Brakes Bringing Me to Insanity

[C4ptainCox]

I just replaced rotors and pads all around, rear wheel bearings, and the rubber brake lines with GAP's SS kit. There was a TON of crud in the system, but eventually I got things pretty well cleaned out. Used over half a gallon of brake fluid In the process.... Things seemed to have gone well with the bleed, I had a buddy pressing the pedal for me. But now the brake pedal is softer than ever.

Could it be my master cylinder? Or do I just still have air trapped in the system?

[ANSAracingb]

You could still have air in the system, but do you know how far your friend depressed the pedal when you two were bleeding the system?

I have heard that you're not supposed to push it all the way to the floor because you're pushing the piston inside the MC past a point it is not supposed to travel (when it has fluid inside). You could potentially damage the seal internally, which would allow the MC to not pump up enough pressure. This is important on older cars like ours, and a lot of people use a vacuum-style pump at each wheel, or even gravity bleed, to not have to deal with this issue (plus, you can do it by yourself with one of these two methods).

Does it build up pressure at all now? Or is it too soft no matter how many times you depress the pedal?

[C4ptainCox]

With the car off, the pedal can only depress half way. With it turned on, it freely travels all the way to the back or just before the back no matter how many times I pump. Either way, it doesn't seem to really build up pressure with repeated pumping.

I do not know how far he pushed the pedal, that wasn't something I was worried about at the time...
I guess I might be in for a new MC... Anything I should try before I order up a corrado MC?

[83mk2scirocco]

We gave the most sensitive bleeding system.
if there is any air in the master it wont hold pressure.
ok,i foind tjis by accident,put a bunch of rags under the master.
so it would catch any drips.crack the two on the same side.maybee half a turn.
let it drip for like 15 to 20 min.Now you should have a consistant drip.
do the same for the outher side.
Now go to tje longest line/rear and open the bleeder.
and watch for air.use a clear tibe.
1 you catch the fluid,2 you can monitor the oit foing fluid.
look for air.
You could have flushed out the master now it went bad.if its old.
Rule #1 never let the reservore go dry.
i did my brake by my self,well gravity is a good friend.

[Culcuhain]

or you can take it to a shop and have them power flush the whole system. It will bleed the master cylinder and all calipers too... plus it will ensure all the crud is out. I had to do that to my F150 because I couldn't get the air out of the ABS unit.

[GoKraut]

Leak, air, or if you put rear mk4 brakes in - upside down (which causes air in line)

Most likely a bad master cylinder if you went through THAT much brake fluid (which is insane BTW)

-Rob

[TheTimob]

I bought a Motive power bleeder from Germanautoparts and I think it's one of the coolest tools I own. It pressurizes the brake system, so you don't move the pedal at all (and then you don't damage the master cylinder)

Pump it up


and then open the bleeders


That's it.

Now, in my case, the car had two bizarre problems with the booster. First? It was full of brake fluid - the master cylinder had leaked into the booster. The other problem was that the pushrod inside that connects the booster to the master cylinder fell off internally. I didn't even know that this was possible. I would consider this to be a freak thing that isn't normal.

[TBerk]

[QUOTE=ANSAracingb;79330847]You could still have air in the system, .../QUOTE]


Just say'n...

[tmechanic]

When I changed my brakes last time I had to bleed them 3times before they firmed up. Take your time and remember they need to be bled in the correct order, starting at the furthest from the MC ending with the closest

[83mk2scirocco]

or you can take it to a shop and have them power flush the whole system. It will bleed the master cylinder and all calipers too... plus it will ensure all the crud is out. I had to do that to my F150 because I couldn't get the air out of the ABS unit.

I work for a shop.

[C4ptainCox]

ok,i foind tjis by accident,put a bunch of rags under the master.
so it would catch any drips.crack the two on the same side.maybee half a turn.
let it drip for like 15 to 20 min.Now you should have a consistant drip.
do the same for the outher side.

I'm doing this now, but I haven't seen any bubbles...

Most likely a bad master cylinder if you went through THAT much brake fluid (which is insane BTW

Bentley recommends that "at least one pint of fluid should be removed each caliper" when flushing the system. Which comes out to a half a gallon... I was just following instructions...

I bought a Motive power bleeder from Germanautoparts and I think it's one of the coolest tools I own. It pressurizes the brake system, so you don't move the pedal at all (and then you don't damage the master cylinder)

Totally buying one of these next time I'm working on brakes! I'm very jealous.

I noticed today in my Bentley that we are supposed to pre-bleed our rear calipers if we disconnect them from our brake lines, so I'm going to try doing this today. Wish me luck!

Thanks again to all of you guys for your wisdom, you're keeping me from giving up!

[C4ptainCox]

Also, do the front calipers need to be bled the same way?

[C4ptainCox]

Nothing has helped. It's just as bad as before.

Does anyone have any recommendations for a new master cylinder?
Also do I need to buy a new reservoir if I pick up a Corrado master cylinder?

[TooClutchVW]

I'm in the same boat as you autohausaz has a meyle master for $41. Get one for a non-abs mk3 jetta with rear discs and its the same thing. Unfortunately I can't say if it will help since even after a successful bleed and going twice around the car with the motive bleeder I can't get a firm pedal. If you have mk4 calipers I might suggest taking them off and flipping them while you bleed.

[prom king]

Ill keep my story short and simple, but I've been where you are. It was a simple fix, I changed everything in my brake system and the last thing I changed worked the cheapest thing.
The check valve was bad....

I now have MKIV Rear Calipers.
A Carquest REMAN Master, ( make sure you bench bleed )
New lines etc.
I have the hardest pedal in the world now.

[tmechanic]

Nothing has helped. It's just as bad as before.

Does anyone have any recommendations for a new master cylinder?
Also do I need to buy a new reservoir if I pick up a Corrado master cylinder?

I'm running a Corrado MC on my 86, it works great and I was able to use the reservoir off of the Scirocco without a problem.

[VWsEatRice]

i had the same problem. jacked the car up and had a friend hold the brake pedal while i went around to each wheel to see which ones held.
one of the rear calipers were'nt working. i ended up (using the right tool) pushing the piston back in.
Rebled system and had a firm pedal.
it was a reman. caliper that i bought for a rear disc brake conversion. the piston was a little too tight.
found out later it seems to have the wrong side parking brake mechanism also.

[rabbitnothopper]

just a question

with a power assisted brake vacuum booster...
does the car have to be running to properly bleed the brakes?

if not then the brakes seem to lock up because they wont retract

thanks

[C4ptainCox]

just a question

with a power assisted brake vacuum booster...
does the car have to be running to properly bleed the brakes?

if not then the brakes seem to lock up because they wont retract

thanks

No. The car should be turned off. Also which brakes aren't retracting? Often that can be fixed by just screwing the piston back farther into the respective caliper.


As an update, I picked up a Corrado MC from GAP which arrived on Friday. I just installed it today and I'm very happy with the results! My brakes work now! Thank you to everyone for all of your help!