[beemer100]

I am attempting to flush my 2002 brakes (wheel and control circuits) and was following instructions I had printed back a few years ago. I think I may not have started this right.

For the front control circuit change, I pulled the front brake lever and then opened the driver's left side (the one furthest from the battery) long bleeder at the pump. I have pulled some brake fluid into the elevated speedbleeder bag but the reservoir level on the handlebar does not appear to be going down. The rear reservoirs are full.

I put a razor blade in the bottom to prevent splashing of the fluid onto the bike. Could this be preventing the fluid from exiting the reservoir on handlebar?

Am I doing this incorrectly and if so, have I possibly messed anything up?

James

 

[beemer100]

Thanks Bob. The write-up I have from the HOW says "driver's left" for bleeding the front control circuit. I assumed that meant the left side as you are sitting on the bike.

I'm just concerned if I have the wrong one and the possibility of having damaged the ABS unit if running it dry of fluid.

James

 

[beemer100]

You won't see fluid loss at the handle cylinder when bleeding the fittings at the brakes. You should see fluid drop in the reservoirs on the right side of the bike when you start to drain the fluid.

The master brake cylinder on the handle bar is part of the brake circuit that runs from the handle bar and also the foot brake lever to the ABS circuit under the seat.

You have closed circuits on this bike. The brake levers activate the ABS circuit for front and rear, but there is a separate circuit from the ABS controller under the seat to both the rear and the front brakes. There is no continuos brake fluid circuits from the activating levers to the front or rear brakes. You could, while on a trip loose your rear brake fluid to the rear brakes but not the front and also not in the ABS controller between the activating levers.

That is why you are not seeing any fluid level drop at the handle bar when bleeding the rear brakes circuit or front brakes circuit at the brake pads. That is why when bleeding at the brake pads you are monitoring the reservoirs to the right side of the passenger seat cause that is where you will refill the brake bluid.

You will refill the brake fluid at the handle bar when you are flusing the ABS Circuit. A tip. Put your bike on the center stand. Remove the handle bar reservior cap and place a quarter over the hole that you can see in the bottom of the reservoir. The quarter will keep you from squirting fluid all over the bike when you squeeze the brake lever. Remember to remove the quarter before replacing the reservoir cap.

Thanks for the reply. Following the steps as listed in HOW, it seems that in reading section c, Front Control Circuit Fluid Change, that one would refill the reservoir on the handlebar upon siphoning out the old brake fluid (step 8). This is a 2002 model and I am following the writeup in the HOW titled "Changing Brake fluid on an 02-later.

By the way, the reservoirs in back are both at full levels.

 

[beemer100]

Thanks Mark and KSBaltz.

Mark, when you speak of the volumes going down relatively small, I was assuming a 1:1 relationship between what's going into the Speedbleeder bag from the ABS unit to the amount I am filling back up in the handlebar reservoir. Is this an incorrect assumption?

It just seemed that more fluid was coming out than was going in. I have about 12 inches of the speedbleeder bag that has filled with the fluid from the ABS unit. I also have the bag elevated above the bleeding point as indicated per instructions.

I'm assuming I continue along as I am doing until I see that all the fluid is clean and bubble free, and that I should at some point have to refill the handlebar reservoir. . .

Thanks again for the help.
James

 

[beemer100]

That is correct. Without seeing your bag set-up, I can't tell whether there's an abnormal flow, or an optical illusion making the "out" amount appear huge.


Yes. I only recall refilling the reservoir once during a fluid change, and then topping off -- but the last time I did an '02 was a *long* time ago. Regardless, the key is to keep your eye on the reservoir so it never goes down too far.

Okay, thanks. I just went back out there and pulled more fluid using the front brake and did not notice any change in the level in the handlebar reservoir. I guess I introduced some air in the system because now the brake failure light is flashing. I'm beginning to think I should have brought this do the dealer to handle.

Regarding the fluid level, I lifted the bag straight up and it did not go down as to indicate the tube was only partially full.

 

[beemer100]

For the front control you need to pull fluid from the "inboard" tall bleeder on an 02. The outboard is for the rear control circuit. Not sure what you meant by left side as the whole ABS unit is on the left side. You will see the fluid go down if you are on the right one. The rear control circuit is fed from the front half of the rear, two chambered, reservoir. As long as that one is still showing fluid you have not introduced any air.

John, can you elaborate on "inboard" vs. "outboard" tall bleeder. Is the inboard bleeder the one closest to the battery?

By the way, I drained the 15 inches or so of brake fluid in the speedbleeder hose into a cup and I would estimate it to be all of one to two ounces. : )

Self analyzation indicates that I like to get "worked up" on a lot of things.

I do truly appreciate all the help I have received over the years on this site. I have learned multitudes about the bike through its membership.

James

 

[beemer100]

I'm not John, but I'll throw out my $0.02 anyway.

Your best best is to follow the link I posted and look at the pictures in the "101" document. Next to John's video, this is the best place I have found to show precisely which bleed valves to use to do each function.

I doubt you have caused any harm to the ABS unit. I suspect you just pulled the level down enough t trigger the level sensor and thus turn on the light. You may have pulled in some air, in which case you get to do the full bleed process. However, no problem as that is what is described in the "101" document. I unnecessarily used this procedure when flushing my system as it appears that you don't need to open the integral and metering circuits for a routine flush, but you do need to do so for a bleed. So, relax, read the 101 guide thoroughly, and then do the #1, #2, #3, #1 (second time) dance.

Be advised that getting a wrench on some of this fittings is a bear. I found the those angled forward (metering cylinder valves) to be the worst. I used a universal joint drive on my 1/4" ratchet to break them loose (and then retighten a little as quickly as you can) and then I could use an open ended wrench for the open-close for the bleed process itself. Mine were quite tight and I am sure I would have rounded them off had I tried to break them loose with an open end wrench. I was going to heat and bend a box end wrench, but decided to try the u-joint approach first and it worked fine.

When done, I used the ratchet and socket to gently snug up each fitting before replacing the rubber covers.

Thank you Matt! I am going to review that document further and proceed according to its instructions.

James