Help!! major brake problem....

GCPRO · 04-14-2006, 02:36 PM

My '90 Supra with ABS has had a soft braking problem for over one year.

So far, I have:
* replaced the master cylindar twice with rebuilts - no difference
* replaced all calipers with rebuilts
* replaced/bled all lines (in the prescribed order)

Symptoms remain: soft pedal reaching almost to floor with limp braking, with an evental more dramatic "grab" as the car slows down.

I am at a loss as to what to do next. A couple of observations that I don't know how to interpret:

When bleeding the lines after caliper replacement, I do a "no backpressure" bleed until the fluid shows no air. Then I have my assistant hold the brake down too build up pressure at which time I open the bleeder. I noticed that sometimes the fluid sprays out forcibly and other times it dribbles - although there is no evidence that air is in the lines.

Assistant reports pedal still travels close to floor even though new calipers have been installed and air is removed from the line.

Questions:
Are there any other components of the brake system that could impeed/limit fluid pressure to the calipers other than the master cylinder? Are there solenoids or boosters or orifices related to the ABS that I should look at?

Any other suggestions?
is there any other part of the system that I should look at?
how about adjustment of the piston in the master cylinder. Is that something that might be fruitful?

04-14-2006, 02:36 PM	#18
GCPRO Stock Join Date: Nov 2005 Posts: 4	Soft fading brakes - tried usual stuff My '90 Supra with ABS has had a soft braking problem for over one year. So far, I have: * replaced the master cylindar twice with rebuilts - no difference * replaced all calipers with rebuilts * replaced/bled all lines (in the prescribed order) Symptoms remain: soft pedal reaching almost to floor with limp braking, with an evental more dramatic "grab" as the car slows down. I am at a loss as to what to do next. A couple of observations that I don't know how to interpret: When bleeding the lines after caliper replacement, I do a "no backpressure" bleed until the fluid shows no air. Then I have my assistant hold the brake down too build up pressure at which time I open the bleeder. I noticed that sometimes the fluid sprays out forcibly and other times it dribbles - although there is no evidence that air is in the lines. Assistant reports pedal still travels close to floor even though new calipers have been installed and air is removed from the line. Questions: Are there any other components of the brake system that could impeed/limit fluid pressure to the calipers other than the master cylinder? Are there solenoids or boosters or orifices related to the ABS that I should look at? Any other suggestions? is there any other part of the system that I should look at? how about adjustment of the piston in the master cylinder. Is that something that might be fruitful?