Squeeky Brakes

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Tanner
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Squeeky Brakes

There is almost constant squeeking coming from the front and rear disc brakes. When the brakes are applied the squeeking is muted but there is a significant pulsing felt on the brake handles. Could the rotors be warped? When I put the scooter on the center stand and slowly rotate the rear wheel there is resistance in one section of the wheel revolution. It sounds like the brake pads contacting the rotor. The brakes work well at stopping the scooter. By the way, I applied the brakes hard one time and the back wheel did lock up and skid a little. I didn't think that would happen with the "ABS" brake system.

andrew
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Re: Squeeky Brakes

First thing I would do is check the caliper alignment, and adjust it if there's a way to do that. Rotor's aren't perfect, and all of them are warped some. But, they can be damaged by side impacts, especially when working on the scooter like by dropping the wheel. You may need to replace the rotors if an alignment of the calipers doesn't help. To quiet down the squeaking take a piece of medium grit sand paper, and sand the rotors. Sand perpendicular to the direction of rotation, or going inside to outside of the rotor.

[url=/forum-topic/motorcycles-and-large-scooters/587-my-kz750-electric-motorcycle-project]KZ750 Motorcycle Conversion[/url]
[url=/forum-topic/motorcycles-and-large-scooters/588-fixing-my-chinese-scooter]900 watt scooter[/url]
Pic from http://www.electri

Tanner
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Re: Squeeky Brakes

Thanks for the recommmendations. It would be nice to have a service manual to know how to adjust the brake caliper. I think that would be worth a try to see if it helps. Does anyone know how to do this on a Zapino? I don't want to just start messing around with something as important as brakes on a scooter.

Steve Tanner

sgmdudley
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Re: Squeeky Brakes

The Caliper Asms are supposed to float around the rotor. Sometimes the caliper pins need some lubrication (use standard brake slider lubricant available from any auto parts store). More importantly is the rotor runout. I will be buying a Dial indicator soon so I can clamp it to the frame and check the runout of the rotor. I found that the machining of the rotor mounting surface is not the best. Needs to be dressed with a flat file and maybe even need shimming or filing to get the rotor to rotate true. The manufacturing process is not as accurate as it could be and this can be a critical area. Any drag on the wheel causes an increase in current to move the scooter.

Robert Dudley
E-Scoot Tech

andrew
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Re: Squeeky Brakes

Here's a message from ScooterTech. This was posted in a similar post in another thread that I can't seem to find.

On our brand new RED XM-2000 back in August, the front brake would pulse at high speeds and grab grab grab at lower speeds, very annoying.

Since we had another bike, we swapped all parts and it still did it on the Red bike, but the SAME RED WHEEL kept making it onto the bike as we swapped calipers, discs rotors. When we moved the wheels the problem moved to the other bike

When we got a new wheel from X-Treme (used actually) the problem stopped.

My best guess was the problem was with the standoffs that the disc bolts to on the wheel which are a cast part of the wheel. If someone dropped the wheel prior to the disc being installed it may have damaged one of the standoffs surfaces resulting in a micrometer deviation that warped the disc when it was tightened down.

If we loosened the disc it would not rubb rubb rubb, once tightened it would rub, presumabley because the standoffs were off and tightening the disc down warped the disc.

In the end a new wheel fixed it and all the other wheel and brake parts are still stock and have thousands of miles on them, and the brakes have been no more problem

Here's what I would do before replacing the wheel, and here are the tools it would require:
Dial indicator, and a way to mount it to something
Calipers or micrometers if necessary
File

Please note that this is a complicated and probably somewhat tedious procedure. Just skip reading this if you are hesitant to do it and buy another wheel or disc or both. Of course, the new ones could be just as bad, so nothing beats figuring out what's wrong and fixing it.

I don't think you can really get past having to use a dial indicator to deal with this unless you just want to replace the wheel. First, measure the runout of the disc on the wheel, and try and find any spec in the manual. I don't know what that spec is, but my guess is that it should be less than .005 inches if not smaller.

If it is within spec, then it shouldn't drag excessively, and the brake pads may just need to wear in some. If it squeaks then try sanding the rotor in the direction perpendicular to rotation some to try and even it out.

If it is out of spec, then take the rotor off and set it on a real flat hard surface like a glass tabletop. See if it will rock back and forth when you press it up against the surface, or if it just sits flat. Turn it over and try the other side. Then measure the disc thickness at several places to see that it is within the runout spec.

ALSO, check the runout of all of the places on the wheel where the disc bolts to. If there are removable spacers, then measure those with calipers or micrometers. As the wheel rotates, the spacing to the disc needs to be uniform so either file down the spacers or the mounting points at the wheel itself to make this happen.

If the spacers or mounting points are uniform in runout, and the disc is warped, then replace the disc.

This may take some time. Bolt the disc back to the wheel and remeasure the runout. Don't compensate for having a bad or warped disc as this will cause problems when you need to replace the disc when it wears out.

[url=/forum-topic/motorcycles-and-large-scooters/587-my-kz750-electric-motorcycle-project]KZ750 Motorcycle Conversion[/url]
[url=/forum-topic/motorcycles-and-large-scooters/588-fixing-my-chinese-scooter]900 watt scooter[/url]
Pic from http://www.electri

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