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1973 412 WAGON
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PostPosted: Fri Jun 05, 2015 2:42 pm    Post subject: 1973 Master Cylinder Reply with quote

Any body got any leads on a master or rebuild kit for my 1973 412? I have replaced everything, and the master 2x and rebuilt it. Thought i finally had brakes last night pedal felt a lot better. When i pressed down on it with firm pressure she started going back down to the floor. I pressurized the system at 13 PSI and it held for over 30 mins. There are no leaks any where. Check all connections just to be sure. I am stumped!
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raygreenwood
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PostPosted: Fri Jun 05, 2015 2:59 pm    Post subject: Reply with quote

So you rebuilt the MC cylinder right?

1. With what kit?

2. What did you do to clean it up and out?

3. What did the bore surface look like when you looked into it with a flashlight? Did it have any remaining rust pits and where in the bore are they?

If you honed the cylinder...meaning literally used a hone....its probably done for.

About the most you can take out of the bore is about .005" total before its just too oversized for normal sized pistons.

Did you reuse the original pistons?...which is fine and required if you are stealing seals from say a type 3 or type 1 kit....but if so did you remove the brass flap valves underneath the inner cup on each piston and carefully remove any rough aluminum and polish it...and in doing so...did you be very careful to keep these areas flat?

I usually use a very fine whetstone to work around the flat areas that the brass flap valves seal against...and then I lap older and sometimes newer brass flap valves on a very smooth flat whet stone. You can use 2000 grit or finer paper wrapped around a flat stiff piece of metal like a .035" feeler blade.

Also when cleaning up a bore I use a 3/4 bottle brush style hone for a few seconds only at low speed. Then I take a wooden down and cut a slot in it and insert folded 800-1500 grit paper (depending on need)....and wet with fresh fluid and run it through the bore at low speed too get rid of hone crosshatch marks. Smoother is better.

You need to wash wash wash in very hot water and soap, rinse well and dry it fast then insert pistons and seals with fluid or brake paste. Ray
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1973 412 WAGON
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PostPosted: Fri Jun 05, 2015 3:08 pm    Post subject: 1973 Master Cylinder Reply with quote

Ray, I bought a NOS Master online (2 actually) Ordered the 72-master rebuild kit for a fastback like you said. Opened the nos one and cleaned it out with brake cleaner. Replaced seals and bench bled it. It felt like it was building pressure up. Replaced all rubber lines, wheel cylinders both front calipers, flushed all hard lines as well. I do not see any leaks coming from anywhere. Bled everything, no more air bubbles to be seen. It has got me totally confused. I have restored 3 cars (all American) Completely, every nut and bolt and this one has me scratching my head.
The only thing i can think of is maybe the master rebuild kit cup seals are old as well? Felt soft to me. Now rock auto does not even have any more.
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raygreenwood
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PostPosted: Fri Jun 05, 2015 5:16 pm    Post subject: Re: 1973 Master Cylinder Reply with quote

1973 412 WAGON wrote:
Ray, I bought a NOS Master online (2 actually) Ordered the 72-master rebuild kit for a fastback like you said. Opened the nos one and cleaned it out with brake cleaner. Replaced seals and bench bled it. It felt like it was building pressure up. Replaced all rubber lines, wheel cylinders both front calipers, flushed all hard lines as well. I do not see any leaks coming from anywhere. Bled everything, no more air bubbles to be seen. It has got me totally confused. I have restored 3 cars (all American) Completely, every nut and bolt and this one has me scratching my head.
The only thing i can think of is maybe the master rebuild kit cup seals are old as well? Felt soft to me. Now rock auto does not even have any more.


Ok...good so far. So the MC that you used the casting from was NOS?.....can you tell me what the box said or looked like?.....brand?

And.....you just used the seals from the squareback kit....and not the pistons...right?

Ok....did you check the adjustment on the pedal stroke to make sure there is approximately 1mm of freeplay between rod and piston?

Now....bleeding type 4 systems is NOT easy or normal. You start from the right rear, then left rear, then right front then left front. Dont take bleeding sequence directions from owners of any other type of ACVW. Its different on the type 4.

When you have rebuilt basically the whole system....you have lots of air and its very very hard to get out because there are high spots in the system between the front and back. When pressure is not perfect....the bubbles stay against the tube in the high spots and are not big enough to actually span the whole cross section of the brake tube....and fluid bypasses it without forcing these small amounts of air out. It gives a mushy feeling.

You need to bleed it as best you can and carefully drive it around for a day or two. Then bleed it again. It will use another liter of fluid. Then repeat. Usually the 2nd or third time gets it all. If you are just replacing a wheel cylinder or caliper.....this does not happen. Its only when the system is fully drained.

When doing your original bleeding work.....you need to do a few things differently.

1. On all of the bleed valves front and rear, do not crack them open more than 1/5th or 1/4 of a turn. You want to have to FORCE the air out. The system has to build pressure in order to get the bubbles in the high spots moving.

Pressure bleeding for the initial bleeding on this system....is next to worthless. This is because pressure bleeding is very low pressure and is done with the system wide open to allow fluid to flow through it. It gets about 3/4 or 4/5ths of the aor out but will not jelp on the rest. It just wastes fluid.

2. While initially bleeding...if you dont have speed bleeders with sealant in the threads......put a very fine wrap of teflon on the bleeder threads keeping it well away from the pointy tip.

Why?......because at the low or no pressure generated by initial bleeding on the empty system.......the SUCTION of the return stroke of the MC......is more efficient at pulling air in through the sloppy threads of the bleeder valves.......than it is.....pulling replenishment fluid back into the cylinder through the replenishment and compensation ports from the resovoir.

MORE ON THIS IN A MINUTE AND THIS IS VERY VERY IMPORTANT AND MAY BE YOUR PROBLEM!
3. Because of what I just noted above. ....the MC will generally not replenish itself well if you stroke it quickly like you normally do to build pressure in most MCs.

You Need to push it down very hard and fast to generate pressure to move air.....but pull it up veeeeeerrrry slowly. ....like 10 seconds....no kidding.

Typically during the inital bleeding phase......I sit on the pavement next to the car with the door open....and push the pedal down with my hand because I have better patience and control in letting it up slowly......and you can feel when its starting to draw.

4. Here is the important part I mentioned earlier. The little plastic elbows on the blue fluid inlet hoses from the resovoir have a tendency on type 3 and 4 to be held all the way down flat against the bottom of the recess where the two rubber grommets are.

This effectively....is like having your soda straw against the bottom of the glass. So you stoke the master cylinder.....and fluid cannot readily draw back and forth from the master cylinder....so at times it starves on replenishment.

There has also been issues from the factory at one time or another with, the grommets being slightly different shapes. ...and I have even come across a few rebuilds and NOS with the grommets in upside down.

The easy fix for this is to pull each elbow out one at a time.....and take a round profile rat tail file of about,1/8" diameter....like you use for sharpening chainsaw teeth......and file across the opening of the elbow to make two little half moon indentions about,1/16th to 3/32nds deep.....so even if the elbows are flat against thebottom of the recess....they cannot prevent movement of fluid. Ray
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1973 412 WAGON
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PostPosted: Fri Jun 05, 2015 5:45 pm    Post subject: 1973 Master Cylinder Reply with quote

Ray,
The box has a label that says IAPCO imported auto parts K-0065-007.
I will try and re-bleed tomorrow and go from there. How do i check the pedal gap?
I only used the seals from the kit.
Right side of the car is passenger correct?
Where can i get speed bleeders for her?
I will file the elbows as well tomorrow.
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raygreenwood
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PostPosted: Fri Jun 05, 2015 8:19 pm    Post subject: Re: 1973 Master Cylinder Reply with quote

1973 412 WAGON wrote:
Ray,
The box has a label that says IAPCO imported auto parts K-0065-007.
I will try and re-bleed tomorrow and go from there. How do i check the pedal gap?
I only used the seals from the kit.
Right side of the car is passenger correct?
Where can i get speed bleeders for her?
I will file the elbows as well tomorrow.


That was probably a reman cylinder. Its possible.....the cylinder was honed oversize....but for the moment, lets look at other things.

With your hand on the brake pedal reach up under the dash and touch the pushrod. Move the pedal just barely.....you should hear and feel a click as the pedal moves forward and touches the piston. There is also a top screw stop mounted on the pedal cluster yo7 can back off to get a little more room to feel the gap.

Go to speedbleeder.com. and look under sizes in the menu.....match up what you have. They may have a dealer list I cant remember. .....but until you get them....you can use feflon tape. Ray
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1973 412 WAGON
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PostPosted: Sun Jun 07, 2015 5:16 am    Post subject: Re: 1973 Master Cylinder Reply with quote

Ray,
You said you lean into the car and bleed it by hand. How do you keep the pedal pressed down?
raygreenwood wrote:
1973 412 WAGON wrote:
Ray,
The box has a label that says IAPCO imported auto parts K-0065-007.
I will try and re-bleed tomorrow and go from there. How do i check the pedal gap?
I only used the seals from the kit.
Right side of the car is passenger correct?
Where can i get speed bleeders for her?
I will file the elbows as well tomorrow.


That was probably a reman cylinder. Its possible.....the cylinder was honed oversize....but for the moment, lets look at other things.

With your hand on the brake pedal reach up under the dash and touch the pushrod. Move the pedal just barely.....you should hear and feel a click as the pedal moves forward and touches the piston. There is also a top screw stop mounted on the pedal cluster yo7 can back off to get a little more room to feel the gap.

Go to speedbleeder.com. and look under sizes in the menu.....match up what you have. They may have a dealer list I cant remember. .....but until you get them....you can use feflon tape. Ray
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raygreenwood
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PostPosted: Sun Jun 07, 2015 6:36 am    Post subject: Reply with quote

Oh....sorry.....I use a piece of broom handle with some padding wrapped around one end. I push the pedlle down and wedge the stick between the bottom of the drivers seat.

Now.....bear in mind....when just starting out.....I will pump the pedal a handful of times to rattle things and get moving as much as possible......then stroke it down.....put the broom handle in to hold it tight.....and it needs to be decently tight....then I get outcand crack the bleeder and then close it up. Then let the pedal up very slowly. Repeat a handful of times jntil you start seeing some pressure.
This is where moving the pedal by hand reaply helps. In the early stages, the increase in pressure on the cylinder at the brake pedal will be light enough that you largely wont feel it with your foot.

Once things get moving a little.....I use a self bleeder unit.....with a spring loaded ball check valve.

This is what I was speakijg of earlier....when I noted that I only open the bleeder valve I am working with....1/4 turn or less.
I put the self bleeder tube onto the valve....and zip tie it on. Then drop the valve end into a small bottle of fluid. I fill the hose up as much as possible before I start.

The reason why I start with single bleeds by hand......is because to start with....the pressure in the MC will be too low to pop the ball check valve on the self bleeder open.

Also.....even though you should bleed in order, in the very beginning. ...if nothing seems to be moving ho ahead and pop one of the front calipers open out of order just to get air moving. Ray
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412Variant
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PostPosted: Tue Jun 16, 2015 3:24 pm    Post subject: Same "bleeding" problems Reply with quote

Wish I had read this thread 3 days ago. Exact same problem/symptoms when bleeding my rebuilt brake system. Installed the new/rebuilt MC, lines, hoses etc.

No pressure buildup, yada, yada, same thing.....

Thought problem was in the MC, so pulled and disassembled it. Piston cups were not pliable and disintegrated upon inspection. Now having trouble finding another MC. Did I read that there are cups from another VW model that will work with my 412 MC piston? What year/model?

If I can get my MC back in service, I'll follow Rays bleeding instructions to a tee.
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ClassicCamper
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PostPosted: Tue Jun 16, 2015 3:41 pm    Post subject: Reply with quote

Hey folks, I found master cylinders on ebay. Said 2 available:

http://www.ebay.com/itm/VW-TYPE-4-WITHOUT-POWER-BR...mp;vxp=mtr

I know Ray has had many posts questioning the reliability of these since they stopped making them in the 80's I believe. However, there were some good posts regarding work-rounds. Maybe you will get lucky and it will work.

Good luck!
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raygreenwood
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PostPosted: Tue Jun 16, 2015 4:39 pm    Post subject: Reply with quote

You can use SEALS AND BRASS FLAP VALVES ONLY....from rebuild kits for a late type 3....1972, 1973.
Throw the pistons away. Use your old ones. The type 3 pistons are a, different spacing.

If you are given a, choice.....use ATE kits for ATE cylinders and FAG kits for FAG......unless you are buying a Shaffer brand kit.....and the seals should work well for either ATE or FAG.

Ray
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19super73
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PostPosted: Wed Jun 17, 2015 8:54 am    Post subject: Reply with quote

I found master cylinders available at Rock Auto.
_________________
1970 Campmobile [url=https://www.vw-mplate.com/mplate-47260.png]Click to view image[/URL]
1970 Fastback 1600 TL
1971 Doka [url=https://www.vw-mplate.com/mplate-14845.png]Click to view image[/URL]
1973 Super Beetle
1973 Westfalia [url=https://www.vw-mplate.com/mplate-31892.png]Click to view image[/URL]
1974 412 Variant
1975 La Grande Bug
1984 Vanagon
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raygreenwood
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PostPosted: Thu Jun 18, 2015 6:29 am    Post subject: Reply with quote

19super73 wrote:
I found master cylinders available at Rock Auto.


Not any more. No listing. they come and go. It may be back again soon. Ray
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19super73
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PostPosted: Thu Jun 18, 2015 7:59 am    Post subject: Reply with quote

raygreenwood wrote:
19super73 wrote:
I found master cylinders available at Rock Auto.


Not any more. No listing. they come and go. It may be back again soon. Ray


Just yesterday it was listed as available. Mad
_________________
1970 Campmobile [url=https://www.vw-mplate.com/mplate-47260.png]Click to view image[/URL]
1970 Fastback 1600 TL
1971 Doka [url=https://www.vw-mplate.com/mplate-14845.png]Click to view image[/URL]
1973 Super Beetle
1973 Westfalia [url=https://www.vw-mplate.com/mplate-31892.png]Click to view image[/URL]
1974 412 Variant
1975 La Grande Bug
1984 Vanagon
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412Variant
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PostPosted: Thu Jun 18, 2015 9:41 am    Post subject: Rock auto MC listing Reply with quote

I've learned the hard way not to trust website part(s) available claims. I always call the sales rep to have him/her check their inventory. Rockauto's site implies the part is available if not stated otherwise.

I called rock auto two days ago, sorry no MC in stock, "but we'll put you and a notify list if we get the part in stock"

Always call the supplier to double check......., I hate back orders!!!
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titan3c
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PostPosted: Tue Jun 20, 2017 1:46 pm    Post subject: Re: 1973 Master Cylinder Reply with quote

Ray, what kind of self bleeding tool do you use? I could use one, but don't know what works best. I've seen the hoses with a slip on connection on one end, and a valve that won't let any air or fluid back in. I'm working on getting all the air and whatever out of my lines. I finally got the new cylinder you rebuilt installed, and it's working fine, but I have a sort of soft pedal. I know I need to readjust the rear brakes which will help, but I'm sure an extensive bleeding process is in order. Bob
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raygreenwood
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PostPosted: Tue Jun 20, 2017 4:17 pm    Post subject: Re: 1973 Master Cylinder Reply with quote

titan3c wrote:
Ray, what kind of self bleeding tool do you use? I could use one, but don't know what works best. I've seen the hoses with a slip on connection on one end, and a valve that won't let any air or fluid back in. I'm working on getting all the air and whatever out of my lines. I finally got the new cylinder you rebuilt installed, and it's working fine, but I have a sort of soft pedal. I know I need to readjust the rear brakes which will help, but I'm sure an extensive bleeding process is in order. Bob


Hey Bob!.....I was just wondering about how thiw worked out for you.

I use a combination of things. If you have speed bleeder valves.....you can just use a length of clear vinyl hose held onto the bleeder valve with a zip tie....and just crack the valve open about 1/5th turn.

For safety sake.....I use one of these as well. It has a weighted hose end to stay in the bottle and has a ball and spring check valve of its own.....so the hose gets fill up air free and stays that way.

https://m.advanceautoparts.com/p/kd-tools-one-man-...wAodjmgJ1Q

The speed bleeder valves for the front calipers are well worth the investment. You only need one for each caliper placed in the top position.

Use part # SB7100 for the front caliper and SB 6100 for the rear.

http://www.speedbleeder.com

Do not use a pressure bleeder unless the blue hoses between the master cylinder reservoir and the elbows that plug into the master cylinder have been clamped. And if you do use one....use no more than 15-18 psi. Ray
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titan3c
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PostPosted: Wed Jun 21, 2017 5:29 am    Post subject: Re: 1973 Master Cylinder Reply with quote

BTW just interesting information. I purchased new reservoir to mc hose, and it is no longer blue. It has been changed to black. Also the inside diameter is a little larger than the blue hose inside diameter. It seems to be tight enough, but a little easier to slip on. PROBLEM: This could be confused as fuel line hose. It does have a slight blue thread in it, if you look for it. Bob
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