Brakes Wheels 1st Gen Tires Most liked posts in thread: Brake fluid change

I've seen one that looked like a hopper, but can't locate it; and then there is this one.

I have no problem keeping up with the fluid level in the reservoir when I use a pressure bleeder without filling the pressure tank with fluid.

 

I've got a Motul pressure bleeder, and it's great for fluid flushes. But I've never put fluid in the pressure bleeder tank! I just fill the brake reservoir up to the top, screw on the adapter, pump up to 18 psi, bleed a corner, unscrew the adapter, top off, and repeat. The fronts don't need as much fluid as the back corners, so you only have to re-pressurize 2-3 times. And the time spent topping off is saved by not having to clean anything up.

 

Best advise is DONT TOUCH the clutch unless you have a tool to hold the slave cylinder compressed, they are a pain to bleed, even if you have the tool.

Yes the Motul may cost more, but it really is better fluid.

 

Gravity over suction is my recommendation for the slave bleed.

After the slave is bled and it is returned to the operation position without pressure on the reservoir, suction on the bleed nipple, or the bleed valve open, is the only time it is safe to actuate the clutch pedal. After the bleed is complete, twelve slow pedal presses is recommended by the factory TIS.

If a tool like the BMW version shown in my how-to, or a home made alternative for compressing the clutch slave is not available, a simple block of wood wedged against the release arm is adequate as illustrated by Terry below.

The clutch slave cylinder occupies the lowest point in the hydraulic system most of the time. Moisture not suspended in the brake fluid will accumulate here. It's not necessary to bleed the slave every time the brake calipers are bled, but the slave should be bled at no longer than a two year interval.

A few cautions when bleeding the slave:
-Don't allow the fluid level in the reservoir to fall below the pick-up tube for the clutch master located on the left side of the reservoir. This is where most of the fear & doubt stories originate; air entering the clutch master cylinder via the reservoir.
-Fully compress the slave plunger, but don't over compress it; damage to the internal diaphragm can occur if pressed too far inward. If not pressed far enough, air can remain trapped in the slave cylinder.
-Don't allow the plunger to extend with the bleeder valve open, or with the cylinder cocked at an angle. There is a small O-ring on the end of the pipe feeding the slave, air can enter here if the pipe is offset during vacuum. Air can enter this juncture just from moving the slave around also.

A tip for unscrewing the bleeder valve on the slave, use a ratcheting 11mm box end wrench. Unlike most bleeder valves, it requires multiple turns to open and close.

 

Look [ame="http://www.lonestarminiclub.com/forums/showthread.php?t=476"]here[/ame] for a guide.

If it is an electric suction bleeder, you're OK; the hand pump types take forever and wear you out. The pump-press-hold-release method using a partner is also fairly rapid, but this method is not appropriate for the clutch slave. Gravity bleed takes longer, but is effective.

 

Keith--does anyone that you know of make an expansion cylinder that you can screw on to the brake fluid resevoir for bleeding? For a complete flush, I just use my motive pressure bleeder, but it takes a ton of fluid, much of which gets wasted (and Motul ain't cheap). It would be so nice for quick bleeds to use an expansion cylinder and use gravity; it'd save on brake fluid. There really isn't much volume in the resevoir otherwise--it's ok if you have an extra set of eyes, but it's a little dicey if you're doing it alone.

 

The problem is my pressure bleeder is such a large tank, it takes a fair amount of fluid just to get the level up to the point where it's entering the hose to the brake fluid resevoir, which is really a waste. I wish motive made a smaller tank....

An expansion cylinder that screwed on to the brake fluid resevoir would be oh so sweet, especially at the track...

 

There's nothing quick about a gravity bleed.

It's not necessary to put fluid in the pressure bleeder tank for bleed only. Fill the brake fluid reservoir to midway in the neck, apply a few pounds pressure using the pressure bleeder, open the caliper nipple, watch the the level in the reservoir, when it falls below the seam, close the valve. Release pressure slowly, refill, and go to the next caliper. I know the bleeder nipple does not always cooperate and hold its place, you can also judge the amount entering the catch bottle while handling a wrench; two fluid ounces is enough for each caliper, but more than that can pass before there is a risk of gulping air up top.

 

Thanks--I'll give that a shot.

 

That's weird....my Motive bleeder has the tube clear to the bottom. I put about 1 litre in it and can do a complete flush with that.

 

Here's the thing--1 liter works great, you can dump a liter of ATE since it comes in 1 liter containers, but Motul comes in 500mls, so you need two bottles to get to one liter (One liter is what Motive suggests filling the tank with). And one 500ml bottle of motul is almost twice the cost of a one liter bottle of ATE, and when you really only need 500 cc's to do a flush, it gets pricey...

It's not that I hate ATE, but I've had better luck on the track with Motul.

 

Gotcha........I myself have never had any issues with running the ATE stuff and the ATE is about half the cost of the Motul per litre. The spec's are so close between the two that I never saw the reason to use it myself.

As to the OP, I personally hate vacuum bleeders as it is real easy to get air into the system. And you definitely don't want to get air into the MINI as it is a bear to get out. The gravity alternative is great if you have the time. Both do req some diligence so the fluid is kept at the proper level.

 

Yeah, that's what I'm going to do next time, never thought to do that until Keith mentioned it. I'll just keep a close eye on the resevoir. I usually bleed at about 10psi--it's a little slower, but not much, and puts less pressure on the resevoir and lines. Probably doesn't make a difference though.

 

I've tried to bleed the clutch myself three different ways but it still felt wrong until I brought it to Dan at Grassroots and he used his BMW tool (and patience) to do it right. The piston is flimsy, it's in a bad location, the nipple is oriented the wrong way, the plastic bleed screw makes it tough to find a consistent bleed point, and it's a poor design. Don't touch it unless you want a headache.

 

I use the Bavauto bleed tool, works pretty good but the trick is to make sure the slave is FULLY compressed. If it's not, air can and will get trapped inside. If fully compressed there is no where for the air to get trapped. Now ask me how I know...... Lol

 

Thanks K, I was thinking of a similar post, but now I don't have to............