I am bleeding my brakes and clutch. Started from furthest away and worked towards the closest to the reservoir.

The clutch just seems to have endless small air bubbles in it. I have a bleeder with a check valve and a friend inside on the pedal with me underneath confirming what is going on. No the reservoir has not been low enough to suck in air. It doesn't make sense after filing the bleeder and repeating about 10x that there are still bubbles in the system (albeit less than when I started, which is why I knew it needed to be bled as it stopped working properly on the track). Any comments on the small bubbles? Does not seem right to me but I don't have fluid leaking anywhere or appear to be sucking air in via the bleeder as it works fine on the brakes.

Then I moved to the front brakes which have lots of metal specs in the brake fluid. I am guessing this is coming from the ABS unit? I probably didn't bleed enough through the rear brakes to see the specs. Is this common and what is the cause?

Thanks

 

If you are getting continuous bubbles on the clutch hydraulics, you may have a small leak somewhere. Are you saying you had trouble with the clutch pedal?

If so, I recommend a new slave cylinder, master cylinder, and stainless braided clutch line.

I've not seen metal shavings before, that's odd. ABS would be a good guess.

Dale

 

On the track the pedal went dead and didn't return properly. It still disengaged fine but naturally I went off the track as soon as possible. Once cooled it was back to normal again.

There are no leaks around the slave or master or anywhere down the lines to the clutch itself. Is it possible to suck in air without having a fluid leak? Most clutch issues I have had on other cars have involved an obvious leak (master, inside by the pedal) or not disengaging properly and I have neither.

Bled a little more through the clutch and still got the small bubbles reasonably often. Could my leak be internal to the bellhousing where the slave shaft goes? That would not be good. However iI would expect my fluid level would drop and then my clutch would get wet and slip?

Bled another 500ml through the brakes today. Few aluminium specs in the rear, still quite a few in the front. Doesn't seem to be going away. I am surprised others have not encountered this before hmm... google search is also inconclusive but says either the pistons/piston holes themselves (but they are probably steel?) or the ABS unit.

 

The clutch master can sometimes have an internal pressure leak - it won't leak outside, but it will bypass pressure.

If the clutch hydraulics are acting up, I would just replace. They're not horribly expensive and it's much easier than fighting with it.

Dale

 

Slaves will normally leak into the bellhousing, never seen one wet the clutch ever, not surprising with the offset. The cast iron Mazda uses on them seems to be far worse than stuff from 40 years ago and rust at any hint of water.

The going away when hot, coming good cold, might suggest a swelling rubber hose...they're notorious for failing due to heat in the FD.

 

I think I have found the culprit. There is play in the bushing where the hose goes into the master. You can see fluid moving under the plastic flange but it is not leaking out. So I need to see if i can get the bushing itself without buying a whole master cylinder cause this is the only problem ...
Or I can try sealing it up with gasket gunk

Anyone bought this bushing before?

Regardless of the solution I will also heat wrap it.

I have added a photo to this message and a video here showing the play:
Went for a hoon in the hills today and no problems. Of course you only notice real problems on the track...

As for the aluminium in the brake lines - still don't know. The pistons will be steel, are the calipers steel or aluminium? I assume the abs unit is mostly aluminium so my bet is still on that.

Cheers

 

Replace the whole master cylinder. If one part fails, the rest isn't far behind. Really, I always recommend replacing all the clutch hydraulics - master, slave, and a braided clutch line. If one goes, you put a new one on, then you put stress on all the old parts - hydraulic pressure increases and the next weak part fails.

The front calipers are aluminum. To be honest with you, I don't know how nuts I'd get with it. Put on new clutch hydraulics, flush and bleed the whole system, then see how it is.

Dale