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Thread: 50/50 vs. 38/62 brake master cylinder

  1. #1
    Senior Member hippieman9's Avatar
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    50/50 vs. 38/62 brake master cylinder

    what is the difference in a 50/50 and 38/62 Master cylinder? I seem to have a 50/50 in my car. Looking to rebuild the brake system. should I go back to the stock 38/62?

  2. #2
    Senior Member DMC-81's Avatar
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    Quote Originally Posted by hippieman9 View Post
    what is the difference in a 50/50 and 38/62 Master cylinder? I seem to have a 50/50 in my car. Looking to rebuild the brake system. should I go back to the stock 38/62?
    The stock front suspension linkage (LCA, sway bar) is relatively weak. The 50/50 unit is from a Saab and while it works, it increases the braking load on the front brakes from 38 % to 50%. The original design is 38/62 because of the rear engine layout. It's up to you if you want to increase the load on the front under these conditions. I chose to stick with the stock configuration.
    Dana

    1981 DeLorean DMC-12 (5 Speed, Gas Flap, Black Interior, Windshield Antenna, Dark Gray)
    Restored as "mostly correct, but with flaws corrected". Pictures and comments of my restoration are in the albums section on my profile.
    2006 Dodge Magnum R/T (D/D)
    2010 Camaro SS (Transformers Edition)

  3. #3
    Senior Member hippieman9's Avatar
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    My VIN:    06668 81' Grey interior, 5 speed, Grooved hood. Previous owner of 16301, in 2001.

    Quote Originally Posted by DMC-81 View Post
    The stock front suspension linkage (LCA, sway bar) is relatively weak. The 50/50 unit is from a Saab and while it works, it increases the braking load on the front brakes from 38 % to 50%. The original design is 38/62 because of the rear engine layout. It's up to you if you want to increase the load on the front under these conditions. I chose to stick with the stock configuration.
    Oh ok, That is good to know. So am I to assume the 50/50 master Cylinders were all that were available for some time then? I see both are available from vendors.

  4. #4
    Senior Member DMC-81's Avatar
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    Quote Originally Posted by hippieman9 View Post
    Oh ok, That is good to know. So am I to assume the 50/50 master Cylinders were all that were available for some time then? I see both are available from vendors.
    Yes, that is my understanding, while the crossover list was critical, and before DMC had them reproduced.
    Dana

    1981 DeLorean DMC-12 (5 Speed, Gas Flap, Black Interior, Windshield Antenna, Dark Gray)
    Restored as "mostly correct, but with flaws corrected". Pictures and comments of my restoration are in the albums section on my profile.
    2006 Dodge Magnum R/T (D/D)
    2010 Camaro SS (Transformers Edition)

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    Senior Member DMC5180's Avatar
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    Also the front caliper pistons are larger than the rear pistons. By reducing the pressure to the front calipers and increasing to the rear, you end up with a more balanced braking force pressure of the pads to the rotor.


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    What's the difference inside the Master Brake Cylinder ?
    How is the 50/50 vs 32/68 done ?

  7. #7
    Customized Member 81dmc's Avatar
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    I switched to a Tesla master cylinder with a 50/50 bias, and my braking is a lot better than the original bias master. Also, lockup occurs almost at the same time in the front and back, so no issues there.


    Quote Originally Posted by DMC-81 View Post
    The stock front suspension linkage (LCA, sway bar) is relatively weak. The 50/50 unit is from a Saab and while it works, it increases the braking load on the front brakes from 38 % to 50%.
    IMHO, all DeLoreans should have LCA brackets installed, either from Owen (spittybug) or Ed @ DMCEU. If stability is a concern, save a few $$ buying a 50/50 master and reinforce the front end down the road....
    Rodolfo
    VR6 Swap in Progress...
    Delorean.eu Roof Box, Double Din, Custom Instrument Cluster w/Cruise, QA1 Suspension.

  8. #8
    Senior Member DMC-81's Avatar
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    Quote Originally Posted by 81dmc View Post
    I switched to a Tesla master cylinder with a 50/50 bias, and my braking is a lot better than the original bias master. Also, lockup occurs almost at the same time in the front and back, so no issues there.

    IMHO, all DeLoreans should have LCA brackets installed, either from Owen (spittybug) or Ed @ DMCEU. If stability is a concern, save a few $$ buying a 50/50 master and reinforce the front end down the road....
    Cool. I'm all for modifications if that's what you want for your car. My point was that if you're going to stay stock with the suspension, then my opinion is that the stock BMC is advisable as that's what the car was designed for.

    If you want to upgrade & strengthen the front suspension then sure, the 50/50 BMC is an option. The front would still be light however, so I don't see what advantage the increased bias provides. A side by side braking distance test would be helpful on that question.

    Although, after seeing the front wheels flexing backwards slightly under braking both on video and in person, I would suggest upgrading the suspension first before installing a 50/50 unit.

    Cheers,
    Dana

    1981 DeLorean DMC-12 (5 Speed, Gas Flap, Black Interior, Windshield Antenna, Dark Gray)
    Restored as "mostly correct, but with flaws corrected". Pictures and comments of my restoration are in the albums section on my profile.
    2006 Dodge Magnum R/T (D/D)
    2010 Camaro SS (Transformers Edition)

  9. #9
    Delorean Guru
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    if you change the tire sizes then changing the bias might be warranted. The reason the bias is so important is you do not, under any conditions, want the rear tires to lock up BEFORE the front ones. Because the Delorean is a rear-engined car, it has a VERY high polar moment of inertia. What that means is if the rear wheels lock up the rear end will try to swing around quickly. More quickly than most drivers would notice in time to correct.
    David Teitelbaum

  10. #10
    Senior Member hippieman9's Avatar
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    Quote Originally Posted by David T View Post
    if you change the tire sizes then changing the bias might be warranted. The reason the bias is so important is you do not, under any conditions, want the rear tires to lock up BEFORE the front ones. Because the Delorean is a rear-engined car, it has a VERY high polar moment of inertia. What that means is if the rear wheels lock up the rear end will try to swing around quickly. More quickly than most drivers would notice in time to correct.
    Right, Because a skidding tire travels faster than a rolling tire.

    I don't plan on changing tire sizes. I just was wondering why there were 2 different BMC. I have ordered a new stock style one and will be replacing it when it gets here. I have boxed in my LCAs just to help with stability too. as I have read that they are a weak point.

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