Front Brake Problems (long, sorry)

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Indawoods
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Post by Indawoods »

Exactly why I push the fluid.
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gertie6car
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Post by gertie6car »

Hi,

the line I had made up was from a uk company called venhill they supply most of the race teams here in the uk.

It is lined and it is braided and the lever is still spongy! I have put a great deal of fluid through this system what with gravity bleeding and using a syringe. I have not seem a bubble for some time but there must be air in the system somewhere as the lever gets more solid if you pump it up!!

I will try moving the caliper. I really dont want to pay someone to do this for me!!
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Post by gertie6car »

Hi Guys,

in desperation I bled the system again and then put the bike in for test - it failed on the front brake! It works but not well enough. I cannot ride uk trails legally without this test being passed so at the moment I am screwed.

Does anyone have any other ideas how to solve this?

Just to recap the front end is a kx125 and the braking system was excellent prior to me changing the brake line. I am considering buying a mityvac but given I have used the syringe method to reverse bleed without sucess I am not sure buying one will achieve anything.

Any further thoughts on how to resolve would be VERY much appreciated. I must being doing something wrong but......

All the best
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frankenschwinn
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Post by frankenschwinn »

Even after pushing fliud you can have bubbles. are you bleeding the brake while its on the bike? You probably mentioned that but I don't want to read through all of the thread again... this may have already been suggested but try this. remove brake assembly. Place caliper above the MC. Let sit. Periodically tap the line with screwdriver handle. Bleed with the caliper above the MC. Or take to a shop and have them do it...

From what I understand the brake line routing makes it a real pita to get a good bleed on them.

Do you have the KDX brake? does it work? Put it on and ride? Lots of hose routing options for that.
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rbates9
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Post by rbates9 »

It might be worth making sure that the caliper is somewhat centered on the rotor. I am not sure what set up you ended up using but if the caliper is flexing the rotor due to being to far off center or binding on the slides, it may feel to spongy. :?

Also, I was reading the topic and debate and read that someone was concerned about being able to pull the brake lever to the bars? Before I posted any thing about this I wanted to make sure it wasn't just my bike so at my last ride I went around to about a dozen different bikes and pulled every brake lever to the bars. All makes and models, brand new and beat to death. So I'm not sure you will ever get a rock hard lever like the pedal in a car :? I could be wrong but it seems that every bike I tried had at least good to great front brakes.
gertie6car
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Post by gertie6car »

Hi guys,

thanks for the comments.

I will take off the set up and invert as suggested and try that.

The front end is entirely a year 2000 kx125 set up.

I tried to use the original kdx brake line but got a spongy lever and with the different kx forks and kdx light unit I was not happy with the routing using it.

I opted for the original kx brake line set up (brake line runs under the bottom of the fork using the original brake clamp clamping point machined into the fork leg). The only difference is the new line is a few inches longer than the original kdx and even longer than the kx one. There is a section of the brake line which is parallel to the bars (where it leaves the master cylinder and before it curves to run down the fork leg. I guess air could be trapping there.
?
Fingers crossed this sorts it!

Cheers for the help!
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