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Michael-Restomod

1975 Rolls Royce Silver Shadow Brake Modifications

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Hello I'm new. I bought a 1975 Rolls Royce Silver Shadow (RR-SS) that had been sitting in a field for 15 years with the sunroof open an inch and the windows down an inch. Needless to say it was only worth what I paid for it, which was only $2500 (for a Rolls Royce). The brake on an RR-SS are a massively complex system, that was bone dry and rusted, with the typical worms in the system (at least that is what it looks like). So I have restored the inside, ripped out all the old brake system, took off the massive carburetor and put on a Edellbrock 1405, and put in the trunk a Dodge van vacuum booster and master cylinder. I tried to use the original RR master cylinder to a clutch slave cylinder to push the brake rod on the vacuum booster but I could not get it working. So now I am looking for an emergency brake cable that is 132 inches (11 feet) long to use to push the rod on the vacuum booster. In other words make it mechanical not hydraulic. Here are some pictures to look at.

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There are some pretty heavy duty marine control cables available.

Morse comes to mind.

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What exactly prevents you from installing a conventional M/C and booster? Is it a space issue? Photos would help.


There are a boatload of innovative brake system components for street rods. I can't believe that a Rube Goldberg design with a pull cable is a better choice. Have you looked at a hydraulic Hydroboost instead of a vacuum booster to save space? FYI, the remote booster you have tried to fabricate in your first attempt is called a Hydrovac (completely unrelated to the Hydroboost) and has been used on cars and trucks since the 1950s. You can buy them new.

 

This is a Hydroboost. Note that the combo valve can go anywhere; it doesn't have to be hung off the side of the M/C. Hydraulic power for the Hydroboost comes from the PS pump.

 

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You can also adapt many other master cylinders, including remote fill styles. There are kits for under-floor mounting, right angle mounting, etc, etc.

 

Hydroboost%20and%20Master.jpg

 

This is a Hydrovac, which uses a small remote hydraulic master cylinder like the one you first tried. This one is a diaphram style vacuum booster.

 

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This one is a piston style vacuum booster. These are commonly used on medium duty trucks now, but were very common on cars in the 1950s. The diaphram one above is for a 1956 Ford.

 

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JACK M "There are some pretty heavy duty marine control cables available.

Morse comes to mind."

 

I can't get any numbers on most these cables out there, the marine cables come in 11 to 13 feet and look big enough and strong enough but no numbers. I want like 3/16 inch cable that can take 3000 lbs of force to be sure even if the vacuum goes out the cable will easily stop the car. 

 

 "Rube Goldberg design" I just got out of a bad relation on another forum where everyone was snobs, may this one will not work out as well.

 

The concept of being poor just is not gotten by some. I'm unemployed bought a Rolls Royce for $2500, yeah I have all the money in the world to buy new systems.

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Normally, I greatly prefer authenticity, but

I like the idea of making unreliable and complicated cars

more reliable and typical.  "Jagrolets" come to mind--

Jaguar style and Chevrolet reliability.  I hope your work

on the Rolls will accomplish the same thing.  If only Rolls

had the mechanics of a GM or Ford Motor product, I think

the resale prices for cars like this Silver Shadow would be

considerably higher.

 

All the best to you in your work---

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1 hour ago, Michael-Restomod said:

 "Rube Goldberg design" I just got out of a bad relation on another forum where everyone was snobs, may this one will not work out as well.

 

The concept of being poor just is not gotten by some. I'm unemployed bought a Rolls Royce for $2500, yeah I have all the money in the world to buy new systems.

 

First, it IS a "rube goldberg" design. There are valid engineering reasons why no one operates brakes that way.

Second, I have no problem with clever, innovative, low cost engineering solutions. Using "poor" as a rationale for doing something half-fast (especially brakes) is BS.

Third, if you really are unemployed, spending $2500 on a non-functioning Rolls is very poor judgement.  You'll have $10K into that car and it will still be half-fast. $2500 buys a whole slew of interesting cars that don't require a dramatic investment or sketchy redneck "engineering" to get running.

 

You clearly don't want to hear solutions that aren't yours. Have fun. I won't bother you any more.

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Cables don't push very well, even if they're heavy duty and encased in sleeves. You'll never be able to get a cable to push a piston on a master cylinder with enough force to provide satisfactory braking. It seems like an odd idea, but what about a small slave cylinder to push the master cylinder push rod? It's another layer of complexity, another separate hydraulic system, but you could pretty easily mount a tiny master cylinder and use the brake pedal to actuate it, and then run a hydraulic line to a slave cylinder that can push the master cylinder's plunger wherever you end up mounting it.

 

But some of the other solutions above might be more direct--there are all kinds of weird configurations people use on hot rods that are probably more direct and certainly safer than using a cable of some sort.

 

Good luck--you're in stage 1 of Rolls-Royce ownership. Enjoy it while it lasts!

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2 hours ago, Michael-Restomod said:

I just got out of a bad relation on another forum where everyone was snobs, may this one will not work out as well.

 

Michael, you'll find that the AACA forum is friendly.

Diverse people express diverse opinions, but almost

everyone is supportive;  and the moderators should

moderate any rare caustic comment.

 

Also, most people here are not wealthy.  Antique cars

are affordable, and $10,000 to $20,000 for most old cars

you see at local shows and tours is a typical value.

So stick with us, because we would like to learn from

your experience in refurbishing the old Rolls-Royce.

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I do not think it would be hard to have the cable pull one end of a lever that would push the rod going into the MC.  The pivot of the lever could be designed for whatever mechanical advantage one required.

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Since people are not familiar with what I have in mind I will put a drawing I made to show what it looks like. It is based loosely on the  Bellcrank Assembly.

See https://techtalk.mpbrakes.com/bellcrank-classic-cars

I have looked at all the systems out there and this was the most elegant solution I could come up with (in my budget).  There is nothing Rube Goldberg about it, (and having not seen it, I'm not sure how anyone can decide it is not up to their standards without having seen it). And not having money means you cannot buy things. And saying "I won't bother you any more" is the best news I could possibly hear.

 

Ok sorry for that. Back to real people. So below is the drawing, it is all pull no push. And cables are part of the braking system, they are called emergency brakes.  There is no  engineering reason why they cannot be used on brakes, (at least not in Texas). The primary brakes on even large three wheelers are often cable brakes.  

 

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You should be able to find room for a small master cylinder, even a single cylinder with no booster and use it to actuate a remote power brake booster. The booster can be located anywhere although, the closer to the MC the better. They usually go under the hood or under the floor.

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The only thing the original hydraulic system does for suspension is the height adjusters. Which unless I have some fat lady sit in my trunk it serves no purpose.  The rat trap. There is not enough room to put a brake system under the car.

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I have been out of the boat business for over twenty years now so don't know where to send you but there are (at least were) many grades, sizes and lengths available then.

I suspect that with the internet now you could have a cable made to your specs,

Your findings at 11 to 13 feet is telling me that you haven't looked hard enough.

I found and used about a six foot cable that I needed for a throttle cable on my racecar. Needed about ZERO resistance, It worked well and was something I could get from a catalogue. (it was indeed overkill but I am like that).

There was no internet then so catalogues were the thing. Now I suspect its google or the likes.

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2 hours ago, Michael-Restomod said:

The only thing the original hydraulic system does for suspension is the height adjusters. Which unless I have some fat lady sit in my trunk it serves no purpose. 

 

 

 

 

Where there you go.  If you're satisfied with the result that's all that matters.

 

 

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It looks to me like it would be a simple matter to replace the stock master cylinder with a conventional one and use a remote power booster.

Some cars from the early fifties had a power brake booster under the floor in the same location as your master cylinder. There was a dent in the floor under the seat to accommodate the booster. Chrysler products for instance. Today's boosters are smaller in diameter and don't take up so much room. This would be even simpler. You would need a hatch in the floor to check and fill the brake fluid, or a remote reservoir.

Here is a modern conversion for a Chevrolet that shows what I mean.

 

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Edited by Rusty_OToole (see edit history)

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Sorry this is kind of a test to see how to post comments in between pictures.

 

This is how bad the Rolls was when I got it.

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And after with a lot of work

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The reason the horn button is a BBQ Temp gauge is someone stole the very nice $350 horn button, on this $1,125 Steering wheel. So I had to make one so it will pass inspection. https://wood-steering-wheels.com/rolls-royce/

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Back seat

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First start and run in 15 years

 

 

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I for one think what you are doing with your projects is wonderful. You are brave and innovative, and your confidence is obviously backed  by competence. Thank you for sharing with us, and thanks for putting an "Antique" Rolls Royce back on the road that no one else would touch. I love it !   -   Carl 

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11 hours ago, Rusty_OToole said:

It looks to me like it would be a simple matter to replace the stock master cylinder with a conventional one and use a remote power booster.

 

 

The "stock master cylinder" is a hydraulic pump that runs off the camshaft powering both the service brake circuits and the hydraulic rear suspension.  There is nothing conventional about it.  It's interesting stuff for anybody into complex control systems.  

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Thanks Carl

 

W Higgins is correct about the hydraulic system on a Rolls Royce Silver Shadow. It is unbelievably complex. It is therefore dangerous to have in America where no mechanic (unfamiliar with at the very least old cars that had brake pumps and accumulators on them) knows how to work on them.  There are horror stories documented by Ronny Shaver of Ronny's Garage. He is rollsroycenut on youtube with lots of how to videos. Here is a case where the mechanic did not have a clue how to work on RR brakes and could have blown himself or the owner up. The accumulators on any car are dangerous. A mechanic friend told me of a guy working on the old Buick (I think) accumulators, one blew up and went through the hood of the car. There are cases where they have blown a hole in the RR engine block. Just imagine what they could do to you or a mechanic that has not a clue just how dangerous these cars can be. 

 

Here is a PDF file of Ronny Shaver talking about a guy who replaced the brake pump push rod, made to break when the accumulator is not working right, with the older style solid push rod instead of fixing the accumulator valves.

 

https://ronnysgarage.com/Files/PDF/are-my-brake-pumps-working.pdf 

 

More PDF Files at:

 

https://ronnysgarage.com/ask-ronny

 

And the videos

 

Here are animations how the brakes work on a Silver Shadow

 

https://www.rrsilvershadow.com/ETechn/Hydr/Menurem.htm

 

Sometimes original is not a good idea in other countries. My Rolls Royce when I am finished can be taken to any American mechanic and they can fix it with the knowledge of American style brakes and American carburetors, and therefore is much less dangerous, and does not need to be taken to a highly paid RR specialist.

 

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7 hours ago, Rusty_OToole said:

If you look at the illustration in Michael's second post above you will see the master cylinder clearly marked.

 

It's a little tiny worthless thing that is there as a back-up in the event the main system fails.  It only activates a piston on each rear caliper and doesn't do boo to stop the car in the event of a total system failure.    

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Gas Monkey Garage or Fast and Loud as it’s called did a RR project where they too trashed the stock hydraulics for a custom system.  They had some $$$$ to throw at it so it may have been more elegant in the execution but wound up doing the same basic thing to solve the problem.

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It's a little tiny worthless thing that is there as a back-up in the event the main system fails.  It only activates a piston on each rear caliper and doesn't do boo to stop the car in the event of a total system failure.    

 

So what? Take it off and substitute a real master cylinder.

Edited by Rusty_OToole (see edit history)

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