Braineack

iTrader: (62)

Initial discussion here:

http://forum.miata.net/vb/showthread...16#post2003716

nicacus

iTrader: (7)

maybe your master cylinder??

jayc72

iTrader: (14)

When you R&R'd the back brakes did you properly adjust them? When you removed the bolt that covers the adjuster, was there any brake fluid present? Possible that you might need to do a rebuild on one or both of the rear calipers. JUST A WAG!

Braineack

iTrader: (62)

The passenger rear is a rebuilt unit. I adjusted to the calipers without issues...no fluid present in the adjustment compartment. The brakes worked without a hitch untill they died on the track. Now I can't even get them to bite with street pads.

firestar_3x

Long shot but the seals haven't turned themselves inside out have they, this cause stop the brakes from working, but usally its only possible to do this when you push the piston back to change the pads, could be air in the abs unit.

jayc72

iTrader: (14)

Is it getting worse? Are you down on fluid in the MC?

kung fu jesus

iTrader: (1)

weakening master cylinder, warped pads, proportioning valve over heated from the turbo(?).

brgracer

iTrader: (14)

Well, it looks like you've already ruled out a lot of stuff with all the changes, etc... If you aren't losing fluid and still have the problem with fresh fluid, I think your master cylinder has probably worn out it's internal seals and is bypassing internally.

olderguy

iTrader: (19)

Did you "balloon" a hose somewhere?

LOLA - 92

Brainy -

You can never tell if your master seals have gone bad, unless the rear seal to the passenger compartment was leaking also.
I replaced my master about six months ago - It "LOOKED" fine, until you pulled it apart. The inner pistons seal/cups were shot. It's only $50/60 for a new/rebuilt master.
Last time I posted this problem POP came over and shot me down, but I still believe that masters do fail - Just not as often as slaves.........

LOLA

Braineack

iTrader: (62)

I bought new fluid in a different color so I can really tell if its been flushed out or not. If you do a search on m.net for "soft brake" im not the only ABS guy with this problem. At this point I think it's user error and I'm not doing something right when I'm bleeding them.

If flishing it again doesnt work then a new MC is in order.

jayc72

iTrader: (14)

I've got ABS in my '93 and have always thought that the pedal was a little soft. Not alarmingly so, and it's been the same since I bought the car, and my fluid has always had a steady level in the reseviour.

Let us know what you find out!

Pop VII

Believe we would have been talking about clutch units and not brakes .... unless I injected something in the wrong conversation!

Never worked on an ABS system, and prefer not to talk without knowledge tools, but sounds like a problem with the proportioning valves. Failure to the front would give that extreme brake fade sensation.

magnamx-5

iTrader: (7)

Your problem realy boils down to one thing junk the abs. you seem like an intelegent and good driver why would you need abs, if i ever get another car with abs i will promptly remove it it just destroys the feel. but i am probably in the minority here.

jayc72

iTrader: (14)

I totally disagree. There is nothing wrong with ABS. Despite the less than firm feeling pedal I can modulate pressure easily and consistantly. You can threshold brake just before ABS becomes active. And it's probably worth it just so you don't flatspot tires.

Idiots and shitty drivers aren't the only ones to enjoy the benifits of ABS

Braineack

iTrader: (62)

I'd prefer not to have it. I've gotten it to engage a few times on the street, but nothing I couldn't have dealt with without ABS. It's a good unit for street cars, otherwise I can brake just up to the point of a lockup.

Newbsauce

iTrader: (2)

I'm a firm believer in the fact that ABS is not needed Then again 2/4 cars I've had were non ABS!

nicacus

iTrader: (7)

if you dont need cup holders you dont need ABS

Braineack

iTrader: (62)

well I beat the **** out of the ABS unit while I reflushed the system, it got a big air pocket out of the driver front. Then I went through each one again to make sure no air went into those lines. Pedal felt better (car still on stands) then I adjusted the rear caliper, they had way too much travel on them. Seems to have cured my problem....The car is still on stands, but I'll see how it goes after work, but so far the pedal feels 75% better, I can't get it to hit the floor when the car is on anymore.

magnamx-5

iTrader: (7)

see i told ya the abs was the problem sounds like you have it on the run. good luck