grrrrr now my brakes are failing.........

[rabbitman]

Seems like I'm having lots of problems these days.

So about a month ago my brake pedal started sinking when I pushed it so I bought a rebuild kit and rebuilt the master cylinder. After I reinstalled everything it still did the same thing.

I readjusted (shortened) the little rod between the booster and MC and that seemed to fix it, I assume it was holding the MC partway down. But now I only have the secondary brake function so instead of pushing harder and harder and getting more and more braking action I get nothing until the pedal is low and then the brakes come on all at once.

Problem #2: When the brakes come on all at once down by thre floor then if I hold my foot there the booster will loose all of its vacuum and then if I push harder it gets kinda scary because I have very little brakes left.

I checked and I have 24 inhg of vacuum and the booster holds vacuum when the engine is off.

It sounds to me like the MC rebuild was a fail since I don't have the first stage of braking but it also seems like the booster shouldn't be loosing its air like that.

Any help will be much appreciated.

[BigVWman]

When you did the MC rebuild was it leaking into the booster? IF so did you extract the fluid as best you could? I have found when i failed to extract the brake fluid after a MC failure the booster seems to be very short lived!

[rabbitman]

When you did the MC rebuild was it leaking into the booster? IF so did you extract the fluid as best you could? I have found when i failed to extract the brake fluid after a MC failure the booster seems to be very short lived!

Hey thanks for the reply. It wasn't leaking anywhere actually, for some reason the booster to MC rod "got" too long and held the MC partway and so wouldn't allow the MC to get a fresh gulp of fluid. I haven't a clue why it did that and I only found it after the rebuilt one wouldn't work.

Today I took apart the MC again, I think the rebuild kit wasn't quite right as the pistons weren't sliding out enough and I think it was letting the cup seals block part of the fill hole so I modified it, bench bled it real good and reinstalled it. It now takes a pump to get good pressure.....

Now I'm starting to think the booster has issues, it's only good for 3 quick pumps and then it's out of vacuum, I seem to recall that it used to last more pumps than that. The car sure stops though as long as I don't pump it too much.........

[rabbitman]

I think I might be able to live with them the way they are now. They still don't hold up to very many pumps and the pedal is too low to the floor but the car stops just fine.........you know how when something changes it's sometimes too weird? The brakes feel terrible compared to a month ago.

[burn_your_money]

Are the rear brake components in good shape and properly adjusted? How about the flex lines, are any of them ballooning?

[rabbitman]

Are the rear brake components in good shape and properly adjusted? How about the flex lines, are any of them ballooning?

New shoes a month ago and new drums in early '07. The rear brakes really stop good with the e-brake and I can skid 'em all with the foot brake but the pedal just feels terrible.

IDK about ballooning lines, it's kinda hard to see. But they aren't soft though they just hit suddenly and close to the floor. Today I lengthened the booster/MC rod too much and while the brakes felt better for a little while it's clear that the MC wasn't able to get a fresh gulp of fluid so the brake system light came on.

I'll shorten it a bit and try again.

[rabbitman]

Still messing with this, the brakes still stop me ok but they kick in obnormally close to the floor. If I pump them once and then push 'em real quick then they work normal.

So I'm sick of messing around and thought I'd get two front calipers and a new MC from these guys. One of my calipers has a ripped boot and I like to keep even brakes on each side.

Looking at the pictures in the link, my MC looks like the one on the bottom.......link is weird, to see the pics you'll have to look up '82 rabbit LS bla bla.

My MC has big reservior grommets and NO o-ring for sealing the booster, instead it uses a seal on the booster to MC rod.

My question then is will one of the other MC's work for me? Small grommets, o-ring and a funny looking rod that sticks into the booster a little ways.........and costs $16 instead of $171.

http://catalog.importrp.com/ShopByVehicle.epc?q=1982-VOLKSWAGEN-Rabbit--Ls--Deluxe/l4_1.6l_diesel_cr-Brake--Components--Wheels&yearid=1982&makeid=VOLKSWAGEN&engineid=1285219%40%40RABBIT%20LS%20DELUXE%2FL4_1.6L_DIESEL_CR%40%40RABBIT%20LS%20DELUXE&catid=Brake%20Components%20%26%20Wheels&subcatid=Brake Master Cylinder&mode=PA

[rabbitman]

Mine looks like the one in the second link.

http://www.amazon.com/Dorman-M39147-Master-Cylinder/dp/B002H5ADAS/ref=au_pf_ss_15?ie=UTF8&Model=Rabbit%7C955&n=15684181&s=automotive&Make=Volkswagen%7C74&Year=1982%7C1982&carId=001

http://www.amazon.com/Centric-Parts-130-33402-Master-Cylinder/dp/B000C031PY/ref=au_pf_ss_5?ie=UTF8&Model=Rabbit%7C955&n=15684181&s=automotive&Make=Volkswagen%7C74&Year=1982%7C1982&carId=001

Can I use either one?

[rabbitman]

Forget it, I bled the rear brakes and now they work better than new. Touch the pedal and the tires stop turning..........

I thought I bled 'em when I rebuilt the MC but apparently I didn't do a good enough job.

[rabbitman]

So all was good until two days ago I though they felt a little soft, then yesterday things got so bad they BARELY work unless I pump 'em twice.

The fluid level is staying up, when I bled 'em I went 'til new fluid got to the calipers and rear wheel cylinders.

[rabbitman]

So I bled the rears last night, took an ounce of fluid from each side and the right side made a huge difference while the left only helped a little bit.

So is it possible for air to enter at the slave cylinders? I know they leak fluid just enough to be slightly wet (I never have to add fluid) but it doesn't drip and make a mess.