Spongy Break Feel

[evil86]

Car - ae86

motor - 4ac

use - daily

problem - spongy breaks

occurs/started when - when motor is off the pedal feel is normal. but when engine is running the pedal feel is soft

personal situation - have bleed brakes twice and also changed the one-way valve. need to fix asap to get blueslip to get car on road

[redsprinter]

have you check the rear drum brake cylinders ? they could be shot .

[H8CHIR6KU]

yeah sounds like rear drums are out of adjustment

[evil86]

^^ can you explain in detail please as im stuck n need to rego the car soon

[H8CHIR6KU]

not something you should muck with if you need someone to explain it to you. have a proffesional look at it

but pretty much your rear brake shoes have worn to a point that they are not properly adjusted in relation to the drum. so its requiring more brake pedal travel to push the shoes against the drums. this will give you a soft pedal

[Faceplant456]

if the drums arent adjusted correctly when you pump the pedal it will pump up solid but it will take a while to get there. a good indication is a bad hand brake, how did you bleed the brakes, what method? if your drums are adjusted good then check the wheel cylinders in the drum brake assembly ... pop the drum off and then you will see the wheel cylinder ( its what the brake fluid gos into and what you were bleeding from before) ... now peel back the rubber boots around it, if brake fluid comes out and watch out when peeling these back as the brake fluid can squirt out quickly if there is pressure in the system, then if you get fluid the brake cylinders need to be replaced.

[evil86]

thanks for that faceplant. done exactly what you did and changed the drum cylinder and still same problem. starting to run out of ideas. what is weird is that i hear a hissing now coming from the carby

[Faceplant456]

Vac leak in the booster line. or booster leaking. with the engine running spray some WD40 or other auto motive spray around the Vac lines, if you spray a line and the idle changes you have a leak. replace that vac line. also after bleeding the brakes when you went to pump up the brake pedal did you just put your foot all the way to the floor or did you do nice little half pumps untill it pumped up hard? if you just dropped your foot to the floor, your Master Cylinder could be fucked. if you just drop it to the floor the seals inside the M/C can tear out and then the M/C will need to be rebuilt or replaced. if you are going to replace it why not upgrade to a better one while you are at it.

[evil86]

booster n master has been changed with jdm stuff already, ill spray the vac lines tomorrow