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1956 Buick master cylinder conversion.


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The problem is the steering column,if I remember right you can not use a vacuum booster more then 7", that`s becuse of the steering column,then you need a short type of master cylinder.They unit are not "bult on" ,but not very much work to do.Drilling new holes for the 4 booster bolts just outside the old ones,and maybe even shorten the rod that goes to the pedal.You also ned a new T-coupling for the new tube about 15" lengts.If you are trying to use a dual brake booster (a little bit longer than the single) the master cylinder needs to be shorter than if you use a single booster.Measuring is a must before doing anything.The Brake oil canister needs to be moved as well,see picture in my next reply.

Leif in Sweden.

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This is how it looks with the old booster ,and the new booster and the new 2 circuit master brake cylinder,the car with the new booster also have a new power steering unit from I think 1990s with a better ratio than the old ones.2 first pictures is from the old booster,the 3 last from new the ones.

Leif in Sweden.

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As the information contained within this thread, originally posted here > http://forums.aaca.org/f162/1956-buick-master-cylinder-conversion-347858.html could be of interest here I am copying it to here. You may want to check that tread for additional posts or information. You are welcome to post in either one.

Edited by MrEarl (see edit history)
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Hera are some additional pictures when I fixed the brake oil canister,the canister needs to be moved from the center about 11/2"-2". (canister from a 1990s Volkswagen I think) .It`s importent that the Master cylinder is not to high on the cylinder "inlet",needs to go free below the steering column.

Leif in Sweden

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  • 2 months later...

Wanted to thank you for all the advice and pictures. The photos were very helpful. I think another option would be to use a hydraulic brake booster out of a small truck, like a Chevy Astro, and hook it up to a dual master cylinder with remote fluid containers. The hydraulics would be tied into the power steering system. If I go this route I'll document with photos.

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That will be very interresting to see pictures of the installation with hudralic brake booster.Buy the way,my friend has tested the new power brakes on his 1956 Buick with very good results.He`s very satiesfied.

Leif in Sweden

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John.I have used the rubber grummits from the new master cylinder in the same place as it was before,then I used the rubber grummits from the older Volkswagen reservoirs (1990s-2000s) master cylinder to fit in the copper plumbing again.All the copper is new plumbing parts.Maybe the reservoir is bigger than it needs to be, but my friend wanted it to be as this.There are an easier way to do this if you are using a single reservoir, you can put the copper tubes togeter just before it meet in the reservoir.Just remember that all the plumber parts are made in millimeter here in Sweden.

I hope this will help you to made it by yourself.

Leif in Sweden

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  • 5 months later...

Hello Leif,

you did a great job. I am going to do the same job in the next month. I bought the same 7" power booster like you and a master cylinder of a 1981 Cadillac Eldorado. The master clinder has only two ports. Where did you connect the brake switch? Did you use the old regulator valve?

I am looking forward two your answer.

Greetings from Germany

Thomas

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It was used on my friends 1956 Roadmaster ,If I remember right the brake switch is placed on the distribution "block" below the power booster,there will be a couple of conections free there and you need to plug one of them too.You connect the front brake tube to the new cylinder and also a new tube from the dist. block to the new cylinder if I remember right.

Hope it helps Thomas.Sorry about the delay.

Leif in Sweden.

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  • 2 months later...

Hello Leif,

I need your help. I have made the conversion last weekend, but I am not satisfied. I have no braking power. The pedal does not move enough and is hard.

Let me explain what I did. I use the same kind of 7" power booster like you. My dual master cylinder is from a 1980 Buick Riviera and I use a distribution block with brake light switch and an adjustable rear exit. I bleed all lines and there is no air inside.

Did you use the original vacuum line and the Vacuum canister? Did you make any special adjustments on the brake unit?

Thanks for your help. If you like , you can directly answer to buicktom at t-online.de

Thomas

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Thomas,Just wonder if your puch rod that goes to the brake pedal are to long,you need a play before you put the pedal and the rod togeter,I remember i cutted off the rod a little bit.I did that for a friend of mine.If the rod are to long you will get the problem you describe.

Leif in Sweden.

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Hello Leif,

I checked the play between the push rod and the pedal and it is more than 5 mm. This should be enough.

After some talks with car mechanics, I switched the brake lines from the front exit of the master cylinder to the back exit ond so on.

Now I have a more soft pedal pressure . They told me that the front exit is sometimes for the rear brakes and the rear for the front. It depends on the inner structure of the cylinder.

No it brakes better, but more worse as the old system. Brake power ist bad.

Here are some more questions:

What kind of brake master cylinder did you use? If I see it right it is a [h=1]ACDELCO PRO DURASTOP 18M974 Brake Master Cylinder[/h]Should be from a Chevy S10.

Did you use the original vacuum lines?

Did you use the original place on the manifold for vacuum?

What kind of distributor block did you use?

Do you use any new brake pressure valves in the rear lines?

How did you adjust the small adjusting screw on the power booster on the side to the brake cylinder?

How do you route the brake lines? In which line did you place your distributor block? Front or Rear?

I don't know, if I only use the wrong master cylinder or I don't have enough vacuum on the unit.

Leif I know a lot of questions.

Thanks for your help in advance.

Thomas

Edited by buicktom (see edit history)
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Hi Thomas.At the first it wasn`t my 1956 Buick it is my friends,but I helped him.

Yes we used the original vacuum line.

Yes we used the original place on the manifold for vacuum.

We used an old block for the front brake lines and that was also used for the brake lights.

Nothing has been done with any brake pressure valves,really don`t know if there are any.

Nothing has been adjusted on the power booster.

At the moment I can`t remember what line was in front or on rear of the brake cylinder.I have to look when I visit him ,maybe tomorrow.

I don`t know what type of brake cylinder he has,becuse he bought it in a shop by himself.

One of your problem can be that you have a brake cylinder for disc brakes,but that`s a guess only.

I remember that the rod between the vacuum and pedal had to be cutted off.

Leif in Sweden

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buicktom:

Short travel and hard pedal really sounds like a bad booster. It may be leaking off vacuum internally and if so you should hear a hissing sound when pedal is depressed. Does it have a rubber boot on the front that is supposed to be sealed by the master cylinder. Try another booster.

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Thanks John. After I switched the lines on the brake cylinder, I have a travel of 2" on the pedal and the no more hard. Feels okay, but the brake power is not good. The power booster is brand new. Yes it has a little hissing sound, when I depress it. It has no rubber boot on the front that is supposed to be sealed by the master cylinder.

Thomas

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I had a talk to the 56 owner today but he couldn`t remember how he had install the lines on the brake cylinder,but I know he changed the booster and the brake cylinder just becuse of a "hissing"sound,but I`l be back later when I have visited him and see it with my own eyes.The rubber boot is for dust only I think.

Leif in Sweden.

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Looked at the brake cylinder today on the 1956 and the rear part of the cylinder goes to the rear and the front part of the cylinder goes to the front wheel brakes.Before he did this I told him to do the opposite way, but his brakes works very very good he say.

Leif in Sweden

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Thanks for your help. I identified the master cylinder on one of your photos and ordered it two days ago. Now I have to wait for it. The MC I have seems to be the wrong one for the 56.

I'll be back with new information as soon as I can try the new one.

Thomas

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  • 2 weeks later...

The master cylinder arrived yesterday. Today I build it in, but it is nearly the same as before. Maybe the problem is the new power booster. It doesn't work that way it should. I have ordered another one last week, but it doesn't arrive til now. So I have another chance to solve the problem next weekend. I will let you know, what's going on. Leif, is your friend still using the drum/drum combination? Or did he change to disc/drum?

Happy Buicking

Thomas

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Today, I tried the new power booster. Breaking power is much better. I did it the same way you did Leif. But Im not really satisfied. For me the system has not enough power for an emergency braking. Especially not when I am on tour with our RV trailer. Next weekend I try to switch the two brake lines from the front to the rear on the MC. Maybe it will be more powerful.

If I can't fix it in the next time, I switch back to the old single booster for summer. But I will try it next winter again.

Thomas

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Today I changed the lines, but no difference. So I went back to the original single mc with power booster. Braking power is much better then with the dual cylinder. Before I put everything back to the original, I dismantled the old cylinder and booster. Cleaned everything and greased the the parts inside the booster. The seals inside the mc are still good, because I changed them 3 years ago.

I measured the piston of the mc and it has a diameter of nearly 3/4". It is much smaller then the duals have. Does anybody know a dual mc with the same diameter or a little bit smaller?

Happy Buicking

Thomas

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  • 10 months later...
Guest snowmansgarage

buicktom- Did you ever go back to the conversion and get it figured out? Also, in one post you mentioned you were using a '81 Cadillac Eldorado master cylinder, then in another post you said it was an '80 Buick Riviera. Do you remember which one it was and what brake booster you used?

Thanks in advance!

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  • 2 months later...
buicktom- Did you ever go back to the conversion and get it figured out? Also, in one post you mentioned you were using a '81 Cadillac Eldorado master cylinder, then in another post you said it was an '80 Buick Riviera. Do you remember which one it was and what brake booster you used?

Thanks in advance!

No I didn't until now, because I opened a new project on 86 Grand National. Will do it next winter. I bought a 7" power booster and the master cylinder was from a 80 Riviera. In my opinion the problem of the newer master cylinder is the volume of the cylinder is to big with a 1" piston. The original cylinder have only half of it in diameter. To much fluid on one push. Need a smaller cylinder which fit to the booster.

Thomas

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  • 6 years later...

When googling, this is the best source of info I've found, so I'm reviving this thread to add my experience/failures/maybe success. This seems like a good spot for the info, but let me know if a new thread is more appropriate. 

 

Recently acquired a '56 special that had the master cylinder and booster removed. Some pieces remained in the trunk, but most were missing. I was told the booster can rusted through and its missing. The master cylinder was there, but pretty pitted. The 'plunger' seems to be from a 57, so I'm not really sure the whole story.  Original parts being extremely rare and expensive, I started looking at options. 

 

1. I found a 7 inch booster, and it does fit, but coming up with a master cylinder to fit on it has proved difficult. This could very well be that I didn't know what to look for since I'm not well versed in this area yet. Specifically was looking for one with a remote reservoir, or a way of adding a remote reservoir. 

2. The kits that move the master cylinder to the plenum look ok. I don't like the idea of loosing the plenum and the glass windshield wiper fluid jar. And the cost seems a bit too steep(~$750 USD at the moment) for a solution that I'm not in love with. After a few failures, it will probably be more appealing.

3. I've seen other cars, never an older Buick, switch to electric boosters. These are very compact. This is the option I'm going to try.

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There are several electric boosters out there. The iBooster seems like the easiest path. It comes in a generation 1 and generation 2. The generation 2 being newer meant I couldn't find as good of dimensions online, so I'm trying a generation 1. Quick measurements seem like it will fit, but its hard to be certain given the non standard shape of the iBooster and the angled/cramped area of the Buick.

 

Cost varies, but buying online seems like about $250 to $350 range would get a used booster/master cyl and if you're lucky the connectors too. I was able to get the whole thing for $180 from a local junkyard. 

 

The 2017-2019 Honda CR-V donor vehicle already has a remote reservoir, which is why I chose this car. We'll see if it is useable.

It is also a dual master cylinder setup. My plan is to fully bleed the unit and plug one of the outputs for now. Then just have a single cylinder output go to the stock brake system. If I decide to split front/back circuits, the option is there. Also if I change to disk brakes, the dual cylinder will support that too.

 

 

I am concerned about the electric draw on the stock generator, and I'm not sure how to wire it in yet without looking ugly, but I'll share along the way. 

 

And if this turns out to be a total failure, then at least the info is out there, so the next guy won't waste his time.

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