Hydraulic bleeding procedure idea.

[twins4life]

Perhaps this is not new but I just thought of it while examining my slave cylinder.

The inlet and bleed ports are side by side.

Just squeezing the clutch lever and opening the bleed port will just move the fluid from port-to-port and not much of the total vloume of fluid.

My idea involves two people:

One to squeeze the lever and the other person to open the bleeder AFTER the clutch lever has been squeezed. Then the piston will be forced down against the diaphragm spring and the the opening of the bleeder will allow the piston to retract and force the traveled volume of fluid back out.

Taking more of the internal fluid out the bleed port (by moving the piston) then just squeezing the lever and opening the bleed port.

[bikerfish1100]

are you talking about bleeding the clutch? "inlet" is at the master cyl on the handlebar, the "outlet" is back by the swingarm (at least on my R11S)- that's not nearly "side by side". were you speaking of the brake system? even so, i still can't quite picture what you're talking about.

[twins4life]

I'm talking about the clutch slave cylinder.

I'm looking at the deceased one on my desk. The inlet and bleed ports are side by side. If new fluid is forced in and allowed to exit, the fluid will take the shortest path, simply going beteen the ports on the slave cylinder itself.

Simply squeezing the lever and opening the bleeder (on the end of the hose) will just flow fluid between the two ports on the slave cylinder.

But squeezing the lever AND HOLDING while the bleeder is opened will allow the piston to travel back up and therby force fluid out. Still not perfect but would seem to be an improvement.

[deilenberger]

I believe I understand what you're saying.. and yes - that would allow fluid that is pressing the piston towards the clutch to be relieved via the bleed port. How different this would be from flowing fluid through the cylinder via the input port on it and the bleed port is unclear to me.. but I don't think it could hurt, so I'd say go for it..

[AntonLargiader]

That's the way I've been doing it for years! But it only takes one person...

[twins4life]

That's the way I've been doing it for years! But it only takes one person...


Perhaps but my back surgery makes me not so nimble :violin

[jyambrovich]

I've got a Mity-Vac and think that it might help a lot in this situation. By attaching it to the bleeder furthest away from the reservoir, opening the bleeder screw and pulling a vacuum, you'll draw / suck the fluid from the reservoir through the system all the way to the bleeder.
The clutch on my 2000 R1100RT is still mechanical (cable) so I haven't had to face a clutch system bleed yet but I've done the brake system twice now and it's really clean, quick and easy.

Good luck!!

[deilenberger]

I've got a Mity-Vac and think that it might help a lot in this situation. By attaching it to the bleeder furthest away from the reservoir, opening the bleeder screw and pulling a vacuum, you'll draw / suck the fluid from the reservoir through the system all the way to the bleeder.
The clutch on my 2000 R1100RT is still mechanical (cable) so I haven't had to face a clutch system bleed yet but I've done the brake system twice now and it's really clean, quick and easy.

Good luck!!That is strong recommended AGAINST on any BMW with ABS. According to reputable sources the vacuum bleeder can destroy the ABS modulator (probably by pulling a seal inside-out..)

[John Brase]

That is strong recommended AGAINST on any BMW with ABS. According to reputable sources the vacuum bleeder can destroy the ABS modulator (probably by pulling a seal inside-out..)

Yes. But it should be safe to use a vacuum bleeder on the clutch circuit.

John

[deilenberger]

Yes. But it should be safe to use a vacuum bleeder on the clutch circuit.

JohnTrue.. my 'duh :)

[bikerfish1100]

That is strong recommended AGAINST on any BMW with ABS. According to reputable sources the vacuum bleeder can destroy the ABS modulator (probably by pulling a seal inside-out..)

so what IS recommended for bleeding brake circuits (and for the moment, let's just assume that all we are talking about is bleeding at the calipers, not at the ABS module itself)?

[deilenberger]

so what IS recommended for bleeding brake circuits (and for the moment, let's just assume that all we are talking about is bleeding at the calipers, not at the ABS module itself)?This really depends on what generation of ABS you have. Later model oilheads with the servo equipped systems use two different means of flushing the brake circuits (and bleeding really refers to an instance where air is in the system.. flushing is what you are most likely doing unless you've done repairs to the system.)

For non-servo brakes, manual hand-bleeding is doable.. just be very careful not to make the lever move further than it normally does during normal use so you don't send the master cylinder seals into un-charted (and possibly damaging) areas of the piston. I also use power bleeding, with a device that pressurizes brake fluid forcing it through the system. In this case - you still are pushing fluid through the ABS modulator.. no way around that since it's in series with the master cylinder and calipers.

This is really something where you need some very specific instructions on your bike. I'd suggest a service manual (or in the case of the servo-assisted brakes - a Goggle will turn up some excellent DIY writeups..)