Brake Bleeding.

[Squid]

Before you bag me out and tell me to search google - I Have!! But there are conflicting reports on how to bleed the brakes, and the method I was taught when I was a kid wasn't similar to any of them

What procedure do you guys use to bleed your brake? I did my mates car last night and when finished the brakes were a little spongy still (despite no air what so ever coming out of the bleed valves) and there was a fair bit of travel in the pedal before getting any feedback, so im not sure. We used motul rbf 600 andbled over a litre out of the system.

Any way I would be keen to here of any procedures you guys use and/or any suggestions for the above problem?

Cheers

[boris]

Taken straight from my celica workshop manual

Brake bleeding should commence at the wheel cylinder furthest away from the master cylinder. Attach a flexible tube of a good fit to the wheel cylinder bleeding plug and put the other end of the tube into a bottle already filled with brake fluid. Pump the pedal several times and then hold the brake pedal in the down position whilst the bleeding plug is opened and closed as the old brake fluid starts to flow out. Carry out this operation three or four times on each wheel until only brake fluid and no air shows out through the pipe. Repeat this operation for each wheel finishing with the wheel cylinder nearest the brake master cylinder. Ensure that the master cylinder reservoir is kept topped up at all times during this operation or further air will enter the system.

[Squid]

Thanks Boris, That is pretty much how it went, but still spongy there was absoloutely no air coming out of the lines... hrmmm ideas?

We did it 5 times on each wheel as we had replaced the front calipers and also wanted to flush out the stock fluid and replcae with the motul.

[ae86trueno]

Try to tighten the nipple while on the downward press on the pedal
Most brake blead hoses have like a 1 way valve to keep preasure in the line, but what i said above works just as well.

Ben.

[o_man_ra23]

Your calipers probably arent adjusted up yet. You will probably find that the calipers will be loose on the discs. To fix this, one at a time, take the caliper off the disk, as a complete assembly(ie with the mounting bracket etc) and just press the brake pedal enough so that when released, the caliper should be a tight squeeze back on (not so you have to hammer it though). put them back on and see how you go. If you have drums at the back, they should be adjusted so that the drum is a tight squeeze then loosen it a touch. That should get rid of the long travel before it does anything, and also should tighten up the feel nicely.

Cheers, Owen

[Squid]

All 4 discs were a tight squeeze to get the calipers back on (after doing what you suggested) so i'm not sure that is the problem didn't need a hammer but was a solid whack with the palm of the hand. On e of the guys at work suggested we bleed the master cylinder in case there is a shitload of air in it? I dont like the sounds of that...

Perhaps we should just take it to a mechanic with a vacuum pump and get him to suck it through?

[o_man_ra23]

You can do the suck through method with a decent sized syringe (not the type with the needle on the end, just regular plastic one). This was taught to me by my bro in law who is into motorbikes. You fill the syringe with clean fluid, and put a clear hose in the end, so that it tightly squeezes over the bleed nipple. Loosen the bleed nipple and squeeze the syringe. Make sure your master cylinder doenst overfill though, you can fill the syringe from the master cyl. Once the syringe is pretty much empty, tighten the bleed nipple. This is best done with 2 ppl, but can be acheived with just 1. Continue for all callipers. Do it a fair few times.

Im not saying this will work or solve the problem you have, but that is how you can do the suck through bleed without a vacuum pump.

Cheers, Owen

[Squid]

How do you avoid adding air bubbles when hooking up the syringe?

Wouldn't the reverse also work? Ie hook up an empty syringe and draw it through?

[o_man_ra23]

It depends how the air bubble is trapped... sometimes they just wanna get pushed back up the pipes. To stop air bubbles getting in through the syrings(this is the messy bit, suggest gloves maybe, unless your a rough nut like me) squeeze the syringe and hold vertical, till no air is left (which is why you have clear hose) and push onto the nipple when it is clear, making sure the syringe doenst suck again. Worked for my ever-so pain the the arse to bleed kawasaki gpx600R

[TRAV-KE55]

If you have just put new pads in at the same time they wont be bedded in and will give a spongy feel untill done so, as for the bleeding
Slow pumps to get the fresh fluid (making sure not to empty resivoir of fluid) through to caliper, once the fresh fluid id trough close the bleed nipple, then 3 pumps and hold pedal down, continue this step untill satisfied no air in that caliper, always lock og bleed screw on a downward stroke.
start from furthest caliper from master cyl and work towards closest.
Also if its an older car what sometimes happens is that there is crud in the master cyl and when you depress the pedal to the floor the crud get pushed hard against the seals in the master cyl (in normall brake operation the piston never travels this distance) and scores them causeing fluid to by-pass the seals and a crap pedal. Good luck!!

[gearb0x]

What about the condition of the rubber brake lines them selves?

As for the fair bit of travel part, my AE71 is doing this now, it only starts to brake on the very last few CM of the stroke, and even then its not strong. ie: wont pull up real fast at high speeds, but will lock the wheels on dirt at low speeds. General consensis is one of the seals in the master Cyl gone and its only running on one circuit. Will confirm as soon as i get around to pulling apart the MC

Good luck anyway

[Nark]

I'd put new seals into the MC anyway, just to remove the possibility. Costs bugger all (less than $30 from memory) but it's a bit of a PITA to do.
Hot water, slippery rubber bits, and screw drivers...

[Squid]

It is a brand new Mini Cooper S, so I don't think the MC or lines will be in anything but top condition.

John has been driving it today and reports that both problems have sorted themselves out, seems they just needed a bit of bedding in and he has been following an extensive betting in regieme.

[Youngy]

Well you used good brake fluid!!

[willwal98]

The way I do it. Get some clear hose and attach to nipple (always work from furtherest to closest). Have an upwards curve in the clear hose and the other end in some clean fluid (to trap air at the top). Pump brakes until hard and release nipple, press slowly but constantly until no air bubles come out and tighten nipple. Also helps to elevate the end of the car you are working on (rear first of course) for about 30 mins before hand, that way all of the air will hopefully be close to the wheel cylinders before you begin.