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[Burton]

So I was out tonight with my zero 2013 SR (see signature) and decided to open her up on a straight where the speed limit was high enough to have a couple seconds of fun from a stop light.

I got up to around 40 and that is when I thought I slipped my belt. I do have video, uploading it now but not sure how good the audio is yet.

The first thing I did is throttle off and started to coast, the last thing I wanted was the belt the come off or worse. To my surprise it didn't come off and I was able to accelerate on but the noise continued and so did the slipping.

I got to my location 1 mile away from where this happened and looked at the belt. It was still on and in the right location but all the teeth were stripped ... and I do mean all!

The only thing that is different from the last time I did this was my belt tension in the past was 40kg and this time it was the MOM recommended 20-30 (25kg to be exact). No, Electric Cowboy (the previous owner of this bike) told me to ignore what it said in the book and go with 40 and stated they even use 50 on the track.

But being a good little mechanic who likes to keep everything in spec I followed the recommended guidelines in setting tension the belt when I put my motor back on from having changed the bearings from ceramic to something closer to stock.

I have no clue if the lack of tension caused this to happen ... all I know is all my teeth are stripped off and I had to limp home and not go over 45 indicated.

I tried to keep my bike moving and minimize stops as it was when the bike was starting from a stop the slipping started again.

I am so frustrated right now ... and I have a feeling my dealer has still yet to get my ordered belt, pulleys, and replacement tank in yet from zero; ordered a month ago.

So ... now back to riding my gas bike for who knows how long ...

Going to have to contact Hollywood electrics to see if they have any belts in stock and have them send them over night if possible.

I am never following the MOM's advice on belt tension again.

The worst part about this is I can't tell anyone I ride with as they would use it as another excuse to bash electric bikes ... I want so much to show them how maintenance free they are, and how fun they are to ride but so far I haven't been able to with this bike.

I keep telling myself it was because the bike was heavily modified that I have as much trouble as I seem to have.

Le sigh 

[firepower]

MOM =  Manufactures Owners Manual ?

Strange, I assume everyone would be using zero belt tension spec. Your is the first report of stripped teeth i know. Maybe because of previous high tension has caused belt to stretch and now lower tension is not enough. Recommend using correct tension on new belt. You wont be racing so wont need to go as high.
I think Gates are the belt OEM. here is some info that might help

http://www.gates.com/~/media/Files/Gates/Industrial/Power%20Transmission/White%20Papers/Proper%20Alignment.pdf

http://www.gates.com/~/media/Files/Gates/Industrial/Power%20Transmission/White%20Papers/Belt_failure_analysis_Final.pdf

I be double checking your pulley alignment when you reinstall new belt.

[Burton]

Belts where dead on when I put them back on and I even went about 350 miles before this became a problem :/

I don't mess around when it comes to chain or belt alignment and even break out my Caliper to make sure I am not off

Applying insufficient installation tension to belts operating on moderately
to heavily loaded drive systems may also result in premature failures.
A common belt failure mode resulting from insufficient belt installation
tension is referred to as tooth rotation. Belt tooth rotation can occur as
belt teeth climb out of their respective sprocket grooves (self tensioning)
and drive loads are no longer applied at their roots. Drive loads applied
further down the belt tooth flanks cause the belt teeth to bend (like a
diving board) and “rotate.” Belt tooth rotation can result in rubber tearing
at the base of the belt teeth along the tensile member. As rubber tearing
propagates, belt teeth often begin to separate from the belt body in
strips, as illustrated in Figure 8. Failures due to excessive tooth rotation
may resemble failures caused by insufficient rubber adhesion to the
tensile cords. Unlike tooth rotation failures, failures from insufficient
rubber adhesion leave the exposed tensile members clean where the
belt teeth were once located.

sounds about right

Great resource ... will definitely check for "alignment" the trick is going to be finding a straight edge that long and skinny to use. Tracking was perfect last I checked it ... I am still betting on tension being the issue ...

I wonder if a belt previously set to 40kg would stretch enough that when set to the recorded 20-30 (in my case 25) it would skip out of the motor pulley on hard acceleration ? I had not opened up on the bike from a stop since making this change, only at a rolling speed of like 10 / 15 ...

[Electric Cowboy]

Optimal belt tension for that bike which was set up as a race bike is 40-50 not the recommended 25.

[Burton]

Optimal belt tension for that bike which was set up as a race bike is 40-50 not the recommended 25.

Where is the like button? lol



I tried to add it inline but got a "device support" error when it went to actual posting. In preview it seemed find :/

Would it be safe to assume SR's should also use the 40-50 ?

When it comes to motorcycles I don't like to be wrong ... because later I know I will have to fix my mistake. >__<

[teddillard]

I'd like to know where the higher tension spec came from.  Did they have trouble with running lower tension when they were racing?  Is it typical for a race-prepped Zero to run at higher tensions?  Do you remember ever looking closely at the condition of the belt before this?

It seems perfectly logical to me that if this belt was run at higher tension, then reduced as you did, it would make it prone to fail.  I'm not sure I'd jump to the conclusion that a new belt with a new pulley would fail in the same way. 

Also, I'm assuming this is on the motor that had a bad bearing?  That's now starting to make sense.

If the argument is that this motor is putting out so much power that it's throwing the belt, it doesn't seem to me to be a viable solution to simply overtighten it.  The options would be to run a beefier belt, or swap to a chain.    ...but what I don't know about belts could fill a book.   

[Burton]

That was my thought to Ted which is why I reduced the tension back down to stock settings thinking that is what caused the bearing failure. At the time I wasn't even thinking the belt stretched.

Beefier in what way though? Wider, stronger, thicker etc ? To me it seems wider would be great but that would mean getting custom front and rear pulleys made.

As for switching to a chain ... after this happened that thought popped in my head as well ... but man I hate chains, especially on the east coast. In the winter you have to clean and lube it a lot if you want it to last more than a year. And the best part about a belt outside lower maintenance is the sound.

Switching to a chain would open up other options for gearing but I suspect rear sprockets would have to be custom made even for the gearing I have now :/ (25/98)

If I order belts today from Hollywood electrics I will likely get three. One for the bike and then two spare since "two is one and one is none," is the general rule I like to follow. I am tempted to set it to 30kg and test it to see if it fails with a new belt which hasn't been raced for 600 miles then ridden for 8200 on the street.

Not to keen on "testing the waters" though as if it fails another way it could really mess things up.

[teddillard]

If you have a bunch of belts coming, I'd run it at stock tension and see if you have trouble.  Brand new belt - unless the previous owner chimes in with an explanation I guess. 

Beefier as in a thicker, or a stronger spec - like I say, I don't know from belts.  Certainly wider would do it, but you can't do that, as you said. 

Also, aren't there industrial or automotive belts you can use instead of buying direct from Zero?  Lemmee see if I can dig something up on the googles, out of curiosity.

[teddillard]

Yeah, check out this site for example: http://us.misumi-ec.com/vona2/detail/110302653730/?CategorySpec=00000029781%3A%3Aa  They also sell pulleys.

The Gates sites aren't too great for looking up a belt by spec.  McMaster Carr even has high-torque belts. 

Also, The World of Timing Belts - a pdf that tells you everything about the specs and stuff: http://tinyurl.com/nfwkxos  I can feel myself getting smarter by the minute.   

[Burton]

Ok rough measurements from the belt.

14mm x 1620mm with 7.5mm spacing ... no clue on anything else since teeth are missing.
Closest belt in the place linked would likely be 15mm x 1600 x 200 teeth (since they only give you one option for teeth that size) and I don't think 200 teeth is right. Granted, I didn't count them either and instead used some basic math to estimate 216 teeth ... so it could be right.

Looking at the belt in better lighting today the teeth look sheared off clean ... I can see where the rubber should have sheared off if it was a tension issue so ...

I will have to hunt around my garage for a thin straight edge which is truly straight or set up a laser to check if the sprockets are not aligned (despite them looking aligned, tracking properly, and the rear wheel being perfect :/ )

[rayivers]

Just for what it's worth... the belt on my FX was set to nearly 35kg from the factory.  I dropped it down to 30, all good so far.

Ray

[Richard230]

The belt on my 2014 S was set at 50 kg from the factory, according to the cheap pot-metal belt tension gauge that I was using.  I have left it at that tension and the belt hasn't loosened after 7K miles.  However, I am not too impressed with the perceived accuracy of the $17 belt tension gauge, which is why I haven't loosened the tension.   

I have checked (with my finger) the belt tension on the 2015 bikes that I have seen on the showroom floor and they all appear to have similar tension to my belt.  Maybe the recommended tension gauge that we are using is not accurate?