Archive for the ‘Shunt mod’ Category

A noisey front-end.

06/05/2010

A couple of weeks ago I started to notice that after using my front break the throttle was slow to respond. I thought it was down to an electrical fault, maybe the cut-off switch on the front break was playing up. I took it off & had a look, couldn’t find any problems so I gave it a spray of good old WD40 & refitted it. Took the break lever off, cleaned it up, lubricated it & refitted it. None of this made any difference, so I kind of resided with the idea that maybe something was failing within my speed controller.
Now a couple of days ago I started to get an intermittent ‘rubbing’ sound from the front end. The sound got more frequent the higher the speed but was not present at lower speeds. Decided that it was time to strip down the front end.

I started to take the front wheel out & found the spindle bolt was so excessively tight that I needed to stand on the wrench to undo the nut. These nuts should never be that tight! Got the spindle out & found that it had never been greased. Took the break calliper off, these came off quite easily. Noticed that one break pad had worn more than the other, so I took a better look at the calliper. The two pistons had a bit of surface corrosion on them so I cleaned them up with a bit of WD40 & a soft cloth, then gave them a good spray of Wd & pushed them back in & pumped them out etc a couple of times to draw in the fluid. Re-lubricated the sliders & pins & then put it all back together. Also noticed a load of very light scratches on the disc, so I guess that the pads must have picked up some grit & was rubbing on the disc.

I thought that before I put the wheel back, I’d take out the crappy screws holding the front mudguard & replace them with some new bolts. !!!!!!!! There’s a lot to be said about greasing bolts before fitting them! On of them sheared (torqued) off! Had to drill-out the bolt & re-tap the hole.
I urge you all to change these bolts or at least take them all (every bolt & screw you can see) out & put some ‘never-seize’ grease on the threads. This will hopefully save you from having this problem in time of urgent repairs….

Anyway, put it all back together (with fresh grease everywhere) & took it out for a ride….. No more noise & the problem with the throttle response had gone 🙂
So…..
The corrosion on the calliper pistons was causing the breaks to stick slightly which was causing the lever to not return correctly & thus causing the poor throttle response due to the cut-out switch staying off until the lever fully returned.
The rubbing noise was caused by debris caught in the pads.

Bare in mind my Scoota has only done 4300 miles, I would suggest that the front end would need servicing at about 3000 miles.

Hope this helps 🙂

Advertisements

To shunt or not to shunt?

27/01/2009

Well…. I modified my replacement controller. When I took it apart I found that it had 2 shunt wires & pre-drilled holes for another. So I added the extra cable & got ready to install it, but when it came to fitting the controller I found that two of the connectors were different to my original controllers.
Also, I noticed that my original controller has a label that says: ‘Break : High Level’ & ‘Current Limit: 35A 1400W’.
But my replacement controller has a label that says: ‘Break : Low Level’ & ‘Current Limit: 34A 1400W’.
And the new controller is a bit bigger.
I thought I’d remove the back-plate from my original controller & find out where the wires all go. When I removed the back, the first thing I saw were the shunt wires. 3 of them!
MMM I thought. It seems that the controllers were actually designed to have 3 shunts in place as standard. What a waste of time that was…….
So I had a quick think & decided to remove the extra shunt I had previously installed.
I tried the the scoota with the ‘2 shunt’ controller & it worked fine, but I noticed that it was a bit slower on acceleration, but the top speed was about 3MPH higher.
I put my orginal back in & the acceleration increased again & the top speed was back to normal.

My conclusion from this is that if you need a scoota to handle hills, you should keep with the ‘3 shunt’ controller. If you would prefer top speed, you can remove a shunt to gain speed but lose power.

I am going to try out the contoller again & remove another shunt (so it only has 1) & see what the top speed is & how slow the acceleration is. I’ll let you know in due course….

If you want to remove a shunt, it can be done by simply removing the back plate from the controller & snipping the nearest wire. You don’t even need to remove the circuit board from the box.