68 Cadillac MM Combo (Restore thread)

the peddle going clear down on start up says leak in the booster. Buster Dewy did a nice job on Paul's 69 it came back looking new. one listed on rock auto now but the pictures is not the same as yours. with them mixing and matching the systems knowing what you have is necessary before ordering one.
one more advantage sending it in is they know.
 
Yeah im going to end up doing that. The reason I was looking for a replacement is because I had planned on bringing it to a friend who would help me with installation, and if I remove the booster then I wont be able to get it to him if the brakes are inoperable.

But after learning what I've learned this week about the master cylinder and booster, and after re-reading the shop manual again it doesnt actually sound that hard.

I will be honest, all this time I always thought the master cylinder was a big drum or cylinder under the car. All these years I never realized the master cylinder was the container where you fill the brake fluid.

With that knowledge it sounds alot simpler than I had initially imagined. Before I knew that I thought I needed to jack the car up to disconnect the master, but now i see all i need access to is the engine and the steering column
 
brake pedal the pivot is on the shaft one bold there, 4 to hold the booster to the fire wall two to hold the master cylinder to the booster. no need to remove any lines except the vacuum hose. get a coffee can or a plastic jar with a lid. put everything you take off in there and put the lid back on. take pictures while you remove for reference on how to go back . set the car were it's out of the way and block the wheels first. if your working on the ground a FEMA roof (blue tarp) under neath will catch what you drop and you can find it.
a month from now as you go back together you will be able to find everything and look to see any question you have. remove the rod from in front. before it leaves you. if the back of the master cylinder is wet. you will need to rebuild it also.
 
If the back of the master cylinder is wet, then you will need to purchase a new master cylinder. The commercial chassis master cylinder the lines come off toward the engine. The other cars, the lines come off facing the drivers fender. As for rebuilding the old master cylinder, it isn't difficult, however, finding a kit for it will be. Rock Auto lists a kit for the commercial chassis, however, after doing some checking, I find that it isn't the correct kit. I did a master cylinder rebuild a few years ago for a PCS member, and I searched for over a month until I was able to find the correct kit for his car. It also was a commercial chassis 1968. That kit also fits the Eldorado, and they don't show a kit for the Eldorado in the online catalog. It is a one year only part according to my parts book, but my book ends with the 1968 model year. Further research indicates that it is a one year only part. It uses a complex system of rubber cups, and that is what makes it unique. You might benefit by reviewing this thread...
 
Paul Steinberg said:
If the back of the master cylinder is wet, then you will need to purchase a new master cylinder. The commercial chassis master cylinder the lines come off toward the engine. The other cars, the lines come off facing the drivers fender. As for rebuilding the old master cylinder, it isn't difficult, however, finding a kit for it will be. Rock Auto lists a kit for the commercial chassis, however, after doing some checking, I find that it isn't the correct kit. I did a master cylinder rebuild a few years ago for a PCS member, and I searched for over a month until I was able to find the correct kit for his car. It also was a commercial chassis 1968. That kit also fits the Eldorado, and they don't show a kit for the Eldorado in the online catalog. It is a one year only part according to my parts book, but my book ends with the 1968 model year. Further research indicates that it is a one year only part. It uses a complex system of rubber cups, and that is what makes it unique. You might benefit by reviewing this thread...
Click to expand...

Good information, thank you. I will look into cleaning it out soon. I have noticed that recently the outside of my master cylinder has begun rusting quickly. Its been extremely humid here lately so i thought maybe that was to blame, since I've seen no loss of fluid anywhere and the levels have been unchanged since I've bought the car, never have had to fill it once.

After reading that thread though I will clean this out. At the very least I can clean out the mud from the reservoir to start. Thanks for the heads up, brakes are pretty important on a car this heavy, or any for that matter. I still have brakes, just not power brakes, so im limiting my weekly "maintenance driving" to my neighborhood for now until i fix it.
 
east wood has a cast gray that is a 2 part epoxy paint that is brake flued resent.
you get two pint cars that you only need a small amount of to paint the master and it stays looking new. I do all my cars with it,
 

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I will look into that paint. I actually wound up on the eastwood site this morning when looking into the best method for sanding paint.

https://garage.eastwood.com/tech-articles/how-to-strip-automotive-paint-the-tools-and-procedures/

Going to be making a trip to harbor freight on my lunch break and probably will be picking up an angle grinder and some cleaning disks.

I've been giving this thought for a long time now on the best way for me to tackle the rust given my limited time slots. Currently my plan is to spot sand the paint off, take care of rust and then clean, primer and apply some temporary spray paint to prevent the primer from absorbing water and rusting if it takes me too long.

The goal is to do a little each day, and cover it up each night with paint to protect it and get most if not all done eventually.

I'm aware that in the end its going to look rather splotchy if im spot painting, but once thats all done I will be properly painting it.

I'd love to do it all in one shot, but as I dont have a place to cover it or keep it out of the elements this is what I have to work with. I also know that realistically i should expect to eventually uncover something nasty that will need some body work done.

And Ed's words to me in another thread still echo to this day "temporary fixes are the most permanent ones"
 
I did some follow up research, and found a reference in an old Delco catalog that you can use the 1969 - 1970 commercial chassis rebuild kit to rebuild the original 1968 commercial chassis master cylinder, with the exception of the limousine. The kit is the same, but the master cylinders are not. Can't explain what the differences are, but the book doesn't show them to be interchangeable.
Paul
 
I would think a little bit on your ida. as you might be greting more trouble for you self down the road. look the car over good rock chips and surface rust are not a problem. they will clean off will with some paper . but you get a number of different products on the car you will end up striping all them off before you can paint. what you need to be doing is making sure the drain holes in the doors are open. Being as it's a MM I can say one at least will be covered over unless someone else has drilled them out. be sure you don't have any rust coming threw from the inside out. spend you money on a decent car cover will do ore then anything else to preserve it. you buy anything right now get the molding door handle and trim pad clip set from the HF . take the doors one at a time and go inside them open up the drain holes flush out the mud treat the bottom with the rust converter and paint inside there with some fish oil base primer. this will prevent then doors from rusting from the inside out. and it's nothing you need to strip off when you re do it. lub the moving parts on the inside and then button the door up go on to the next one.
 
Your right on those doors, my rear passenger window has gaps between the glass and the frame on both sides, rainwater just goes down into the door so i am sure theres alot of gunk down there. Good idea. I will give that a shot.

I did go to harbor freight today (first time ever), and was amazed at the prices. I ended up getting an angle grinder, a few abrasive wheels, gloves, magnetic bowl and a piece of firesteel all under 40 dollars. I may have to start going there more often
 
for a one time hobby guy they will work. but if you have never worked in a shop before I would suggest that you get the how to paint your car DVD from Eastwood. there are a lot of hints on it. just remember is is geared to selling you Eastwood tools. some of which are harbor fright painted blue. but I was for real when I sad get a decent car cover for it it the best thing you can do for a outside car. I had on over this 53 for 10 years before I moved it inside.
 
I was asked to post a picture of my master cylinder / booster. Was able to take a new picture yesterday. Here it is. Also I was curious, is this the original floormat or an aftermarket that was placed in the passenger coach area?

I'm inclined to think its original, as it seems to break rather easily. Its not brittle, but the torn part tears more very easily. Realized this when I was drying some water back there from all the recent rain and it was wet under the mat. I picked the mat up and set it out to dry and that little torn bit almost ripped all the way off.
 

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a after market the original was gray and would have the MM logo on it. they are a rare bird. that master cylinder is not the correct one for the CC the lines should come out on the left.
 
bit my tongue it is here is the one off my former 68. it was just painted with the east wood paint.
 

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Should have also painted the booster, or sent it out for gold iridite plating.
 
Paul Steinberg said:
Should have also painted the booster, or sent it out for gold iridite plating.
Click to expand...

yes but I had the epoxy mixed up, and it was a use it or loose it thing. that stuff goes a long way. don't remember whose car I was using it one when we did the quick toss the hood up and paint trick. to use it up. a acid brush works great to spread it around. this booster was painted black from the factory.
 
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