lasts for 4 years

 

[regmeister]

I've no ideas for you, but you may find these videos useful assuming you haven't seen them already.

http://www.jozztek.com/shop/content/category/2-technical-support-videos-agni-motor-reconditioning

 

[sdeluca]

major -
Thanks for the info and explanations on several of my "observations". Everything you mention makes sense, but it still does not explain the grinding or rubbing sound I was hearing before the I smelled the burnt odor and got the throttle warnings. Perhaps it does not matter what the problem was and you are correct that the motor is shot. It only lasted me 5000 miles actually. This bike was not purchased/ridden until 2012 and "died" in early 2014 so it lasted less than 2 years. Now I am faced with a $1000 motor purchase on a bike that is barely worth $2000...

regmeister -
I have come across these videos and they are rather informative, but were not in depth enough to help me wrap my head around what the problem may be.

 

[Njay]

Not really much more help, but a few things you can check, if not already:

- bearing(s)
- can the grinding sound also be eard with the brushes removed
- is any rotor "metal piece" loose? Sometimes things are sligthly loose but stay in place and we don't notice; you should however see some grinding on the magnets or somewhere on the case, which doesn't seem to be the case
- the end connection of the rotor blades, I think I saw somewhere that they are soldered and can de-solder on high heat
- the brushes' surface is in good condition and pieces are not missing
- the brushes' springs have tension, the brushes are not getting stuck in their movement
- an unbalanced rotor vibrates (even at just 12V)
- the grinded tips are for rotor balancing.
- I suppose unevenly demagnetized rotor (some magnets stronger than others) can show as strange effects.

With less magnet strenght makes sense it pulls more current, as it looses torque (and gains rotation).