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[tafka]

Hi All,

I thought I would share the story of my experience with my 2017 Zero DSR with you just in case anyone has seen similar problems to me.

I live in the UK and I got the bike in March 2017.  I used it almost continuously (mostly commuting 50 miles a day) for a year with no issues, took it in for servicing when it needed it etc.  After about a year, the original tyres were looking a bit worn so I ended up changing them to road tyres.  I spoke to my dealer and they recommended a brand for me.  Incidentally, I think this added about 10% to the range and made for a much smoother ride. (130/80V17 AVON ROADRIDER, 100/90V19 AVON ROADRIDER)

I rode it for another year with no problems then just after the warranty ran out (isn't it always the way), I started having issues (maybe april(ish) 2019).

First the belt snapped (after only about 14k miles), which was not too much of a problem, I replaced it and carried on.  A few days later, I noticed (just once) that the front brake didn't work.  I tried to pull the lever and it was locked solid (the lever that is).  After a few more yards the brake released (with a sort of shuddering feel to the lever) and then everything was fine again.  I thought the front calipers might have been sticking, so I took then apart, checked them, put new pads in etc.  All seemed fine.  Then a few days later it happened again.

At this point, I contacted the dealer and explained what happened.  They arranged to take the bike in (they are some distance from me) and did some investigation.  Of course, they couldn't reproduce the problem and as a precaution (under advice from Zero) they replaced the master cylinder which I paid for.  I got the bike back and all seemed fine for a while until it happened again on the way to work.  Then when riding the bike back from work, I noticed that the ABS light was on.  I just happened to be looking at it when I used the front brake and the lever locking happened again.  This time I noticed that as that problem happened, the ABS warning light went out.

Of course, I passed this information onto the dealer and they took the bike back in.  Under Zero's advice they replaced the ABS pump.  This time, Zero did pay for it because they had given the advice to replace the master cylinder.  I got the bike back and all seemed fine for a month of riding.  Then one day, the bike stopped charging.  So off it went back to the dealer again to get the charger replaced.  In fairness to Zero, they covered the cost of the parts because of the other issues I had had with the bike.

I got the bike back and this time didn't even manage to ride it because the ABS warning light was on again.  So, back it went.  By now (I've missed out a lot of to-ing and fro-ing for brevity), it was getting to Winter.  Eventually, Zero said it must be because I have non-standard tyres on there.  I explained that (on and off) I had ridden the bike for 18 months or so with those tyres, a year of which I had no issues - note that the dealer doesn't understand this explanation either.  I sent the logs from the bike (which apparently just say "ABS SILA reporting an error") and Zero just insisted it is because of the tyres.  I asked the dealer if there would be any other issues, other than the ABS being disabled (remember the ABS system had been replaced at this point and since then the front brake locking hadn't happened).  They said, no it should be fine.  So I accepted their explanation that the tyres were the issue and thought I would ride with them until they needed changing and then put the 'official' tyres back to see if it solved the problem.

I was reasonably happy with that situation until (last night) going home, just riding the bike up onto my driveway (obviously there is a bit of a bump), the ABS light went off and the front brake lever locked up again.  I test rode it after that and the ABS light is staying on (as it has been since I got it back from the dealer the last time).  So, now I have a bike where (randomly) the front brake may or may not work one time when I pull the lever.

It certainly makes for an interesting Russian roulette experience when riding.

So, today, I am waiting again for a reply from Zero in order to work out what to do next.

I have to be honest, it has completely destroyed my confidence in Zero that they actually know how their own bikes work as I have never really had a satisfactory explanation as to what mechanism could cause this behaviour (Again, I have missed out a number of conversations in this explanation). Even if it is the tyres (which I don't believe), causing a critical failure in the front brake doesn't seem like the fail safe option.  Okay, disable the ABS but not the entire front brake.

I have sent emails to Zero directly but they just forward onto the dealer.

Does anyone on this forum have any ideas?

thanks,

Taf

[TheRan]

The light is supposed to go off once you get over 3mph, if it stays on that means the bike has a detected an error with the ABS system and it won't be active (you should still be able to apply the brakes in most cases). I've heard from some people that if the valves in the ABS system aren't used in a while they can become sticky, although that could just be bullshit from them hating on ABS, but if that is true and you've been riding around all this time with ABS not functioning then perhaps that could be the cause. Of course there is also an underlying issue that is preventing the ABS from functioning that should also be fixed. I personally don't think this would be the cause and it doesn't sound like you'd been riding for all that long on the replacement pump.

As for the tyres, as long as they're the same diameter as the stock ones (which your's are) then the ABS system should function the same.

[Crissa]

It's also not legal, in the US, to blame the tires, unless they can affirmatively prove the tires are causing the issue.

Since Zero is in the US, you can bug them about it.

-Crissa.

[Curt]

How could the front lever lock up? The only explanations would seem to be mechanical impingement at the lever or master cylinder, or hydraulic fluid completely blocked from the viewpoint of the master cylinder.

When ABS is turned off or not functioning, fluid should pass right through. I would think there is no failure mode where the ABS would block the fluid flow entirely. And it's been replaced, so the ABS is probably fine and the circuitry is detecting some other problem.

Could you disable the ABS (remove 25A fuse) and ride it that way for a while?

Could a brake line have gotten badly pinched or pulled?

Could a rotor be warped? Try a runout test. How far down is your rotor worn? Does it have a lip on it? (Mine lasted only as long as the brake pads, but the FX has only one small rotor).

[TheRan]

How could the front lever lock up? The only explanations would seem to be mechanical impingement at the lever or master cylinder, or hydraulic fluid completely blocked from the viewpoint of the master cylinder.

When ABS is turned off or not functioning, fluid should pass right through. I would think there is no failure mode where the ABS would block the fluid flow entirely. And it's been replaced, so the ABS is probably fine and the circuitry is detecting some other problem.

Could you disable the ABS (remove 25A fuse) and ride it that way for a while?

Could a brake line have gotten badly pinched or pulled?

Could a rotor be warped? Try a runout test. How far down is your rotor worn? Does it have a lip on it? (Mine lasted only as long as the brake pads, but the FX has only one small rotor).

I was confused as to how it could lock the lever too, I've never actually researched how exactly ABS systems work (I knew what they do, just not how they do it) but apparently it uses valves to shut off the flow and doing that could cause the lever to become stuff. I always just assumed they diverted the flow somewhere.

One interesting thing that Curt mentioned is that he felt pulsing at the lever when it started working again. I've never personally felt my ABS system kick in (it either hasn't or I'm not sensitive enough to tell) but I've heard other people describe a pulsing sensation when it's working. Not sure if it comes from the operation of the valves or from the pump that increases the pressure when the system knows the wheel is no longer slipping.

[dalamario]

Did the ABS speed sensors on the wheels are working properly? When ABS see a difference in wheel speed it activate and block or release the pressure on the circuit to control brakes. Maybe if it's happening on bumps, it's a wiring problem on the sensors that trigger the ABS and block the lever to avoid front brake to actuate.

[Curt]

Pulsating brakes is also a symptom of a warped rotor.

[talon]

temporarily seized piston, worn-too-thin or warped rotor, mechanically stuck lever (worn at the pivots?), pinched brake line. I feel these are by far the most likely for intermittent issues.

Piston seal in master cylinder bad? Air? Leaking fluid?

The determining factor would be the exact symptom. When trying to squeeze the lever does it move during this issue?

[tafka]

Hi All,

Thanks for the replies. I appreciate that this brake lever thing is difficult to understand but I'll give it a try.

So, when I say locks up, I mean it really locks up.  It is absolutely solid, almost like there is a mechanical block as someone said.  However, this *always* seems to coincide with the ABS light going off.  No matter how much I pull on it it will not move.

BUT, that only lasts for a second or two, next time I pull it, it moves a little bit but it feels 'jerky'.  Not like brake pedal in a car when the ABS is triggering jerky, but almost like stuck caliper or releasing valve jerky.  Bit by bit, the brake lever moves in and eventually the front brake engages with more and more force.  After that, the brakes work fine again.  This has never happened again after the ABS light has gone off during a riding session.

So, just to clarify, the behaviour is this...

Riding with ABS light on (maybe for miles and miles) - brakes work fine
ABS light just switched off - front brake fails for a few seconds
Riding with ABS light off - brakes work fine

Also, note that the master cylinder has been replaced.  The disc is fine (not warped), the caliper seems to move freely.

As I said before, the biggest problem with this is that "Brakes not working" is not an acceptable failure case for an ABS system.

I'm going to (at least visually) inspect the wire to the sensors at the weekend to see if I can see anything obvious but otherwise I am at a loss.  I will try removing the fuse and hopefully that will at least stop me from soiling my underwear occasionally.

:-)

Taf.

[tafka]

Hi Again,

I just thought of one thing...

Would the dealer have to take the back wheel off to replace the charger?

That was the last thing replaced on the bike when it last went from ABS ok to ABS light on.  I was just wondering if they disturbed the sensor/cable?

regards,

Taf.

[Richard230]

Hi Again,

I just thought of one thing...

Would the dealer have to take the back wheel off to replace the charger?

That was the last thing replaced on the bike when it last went from ABS ok to ABS light on.  I was just wondering if they disturbed the sensor/cable?

regards,

Taf.

The rear wheel does not have to be removed to replace the stock charger.

The subject brake failure problem sure sounds like it is caused by an ABS failure, either by the ABS pump or the ABS computer or a combination of the two. To me it sounds like the ABS pump gets activated and then is locking up for some reason.  Although I suppose that it could also be caused by a wonky ABS wheel sensor.  As they say, garbage in, garbage out.  Maybe a sensor is sending a bad signal once in a while when the wheel hits a bump and that is triggering the ABS system which hits the brakes and then the pump valving sticks and is not releasing as it should.   

[talon]

Just tossing more ideas at you: 

It could be caused by the tires being just outside the range of diameters the algorithm supports for the ABS configuration... a sticky brake lever switch (activating brake light after you stop pushing) can throw ABS codes.. an intermittent open/shorted connection on a wheel speed sensor (every time you turn your handlebars for the front, or perhaps when you did that belt change you pinched the rear sensor somewhere inside it's sheathing).

I've never had the front ABS activate due to how I brake, but the rear feels like the pedal is fighting you when it does. If you have had your ABS pump (and internal ABS computer) replaced it is most likely a brake line or a wire/connector. I would have the brake lines bled at the master cylinders and the caliper itself, see if fluid moves freely (if its been 2 years since ABS replacement you need it anyway). Then I would check the sensor connections and harness at wear points (where the swingarm pivots and the handlebar harness moves back and forth).

A very weird place for an issue could be the multi pin connection where the mc harness gives power and communicates with the ABS module. The modules are very hard to remove from the bike physically, especially if you have a charge or powertank. I *may* have an extra wheel speed sensor from a wrecked Zero I could send you to try (at your own risk) if you pay shipping, it's in storage. Your rear brake shows no symptoms when this happens? Does it occur when you brake with the front only, or front and rear together? Outside of finding a nice fine gravel area and testing at speed (dangerous) I don't see how you can test it without very specific tools.

[talon]

https://thebrakereport.com/2017-zero-motorcycles-recall-abs-brake-problems-s-ds-fxs-models/

Could yours be an affected model?

I believe the sensors are quite sensitive to being hit as well (magnetism?)

Do you use any heated gear or other 12V accessories? If the DC/DC has too large a draw I could see a brownout like issue at <10V operating voltage of Bosch Gen 9 ABS screwing up solenoid valve positions... even a loose connection near the fuse block could be the culprit.

Edit:
https://blog.motorcycle.com/2016/09/22/recall-2/2015-zero-models-recalled-abs-failure/
This describes what I was thinking, and apparently it has happened!

While I doubt the replacement pump is bad, perhaps these people could help:  https://www.ecutesting.com/categories/abs-pump-modules/bosch-abs-pumps-modules/
for Bosch-specific testing procedures?

[KuRi]

Hi, I have a 2020 DSR and the ABS light is never on while riding... is this a change for 2017+  models or am I missing something?

When I turn on the bike, the abs light is intermittent and orange, then after some move it just goes off...

[Richard230]

Hi, I have a 2020 DSR and the ABS light is never on while riding... is this a change for 2017+  models or am I missing something?

When I turn on the bike, the abs light is intermittent and orange, then after some move it just goes off...

They all do that, sir.