My recently acquired low mileage 2008 VX-1 (1,159 miles) is booked in for an MOT Test on Monday but I am concerned about the very spongy feel to the rear brake. It seems to work OK and will lock up the rear wheel, but it is very spongy compared to my other Vectrix and the lever pulls right up against the hand grip if I pull hard enough. (Whereas the front brake lever on this bike and both of the brake levers on the other Vectrix do not)
I have tried bleeding the brakes normally with a piece of tubing and bottle and have flushed a fair amount of brake fluid through it but it has made no difference. I even removed the rear caliper and wedged a spanner between the pads and tried bleeding it whilst it was raised up ensuring a straight and uphill route for the trapped air but none appears top have come out.
I have also tried applying pressure and carefully slackening the bolt on the banjo union, but still no sign of air escaping or any noticeable improvement in the feel of the spongy brake lever.
I thought about putting a brake hose clamp at the rear end of the hose just before the caliper to try and determine whether the air is trapped in the brake hose or the caliper, but I am a bit concerned about damaging the hose.
Has anyone experienced a similar problem? If so, I'd love to know how you managed to cure it, as I have a horrible feeling that the tester is going to fail it on the MOT test because of the spongy rear brake.
Alan
I HAVEN'T HAD A PROBLEM WITH MY VECTRIX BRAKES BUT IN MY 60 YRS OF DRIVING THE SPONGY FEEL HAS ALWAYS BEEN ( AIR) IN THE LINE AND SOMETIMES IT IS VERY HARD TO REMOVE USUALLY TAKE (2) PEOPLE TO DO IT. HOPE THIS HELPS.
I have no VX1, but my electric horse has a rather wavey rear brake line that took around 10...15 minutes of constant brake lever pumping and filling up the reservoir again until all air was out.
After the brake fluid change I could pull the rear brake lever right to grip handle. That was after the "normal" motorcycle mechanic's de-airing cycles. Then came that arduous additional action. They were also fiddling with the de-airing screw on the rear caliper from time to time, with a hose and container attached. Sorry I can't detail that further, but a seasoned motorcycle mechanic should able to perform the de-airing process for you and thus get the sponginess out.
My rides:
2017 Zero S ZF6.5 11kW, erider Thunder 5kW
I hope someone comes up with an answer. Mine has the same problem (not that I ever use the rear brake) and I've tried normal pumping bleeding and a vacuum bleeder...made no difference.
Spongy brakes can be caused by flexible brake lines bulging, soft pads, loose brackets or air in the line.
Sometimes the type of installation of the brake caliper can cause the bleed screw to not be at the highest point of the caliper leaving an air pocket when bleeding is attempted.
Also, some brake master cylinders will gulp in a tiny bit of air when bleeding if the brake lever is pulled too far toward the handle bars when bleeding the brakes. Try only pulling the lever half way to the handlebar during the bleeding process.
I hope this helps!
LCJUTILA
These are the instructions for bleeding the brakes on the Vectrix but it hasn't made any difference to mine:
I have just been looking at a video on YouTube where the fluid is pumped through in the reverse direction to push any air up to the master cylinder instead of down to the caliper, which sounds like a sensible thing to do.
I might have to try this technique with a bit of improvisation (I'm thinking a modified fizzy drinks bottle, some tubing and around 5-10psi of air pressure) to see if it makes any difference.
Alan
EDIT: Picture link repaired
When I changed my front brake hose to the left side (as a recommendation to everybody with a Vectrix) it necessitated bleeding both front and back brakes. The front was easy but I remember spending a lot of time on the rear. I blead and blead it but it did not seem to help much - so I ended up putting it back together (as I never use the rear brake anyway and there is no such thing as MOT where I live) and very shortly afterwards it was fine - all by itself.
Hope this helps,
Jonathan
Hi - An equally unhelpful reply, I'm afraid. I had this problem 3 years ago when I swapped the brakes over (so rear brake is on the left handlebar). I then had the same issue despite trying for hours to get the air out. The front one was fine. It must be getting trapped somewhere, most likely at a junction. In the end I just left it and when I had it serviced next, the mechanics sorted it. I never use the rear brake anyway. The only thing I can suggest is to try pushing the fluid the other way - i.e. from calliper to reservoir. It'll be tricky tho! MW
Regards, Martin Winlow
Isle of Colonsay, Scotland
evalbum.com/2092
I was busy with other things yesterday and didn't have enough time this morning to construct equipment for reverse flushing, so I ended up taking it to the MOT test with the spongy brake lever.
The brakes worked fine on the road and obviously performed as necessary during the MOT (which it passed without any other problems or advisories).
Although one interesting point was raised regarding the tread depth of the tyres, because (according to the tester's manual) "Where the engine capacity is not greater than 50cc, tread depth may be less than 1mm, if the tread pattern is clearly visible around the entire circumference and across the whole breadth of the tread."
Here is a legal definition of the required tread depth that I found online:
As far as I understand it, a capacity of 0cc is definitely not greater than 50cc, but with only 1161 miles on the clock it still has plenty of tread on the tyres so it is not really an issue now, but it would be nice to know how I legally stand if the tyres did accidentally wear below 1mm.
As the trip to the MOT testing station was the first time I have been out on the road with this bike, I was pleasantly surprised to discover that the reduction gearbox on this bike is a lot quieter than my other one, but the strange thing is that I could feel an obvious vibration of the gears being transmitted through the bike even though the audible noise is considerably less.
I was also aware of a regular clunking sound coming from the rear motor/gearbox area when manoeuvring the bike forwards or backwards, yet my other Vectrix (the 3,286 mile noisy one) does not make this unexpected noise.
So now I need to find the cause of the clunking sound on this bike and also try some additive in the gearbox on the other one to reduce the loud whine, which has often been described as a "milk float on steroids".
Alan
The clunking you describe is the motor 'cogging' between poles - usually nothing to worry about as it only does it whilst the bike is being wheeled. Effectively, the motor jumps to certain pole positions as the wheel is rotating slowly; each clonk you hear is the straight cut gears loading/unloading in the gearbox. Different gearboxes have different assembled tolerances so some bikes do it to a greater extent than others.
With respect to bleeding the brakes, I'd use a 'dumb hand'. This is similar to a 'dumb leg' in the automotive world. Pressurise the rear brake lever firmly (ie apply the brake hard) and then wrap round the handle and lever with a zip-tie or similar, keeping the brake applied hard. Leave it pressurised for as long as you can; ideally 24+ hours. When you release it (cut the tie), release it slowly (ensuring you definitely have enough fluid in the reservoir) and then try the brakes again. The pressurising of the system causes the trapped air to be very gradually expelled past the seals in the slave cylinder but it takes a long time to do it.
Let us know how you get on.
Best wishes
Drew
Hi Drew, I have uploaded a video on YouTube so you can listen to the noise in reverse:
Is this the noise you were referring to and does it sound acceptable to you? Because it does not sound very nice to me.
The noise improves slightly if I apply the brake and load the motor but still does not disappear when all the backlash in the gears is placed under a steady load/torque, so I'm not convinced it is just the motor "cogging" between poles.
Alan
Hi Alan,
Good video, very helpful. I agree, that's not cogging.
The sound your bike makes is too regular at a higher speed of rotation than when you would be able to hear the cogging noise. It's hard to see from the video but does it happen one every revolution of the wheel or six (ish) times for every revolution?
I think the only way you will know what is happening is when you take it apart. It's a relatively straightforward job to inspect it and can be done of you have something to raise the rear wheel from the ground.
If you're happy to have a look, I would suggest you do so sooner rather than later as it sounds like a tooth is missing or there is something else stuck in one tooth. You will lose any remaining gear oil, so bear this in mind.
There's a good re-filling mod you can do when you have the gearbox case apart. Remove the brake disc and drill through one of the four mounting screw holes so that upon assembly, the gearbox can be refilled by removing said bolt, rotating it to the uppermost position and then filling using 80-100ml of your choice of gear oil. Refit the bolt with a sealant such as Hylomar to stop the oil from creeping out and contaminating the disc. It's also a good idea to dimple the casting with the drill bit local to the chosen filling hole so that it can be easily identified later on. If I get a chance, I'll take a pic as an example.
Does the noise go away at speed? If you don't investigate it, I'm concerned that it may exacerbate any damage.
Best wishes,
Drew
Drew
I made another video with some illumination so I could see the wheel easier and it appears to be 4/5 clonks per revolution:
The noise is much more pronounced when the wheel is running backwards, but sounds almost "hollow" to me.
I think I will pull off the end cover where the encoder is as that seems to be where the noise is coming from.
Alan
Another thing you could try is swapping wheel /disc assy from your other Vectrix to the one with the spongy brakes I have tried this and Found a big difference in the feel It could be that you have a little run out of your disc which causes the Pistons to move away further than normal Worth a try
rob white
Rob, it can't be the brake disc causing the problem with mine because it was still just as spongy when the pads were clamping against each other (instead of the brake disc) when I tried it with the caliper removed. But thanks anyway for the suggestion.
I have also experienced excessive brake lever travel on other bikes when the caliper becomes tight on the sliders forcing it to flex the disc sideways instead of moving the caliper, but I have already checked the calipers (and brake pads) on the Vectrix and they were nice and free.
Alan
Just had a quick thought Alan,
I have seen a Vectrix that had the rear disc fitted the wrong way round (by a previous and inexperienced Vectrix UK tech). This meant that although the assembly worked, no recesses where present for the shallow-head disc-mounting cap screws to sit in, meaning that they fouled marginally on the caliper as the disc went round. Check to see if it's fitted correctly. The recesses in the disc are there for a reason! These would give your four knocks per rev as there are four of them.
If it's not that, then the only other thing I can suggest is that the motor drive shaft end float is for some reason too much. This will become apparent or not upon disassembly. Too much end float may lead to encoder issues as well.
I certainly don't like the 'mechanical' nature of the noise, despite the fact is seems to disappear when you wind up the forward speed.
Good luck. Let us know what you find.
Drew
Drew
I have checked the disc bolts and they are correctly fitted in the recesses and are not touching the caliper, so I've taken the cover off the end of the motor and the clonking noise is directly linked to the motor rpm:
There is no sign of any end float or looseness on the shaft and it is too regular for a bearing noise, so I presume it must be somewhere in the motor/drive shaft coupling or even the gearbox, but I don't really want to start pulling the gearbox apart at such a low mileage (1170 miles) unless I have to.
When I get the battery cover and panels back on again I will use it for a bit and see what happens to the noise.
The gearbox whine is a lot quieter on this one than it is on my other one, so it is more likely that I will pull the other gearbox apart (before I strip this one down) to see if I can make it a bit quieter by swapping the gears around and adding some anti-friction additive to the oil etc.
That might also allow me to see how the driven shaft is attached (splines or keyway etc.) and see what backlash there is from the gearbox end.
And this is presumably the cogging effect you mentioned when the motor shaft jumps during the encoder test:
Alan
It somehow sounds like something is loose inside and flipping back and forth once each turn! And at higher rpm the centrifugal/centripetal force biases the loose end so the noise basically stops.
My rides:
2017 Zero S ZF6.5 11kW, erider Thunder 5kW
HI BIKEMAD, The motor shaft is(splined).
I agree that the noise is something loose rattling around. Sounds like a ball bearing or little nut tapping against the casing as it goes round and round.
LCJUTILA