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If affordable and easy to install, would you prefer power assist brakes on your T4?
Heck Yea!
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 90%  [ 9 ]
No Way
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ClassicCamper
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PostPosted: Wed Aug 10, 2016 10:09 pm    Post subject: Power Assist Brakes Reply with quote

Although I'm aware that the 412 has sufficient brakes without a booster, I was hoping to hear from some folks who have a type 4 with power assist brakes, and how you like them.

As I understand it, none of the T4's imported from VW to US had power brakes,however, they were required in Scandinavia. (or at least part of Scandinavia)

I may be able to get a power brake set-up, and now that I have everything apart, I'm considering installing a booster. My plan is to obtain the booster, master cylinder, pedal cluster, firewall stability plate, etc.. Any thoughts/suggestions?
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raygreenwood
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PostPosted: Wed Aug 10, 2016 10:30 pm    Post subject: Re: Power Assist Brakes Reply with quote

Having driven many cars with and without power brakes. ...but never a 411/412 with power brakes.....but many miles un 411/412..... maybe 500,000 or therabouts.....and having made numerous improvments to non-power brakes with better pads, shoes, vented rotors and higher temp brake fluid.......i personally do not see the lure of power brakes on these cars.

It lowers the pedal effort....but does not increase the braking action. The master cylinder has the same piston stroke and diameter. Its simply an effort/feel issue.

And..... if you are trying to lessen the brake effort......and are willing to add parts and fabricate......there are many ways to do that without the added complexity.....master cylinder diameter, balance point etc.

The main benefit I saw of the power system....just from looking at its pictures...os getting the master cylinder out from under the dash....which also simultaneously will get me into a more readily available master cylinder. When mine is ready to assemble. ....it will have the MC in the trunk. It will also have the clutch MC in the trunk.

It will entail a mounting plate in the trunk for the master cylinder in the same place that the power unit would go....and drilling out the factory stamping knockout...and making a relay bracket that mounts in the two 12mm bolt holes that the brake and clutch master cyliners currently are. The brake pushrod is a straight shot. The clutch pushrod will have to have a cranked section to line it up within 10mm of the brake pushrod to go through the same hole.....and the clutch master wull be slightly forward of the brake master.

I just do not see enough benefit for the power unit....plus...you will need to run a vacuum line and a vacuum resovoir. ..and its not ideal for its vacuum effect with the auto trans. Just my 2 cents. Ray
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Lars S
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PostPosted: Thu Aug 11, 2016 6:57 am    Post subject: Re: Power Assist Brakes Reply with quote

Agree with Ray it lessens the effort but the braking action is the same (if you can apply enough force on your pedal quick enough).
Still, since my 412 has it, I would not like to be without it...the car feels more modern and my wife has one less thing to complain about 😊....its like power steering which also lessens the effort (not that a 411/412 with normal/moderate tires would need power steering).

Lars S
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raygreenwood
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PostPosted: Thu Aug 11, 2016 7:56 am    Post subject: Re: Power Assist Brakes Reply with quote

Lars S wrote:
Agree with Ray it lessens the effort but the braking action is the same (if you can apply enough force on your pedal quick enough).
Still, since my 412 has it, I would not like to be without it...the car feels more modern and my wife has one less thing to complain about 😊....its like power steering which also lessens the effort (not that a 411/412 with normal/moderate tires would need power steering).

Lars S



Totally agree with that. If it had it...its a comfort thing. I would not remove it. Having power brakes does make stop and go city traffic a little less of a chore.

Also...if back in the day when I was driving my 412 full time....if I had another car that I occasionally switched back and forth with that had power brakes it would lessen the attention span required getting used to them back and forth.

I remember when I picked up my 82 Saab 900...and still was driving my 412 as well for a short period. If I forgot what I was doing....when I jumped into a car...it was risky for a few minutes getting used to the brakes...acceleration...actually....was better in my 412 than my 900...or maybe about the same.
Ray
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titan3c
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PostPosted: Fri Aug 12, 2016 6:20 am    Post subject: Re: Power Assist Brakes Reply with quote

I will be taking my mc out for a rebuild soon. Would love to look at the possibility of relocating it in the trunk. Don't quite understand how the brake pedal is a clear shot since it looks like it would be pushing in the wrong direction. Do you have any drawings or sketches how you do that? I think it would be a fun project, and I was glad to read your pros and cons on the booster. Leaving the booster out of it makes it much simpler. Bob
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raygreenwood
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PostPosted: Fri Aug 12, 2016 7:40 am    Post subject: Re: Power Assist Brakes Reply with quote

titan3c wrote:
I will be taking my mc out for a rebuild soon. Would love to look at the possibility of relocating it in the trunk. Don't quite understand how the brake pedal is a clear shot since it looks like it would be pushing in the wrong direction. Do you have any drawings or sketches how you do that? I think it would be a fun project, and I was glad to read your pros and cons on the booster. Leaving the booster out of it makes it much simpler. Bob


Take a look in your books. In the Haynes manual......you see a diagram of the power brake unit. Page 138 in the Green Haynes book #091

You will notice that there is a bracket under the dash that bolts to the inside of the firewall....and the counterpart bracket in the trunk that holds the power vacuum unit and master cylinder.

Notice part #16 and everything attached to it. That is a relay pivot or lever.

The way the non power MC is currently arranged.....it is bolted with the open end facing toward the front of the car....page 140.

When you step on the brake pedal.....the pushrod mounted to the top of the pedal....above the pivot shaft.....makes the pushrod pivot toward the driver...toward the rear of the car....pushing the MC pistons.

Now.....remove the stock MC under the dash......and flip the pushrod over so its facing the front of the car. Now when you push the pedal......the pushrod "pulls" backwards instead of pushing.
With me so far?

Now.....where that interior under dash bracket is on the the power brake diagram. .....you need to fashion a similar bracket.....like a short A-frame.

That A-frame bracket will hold a cross shaft or axle. On that axle will be a pivot or relay lever. It can be as simple as a bar....or you can use a disc of steel.

The existing pushrod on the top of the brake pedal attches attaches to the relay lever or pivot disc at the 6:00 position. At the 12:00 position you attache another pushrod leading forward through the hole in the firewall.

So when you push the pedal.....it pulls the bottom of the relay lever towards you.....making the pushrod attached at the top of the lever push forward away from you.....on the master cylinder pistons. Its just a version of what the factory made for the power MC.

Ray

EDIT......I'm not really saying that ClassicCamper should not install the power brake unit......just that unless you have every last part required......every last part.....of a factory set up including the vacuum line through the chassis.....which I "think" had a hard line through the tunnel........as hard as you are working to keep your car as a 100% original "museum" of a car.....very worthy by the way. ......I would not do the power brake conversion unless it was 100% factory. Every last detail.

The benefit of it is just not enough to make something cobbled together worthwhile.

Also you have to think about the fact that getting 412 brake MC whether they are manual or power......is not easy either way. Same for the power brake booster itself even though you can get them rebuilt.

If you were going to fabricate to move the brake unit out from under the dash anyway......sure put in power brakes by any means if you want them. You can use a booster from a,VW Fox. Right size and shape ......which is changing the car either way.

I am moving the MC out from under the dash for two reasons. ...which come from long esperience.
1. It makes it much easier to get master cylinders for. There are several I can use.
2. Most importantly.....most of the most common rust damage in the drivers floorboards, damage to pedal pivot bearings, damage to the relay on the ledal mount and rust on the pedal cluster and damage to pedal pads and carpet......is caused by fluid leakage either as master cylinders start to wear out....or when replacing master cylinders and having to disconnect lines and the fluid reservoir tubes.

Its just a poor place for the MC....and after I get all of the carpet and interior fixed and parts painted....I'm not putting brske fluid back under the dash again. Ray
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titan3c
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PostPosted: Fri Aug 12, 2016 8:20 am    Post subject: Re: Power Assist Brakes Reply with quote

Ok I got the basic description for the under dash part. It would be nice to find a salvage type 4 with a power brake system, and remove the inside mounts and relay lever.

Now about mounting the mc under the hood? Bob
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PostPosted: Fri Aug 12, 2016 10:24 am    Post subject: Re: Power Assist Brakes Reply with quote

titan3c wrote:
Ok I got the basic description for the under dash part. It would be nice to find a salvage type 4 with a power brake system, and remove the inside mounts and relay lever.

Now about mounting the mc under the hood? Bob



I have NEVER...seen a single car on the road or otherwise in the USA with power brakes in my life.

Also....on the power brake version....its not clear whether the relay pivot is on the inside or outside...meaning in the trunk or under the dash. From years of looking at the pictures and parts books....I think you would have more trouble adapting a working factory system to a non-power MC than it would be worth.

The fabrication is really easy for this. The bracket will be fine made of 3/16" or 1/4" steel plate cut with a jig saw....holes drilled. The two bolts that hold the master cylinder to the pedal cluster are the perfect mounting points for the "A Frame"....and since you have the same two holes on the other side already...that are there to hold a clutch master cylinder (they are in every car even those with automatics) ....you have a perfect place on the other side to mount the other matching "A frame" Wink

....and since I have a four speed....its good reason to want to get the clutch master out from under the dash and put it in the trunk too.

All of the fabrication can be done by a nice jig saw and a drill press....and be made from plate stock, stock bushings and shaft materials available and rod or bar stock.

As I move into winter this year I will lay this out. Ray
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titan3c
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PostPosted: Fri Aug 12, 2016 12:04 pm    Post subject: Re: Power Assist Brakes Reply with quote

OK I'll keep in touch. I have the skill, but don't have the equipment. But, I live in the country, and my closest neighbor has a well equipped shop bldg. , and I can get his help and assistance. With the layout done he would have the "A" frame, regulator arm, etc. done before I could find the first tool. Sounds like a fun project, and a very practical modification. BTW I'll be checking with you on the rear window trim your planning to do this winter too. Bob
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Lars S
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PostPosted: Sat Aug 13, 2016 1:40 am    Post subject: Re: Power Assist Brakes Reply with quote

raygreenwood wrote:


Also....on the power brake version....its not clear whether the relay pivot is on the inside or outside...meaning in the trunk or under the dash. From years of looking at the pictures and parts books...Ray


Possibly this picture can help upon how the factory did it.
When photoing this on my -73 I discovered the round service opening under the arrangement which isnt there on my non power assisted -70, guess thats because power assist was not an option until -71 or -72...but what could you reach to service through that opening?

/Lars S



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titan3c
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PostPosted: Sat Aug 13, 2016 5:32 am    Post subject: Re: Power Assist Brakes Reply with quote

tHE







OK---the way I see it everything is in the trunk area. The relay pivot shaft is connection is visible. The push rod for the modification extends thru the firewall to the relay. The next question, is the push rod long enough to extend thru the fire wall and connect to the relay? If it is this modification should be fairly simple, because all the change is in the trunk. Thanks Lahr for his picture. Bob
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PostPosted: Sat Aug 13, 2016 5:47 am    Post subject: Re: Power Assist Brakes Reply with quote

Also---just thinking out loud----. The bracket under the hood could be designed to accommodate the mc plus the reservoir. Then the brake lines could be routed thru the holes made vacant for the brake fluid lines to the reservoir. As I said just thinking.
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PostPosted: Sat Aug 13, 2016 5:52 am    Post subject: Re: Power Assist Brakes Reply with quote

Correction: I meant to say brake lines to the mc
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PostPosted: Sat Aug 13, 2016 7:08 am    Post subject: Re: Power Assist Brakes Reply with quote

Again just thinking----the more I study this over it looks like to me that all the bracket assembly used for the power brakes could be used for this modification, and just eliminate the servo. The reservoir could be plugged directly into the mc. The MC could be bolted to the side of the metal box assy., and secured solidly to the rear. Bob
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PostPosted: Sat Aug 13, 2016 7:24 am    Post subject: Re: Power Assist Brakes Reply with quote

titan3c wrote:
Again just thinking----the more I study this over it looks like to me that all the bracket assembly used for the power brakes could be used for this modification, and just eliminate the servo. The reservoir could be plugged directly into the mc. The MC could be bolted to the side of the metal box assy., and secured solidly to the rear. Bob


This is how the stock reservoir sits at power brakes.

The vaccum tube from plenum to the power unit is approx 1/2" dia.
EDIT: the tube seems to be of hard plastic except at its ends where it has the common wowen vaccum hose type.

Lars S

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PostPosted: Sat Aug 13, 2016 8:05 am    Post subject: Re: Power Assist Brakes Reply with quote

Lars S wrote:
raygreenwood wrote:


Also....on the power brake version....its not clear whether the relay pivot is on the inside or outside...meaning in the trunk or under the dash. From years of looking at the pictures and parts books...Ray


Possibly this picture can help upon how the factory did it.
When photoing this on my -73 I discovered the round service opening under the arrangement which isnt there on my non power assisted -70, guess thats because power assist was not an option until -71 or -72...but what could you reach to service through that opening?

/Lars S



Image may have been reduced in size. Click image to view fullscreen.


Great picture!

Yes....I would bet you money.....that the round opening is there on your 1970. It is typically under the carpet/trunk liner. It is there to primarily service the small bore 3mm gas tank vent line. You can also reach the two 8mm studs that protrude through the firewall into the area under the dash that the front of the pedal cluster connects to.

If you have not pulled the trunk liner away from the deck of your 1970 411 in that area....you will not find that lid.

There is a lid on both sides of the car in the same position. The lid on the passenger side (meaning right side of the car in right hand drive cars).....allows service to the larger bore hose ....12mm....for the fuel filler neck overflow.......and......this is really cool.......if you look right above the round opening on the passenger side you should find a stamped indentation in the vertical part of the firewall......that is where they would knock out the metal to install power brakes on a LHD car. Wink

Down below the access hole to the rear of the fuel tank.....on the passenger side....you will also find a stamped indentation where they would knock out the hole for the steering column shaft for a LHD car.

It was interesting on all 411 and 412 that I have ever seen.....that all stampings and underpinning points were made pre-installed....so a car could easily be made LHD or RHD....and could be made manual transmission or automatic transmission.

On cars with automatic transmission. .....under the undercoating at the rear end of the chassis tunnel. ...are rubber plugs that fill the holes where the clutch slave line would go through on a manual transmission car.
Also the metal bend over tang that holds down the clutch fluid tube...and the indentation where the steel line pressure union fits next to the floor......is pre-stamped in the automatic cars.
Ray
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Lars S
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PostPosted: Sat Aug 13, 2016 9:00 am    Post subject: Re: Power Assist Brakes Reply with quote

raygreenwood wrote:

...
If you have not pulled the trunk liner away from the deck of your 1970 411 in that area....you will not find that lid.
...
Ray


No, I insist Laughing , there is no lid in that position on my -70 and possibly some of the stampings for the power assist are missing...likely because the power assist was not ready designed in -70(?). From what I know the power asistance was not an option until -72 model year.


/Lars S

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VW411 2-d -70, White, sold Sad
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold Sad
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PostPosted: Sat Aug 13, 2016 9:39 am    Post subject: Re: Power Assist Brakes Reply with quote

Lars S wrote:
raygreenwood wrote:

...
If you have not pulled the trunk liner away from the deck of your 1970 411 in that area....you will not find that lid.
...
Ray


No, I insist Laughing , there is no lid in that position on my -70 and possibly some of the stampings for the power assist are missing...likely because the power assist was not ready designed in -70(?). From what I know the power asistance was not an option until -72 model year.


/Lars S


Wow! even more cool! See something new almost every day with these cars!

And you do have the 3mm vapor line...which means without that access hole....replacing that line is an ugly job! Thanks Lars!
Ray

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PostPosted: Sat Aug 13, 2016 10:18 am    Post subject: Re: Power Assist Brakes Reply with quote

This is a quick crude sketch. None of the dimensions are to scale...or the angles...but there is enough room to do this under the dash. I really can't start it until I am ready to remove the dash. Maybe this winter.

Image may have been reduced in size. Click image to view fullscreen.


The black lines are an approximation of where the firewalls and sheet metal are.

Note the pivot motion. With a pivot wheel or bar...you can actually change the leverage point. You "could" make the pedal complete the stroke with a shorter pedal throw by adjusting the ratio of how far the outgoing pushrod is from the center of the pivot wheel or bar.

While that would make the brake pedal slightly harder to operate because the leverage advantage would be on the master cylinder end....it could allow you to complete a whole brake stroke in say...half the pedal travel.

Image may have been reduced in size. Click image to view fullscreen.


Oh...and here is the front view from the driver just so you know how I am thinking

Ray
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PostPosted: Sat Aug 13, 2016 12:29 pm    Post subject: Re: Power Assist Brakes Reply with quote

Looks great-----but you mentioned a type 3 mc. Will that work OK? Are there other mc's with the front 2 hole mounts that will work on type 4?
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