brakes still "spongy" after bleeding

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brakes still "spongy" after bleeding
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flag ishredh2o
Posted: Aug 20, 2015 at 15:42 Quote
My brakes were starting to get soft or "spongy on my 2015 specialized enduro. The brakes are shimano deore. The bike is only a month and a half old but I've been doing a lot of heavy park riding and things of that sort so I thought they must need to be bled. After bleeding them about 3 times they are still not where I'd like them to be performance wise. The front ones work well and are stiff but the rear ones are still "spongy" any ideas on anything else that could be going on. Any suggestions would be appreciated. Btw the brake pads are good
flag Ploutre
Posted: Aug 21, 2015 at 1:39 Quote
Welcome to the Shimano world of bleeding, where you never know where the last air is trapped ...

Rant aside, you could try to bleed them like Hope brakes (or most motorcycle brakes actually). Check for howto videos on Hope website, but basically:

- fill up the reservoir
- put some tubing at the bleed nipple on the caliper with some reservoir to receive the oil
(*) - squeeze the lever
- open the bleed nipple
- close it
- release the lever, pump it a few times untill it gets stiff again
- check oil lever in the lever

Repeat from the (*)

If that doesn't help, well you can always send it back to Shimano. Here in Europe they don't ask questions and just exchange for a new brake.
flag RunsWithScissors
Posted: Aug 21, 2015 at 5:45 Quote
There are multiple schools of thought on bleeding technique. Which one is best? I have no idea. Here's a few things that I do...

Before doing ANYTHING, check the fittings at the ends of the brake line and the master cylinder cap screws. If they are loose, then you'll never get a good bleed. I've wasted fluid and time trying to bleed brakes with loose fittings more than once. Makes you feel like a real genius. Also, remove the pads and use a bleed block. This will prevent contaminated pads and ensure that new pads can be installed when needed without having to re-bleed the system.

When filling the syringe that will be placed on the caliper, don't fill it all the way. Leave a little bit of room to pull bubbles out of the caliper. After attaching the syringe to the caliper and opening the bleeder, pull back on the syringe plunger a little bit to suck out any bubbles that may be sitting in the top of the caliper BEFORE pushing fluid toward the master cylinder. Otherwise, you have to push those bubbles through the system and hope none of them get stuck somewhere.

Next, push fluid FROM the caliper up to the bleeder cup or syringe at the lever. The caliper sits lower than the lever and air rises, so bubbles naturally want to go up from the caliper toward the lever anyway. Might as well let gravity work for you. Partially operating the lever and tapping on the master cylinder reservoir with a small wrench as you push fluid can also help dislodge bubbles.

After pushing fluid from bottom to top, push some back down into the syringe at the caliper if you are using two syringes, or pull back on the plunger and suck some back down to the syringe if you are using a bleed cup at the lever. Be careful not to suck any air back into the system when you do this...

Next, tie the lever back against the handlebar to isolate the caliper and brake line from the master cylinder. Now push on the syringe plunger at the caliper several times to pressurize the caliper and brake line, then retract it a bit and see if you get any bubbles coming out of the caliper. You might have to do this a few times to get all of the bubbles. It's important to tie the lever back before doing this. If you don't, then the fluid will just flow back up and out of the master cylinder instead of pressurizing the line and caliper.

When you stop getting bubbles, untie the lever from the bar, and slowly release it while pushing on the syringe plunger at the caliper. At first, no fluid will flow, but as the lever moves forward, eventually the fluid will be able to move and you can push any remaining bubbles in the line out through the master cylinder. This is also a good time to tap on the master cylinder to dislodge any remaining bubbles there.

Reinstall the bleeder screw at the master cylinder FIRST, then close the bleeder at the caliper. You can also pressurize the system A LITTLE BIT with the syringe as you close the bleeder. Don't go crazy with the pressure though, or you'll push fluid past the master cylinder reservoir seal and make a mess.

After the system is sealed up, hose everything down with alcohol to clean it, then operate the brake several times and look for seepage at all connections.

Hopefully that helps. Best of luck.
flag bigburd
Posted: Aug 22, 2015 at 2:19 Quote
In my experience it's the bleeding of the lever that is crucial with shimanos , be sure that the lever port is the highest part of the system , higher than the brake lines and make sure that you tilt the lever up and down several times while pumping to get the last of the bubbles out.

Try this rather than bleeding the whole system again. : https://www.pinkbike.com/news/tech-spotlight-5-minute-bubble-bleed-2014.html
flag ishredh2o
Posted: Sep 2, 2015 at 14:29 Quote
Thanks to all!! Sorry for the long wait on my response. New to posting on pinkbike and didn't realize you guys responded. Thanks for the help
flag markg1150
Posted: Sep 6, 2015 at 13:41 Quote
Probably not air shimanos are a doddle to bleed and don't leak . Try holding one piston back while pumping lever. Then repeat with other side. Some times the pistons retract excessively giving a spongy feel as they have a lot of play to take up before contact with disc. Getting pads right up close sorts it.
Deore are brilliant Brakes. I spent a crazy amount of money building my dream bike and the very last thing I swapped from the stock setup was the deore brakes because they are that good.
flag half-man-half-scab
O+
Posted: Sep 6, 2015 at 22:10 Quote
What's the pad life look like?
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