bleeding brakes 2003 rapier Hdi

[steve_earwig]

Did them with a power bleeder that connects to the wheel valve and brake resivour took about 5 mins, peddle is good, brakes not so good but they will bed in soon enough, did it with engine on in case abs pump had air in too

That sounds damn nifty!

Oh dear, can of worms, everyone talking at cross purposes and it's my fault, sorry

The seat... I think we could do with a diagram here but best I can do is


Right, the conical part on the end there screws into a hole inside the calliper to form the seal. Above that is a small hole which leads into the central part of the nipple, so when the nipple is loosened the fluid is pushed past the seal, through the little hole and out through the centre of the nipple where, hopefully, you have a tube waiting to drain it into a jar or something.

My issue with the one-way valve bleeders is that, unless the threads form a perfect seal, when the peddle is released the remaining vacuum can pull air back past the threads and into the braking system, rendering the bleeding pointless. I know this won't always happen, but it's such a nuisance when it does I've long since given up with it.

Jasper's method involves (I think) shutting the nipple, making it impossible for air to get in and the subsequent vacuum forces brake fluid past the piston seals in the m/cylinder to replenish the system. I'd also call this the "old fashioned" way, it's pretty much fool proof (unless the m/cylinder seals are shot, in which case you're wasting your time anyway). This does rather require two people though, one to pump the peddle, the other to work the nipples ( ).

And now I'm wondering how you managed to bleed that Z4's brakes on your tod, unless you have extremely long legs

[steve_earwig]

My Mityvac uses vacuum to suck the fluid through,

I'vwe got one of them, very useful. I picked it up a while back, not really for bleeding brakes, I got it because loads of the service instructions on 2-stroke lawnmower/strimmer/blower carbs involve vacuum testing stuff (especially on the Stihl 4-mix engines, where it's critical). Held out for one with a gauge and got one for 20 quid-odd off the bay, turns out it was cheap because it didn't seal properly, but I took it to bits and found a misplaced seal, it's now perfect.

[steve_earwig]

Btw this seems to have been rather therapeutic as the headache that's laid me up all day is finally going (well, it's either that or the fired egg sandwich I just scoffed...)

[stevewalsh]

Mityvacs are a good piece of kit with dozens of uses, apart from one person brake bleeding, used mine today to pressure test a walbro fuel pump/carb for a chainsaw,

[jasper5]

To be fair, I've never come across one of these Mityvac things, so can't relate to them.

Bleeding the Z4 on my own....fitted the reconditioned ABS unit and the 6 brake pipes that fit into it.
Left the brake pipes a little bit loose then filled up the brake master cylinder.
Pumped up the brake pedal until fluid came out of each brake pipe at the ABS unit then left each pipe loose until fluid leaked out by gravity and atmospheric pressure.Tightened the pipes up then checked the brake pedal...brake pedal nice and solid so undid each bleed nipple one at a time then pumped the brake pedal...left the bleed screw undone until gravity/atmospheric pressure allowed fluid to leak out....did this with all 4 bleed screws and checked the brake pedal, filled the master cylinder...pedal nice and solid so took it for a test drive and all was well.
Bear in mind that fluid was still present in the brake system apart from the ABS unit and master cylinder.

I have worked by myself for 34 years so have had to be creative at times.

Before I remove a caliper or brake cylinder I always clamp off the flexi brake hose that goes to the relevant caliper/cylinder as fluid cannot leak out then, making it much easier to bleed.
Gravity and atmospheric pressure is a wonderful thing