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Problems bleeding promax brakes


kymbolino's picture

By kymbolino - Posted on 27 August 2011

NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.

Hi,

I've bled avid juicy 3 brakes before with no problem, but now trying to with my front Promax Hornet brake and not having much success.

The process I've been following:
1. Prepare syringes (one with 3/4 filled dot4 and the other 1/4 filled) and try to remove as much air as possible (de-gas).
2. Attach 3/4 filled syringe to calliper.
3. Attach 1/4 filled syringe to lever.
4. Bleed cable, from calliper to lever.
5. Close lever handle and bleed calliper to remove as much air as possible (by applying pressure then suction alternately to get bubbles out).
6. Allow lever to open slowly under pressure from calliper syringe.
7. Remove calliper syringe and reinstall bleed port screw.
8. Bleed lever cylinder to remove as much air as possible (similar to step 5 above).
9. Once no more air is coming out, remove lever syringe, add a drop of dot4 to the bleed port and reinstall screw.

Result:
1. Pistons do not move at all under movement from the lever.
2. Zero 'feedback' on the lever. The handle totally bottoms out on each press.

Just to see whether the lever was pushing any dot4 down the cable, I reinstalled the calliper syringe, and I could see fluid entering the syringe when I pressed the lever, and return when I let go. I've also repeated the above steps just to make sure all the air is coming out.

Does anyone know what I'm doing wrong? I've thought about trying this on my back brake for comparison, but it's working at the moment so tempted not to touch it and possibly break it too.

Before bleeding the brakes I pushed the pistons backs in manually, and I'm worried I used too much force. Could this have damaged them?

I appreciate these aren't the greatest brakes on the market, but even so they should work a bit better than this.

Any help is appreciated.

Cheers,
Kym

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