I own a M596 2012 rear brake. I find it very good, except I need to pump the brake a few times to get it brake with more power (and also the lever gets firm after doing that). Even during long descents, when I pump the lever it is firm for only a second or two.
So I tried to bleed it.
I have 2 syringes, one with a M4 i think fitting, that fits the reservoir bleed port like a glove. The other syringe is on the caliper connected with the plastic tube (like Shimano recommends it).
When I tried to push fluid from the caliper to the lever reservoir, it started to leak mineral oil at the place where the reservoir cap and the rest of the lever meet. Same thing when I pushed from the lever syringe to the caliper. Of course I didn't push like a maniac, but very slowly.
Something is wrong, but can't tell what. Then I removed the reservoir top cap, found another screw that holds the metal plate over the rubber membrane so it doesn't leak oil. Either the membrane isn't sealing, something is missing or the membrane isn't sealing like it should. Therefore I opened the lever and removed the reservoir top cap.
This is the picture taken from the web (since I didn't take pics with the top cap on):
There are 2 screws. One on the left that lets you enter the bleed port, the second one (the one with the torx screw head) that keeps the top cap on the lever.
After removing the right bolt (the torx one) the inside looks like this:
See the metal plate covering the membrane, with one torx screw on the left (hard to see, this black thing on the left).
After unscrewing the last torx screw under the top cap, you can see a white plastic part under it (so the screw presses it, then the plastic thing presses the metal plate which presses the membrane to seal oil). As you can see, I saw that under the right torx screw (which was removed when the top cap was going off the reservoir) there isn't any plastic part.
Removing the metal plate, gets us to the membrane:
After carefully removing the membrane, I can acces the oil in the reservoir:
I tried to bleed the brake old style, pushing the lever so the oil goes to the caliper syringe. Also tried to push the oil from the caliper to the reservoir (removing it before spilling with the other syringe). Some bubbles had risen from the compensating port at the reservoir when the lever was operated pushing the oil to the caliper syringe.
I saw a little improvement on the brake, but it still need to be pumped to get firm and to increase power.
What could be the problem ? The missing plastic washer/part on the other torx screc (but the plastic reservoir top cap should be pressing it when the screw is tight. Checked the membrane - no holes or anything that would indicate it is damaged.
The top syringe screws right into the lever bleed hole, oil leaks right trough the membrane. Really, very similar to the 2012 bleed kit with the yellow funnel or what it is called:
Any advices to get the brake bleed properly ?
Results 1 to 6 of 6
Check out the hottest mountain bike products from these brands!
See All Interbike Coverage - Click Here »