I still have my booster bypassed and I dont have trouble stopping the car but do have to aply alot of force to the pedal. But if you dont have any leaking wheel cylinders as evidenced by fluid all ove the inside of your wheel and you havent been putting out alot of smoke indicating fluid being sucked from the booster into the intake maniofold and burning like mine did then look for the other place that min did bad. Pull up the carpet by the gas pedal and brake pedal and I bet you floor is completely saturated like mine was from fluid leaking out the back of the master cylinder and thru the hole in fire wall and running down under the carpet. Thats just what mine did and I tell you before I found it It was a real mystery to me where it was going.

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Pat McCusker
1963 220B

Pat/Mark - thanks for the information - I managed to pull out the bolts for the master cylinder yesterday afternoon before I broke the bulb on the worklight and didn't have any replacement bulbs. In any case, I will look at the carpet again and see if the fluid is there, although didn't notice any stains on it. There is none in the resevoir at all, and when I was unscrewing the brake lines from the master cylinder, there was a little brake fluid that came out. I would rather have the stuff all over the carpet than a leak in the servo...

So with regards to this bypass - where do I route the line that goes to the booster now - is it just disconnected and the point in the master cylinder is blocked with another fitting? What has to happen on the vacuum end? Also, I have seen no smoke, the car starts and runs really well, stopping is another story... however, if I can't find the fluid, I will have to assume it has gone into the booster - although I haven't run the car a lot lately. If the fluid is getting sucked into the intake from the booster, is this bad news for the engine, or does it really matter?

Do you know how much a rebuild is on the booster and why is there only one place that seems to do it? I would have thought this would be a reasonably common problem with older cars.

Sorry for all the questions - brakes are a new thing for me...

Rory

The servo's were one way to add power assisted braking to cars until the mid '60s, by which time the integral vacuum brake booster / master cylinder combo was almost universally adopted. The servos were mostly used on cars where the brake master cylinder was location under the floor or mounted in a tight space, close to the clutch master cylinder or other obstruction, where there wasn't room to accomodate an integral booster. The servo had the ability to be mounted anyplace on a car, but had the disadvantages of more complex plumbing, the additional potential for leaks at the servo cylinder and the usual requirement of fitting a larger bore brake master cylinder.

The servos were used on some American and foreign cars in the '50s and '60s, including Buick, Ford T-bird, Mercedes, Volvo, Sunbeam sportscars and Rover sedans.

My experience with a faulty servo involved a 1967 Sunbeam Alpine. It had a Girling servo which, unbeknownst to me, would leak brake fluid internally, especially if the car was parked for an extended time, like over winter.
One spring day as I left my driveway, my brake pedal went to the floor. Fortunately, my handbrake still worked! The Sunbeam's Girling Servo, like the ATE unit on my Mercedes, has the vacuum fitting mounted fairly high up on the vacuum chamber, so a considerable amount of brake fluid will accumulate inside before it can be sucked out and burned. I was able to order a Girling servo repair kit from my local Volvo dealer. Meanwhile, I installed a bypass fitting / union to connect the two brake fluid lines to each other, instead of to the servo cylinder. I left the vacuum hose connected to the servo but I could have disconnected it and plugged the nipple on the intake manifold if I had needed to. My Sunbeam was driveable while I waited for my rebuild kit, but I strongly disliked braking without the power assist. If I had permanently eliminated the servo, for more acceptable brake operation, I would have installed a smaller bore brake master cylinder, as used on the early non-servo Sunbeam Alpines.

I don't recall what Patmccusker said his servo rebuild was going to cost. As I recall, 'Joshol' also had the servo rebuilt on his Fintail, with mixed results. Try a Forum search for their postings. You may also find other rebuilders in 'Hemmings' magazine.

I went to look at the ATE servo on my '60 Fintail 220Sb.
If yours is like mine and it turns out that your leak IS in your servo. It looks like you could install a union to connect the servo two fluid lines together.
This would involve some bending/strain on your original metal brake lines. Or you could make up a bypass loop from some new brake line and fittings and bypass the servo lines at the brake master cylinder. Like my Sunbeam, If I needed to permanently bypass my Fintail's servo, I'd want to eventually replace my brake master cylinder with a smaller-bore brake master cylider from a non-servo Fintail.

Happy Motoring, Mark

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DrDKW

My servo repair from Will Samples was going to cost approx 300. but he was going to do a repair and not a rebuild. The servo has two brake lines going to the master cylinder. remove them both and I bought a one foot section of brake line at autopart store with metric fittings and bent it and put it on . Attached is a picture showing which two ports are jumped. I agree that it would be much better with the booster working and If I had more ambition mine would be fixed. I am sure when I find time to spend seriously looking for seals I will find them. Probably over the winter when I'm not so busy but you can take the thing out and remove the drain screw from the bottom and see what comes out. I got about a quart of the ugliest liquid you ever saw. So to sum up bypassing it is a temporary fix but you can drive the car with out it. I am actually used to it and it is not bad.

Attached Thumbnails

 

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Pat McCusker
1963 220B

forgot to mention , the vaccuum line is a metric 12 mm (.472) inside dia tube. I turned a piece of hard plastic in a lathe to .472 dia about 1 inch long for a tight fit and stuck it in there and put a hose clamp on it and it doesn't leak.

__________________
Pat McCusker
1963 220B

Pat - thanks for the photos - I think I will go the same route and do the by pass. I think we have the same set up (the light switch on the master cylinder). On mine, I am pretty certain that the line for the booster comes from the passenger side bottom of the master cylinder. Where you have your bypass lines seems to be where I have other brake lines for the four brakes. The fitting on the bottom which I am certain is for the booster is quite a bit larger that the other brake line screw on fittings - I am actually having a little trouble trying to get it off.

I emailed Will Samples today and he sent me an email back saying that this booster cannot be rebuilt - seemed to me that I thought it could be rebuilt from what I was reading in some of the other threads.... so I am puzzled about that. Still no sign of the master cylinder kit, but I will worry about that part when it comes. Will wanted the VIN# and he was going to do a little research about what I could do. I don't mind sending the thing down to him to rebuild, alhtough I would rather have a kit and do it myself, and save some money and learn something at the same time.

Also, one guy I know said I should replace all the brake lines, but I think that if they are OK, then I should leave them since replacing them all would probably be expensive and a pain in the backside.

Oh yes, how did you get the fittings on to the piece of brake line that you bent into shape? I will see if I can get a picture of mine later on and try and figure out how to post it for all to see.

Rory

On my '60 220Sb Fintail, the servo lines are connected to the master cylinder at the same places where Pat's bypass line is connected. If you're standing at the radiator, facing the firewall, one line from the servo is screwed into the port at the vertical/12 O-clock position and the other is screwed into the port above the brake light switch at the one 0-clock position. That second port is slightly to the rear of the others. Both of my servo lines appear to use the same size nut at the master cylinder.

If they haven't been replaced in recent memory (say 10 to 15 years) it's recommended to replace all of the RUBBER brake hoses. If the metal lines aren't badly rusted, I'd leave those alone.

Happy Motoring, Mark

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DrDKW

Well - got under there again tonight, and yes, my arrangement is the same, the two lines that Pat bypassed are the same on mine with those going to the booster. I am having a heck of a time getting the master cylinder out though, the two bolts go through the firewall, with the nuts and washers on the engine side of the firewall, I managed to get one nut off, but the other just spins the bolt, and it is quite impossible to get a wrench around the bolt on the other side... any tips would be appreciated as this task is going more slowly that I had hoped!

Rory

Got the rebuild quote from Will Samples this morning: $800. It is a little rich for my blood, so the alternative looks like no power assisted braking, which, is fine by me. I will take the booster out, clean it, and empty the fluid out of it, plug the vacuum line and leave it where it is, and then bypass the booster per Pat's instructions. Still can't get the master cylinder out though (the one spinning bolt on the firewall).

Rory

Rory, good technique for snagging bolt thats impossible to reach is try sneaking a 12 pt. socket onto it held between two fingers and then work from there.

I have tried that already (when you say 12 pt, I assume you mean the 14 mm ratchet?), anyway, tried to work that over the head of the bolt on the driver side to hold it, but there is not enough room for the 14mm ratchet - there is a black metal flange (for lack of a better word) where the pedal goes through the firewall, with the bolts on either side which leaves no room for playing with the bolts.... very frustrating! Tonight I will see if I can wedge a flat head screw driver underneath it to stop it from turning, and I will try and get the nut off on the other side.

Rory

No, not the ratchet..... just the socket

And then figure out how to grab the socket...... This worked for me using socket with vise-grips on 114/115 starter bolt (allen) on bell housing thats impossible to reach.

Sorry - yes, I meant the socket - there is not enough room between the hex bolt head and the flange wall to put the socket on, nor is there enough room to bend the metal flange to make room for it... I think I will try the flat head screwdriver method tonight. My wife came to help last night (trying to hold the bolt whilst I turned the nut in the engine compartment) and I think finally realized why I come back up with cuts and covered in grease... will let you know how it goes tonight.

What do you all think about using a screw type plug in both of the booster holes in the master cylinder instead of the brake line piece? Is there a reason why they both need to be connected together? I would think there is some sort of screw type device that will thread into the socets where the booster lines originally went.

Also - is there anywhere I can buy a replacement master cylinder? I saw one on Ebay from a guy in Portugal, but I think it doesn't have the brake light switch fitting.

Thanks
Rory

the way the master cylinder works is there is only one port comming out of the master cylinder it self and thay line goes to the power booster. the front of the master cyl where the brake light switch is screwed in is actually a seperate chamber and not actually connected to the inside of the master cyl. the one open port goes to the booster then the return line from the booster goes to that front chamber and feeds all the wheel brake lines and the switch port and the jumper goes from the only outlet of the master cyl to the chamber that feeds the other ports so it has to be connected that way. It takes two people to remove the master cyl. Believe me you can get a wrench on the back of those bolts up under the brake pedal by the steering colum inside the car while somebody else turns the wrench on the firewall. Will originally said it couldn't be rebuilt because he doesnt have any more seals. It is hard to find them. If you want to see part of my recent search for seals check my thread called t50 /26 booster on MBCA(mercedes benz club of america) web site. The booster is a pretty simple thing inside and really only a few little seals to replace. If I find a source for the seals Id do them for 100. I have a feeling that your booster is OK because you have no smoke. rebuild your master cyl first and see what happens. Once you get the master cyl apart you will be surprised by how simple it really is. When you put it back together be sure to run a tube from the top bleeder to the resevoir and push the piston from back and bleed it before you re install it. forgot to mention that the brake line I bought at auto part store allready had fittings on the end. Two dollars.

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Pat McCusker
1963 220B