Sometimes due to the breakage of certain elements of the bike or simply to improve the behavior of these elements, in this case the brake pump, we decide that the time has come to change them. In this manual we are going to learn how to replace the brake pump, something that many of us are afraid to do because we don’t know how to bleed properly or because we don’t know how to do it. The first step we are going to do is to remove the screw that holds the brake hose. It is usually a screw with a nut head. If it is hard, do it carefully. It is advisable that you put a rag underneath since probably some of the brake fluid will fall.
Next we remove the other two screws that hold the lever to the handlebar. I have to say that there are levers that only have one screw and the clamp itself tilts on an axis without disassembling completely but allowing us to remove it perfectly.
Once this is done, we place the new brake pump. The process is the same but the other way around, first we place the way and then the whip. At the time of placing correctly the height of the lever it is advisable to tighten it without fixing it completely, that it moves a little. We sit down on the motorcycle and we are tanteandola until we give with the height that we like more.
Now we have everything ready for the step so dreaded, bleed the brake assembly. Well, the first thing we are going to do, since we are is to change the liquid and for this we must release go to the brake caliper. Each caliper is a world, but all usually coincide in having a rubber plug that we remove and just below a kind of hollow screw with a nut.
It is very very advisable that we get a rubber tube of that size, sometimes come in the bleeding kits themselves, and what we do with the tube is “plug it” to that output, in this way, when we loosen the nut does not fall all by the caliper if not that we direct the brake fluid to a pot and then throw it where it is appropriate. Well, having said this and having everything well placed (including lever), we loosen the nut to empty the circuit. It is very advisable to remove the cover of the pump (lever) where we will pour the oil later because this way it will not make the vacuum and the oil will come out much better.
Having emptied the circuit now if, we are going to fill it with the new oil. Without closing the screw we are pouring liquid through the pump until we see that it begins to come out smoothly through the tube that we have placed in the clamp. It is now when we close the brake caliper outlet and start pumping the lever. It is best to do it smoothly and slowly to the bottom to give time to raise all the air bubbles because, if they do not come out, they will give a spongy feel to the brake.
We continue giving it and we will see how the fluid level is going down, the pump is sending it to the hose. We must not let it run out and suck air because if this happens to leave the brake well, we must start from scratch so it is advisable to go refilling little by little as the level goes down.
As the hydraulic circuit is being filled we will see that the lever is losing travel, or better yet, that is taking the touch that should have. At this moment we must begin to go pumping faster and always squeezing hard in its final travel and so until we see that the touch is what it should have. Now we must close the pump with great care that no dirt enters. We must make sure that the oil level is optimal and this we can see it from the porthole that all the “classic” pumps have or in the glass of the “pro “m pumps where it is marked.
Finally, we clean everything, we make sure to put the cap of the fluid outlet of the caliper and ready. We already have the brake bled.
As a final note to say that it is not always desired to change the brake fluid for whatever reason. In these cases there is a method to remove the air and go introducing liquid instead. It consists of opening the oil outlet as we go pressing the lever, when we finish pressing the lever and before releasing it, we close the outlet so that it does not suck air again. It is a somewhat more tedious but useful method, although personally I think it is more effective to change the fluid directly.
Brake fluid is highly corrosive so keep a rag handy to wipe yourself and the bike if it gets dirty.