spongy/soft brakes
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Suspension, Brakes and Tires Discussion, spongy/soft brakes in Item Specific Cadillac Discussion; I have an 84 Eldo HT4100. The brakes are spongy and it does not stop well when going ove 30 ...
  1. #1
    tmgore is offline Cadillac Owners Member
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    Question spongy/soft brakes

    I have an 84 Eldo HT4100. The brakes are spongy and it does not stop well when going ove 30 mph. When I press on the brakes the pedal travels too far for my comfort. The brake light comes on dimly when I first start it up then goes out after @ 1 minute. I have a new m/c. It has 4 new disk brake pads. I bleed the m/c and all four wheels according to the factory manual.

    Please help, I have searched and searched with no success and I am afraid to drive this car. It runs well.

    Thanks in Advance,

    84eldo

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  3. #2
    Stoneage_Caddy's Avatar
    Stoneage_Caddy is offline Cadillac Owners 10000+ Posts
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    Re: spongy/soft brakes

    Quote Originally Posted by tmgore
    I have an 84 Eldo HT4100. The brakes are spongy and it does not stop well when going ove 30 mph. When I press on the brakes the pedal travels too far for my comfort. The brake light comes on dimly when I first start it up then goes out after @ 1 minute. I have a new m/c. It has 4 new disk brake pads. I bleed the m/c and all four wheels according to the factory manual.
    Please help, I have searched and searched with no success and I am afraid to drive this car. It runs well.
    Thanks in Advance,
    84eldo
    I would consider a few things if i were you , one would be to take the car to a shop that has a machine to bleed the brakes. After master cyalnder replacement it can have lots of air trapped in funny places that would take lots of time to force out ...

    Another thing i would consider is the flexible brake hoses. How old are they ? Sometimes as these age you can get spongy brakes , and sometimes a sticky brake on one wheel.

    How long ago were the brake pads replaced ? How many miles since ?

    Another issue i see is the pads or rotors glazeing , either due to not cleaning everything up when the brakes were installed or poor materials or workmanship on the turned rotors ....

    Just some things to think about , as i move this thread to the suspension brake and tire forum

  4. #3
    CADILLACSAM's Avatar
    CADILLACSAM is offline Cadillac Owners Fanatic
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    Re: spongy/soft brakes

    I Was Looking F/some 411 On The Same Problem. I Have A '80 Eldorado And I'am Having The Exact Same Problem, The Only Diff. My Car Sat F/almost 2yrs I Started It Up Regularly Jus Didn't Drive It . So Check The Mc, Rubber Brake Lines, And Also The Rotors Might Need 2 B Cut?

  5. #4
    Stoneage_Caddy's Avatar
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    Re: spongy/soft brakes

    it might be an idea to cut your rotors in your case if they have alot of surface rust on them ...but mroe than anything check for leaks , replace the rubber lines , then replace 100% of the fluid int he system

  6. #5
    carnut is offline Cadillac Owners Master
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    Re: spongy/soft brakes

    Both the 80 and the 84 use a rear caliper that rotates a piston inside it to force out the pad when the park brake is used. If the park brake is not used then the piston seizes in the caliper bore and the pad ,after worn ,will not span the distance to apply force to the rotor. Verify by starting car, depress park brake pedal HARD and hold it down, then put car in D, if the car moves forward, then the pistons are either seized or way out of adjustment. When these cars were 3 to 5 yrs old we used to remove the park brake cables from the caliper and ratchet the lever where the cable attached back and forth to rotate the piston out to the rotor surface, then reattach the cables and adjust them so no slack and the lever continued to rest on the caliper stop. After this many years I would assume the rear calipers need replaced with rebuilt because the pistons are in fact seized. The factory manual will explain the adjustment. This occurs because nobody uses the parking brake and use of it is the only way the rear brakes adjust for normal wear. I agree the surface of the rotor is important, not too smooth or shiney but a little rough to provide better friction and better pedal feel. If the rear brakes are working as designed, then depressing the park brake should make the car squat in the rear and hold the car at idle in gear. the park brake pedal should drop about half its travel to do this. Be very aware that improper brake cable adjustment will cause rear brake pads to drag and overheat. Any brake shop that was around during this era can replace the calipers with LOADED units that have pads in them already and know how to adjust the cables correctly. Good luck. and keep using the parking brake all the time!

  7. #6
    carnut is offline Cadillac Owners Master
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    Re: spongy/soft brakes

    As an aside, I would flush the fluid just because its old and will absorb moisture which can lead to seizing pistons in calipers and cause master cyls. to fail. Hoses are a good idea but not the first items on the list. The rear caliper issue was also a problem with Rivieras and Toronados as well. Every car would benefit by flushing brake fluid every 2 to three years, but then the brake repair shops would loose alot of income! German cars for years recommended fluid flushes every 2 yrs and rarely did calipers and masters fail! The hoses would deteriorate over time going to the calipers, but thats it.

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    CADILLACSAM's Avatar
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    Re: spongy/soft brakes

    Thank God!!!! The Cadillac Gods Have Answered My Prays!!! Finally Got Some Answers 2 The Questions I Asked. This Will Narrow Down My Troubles Now I Know Wat 2 Look For. Thank U Very Much.

  9. #8
    tmgore is offline Cadillac Owners Member
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    Re: spongy/soft brakes

    Thanks for All the info. It will help me remember the parking brake in the future. I bought this car because I liked the convertible model. I have done a lot of work and have it running well. I just had the brake fluid flushed today while having an inspection. It passed the inspection. As a rookie I was proud of the work I have done since the car was not running when I bought it. We have the EPA inspection as a part of it.

    The same brake symptoms existed though. The shop did some futher testing after flushing and said it was the M/C. The told me it needed a new M/C and it has to be a new one, not a rebuilt one. (does that sound correct?)

    They will replace it tomorrow. I will keep you posted on the outcome. Glad I found this forum again, I had lost it when my old computer crashed.

    Thanks,
    84Eldo

  10. #9
    carnut is offline Cadillac Owners Master
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    Re: spongy/soft brakes

    BEFORE the master cyl is replaced I would verify the rear calipers are working correctly. Master cyl usually bypass fluid internally or externally and cause pedal to drop slowly. With the rear wheels off and using a large screwdriver or pry bar move the arm connected to the park brake cables. It should move forward (towards front of car) about an inch and at that point you should not be able to rotate the disc by hand. Make sure and reinstall a couple of lug nuts so the rotor's not loose when you attempt to rotate it. If it moves more and the disc still rotates the rear caliper pistons are seized. Fix this first then re examine the master cylinder. Good luck and happy new year!

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    tmgore is offline Cadillac Owners Member
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    Re: spongy/soft brakes

    Turns out the M/C was a rebuilt on and had problems. Replaced it with a new one $263.00 parts and labor. There is some improvement. However the spongy feeling is still there. I put on a new driver side rear caliper and brakes a couple weeks ago. Maybe I need to replace the passenger side rear caliper. We set the parking brake according to the manual. Both rear wheels lock and the lever is raised about an inch or so. I also put the care in drive and pushed on the parking brake. It held still while idling in drive.

    One other thing, I can hear squishy sound (lack of a better word ) when applying the brakes, sounds like squeezing a sponge.

    Could this still be I need to replace the other caliper even though it works with the parking brake? I have no idea how old that one is. I can see the brakes look new.

    Thanks for the responses and patience,
    84Eldo

    Happy New Year

  12. #11
    The Ape Man's Avatar
    The Ape Man is offline Cadillac Owners Connoisseur
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    Re: spongy/soft brakes

    Replace all parts in pairs, left and right. Verify that your emergency brake cable sheath has not collapsed. Visual inspection by a seasoned meck-a-nik will work for this. Nail the service pedal and apply and release the parking brake lever until you turn Blue. You need a good pedal feel on the emergency brake before the service pedal can be expected to work properly. CarNUT spelled it out perfectly. Re-read his post. Pedal feel comes from the rear brakes. Sounds like the calipers have not ratcheted out properly.

  13. #12
    CADILLACSAM's Avatar
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    Re: spongy/soft brakes

    Quote Originally Posted by tmgore
    Turns out the M/C was a rebuilt on and had problems. Replaced it with a new one $263.00 parts and labor. There is some improvement. However the spongy feeling is still there. I put on a new driver side rear caliper and brakes a couple weeks ago. Maybe I need to replace the passenger side rear caliper. We set the parking brake according to the manual. Both rear wheels lock and the lever is raised about an inch or so. I also put the care in drive and pushed on the parking brake. It held still while idling in drive.
    One other thing, I can hear squishy sound (lack of a better word ) when applying the brakes, sounds like squeezing a sponge.
    Could this still be I need to replace the other caliper even though it works with the parking brake? I have no idea how old that one is. I can see the brakes look new.
    Thanks for the responses and patience,
    84Eldo
    Happy New Year
    AUTO PARTS GIANT WAREHOUSE SELLS THE CALIPERS ALREADY LOADED W/PADS MAYB THAT WILL HELP?

  14. #13
    carnut is offline Cadillac Owners Master
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    Re: spongy/soft brakes

    By stating the lever is raised about one inch do you mean with the parking brake set? or released. If the parking brake is set thats great, if you mean released then the cables are too tight. The squishing sound could be the rear caliper surface or because you fixed it the pads need to seat.

  15. #14
    carnut is offline Cadillac Owners Master
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    Re: spongy/soft brakes

    Also please be aware that with four wheel discs you are squeazing pads not pushing shoes against a drum, it does feel different. Disc brakes do not self energize like drum brakes do. Good to hear you are making headway!

  16. #15
    tmgore is offline Cadillac Owners Member
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    Thumbs up Re: spongy/soft brakes

    Ok,
    I took some time off working on the brakes to enjoy other things since this is a project and play car for me. I put the second new rear caliper on, the rear brakes adjusted (per carnut's outline), a new M/C, a new proprotioning valve (sensor quit working), flushed with new brake fluid, and brakes bled. Better but still not to my whishes.

    Someone suggested the following which I did. I put the car on jacks in my garage. I wrapped a shop towel around all four brake hoses and pinched each one with a small vice grip. The brake pedal was more firm now. I released the vice grips one at a time until the brake pedal became spongy again. It was the right front wheel. I replaced both front calipers (replace in pairs as suggested by The Ape Man). Bled the brakes and bingo!!

    Thanks Gentlemen, I learned from this and I will definitely remember Carnut's sequence and to set the parking brake.

    84ELDO

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