The master cylinder is dead.

[Bradey Bunch]

I have had problems in the past even installing BRAND NEW brand name MCs on other cars... one van required 3 MCs to get ONE that worked. I do not even touch rebuilt masters either because of the issues associated with those. I did try a NOS one that blew the seals within a day, which was pretty scary.

It is going to cost money to keep one of these going, so spend the money where it counts. Brakes are not something to skimp on.

This is why I recommended a re sleeve, IMO it is the only way to do it right.

[Hamsterben]

I ordered another rebuilt one mostly for the cylinder its self. i will most likely install a rebuild kit if it does not work properly. If all else fails i can weld a mount together for a van master cylinder but id rather have a stock master.

[bb412]

hi,,if you d,t find one at your choise,,you can oder one to,,,the past-parts. com,, they are in ,,UK,,and they sale fresh remain ,, for all the mc,,cluth mc or cluth slave,,all the hydrolic things,,,tork convertor too,,,for the 411-412 at a faire price ,, 30 PS,,or 50.-60$,, to my home,,for a cluth slave,,they are on ebay,, very good quality on her job,,cheer,,bb412

[raygreenwood]

Before jumping into things everyone needs to know and understand just what the deal/deals are with the type 4 master cylinder.

(1) There were two makes: FAG and ATE. Both are extremely similar and interchangeable...but the internal pistons are not. Even though the stroke lengths are the same on each cylinder...the pistons are slightly different and therefore lead to differnt drillings for the compensation and feed ports.

(2) The seals from a type 3 of the same make (not the pistons...the seals and flap valves) will rebuild a type 4 cylinder if the bore iss clean the pistons are not corroded. The seals are very slightly different for each make of piston design. Do not mix them. They can work when mixed...or not. been there...done that. Bad method.

(3) Warning....welding a bracket to the cluster and using a late model super beetle dual circuit AtE cylinder does not work well. Been there and done that back in about 2000. The volumes or pressures are not quite right even though the stroke length is very similar.

(4) The issue that destroys the type 4 cylinder most of the time are rust ridge forming at the opening to the bore that destroys the outer shaft seal and causes leakage and air entrance. It rusts because its inside the car (and most of these cars have at least small leaks so lots of humidity)...and no airflow to get th hunidity out of the way.

(3) Th other issue is water in the brake fluid causes corrosion between the brass flap valves and the pistion faces causing pressure leakage or stuck valves.

If you can find seals....the type 4 cylinder is easily rebuilt as long as ther are no rust pits more than .002" deep. Also if there are scores in the length of the bore that have rust in them....the cylinder is shot.

Brake cylinders should not be honed for more than a few sedconds on low speed. You can remove surface rust but then you need to lap the bore smooth...no hone marks.....with 1000 grit or better. You must not expand the bore size more than about ,001" max...because you cannot get oversized pistons.

The pistons...if uncorroded...will never wear out. They do not contact the bore. They are smaller than the bore and teh cups keep them centered.

I have come to the conclusion that the best mod is to build the underdash bracket and adjustable transfer rocker that the power brake model used....then drill out the MC mounting stamping in the trunk....and install a 21mm bus master cylinder with an adjustable proportioning valve in the back in place of the stock fixed one.

I have a 5 gallon bucket of type 4 master cylinder cores Im about to chuck when I move. Its just npt worth it. A trunk mounted master cylinder may not be original...but it will look factory...and work perfectly. Ray

[Hamsterben]

I have ordered two master cylinders from different people and both were not shipped however I was refunded I'm still pissed.

[Mike Fisher]

So, you are ready Now to have yours sleeved/rebuilt by www.applehydraulics.com or your local Brake Shop. Have you even called any local Brake Shops?
_________________
https://imgur.com/user/FisherSquareback/posts
69 FI/AT square Daily Driver
66 sunroof,67,70,71,71,71AT,72,72AT,73 Parts
two 57 oval ragtops sold
'68 Karmann Ghia sold

Society is like stew. If you don't keep it stirred up you end up with a lot of scum on the top! - Russ_Wolfe/Edward Abbey

[ubercrap]

Did anyone actually try order the BRAND NEW Raybestos master cylinder or not? According to current their own application guide that I just checked, they are available (even the picture shows the correct part). If available, I wouldn't jack around with anything else for stock performance- waste of time and money!
_________________
'74 412 wagon
(2) '74 412 2dr. sedan
'73 412 2dr. sedan

[Bradey Bunch]

for what its worth, I had my parts guy check out the raybestos part, and it was NLA. maybe someone else has better luck?

[Hamsterben]

I checked Napa auto parts and they have them advertised so I ordered one and we will see if I get one this time.

[raygreenwood]

Yes....I have order the TRIED to order the Raybestos part no less than 6 times. each time I get somethong that is actually a type 3 part. This is over a span of 10 years.

Skip it.

If your cylinder does not have pits or scores deeper than .002" or corroded piston faces where the brass flap valves sit....you can rebuild them as good as any factory by buying a type 3 master cylinder of the same make....or a mid-80's rabbit/golf master cylinder an stealing the seals out of either.

There is no local brake shop anywhere than can give you any assistance at all. To do so....they would have to have kits (which they cannot get any easier than you can)....and your cylinder would have to be in proper shape.

This is what I am getting at. Most people do not know how the cylinders operate or why....or why they fail.

They are very simple......but very specific in what they require. If you hone one...and make it oversize by too far or leave hone marks in it....you may as well just throw it in the trash. In the old days.....like 1970's or easrly 80's.....a brake shop "could" rebuild the average american master cylinder because you could get oversize psiton kits. These have never been made ever...for most VW's..and especially not type 4's.

If the rust is too deep for very light honing for cleam up...the cylinder is shot.
You have to get the same make of seal that works for the piston for that make.
None of this is hard...it just has to be right. Ray

[raygreenwood]

[Mike Fisher]

We could All listen to Ray tell us "it can't be done" all the time OR we could contact Apple Hydraulics/ local Brake Shop?
_________________
https://imgur.com/user/FisherSquareback/posts
69 FI/AT square Daily Driver
66 sunroof,67,70,71,71,71AT,72,72AT,73 Parts
two 57 oval ragtops sold
'68 Karmann Ghia sold

Society is like stew. If you don't keep it stirred up you end up with a lot of scum on the top! - Russ_Wolfe/Edward Abbey

[Bradey Bunch]

What the heck is a flap valve? Never heard that terminology before Ray.

Braden

[raygreenwood]

[raygreenwood]

[raygreenwood]

By the way....yes...I have looked at Apple Hydraulics site. I'm sure they have the skills since this is all they do.

What I would like to point out...is that they are sleeving these with brass. No the way I would go if I were sleeving them. I would use stainless.

The brass sleeved cylinder while precise...will have not much longer of a life (if any) than a stock cylinder. Brass corodes quite well in the prescence of water, oxygen and brake fluid so all the same rules apply...bleed often, catch the leaks when they start and tear it down early.

If you notice the list of makes and models on their site....they serve cars that are very old, currently obscure....that you generally cannot get cylinders or rebuild parts for at all. Add to that....most of the cores available for those cars are far oversized already. The sleeving is the only option to get an opo=erating cylinder at all.

We have it bad....but not quite that bad yet. We at least have other options for the moment. Ray

[raygreenwood]

My apologies for my snappy remark earlier Mike Fisher

I realize that you also are looking for answers for these parts. I have spent the better part of 33 years working on type 4's and I forget that not everyone has beenfoloowing along. In my 10,000 plus posts on STF...many are brake and hydraulic related and almost all are type 4. I forget that many here do not hang out there and probably have not read most of it. So I sometimes feel that we are just rehashing old issues.
Sorry.

So...maybe I should get into type 4 master cylinders a bit more. It may help.



OEM make

There were two brands of cylinder used by the factory: FAG and ATE.

The stroke lengths are identical...but there are no interchangeable parts. Why?
Because the vent hole drillings for fluid ingress/egress are not in the exact same place. If you get an ATE piston next to an FAG piston...you will see the subtle differences as well as the cast in part # differences.
Also....due to different thicknesses of slots and piston heads..the seal designs were just slightly different enough to not work. ATE parts will not fit FAG and vice-versa.

This same holds true for the power brake units. So for rebuild kits there are four kits: One each FAG and ATE for power and one each FAG and ATE for non-power.
There were also four different kits available from Schaffer...superb rebuild kits...again two power two non-power for ATE and FAG respectively. I have not seen those in 20 years.

At some point I think Wagner made a replacement cylinder that was different still. Saw one....did not buy it....long ago.

Many of you note that you have bought cylinders that did not work. How did they not work? explain please? Some may be age..some may be corrosion...some may just need cleaning.

The differences in make of cylinder are generally not carefully noted in third world rebuild houses. I have bought numerous rebuilds over the years that when opened...had the wrong piston set and seals inside. They would never work. One more good reason to always open them up to clean them.

Yes...about two years old on the shelf and without excercise and brake fluid..the seals can harden up and take a set and not floex properly. NOS is not great unless you know how old it is.

No matter the make or age of the cylinder..even brand new....it must be stripped and cleaned with alcohol. If you are not doing this....many of your failed cylinders may be your own fault.

Why is this?

Because they use COAL OIL based brake paste to assemble them! Brake paste sucks.....again....brake paste SUCKS.
Its probably not too bad if you use it sparingly and install the cylinder soon....but its basically not much differnt than an EPR rubber compatible grease. As you apply it...it picks up the mositure in the air.
If it sits on the shelf for a year or two...it congeals...thickens...and usually glues the brass compensation port valves to their mating faces on the piston...effectively disabling the cylinder.

Also its not uncommon to find green corrosion between the brass and aluminum parts in a brand new master cylinder. This is caused by moisture entrained in the brake assembly paste during assembly. It can ruin the pistons. Its the 2nd leading cause of NoS brake cylinders failing to work.

Also...brake part plants are not clean rooms. They are sweat shops. You woul be stunned at the amount of grit and crap that comes out of a brand new unit when you clean it.

Type 4 master cylinders have always been scarce. I got my first 1972 vw 411 in 1979. It had 55,000 miles on it. I couldn't get a new master cylinder even then...without ordering through VW and waiting for it to come from Germany. Remans were just as hard to get because the car was already rarely seen. But rebuild kits were readily available...and almost always not the one you needed.

My point with this whole diatribe is that the type 4 brake master cylinder was another one of those odd defects that the type 4 had. Its location was detrimental to its health and to the helath of so many other soft parts inside the car that are just plain not replaceable.

Many people lately just getting into these cars really need to realize that you cannot count on parts being handy...and you cannot drive them until a part fails. The only way I have found to guarantee that every 3-5 years...your cylinder wil not leak and rust....sending you on an ever harder parts chase for a new one.....is to invest serious maintenace.

I found that if you pull the master cylinder about every 1 to 1.5 years max...and simply lap away any growing rust from seepage before it forms the rust ridge that kills both seal set and cylinder....you can drive on that cylinder for the rest of your life...no kidding!

If you don't allow it to rust or get crap in the fluid....there will never be ANY wear on that cylinder. The pistons do not contact the bore. Clean it out every 1 to 1.5 years and put in new seals every 5 years...and you are good to go. To much work for you?

Then go the other route....install a cylinder in the trunk where the power brake cylinder went. It allows using bigger, easy to get cylinders...and solves the rust issue. Not beacuse it prevents it to much better (but it is better)...but because when it starts to drip...I just throw it away and buy another one for cheap and its easier to replace.

To those who have the fetish that they want original design brake cylinders...not a modified brake system (I know you have to in Germany)....I say that unless your car is concours condition....you are just whacking off.
Fenders, doors, glass, rubber...even seats...sure keep it original parts. Brake parts make no difference. If they work perfectly and I can make them fit...like using a bus master cylinder mounted in the trunk....I will. That will be the difference between reliably driving your car and watching it rust into the ground while you look for a good used cylinder on she-bay.

Having the cylinder sleeved is a good fix for having to replace the cylinder when the seals crap out...but does not fix the hideous problem of fluid all over the place when you have to pull it out. Thats why I'm just not into spending that much money. If I had stayed with the original master cylinder design...I would still be doing the once a year maintenance. For what a sleeved cylinder costs...I can do that about 10 times.
Just some things to think about. Ray

[Bradey Bunch]

I agree with Ray (though I must admit to skimming through a bit), and when he talked about using non original parts he hit the nail on the head, in fact he is the one who recommended the bus CLUTCH master cylinder that I currently have in my car...

Looking through Wilwood and jamar and other catalogs there seem to be alot of remote resevoir MCs available with a pedal and linkage which is where I would start looking if I needed one.

Braden

and Ray, IMO compensation port makes alot more sense

[Hamsterben]

I'm all for the idea of moving the master cylinder. How should I go about doing that?

[reluctantartist]

I found this link on the shoptalk forum
http://www.vwnorge.no/index.php/topic,32276.0.html

As Ray pointed out in the shoptalk forum, the bracket needs some adjusting but this looks like an ok solution although I would use a bus cylinder instead of a $275 porsche cylinder.

Here is the shoptalk forum discussion:
http://shoptalkforums.com/viewtopic.php?f=12&t=110018&hilit=master+cylinder&start=30
_________________
1982 Westy, 1974 412 Variant... Yes, Aircooled's are great! Oh and I do have modern computer controlled vehicles too, but I just don't care about them.