skinney6

my gf's 93 accord ex 4dr has bad brakes. you really notice it when you have to stop short. you gotta really stand on the pedal. she said she had the master cylinder replaced a year or so ago. two mechanics told her she needed new front rotors. i just replaced those last night. didn't seem to make much of a difference. plenty of pad left. is it the booster maybe? is there a way to test a break booster?

Hidenplanvew

You can use a vac pump on the brake booster and see if it holds a vac... Is it really hard like when you shut the car off or the peddle goes to the floor?

Fliptard

is there a one way valve from the booster to intake? usually Honda ones are integraded INSIDE that hose. Take it off and flip the ends around.

doctorbee

bleed brake system. if you're having to apply that much force there's probably air in the lines that's being compressed by stomping on the brakes instead of compressing the friction material

if still crappy then check caliper pistons, there should be no fluid leaking from caliper onto pads or shoes.

if still crappy then check master cylinder.

skinney6

my girl has got the car right now but there is a hose that goes from booster to like a coupler then to intake. i'll look closer when she gets back. maybe that coupler is the valve?

skinney6

brakes are firm when car is off

skinney6

so the hose out of the booster has an arrow pointing away from booster and the valve has an arrow in the same direction

skinney6

i've had air in break lines before this feels different. feel pretty normal until you need to stop short and you have to press really hard. when i had air in the line it was soft right off the bat cuz the air compresses so easy

doctorbee

Unhook the hose from booster to intake manifold, make sure you can apply vacuum to it and have it hold

skinney6

i don't have a vacuum tester

jdowen2

It is possibe that the master cylinder was not bench bled when it was installed. It sounds like you need to bleed the system again.

skinney6

alright, the only way i know is a tube in a jar going around to each caliper (furthest first) while someone pumps the pedal. or is there something i should be doing at the master cyl?

jdowen2

Disconnect brake lines at MC, use soft plastic tubing to route MC fitting back into MC resevoir and pump pedal until air is no longer present. Reconnect brake lines then proceed with bleeding the rest of the system.

MAD_MIKE

skinney6 the easiest way to check if the brake booster works is by depressing the pedal several times with the engine off to bleed any assist.
With your foot on the brake pedal, turn the engine on. Does the brake pedal drop ~1" when the engine starts?

Is the pedal hard and short? Or long and soft? Does it change at all if the engine is on or off?

doctorbee

right on MAD_MIKE, it should also be easy to press on the first press with the engine off and get harder and harder

skinney6

the pedal is hard/short. if i pump it and hold and turn the engine on the pedal drops and inch or so

groundhog52279

i agree that doctorbee's suggestions seem likely culprits. also, make sure no brake fluid leaked onto the pads/shoes. no holes in the brake lines, themselves.

rival12

Sounds like a Brake Master Cylinder, I've replaced.... 3 This always happens when they fail. There are rebuild kits, and replacements in the $60-$120 Range.

Rebuild
-Raysbestos

Replace
-Honda
-Fenco
-Many others.

MAD_MIKE

Does it maintain this same pedal travel or does the assist go away and the pedal becomes hard again?
It seems like there is no booster assist, yet you still get the pedal drop at start up. I wonder if the vacuum hose, check valve or booster has a leak that bleeds off or does not allow a continuous vacuum feed ending with your lack of boost assist.

skinney6 Remove the hose to the booster and inspect it for cracks. Cap off the hose and go for a drive around the block. Does the pedal feel the same short and hard? If so there is something most likely wrong with the brake booster system.

MAD_MIKE

Rockauto has them new from $30-$60. I'd recommend Centric brand.
5% off > 106674168636266 Expires 10/07/2012

*Edit: I love it when the damn window hangs up for three fracking hours*

skinney6

thanks all, i'm going to test with vac hose unplugged from booster
i'm looking at master cylinders on rockauto and there are many options
i believe this is a 93 ex, 4 wheel disc with at least front abs
she said the m/c was replaced a while back. given some of the other shoddy repairs i've seen on this car i wonder if they didn't use the correct m/c?