Mike RT4

As an aside, have you read the "Soft brake pedal" in the Suspension and brakes section, there are some suggestions in there that I don't think you have tried (bleeding the brakes with engine running)?

DaveUK

Thanks Mike, I've never read that. I'll try that tomorrow, and tomorrow night I'll leave a concrete block on the pedal because most people get good results from that.

Here's to hoping!

BenRNBP

I don't know what magic it performs but the one time I wedged my pedal down with a block of wood it did improve the feel - I'm not sure if it allows the piston to move further out in is seal or compresses air into the fluid (to be released like a fizzy drink when you release the pedal) - but hope it worked for you.

DaveUK

Thanks again for everyone's help.
Quick update. I figured if wedging the pedal down overnight does work by making a sort of fizzy drink (good analogy!), then it might be best to do the bleed afterwards. So right now, the pedal is pushed down with a block of concrete, I even switched on the engine after I'd placed it to make sure the booster is helping as much as possible.
Tomorrow, I'll bleed them with the engine turned on, and I'll let you know how I get on. If that doesn't work, I think it's going to be a dealer flush. Then if it's still not great, new pads and discs. Then if that doesn't work, a new master cylinder (but from what I've read, if a seal has broken or got damaged, then they leak and mine doesn't leak anywhere). Then if that doesn't work, I cry.

Mike RT4

Fingers crossed!

Nick Graves

That's not nest of celery true; the pedal rod seal isn't really pressurised, because it moves forward under pressure. If the seals (or bore) are tired, the fluid can blow by them back into the reservoir. Or suck in air.

It WAS true in the case of my NSX, though. I knew the Project Mu discs were still flat, but I suddenly got the 'dropping' pedal feel occasionally, as if they were warped. One application restored hardness (oo-er) and so I went for the M/C. Sure enough, it was beginning to weep at the top of the pedal. One may purchase the rod C/W seals for an NSX, which is good because the M/C casting is expensive and RHD-specific so Acura's no help. That cured it, anyway.

DaveUK

GAAAAH! So it could be the master cylinder even without external leaking?

OK then change of plan. I'll still do the block on the pedal and the bleed with engine on tomorrow, but then (if that doesn't work) instead of a dealer flush, I'll get a second hand master cylinder, take it apart and try to buy the correct size o rings for it. Fit it, THEN go to the dealer for a flush.

On the lings parts website, I can only find the piston assemblies. I don't think Honda sell refurb kits like they do for other cars.

Nick Graves

Correct me if I missed it, but what are your discs like? Lippy & grooved, or like an engineering flat?

My Leg End had horrible brakes too, until I changed the disc/pads. But I knew they were corrodey on the insides. It's less spongy now, but slightly over-servo'd, unlike the S2000.

DaveUK

The discs aren't flat like new discs, but they're not crazy wavy. You can feel the grooves easily though. The lip on the edge is maybe 1mm at most.

The pads would have taken up the shape though wouldn't they? Having said that, they didn't feel grooved when I took them out last week, but then I also wasn't checking for it, so it might just be that I didn't notice it. They've had over 4K miles to mate to the surface.

DaveUK

This is the front right disc. All the others are similar.

I know I keep saying thanks, but I honestly appreciate it.

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