78 Seville Brake Mystery

[John Mann]

Please help !!!
My 1978 Seville has some strange brake problem. I can only slow the car to a stop. This is a real problem. We have replaced the master cylender, the callipers, and the pads We have a reasonable pedal and all lines seem to be fine.The fluid is not low. Something is not working !!! I will try any suggestion as it is time to put the car on the road for the summer.
Thanks for the help.
Best,
John

[Rhino 21150]

Something is sticking. I would suspect the front calipers first. Jack her up, pull the front wheels and have someone press on the pedal while you try to turn the rotor. If you can turn it, the caliper is frozen.
You also need to check the proportioning valve. Loosen the bleeder on the caliper and press the pedal. If fluid squirts and the caliper doesnt move, it is frozen. If little or no fluid comes out, suspect the valve.
If all the above works, start all over in the rear.
Good luck!

[Michael Stamps 19507]

Im assuming here because I can only slow the car to a stop. doesnt make sense.  I like my brakes to slow me to a stop.  Anyway ... I assume you mean they lock up and dont release.  You say that all lines seem to be fine but I suspect they are your problem.  A way to check is to release pressure at different points in the system when they lock up.  By doing a divide and conquer you will find where the stoppage is.

Stampie

PS - Just thought about it more and you cant really divide and find the problem.  I would start at the MC by releasing the lines.  Then work your way down to the calipers.  Are all wheels locking up or just one or ... more info needed.

[JIM CLC # 15000]

05-09-06
John, Just a wag But I would put my money on the flex hoses in the system.
Good Luck, Jim

[John Mann]

Thanks fellows:
I see that I did not explain the problem very well. Ill try again.
When I apply the brakes, the car slowly comes to a stop. No matter how hard I push the brake pedal, it takes forever to stop the car.
It does not seem to pull in one direction, so I do not think that only one caliper is working. Seems that none of them are making good contact. Or that there is not much hydrolic pressure getting to the calipers. This was not the case when the car was stored for the winter. All was well then.
Best,
John

[Dave CLC#18575]

Seeing as you have replaced so many of the parts, It sounds to me like it could be the brake booster.  I dont know much about how they work or the $ involved.  I think I would begin there.

Dave

[David Harrison]

   I had a similar problem with a 65 convertible after I replaced the booster.  There is a metal pin (a bit thicker than a pencil, but I dont know what else to call it) that transfers pressure from the booster to the back of the master cylinder.  If the pin is too short for the booster/master combination, the pedal seems relatively fine but not enough pressure is getting to the master to stop the car efficiently.  Basically it feels like you are always just lightly applying the brakes no matter how hard you press the pedal.  If the problem started after you replaced the master then this could be it.  

David

[Norm Ellis]

John:  I really think you need to put your Seville back in storage and buy my beautiful 71 Fleetwood; the brakes work great and, even if you cant stop, that six foot long hood will give you time to duck.  BTW, when are you going to come down to see it and/or have coffee?  Regards, Norm.

[John Mann]

Hello Norm. I am at home, as you can tell. Row up in a few days and we can look for that air cleaner.Hope you can tell one from the other.
Be sure to let me know a day or so before so I know to be here.
This Seville is giving me heartburn. Like any beautiful woman that is miffed at being left alone far too long.LOL
Fellows----I am also thinking it is the booster. But shall look into all the other suggestions as soon as the monsoon stops.
Best,
John

[Gene Moscicki]

John
These 4 wheel disc brake cars are difficult to get the rear brakes working properly. Does your emergency brake function properly? If not the problem is with the rear calipers. Best advise I can give is to read up in a shop manual and adjust the arm on the caliper. In the past I have driven a car with simmilar braking and after a week or so the problem went away.
Make sure all air is out of the system!! I do not think the booster is a problem.
I have had many of these cars and they all are the same.
Good luck
Gene