Clunk on startup

07GtS197 · Oct 4, 2016

Im leaning towards the master cylinder failing or the cup seals. The hydroboost should be ok because when they go bad the pedal gets really stiff. Im going to keep on bleeding and see what happens. Since the caliper is still sticking and the drivers side front is closest to the master cylinder Im thinking thats what it is. It would make sense if the cup seals are going because brake fluid will get past the seals causing the brakes to go to the floor and then when you let off, the brake fluid needs to move the other way past the cup seals which creates a temporary vacuum effect and temporarily keeping the brakes applied. We will see.

07GtS197 · Oct 6, 2016

So that same day I took it out and after about 10 minutes I smelled burning brake pads so I took it home where I got out and tried to push it to see if the tires were locked up and sure enough it wouldnt roll. Im thinking my master cylinder is bad.

Nighttrain · Oct 9, 2016

07GtS197 · Oct 9, 2016

Its slow going but Im just gonna bite the bullet and buy a new master cylinder. Both the old caliper and new one cant be bad. And when I had my car on a lift last year to get the exhaust done I remember both front wheels being hard to turn but the drivers side front being the worst. It makes sense because that caliper is closest to the mc and the pass front is the second closest. From what Ive read a failing mc will cause inconsistant braking. Its not doing that though. Im still going to swap it out because more than one wheel is affected. And I dont think there is more air in the lines either.

Nighttrain · Oct 10, 2016

07GtS197 said:
Its slow going but Im just gonna bite the bullet and buy a new master cylinder. Both the old caliper and new one cant be bad. And when I had my car on a lift last year to get the exhaust done I remember both front wheels being hard to turn but the drivers side front being the worst. It makes sense because that caliper is closest to the mc and the pass front is the second closest. From what Ive read a failing mc will cause inconsistant braking. Its not doing that though. Im still going to swap it out because more than one wheel is affected. And I dont think there is more air in the lines either.

Sounds good!