Shimano Deore brake problem ?!?!?!



alexcoist

New Member
Oct 25, 2011
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Hi everyone, first post here and relatively new to bike maintenance so take it easy on me!

I will try explain this properly but don't expect technical terms as I'm still new to all of this.

Basically by rear brake (Shimano Deore hydraulic) was sticking slightly so after reading that I would just have to undo a couple bolts, hold the brake and re-tighten i went ahead and managed to undo the wrong bolts, ending up with brake fluid dripping out.

So now after re-tightening those bolts my brake lever pulls all the way down to the handle and has no effect on stopping the wheel.


So after coming to the conclusion that I am a spanner I rang the bike shop and described what I did, they said i need a special tool to sort this out, is this true or are they just trying to squeeze me for more money?


Any help would be appreciated!
 

doiturself

Member
Jul 4, 2011
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You opened the bleeder valve and lost fluid and got air into the system. The system now needs to be bled and refilled. You could do it without a special tool if you knew what you were about but as you got into the trouble in the first place you had best go back to the agency and make it right because brakes are important. Then get a book or something and read up on it if you want to know more. They are not trying to squeeze you.
 
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alexcoist

New Member
Oct 25, 2011
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thanks for the reply.

I have read up on the shimano manual and found a couple of tutorials on the net on how to bleed the system however none of them seem to mention this tool I need...?

Thanks again.
 

dabac

Well-Known Member
Sep 16, 2003
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Originally Posted by alexcoist .

thanks for the reply.

I have read up on the shimano manual and found a couple of tutorials on the net on how to bleed the system however none of them seem to mention this tool I need...?

Thanks again.

It's usually a syringe of some sort, together with a short length of tubing or two. You need it to be able to top up the lost fluid w/o getting more air into the system.
 

alienator

Well-Known Member
Jun 10, 2004
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You don't really need any special tool to bleed a hydraulic brake system. The old fashion way has you pumping the brake lever until it won't move much. Then just slowly crack open one of the banjo bolts at the brake caliper until the lever starts to move toward the handlebar. Then retighten the banjo bolt. Don't leave the bolt open so much that the lever travels all the way to the handlebar. Repeat this process until you get a firm lever all the time. Firm is, of course, a relative term. You want a bit of travel, but theoretically when the system is perfectly bled, the lever will end travel at that same point which will somewhere short of the handlebar. That's how I did it with cars, and that's how I did with motorcycles and road racing motorcycles. It's a damned reliable method. Special tools just speed up the process.

Here's one very important point that I forgot to mention: during this process, you need to keep an eye on the brake fluid level in the fluid reservoir. If you let that fluid level drop beneath the minimum level indicated on the reservoir, it's possible that in the bleeding process the reservoir could empty. If that happens, you'll suck more air into the lines.

Eventually, I bought a product for bleeding my road racing bike brakes (the brake fluid in racing motorcycles can get very hot with the hard braking and cause water in the fluid to boil out and produce water vapor bubbles. Also, all that heat would make any air in the system expand, and it's never comforting to be braking hard for a corner only to find your levers going to the bars). That product was something called MityVac. I don't know if it's still around. I found it worked ok, but I eventually went back to doing it the old fashioned way.

There are also directions in the internet tubes for building your own electric pump driven brake bleeding system. I've seen them in use, and they work pretty damn well.

Another point I forgot: when you go to crack open the banjo bolt to let air out of the brake lines, you should be squeezing the brake lever. This maintains a pressure in the line which is higher than atmospheric pressure, which in turn keeps air from entering the brake lines. Do not release the pressure on the lever until you've closed the banjo bolt. If you release pressure before closing the banjo bolt, you'll have to go back to square one and start all over.

Another option would be to buy a case of beer for your LBS, and ask them if the can show you how to complete the bleeding process.

Once it's all done, you have to be sure to clean the brake fluid off all surfaces, especially the brake rotors since that brake fluid will reduce the coefficient of friction of that rotor to zero. It's never nice to have no brakes. Also, take care to cover plastic surfaces so that brake fluid doesn't spill on 'em. It's corrosive and can damage plastic, paint, and a few other materials. Likewise, if you use brake cleaner to clean your rotors, guard plastic and paint as the cleaner can all damage some materials.
 

alexcoist

New Member
Oct 25, 2011
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Right, thanks for all the advice guys.

As I had a ride planned this morning I played it safe and went down to the LBS, the guy was awesome and talked me through the whole process. He even gave me a couple little lengths of tube for the bleeding process for next time. Unfortunately I managed to get fluid on the pads and as they had been sitting there all night they needed replacing, however £30 for labour, parts and a tutorial sounded like a good deal to me!

So thanks again guys, another bit of knowledge gained and one step closer to looking after my own bike.