Leaking master? Hmm help !

Ok, gorgeous Tennessee day. I have the day off... So, I spent all day bleeding brakes and not driving! Arrrrggg. Anyway. I notice my car is wet on the pan near the master cylinder. I notice the resevoir is low, not empty, but very low. I have a longer pedal travel than I recalled last fall when I put it away. I have my best friend give me pedal effort and bleed the drivers front Caliper. No air, no change. I went to the passenger front, and noticed the bleeder nipple was cocked! I broke it off with my fingers. It was all but snapped off. I couldnt get it out with an easy out. I'm doubting air in the passenger front, as both fronts locked equally on level pavement. We bled and bled and bled the rear drum wheel cylinders... No change in pedal, but there was clean fluid coming out. I'm guessing at this point its getting internal leakage inside the master.
Can somebody explain the master so I have an idea what I'm in gor tomorrow in the shop? I ordered a new caliper and master today. They should be here tomorrow. I see two rubber hoses out the top, I can see 4 lines, plus I'm guessing the brake light switch on the end? Are the master bolts under the carpet? Dreading this project! Thanks guys!

I just did this to my car about 3 weeks ago. Not too difficult. It took about 4 hours, but I'm a slow worker.

I have a hand operated vacuum pump which made the job must easier.
I worked from the underside of the car first by removing all the lines, hoses, and brake switch leads on the master cylinder. Then cleaned everything with brake parts cleaner. This stuff is pretty toxic, so use gloves and eye protection.
Once that is done, move to the inside of the car. You do have to pull up the carpet a little bit around where the push rod comes through the firewall. First remove the spring clip that holds the push rod to the pedal assembly. There is another spring with a hook that holds the push rod in place. It can be a little tricky. I used needle nose pliers and a screw driver. Once the spring is removed, loosen the two bolts holding the master cylinder, but do not pull the bolts out. Leave them in place to hold the spacers that are between the two layers of sheet metal of the firewall. If you drop those spacers in the firewall, you will have a hell of a time getting them back out and in place.
Once you have the old master cylinder out, remove the brake light switch and any other fittings you will need. I would recommend replacing the switch since you have it out.
Inspect your new master cylinder to make sure it is the same as your old one.
I then mounted the new master cylinder, attached the reservoir and lines and bench bled it in the car. I bled the front portion first then the rear. then hooked up all the brake lines, replace the spring and spring clip, and started bleeding the system working my way from the brake farthest from the master cylinder.

I would also recommend replacing both calipers.

Maybe someone else on the site has an easier method or some input, but this worked for me.

I don't recall any springs on or around my pushrod to master! Thanks for the heads up on the spacers....!!! I've put 5 or 6 masters on cars over the years, and never bench bled a one and always had a great pedal. I've been cautioned a lot on VW bug masters... What makes them so finicky?

What makes them so finiky?

They're German.

The spring Bob's referring to is a return spring for the pedal. There are one or two spring clips holding the spring on it's perch as well as the push rod to the pedal arm (the number of clips depends on the vintage of the pedal arm). There is no spring, per se, between the push rod and the master cylinder.

Once you get the push rod out, you may look at it and see that, "Hey! It's adjustable!!" Unless you've had years of experience making this adjustment on older (like 1952-1974) VW's do not mess with the pushrod adjuster!!!!! It looks simple, but it's wicked easy to screw it up if you don't know what you're doing and a MAJOR PITA to get it back and get your pedal feel right. Just leave it alone and it'll be fine with the new MC.

Other than that, everything is pretty straight forward. I've installed all sorts of master cylinders over the years, from go karts up to big trucks. Some of them don't need bench priming, others do. VW's seem to work better from bench bleeding (I even made up a tube set to make it easier) and Speedsters seem to bleed easier if a pressure bleeder is used, but the little hand-operated vacuum bleeders work pretty well, too. I think we used one of those on someone's car at Carlisle a few years back.

When a VW MC leaks enough, it can get between the central tunnel and the floor boards and eventually rust out the seam. Blast the hell out of everywhere that it looks damp from brake fluid with aerosol brake cleaner to flush it out and let it dry, then go back in a couple of weeks (or months) to find where the paint has bubbled off (and it WILL bubble off), wire brush those spots and then spray them with Rustoleum or rubberized undercoat to reseal those areas.

I have also found that you need to adjust the shoes out so they are firmly making contact with the drums. Then bleed the brakes. When you have a very firm pedal then back them off to a slight drag.

I have never been successful in bleeding VW brakes unless I do this.

How do these drums adjust? Is there a slot and star wheel like most drums have? Thanks guys...

Jeff: That's interesting. I have never done that and have always gotten a decent pedal. I've also bled them by pumping the pedal, by using a vacuum device on the wheel end and by a pressure bleeder mounted to the MC reservoir - the power bleeder is, by far, the easiest, but the other two methods always give a decent pedal - albeit with a bit more aggravation.

The adjusters on the drums are star wheels. There are two, and are adjusted in different directions as outlined in your VW service manual. But......if they were working OK before you change the MC, I wouldn't touch them, other than to bleed them and leave it at that.

Gordon,

It might be because I am starting from a totally redone braking assembly. When I rebuild my kits I gut,paint, and replace everything. If the shoes aren't properly adjusted I seem to just get more piston travel in the wheel cylinders then I get air. I use the old "Honey....you got a second" method...and her leg tires easily.

So I have found it easier to just crank the shoes against the drums. That way there is very little piston travel within the drum and I get lots of fluid through the bone dry system. Once I get no more bubbles its just a couple of clicks on each side and I am good to go.

Maybe when your just replacing something its different.

Sounds good to me.

Nothing succeeds like success!

I still find it hard to imagine all this elaborate bench bleeding, and then you take off all of the lines, and dribble all the way to the car, and rebelled it there. I've owned and worked on a lot of race cars and just put the master on, bled it out, and was good to go. I didn't know what the trick to these were.... I hear to much hype about bench bleeding is a MUST... Im bolting it on and buying the wife dinner for working the brake... plain and simple!

Keith, sometimes the calipers are flipped and swapped in association with a narrowed beam and a dropped-spindle kit. That makes the brake impossible to bleed by bubbling it in place. If the nipple isn't at the top and you can't get it with the kit, you may have to dismount the caliper and invert it, or at least hold the bleeder valve so that it's at the highest point -- just like a doctor bleeding the air out of a syringe.

As for the master cylinder, they're a very simple design. There should be two bolts holding it into the firewall, and everything else is attached to it, minus the plunger piece which goes to the pedal. It really is as simple as it appears to be -- if I can figure it out, you're in like Flynn.

Keith said: "... Im bolting it on and buying the wife dinner for working the brake... plain and simple! ". Great line-true!
Always worked the same for me.

The vacuum mity vac really helped get me close, and eventually a long and spongy pedal. I got it feeling and stopping on front only. I got too tired to dig into the rear bleed. I'm hoping it will go easier than the fronts.... American style master/reservoir setups are the way to go.... I'm not convinced the "loops" to go around the front beams. I'd almost prefer to have that reservoir way closer to the master... Anyway. I'll attack the rears tomorrow. What a pain in the rear. Hardest car I've ever brake bled....

You can always install a Volvo reservoir. I do it on all my kits (non-speedsters).

Available in junk yards, on ebay, or CBPerformance

http://www.cbperformance.com/catalog.asp?ProductID=91

Keith:

Now that you mention it, VW's do seem a little more temperamental than some other makes, although I've had easy and hard ones from all makers - Depends on whether the "Force" is with you or not. I've had very mixed luck with those little "Mity-Vac" gizmo's - usually got about the same results as you've gotten - almost there, but not quite, and then finish it by foot pumping, but wasn't that what I was trying to avoid in the first place? Still, I usually pack one in the truck for Carlisle, just in case, 'cuz they don't take up much space.

Finally, after I threw my MIty-Vac across the garage one night in frustration, I followed a link somewhere which described how to build a pressure brake bleeder from a 1/2 gallon garden sprayer and built one up. Whole thing cost about $25 bucks and works like a dream, especially for one person. No pumping, no bubbles, great pedal AND when the bleeder is removed it sets the fluid level in the reservoir at just the right height. Plus you can load it with a quart of new fluid, bleed everything and there's still a bit left (which I drop off at a local garage to recycle the stuff - it absorbs water if left sitting around). My version has a cap for just my MC reservoir but it would be relatively easy to make one with different caps for your needs.

I may be building one up for the upcoming Carlisle raffle. I did one for Carlisle a few years back and I think Lenny C. won it. Not bad for the price of a raffle ticket.

BTW: I think Al Merklin uses that junk-yard Volvo MC reservoir that sits right on the MC and swears by them. The only thing I don't like about them is that they're buried down inside the car where they're difficult to see and check from time-to-time, as opposed to having a 'remote' one up in the trunk where I see it a lot. Either version has it's drawbacks.

I use a Motive Products Power Bleeder. I got it at aircooled.net with a fitting for the VW fluid reservoir.

It uses pressure instead of vacuum.

I works well.

I think some people here have made their own similar things.

I'm learning that the Volvo Reservoir doesn't fit the Super Beetle MC.... Hmm really clever idea. Certainly makes the trunk neater!

I did 0 bench bleeding on my master. I plugged and played. I wanted to buy myself a mityvac for years. So I did, and does this $135 make it a one man stress free job. I sucked out the dark fluid from the rears, etc... The car has a rock hard pedal, little travel, brake bias feels close. It's a little more front than I like, but it's solid. I also adjusted out the shoes until they drug a little. Project DONE! Just reporting back to you guys.

The VW beetle reservoir for I think '68 is what I have. A single small cap on top and two hoses to the master, one front, and one rear. The single fill makes it easy. I think I used a quart oil can cap, and just threaded in a schrader fitting. Not a big deal to pick up an extra cap if you can't find one that fits. Set your air for no more than 10 psi, that's really all you need. Works like a charm. If you don't have a compressor use the garden sprayer method, just as effective.

I change my brake fluid every other year, and YOU SHOULD TOO! It absorbs water over time and becomes less effective, i.e: less than what it was when it was installed!