Brake Question

[1067]

Our recently purchased '91 has a "soft" brake pedal on initial start-up and when frequently used in stop/go traffic. Problem does not occur at steady state or accelerated speeds.

Referencing the Service Manual - 1991 NSX, Volume 2 of 2, page 19-14 led me to go through the Brake Booster Tests:
Functional Test - passed
Leak Test - passed
Check Valve Test -passed

Any ideas ??.

 

[Scrapdog2grand]

Bleed the system at all 4 corners as per manual.

While you are there for the bleeding procedure, check that none of the caliper slides are binding or seized, and check that all caliper pistons move easily and not binding or starting to seize. Check the condition of dust boots on the pistons, make sure they are all in place and not torn.

Uneven wear on the front or rear pads are a good indicator of these types problems. When this happens the pad has to travel a little further to make contact with the rotor, and you will end up having soft pedal feel. Normally you can pump the pedal kind of quickly and on the second or third application the pedal will feel better.

 

[Larry Bastanza]

1. How many miles?
2. What is the condition of the brake fluid (Dirty? old?)

 

[DocL]

Maybe bad seals in the brake master cylinder. If you can stab the brakes really hard and they bite for a second, and then when coming to a stop slowly they seem to not work, that is your most likely culprit. I had it happen with my NSX.

 

[USAFguy22]

What Doc said, same issue here. Pretty simple replacement with some helpful DIY's on here.

 

[1067]

Maybe bad seals in the brake master cylinder. If you can stab the brakes really hard and they bite for a second, and then when coming to a stop slowly they seem to not work, that is your most likely culprit. I had it happen with my NSX.

That looks like the problem.....thanks !!