Those bleedin' Miata ABS brakes

Or rather, bleeding those Miata ABS brakes.

I put braided hoses on my Miata and attempted to get the brakes bled yesterday. The first attempt was a bit of a disaster - my vacuum bleeder didn't manage to pull through enough fluid even after I sealed the cap against the bleed nipple using some grease. So I went and did the old fashioned "pump the pedal" approach. No air showing in the bleeder hose (I'm using ATE Super Blue, so it's not like they're hard to spot) but still too much pedal travel for my liking and the pedal firmed up after a couple of pumps. So, clearly there is still some air trapped.

After consulting the Internetz, I noticed that a lot of people recommend bleeding with the engine running, so I tried that. That ejected a couple more air bubbles but I don't think the pedal travel has improved, even though it's not firming up as much as it used to when attempting to pump the pedal. There are no visible fluid leaks, by the way.

There seems to be an opinion that you bleed with the engine running, then take the car for a drive, try to trigger the ABS, then bleed again, etc until fed up. Is that really the way to go or is it just time to get a pressure bleeder and be done with it?

I've always just gravity bled everything. Might take me a hour, might take me until tomorrow to finish. Never had an issue yet.

Those bleeding ABS brakes, we salute you!

Doing my Corrado was a nightmare. I'm hoping Miatas treat you better.

In reply to Ranger50:

Slight problem with that on an ABS MIata - the top of the ABS block that has the lines going in it is higher up than the master cylinder.

Any further comments, especially re the use of a pressure bleeder?

Remove the ABS?

I'd rather not, TBH.

Not that this will help now - but on most cars if you slightly depress the brake to engage the MC piston it will block the top and not allow fluid to drain when you open the line before removing the hoses. That way - you limit air in the system to the immediate area of the couple no matter how long you leave it "drip" between getting the old hose off and the new hose on. Like blocking the top of a straw with your tongue and lifting it out of the glass.

I have a '95 with ABS and have vacuum bled them a million (well 30-40) times with no problems. I do not run the car while bleeding. You've got something else going on here. Did your reservoir run dry in the process?

The reservoir was dry due to me changing the hoses. I haven't got a good history with vacuum bleeders so I wasn't surprised that the HF special didn't work too well, though. But I wouldn't be overly surprised if this is still user error.

You can build your own pressure bleeder if you happen to have a spare master cylinder cap and a Home Depot around.

BoxheadTim wrote: The reservoir was dry due to me changing the hoses. I haven't got a good history with vacuum bleeders so I wasn't surprised that the HF special didn't work too well, though. But I wouldn't be overly surprised if this is still user error.

Ahhh... you put air in the top. You need to bleed the master (on the bench if you can so you can flip it around), then gravity or pressure bleed the rest, then skid on some dirt to pump the ABS, and pressure bleed it again. Go get a huge bottle of cheap fluid and when you get a hard pedal - then go back to ATE blue and bleed until the color comes thru.

Gravity bleeding is surprisingly effective. Never tried it on a set of ABS Miata brakes, but it's worked well on other cars with difficult systems.

I'm digging GPS's suggestion about blocking the return hole. I might have to give that a try.

to block the comp port in the mc:

• move drivers seat back about halfway
• measure distance from front of seat to brake pedal
• cut broomstick to that length
• put broomstick between seat and pedal
• slide seat forward about an inch

Keith wrote: Gravity bleeding is surprisingly effective. Never tried it on a set of ABS Miata brakes, but it's worked well on other cars with difficult systems.

Speaking of which - Has FM ever considered whipping up an ABS bypass kit? I'd love to get that contraption out from under my hood, but I understand all the lines have to be changed out end to end. Some pre-bent stubby hard lines sure would be nice.

And completely off topic - Weren't you toying with the idea of selling a pinion welded depowered/depistoned rack OTC?

No, we've never considered an ABS delete kit. It wouldn't be hard to do with 6 brake line unions from your local NAPA and a bit of bending. We can sell you the brake line unions if you want. No need to replace all the lines, just hook 'em together.

We've modified a few racks for people in the past. We've never welded a pinion, that's a newer trend that's shown up since the last one we modified.