GreekDrifter91

dont know if anyone has or has had this problem but... when driving at realy high rpm or a just flooring it on the on ramp then slowing down with the breaks. the pedal feels very firm and unresponsive. then i have to push even harder then it will "catch" then pedal travel and feel returns to normal....... or i guess i could describe it as that there is something in between the pads and rotor that are making them ineffective then i just push harder to squeeze it out then it works fine. (are they off gassing?) it does not do this just driving casually or even just a little more than casual.

brakes are completely stock. but am unsure about the pads. i have had them on the car sense i bought it 5 years ago at the dealer. still with plenty of meat on them

i have never felt this find of brake feel before on other non-abs cars. i dont even know what would be causing this. any ideas?

GreekDrifter91

bump...

clokker

iTrader: (2)

Given your description, I'd suspect the booster is the culprit.

GreekDrifter91

hmm do you think the booster is seeing boost? or to much vacuum?

clokker

iTrader: (2)

Dunno, but I'd check it out.

Molotovman

iTrader: (49)

Check the vacuum hoses feeding the brake booster. It sounds like your booster is not getting proper vacuum, one of the hoses is probably rotted on the passenger's side of th car because of the heat.

farberio

iTrader: (7)

I think there is a check valve in one of the lines right off the booster. Maybe it started sticking shut and that may explain why it works sometimes and not others.

j9fd3s

iTrader: (3)

that would do it. the reason its there is so the booster stores vacuum when the engine isn't providing it, like when there is boost

RotaryEvolution

iTrader: (30)

or the brake booster hose was replaced with a generic hose and is kinked.

FirstRotaryExp

iTrader: (3)

How many miles have you put on these "5 year old" "Stock" pads and rotors? How does the fluid look and when was the last time it was bled properly?....kinda surprised everyone pointed to the upper hydrolics first.

misterstyx69

iTrader: (142)

boom..culprit.

FC3S_nataku

iTrader: (3)

Where do you get a new line with the check valve?

misterstyx69

iTrader: (142)

it comes molded inside the hose.

RockLobster

iTrader: (7)

yep get a factory replacement brake booster vac hose with the integral check valve. Especially for a turbo car, you need the check valve in there or the brakes will do really wonky stuff. And the vacuum will collapse all but a fully reinforced hose so stick with the factory unit or equivalent.

GreekDrifter91

dont know lol, and the fluid was changed in the early spring. but i looked at the pads and rotors still plenty left on them


good to know i will have to check this out. i have not had any time to touch the car yet.

RockLobster

iTrader: (7)

It still could be the booster but id start by checking the vacuum hose(s).

Being your signature says "turbo" tells me when you are boosting it is pressurizing the booster because of the absence or malfunctioning of the check valve. It takes some time to bleed that pressure off before the vacuum comes back and the brakes feel normal again.

Basically your brake booster is acting like a pressure accumulator, instead of a vacuum accumulator like it would with a working check valve.

TonyD89

iTrader: (10)

I have seen failure of the soft lines cause this problem. The rubber and fabric start to de-laminate, a piece of the inside rubber rips loose. and the flap of the rubber causes an intermittent blockage. It maybe rare now but some of the older American cars I have worked on were quite prone to it.