Brakes Question

Discussion in 'Technical' started by TeeEl, May 4, 2023.

  1. TeeEl

    TeeEl Senior Member

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    I noticed that the early Mavericks with 8-inch rear-end list a rear wheel cylinder with a smaller (7/8") bore than the later Mavericks (15/16"). I am wondering what the benefit of the larger bore is. I know front disc brakes became standard for '76 models. Is there a reason that a larger bore rear wheel cylinder would work better with having discs up front?...
     
  2. greasemonkey

    greasemonkey Burnin corn

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    Less brake pedal travel.
     
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  3. bmcdaniel

    bmcdaniel Senile Member

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    That's my guess, too. Disc brake pads don't have to move as far as drum shoes so the larger cylinder moves the shoes with less pedal travel.
     
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  4. TeeEl

    TeeEl Senior Member

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    Upon further research, according to the information I've read, larger bore wheel cylinders for rear wheels will cause rear brakes to apply more force and make pedal stroke a little longer.
    This seems to explain the longer push-rod and higher pedal on the '74-'77 models with manual brakes...
     
  5. greasemonkey

    greasemonkey Burnin corn

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    That makes sense of you think about it. I was thinking backwards.larger bore master would make it shorter travel.
     
  6. Krazy Comet

    Krazy Comet Tom

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    Large bore cylinders move more fluid, increase braking effort. Offset by adding power brakes.
     
  7. CaptainComet

    CaptainComet Large Member

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    When we added disc brakes to my 72 Comet, I found it necessary to add an adjustable proportioning valve to DECREASE how well the rear brakes were working. We did not change the wheel cylinders to the larger size (didn't know that was a thing). The car was locking up the rears too easily after the change. The larger bore cylinders likely would have fixed that.
     
  8. TeeEl

    TeeEl Senior Member

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    I had noticed that '76 and '77 calls for the 15/16" bore while all the previous years call for the '7/8". The '75 Granada rear-end on my Maverick also calls for the 15/16" bore.
    Obviously front discs were optional for Mavericks in '74 & '75. I'm pretty sure '74 didn't even have a proportioning valve. It looks like these brake systems gradually "evolved" over a few years...
     
  9. CaptainComet

    CaptainComet Large Member

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    Instead of a proportioning valve, they had a combination valve that I believe had Prop function along with housing the sensor to tell you the brakes crapped out.??

    Someone help here, I am firing some really old brain cells trying to remember this. LOL.
     
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  10. Krazy Comet

    Krazy Comet Tom

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    Right...

    Through '69 disc brakes used separate distribution/pressure differential block & proportioning valve. Beginning 1970 the porp valve along with brake differential was integrated into the dist block. Drum brakes used a dist block/pressure differential without proportioning. Other than mounting, one on my '69 Fairlane was same as Comet.
     
  11. TeeEl

    TeeEl Senior Member

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    That's what I mean. The '74 distribution block looks just like the '71-'73, and the fittings are the same size, including on those with the front disc option. '75-'77 is different. Different size fittings, and mounts differently as well. It appears to me that '74 was the only year that used that distribution block with disc brakes...
     

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