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Brakes question

Started by STEVE CLC #16187, January 24, 2015, 10:04:49 AM

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STEVE CLC #16187

I have  a 1968 Cadillac Calais with front disc brakes.. When stopping you really need to push hard , and pumping don't help . There is very little pedal, they go almost to the floorboards. I checked the brake fluid and found only the secondary cylinder empty, the main was fine . There are no leaks in the MC or wheel cylinders . I Am likely going to have do a complete brake ,but I can't until this Fall. Would like a quick solution until then so I can drive it this summer. Appreciate any suggestions

Steve .
steve hales
clc # 16187

Bobby B

Steve,
  Hi. Are they Power assisted?  Need more info…...
                         Bobby
1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH

TJ Hopland

Quote from: CDV_Chumley on January 24, 2015, 11:24:19 AM
Well since fluid is missing, there has to be a leak. Maybe the fluid is leaking into the brake booster?

I suspect your master cylinder has a bad seal and is leaking. I would not drive the car. You're asking for trouble trying to stop a 5000 lb car with no brakes.

Also if the booster has fluid getting into it, the booster will eventually go bad also. So you might want to replace it too.

Same things I was thinking. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Bill Young

I got a new booster and master cylinder and they both were rebuilt and attached to each other from Rock Auto for like $130.00 for My '72 Eldorado. A good investment, I think it's the way to go. By the way, front disks on a '68 Calais is rare.
Bill Young

Bobby B

#4
Steve,
  Pull the vacuum line and see if there is any trace of fluid either in the line or a bad check valve will do it. Do you notice anything coming out of the tailpipe on de-acceleration, like it would with bad valve guides. Could be sucking down into the engine and burning. Do you notice any funny odor other than CO out of the tailpipe? Obviously, fluid is going somewhere. How long after you fill it and bleed it does it take to disappear? Are you 100% positive than none of the lines or cylinders/calipers are leaking very slightly and you just don't notice it? I chased a pinhole leak in a rear cylinder once that drove me crazy, until I pulled it apart. A rock hard pedal is usually a sign of a bad booster diaphragm, similar to the pedal before you start the car and vacuum is introduced at idle. You need to do some detective work. I'm sure you'll find out what's going on. Simple troubleshooting…….
                                                                                             Bobby
1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH

bill06447

It's not going to leak, the reservoir is empty. Fill it up and pump the brakes a couple times, you'll find the leak real quick.

Bill

R S Steven

Way back in high school I worked rebuilding brake boosters and master cylinders.  I would bet that the rear seal in the master cylinder, the front seal in the booster and vacuum check valve are bad.  GM's vacuum check valves didn't last as long as the Bendix ones did.  The diaphragm in the booster may also be swollen from brake fluid. 

STEVE CLC #16187

Thank you very much for the info guys. This information will give me a head start. I usually don't just fix the problem at hand , i end up doing a complete repair with all new parts, just the way I am. BTW this Calais is a loaded one with a lot of options. Thanks again guys I appreciate all the input.

steve hales
steve hales
clc # 16187

Bill Young

Very interesting Car. You say a '68 Calais that is loaded? The Calais models were usually fairly sparse as the Coupe DeVille came standard with power windows and 2 way power seat and the upgrade to 6 way was not a lot. A friend of My Grandmothers ordered new a '68 Calais coupe in silver with black cloth. It was ordered radio delete and had manual seat. She only ordered 2 options Climate Control and factory installed clear plastic seat covers.
Bill Young

Scot Minesinger

I lost my power brakes (brakes worked, power did not and no vacuum leak) recently on my 1970 Cadillac and the entire system had been replaced in the last 5 years, so replaced booster and master cylinder as a unit.  Not a bad job, you can easily knock it out on a Saturday with time to spare. 

If you replace the entire system, the rear metal brake line is difficult to remove clips above rear axel, just takes patience.  Also, the nut that connects the rear brake line to master cylinder is special and the replacement from u-line will likely be wrong (I had to cut u-line tube flare off, slide original flare nut on and re-double flare it-yes there was enough slack in the line to work well).  The rear rubber brake line is difficult to find, check the length before you start, as most advertised replacements are too short.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

STEVE CLC #16187

Quote from: Bill Young on January 25, 2015, 11:22:28 AM
Very interesting Car. You say a '68 Calais that is loaded? The Calais models were usually fairly sparse as the Coupe DeVille came standard with power windows and 2 way power seat and the upgrade to 6 way was not a lot. A friend of My Grandmothers ordered new a '68 Calais coupe in silver with black cloth. It was ordered radio delete and had manual seat. She only ordered 2 options Climate Control and factory installed clear plastic seat covers.
Bill Young

Bill ,  This is a 4 door hard top and I haven't looked at the ID plate yet but I do know it has  Automatic  Climate control. disc brakes, trunk opener, 6 way power seats, power windows,steering and brakes, also auto select am radio and rear  window defroster. Oh , and Cruise Control. Only driven it a few miles from where it was taken off the transport truck, that is how I found out about the brakes, going to check the check valve and vacuum booster today.

steve
steve hales
clc # 16187

cadillacmike68

Are you sure it's a Calais? What is the first letter of the VIN?

68 Discs are uncommon.

When you get it all fixed, replace the fluid with DOT 5 - silicone. It doesn't rot out lines , rubber, or eat paint like the glycol based fluids (DOT 3 and 4).
Regards,
"Cadillac" Mike

Julien Abrahams

I would also take a good look at the VIN :). To me it does not make a lot of sense if someone ordered a Calais, then load it with options like power seats and power windows (on top of all the other options).
Here is a link to the Data Book for the 1968 Cadillacs. Kind of cool to see what the options and color combo's were :).
https://www.gmheritagecenter.com/docs/gm-heritage-archive/vehicle-information-kits/Cadillac/1968_Cadillac_VVI.pdf
1954 Cadillac series 62
1967 Cadillac Sedan De Ville HT
1969 Austin Healey Sprite
1979 Opel Kadett

Gene Beaird

#13
Steve, it sounds like a nicely-appointed Calais.  Compared to your car, our 68 is missing the disc brakes, auto-select radio, trunk opener, rear defroster and cruise control, but has the other options.  It was probably easier to order a Calais that way than to try to get a SDV or Fleetwood without a vinyl roof! 

As far as the brake fluid leak, depending on which brakes you have (Delco or Bendix), you may be able to just replace the master cylinder, but I agree with others, your MC is leaking into the brake booster, and the fluid is probably getting sucked into the engine.  That's the way ours was leaking, but most was running down the front of the booster and dripping onto the frame.  It was quite a cleanup required to get the mess fixed.  The Eastwood Cadmium finish paint did a very nice job of making the brake booster look brand new. 

Gene Beaird,
1968 Calais
1979 Seville
Pearland, Texas
CLC Member No. 29873

Jeff Rosansky CLC #28373

Give them a very good bleed before you start replacing things.
When I picked mine up a couple of years ago, I had almost no brakes for the drive home (That was fun by the way).  Turns out the rear system was empty.  I guess the seller put some fluid in the master but the lines were completely dry.  I tried to bleed them and nothing came out....Thought just a plugged bleeder so I took it off and still nothing.  Finally attached a clear hose to the bleeder and sucked.  Horribly think engine oil colored fluid finally came thru.  The car had been sitting for a long time so I don't know what really happened.  Have driven it a year and a half and the brakes still work fine and haven't lost a drop. 
Jeff.
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Raymond919

How long to get that taste out of your mouth?

Jeff Rosansky CLC #28373

I learned that lesson years ago.  That's why I used CLEAR tubing.  Can see it coming!
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille