How to: NBS master cylinder swap for firm brake pedal

Discussion in 'Tech Info' started by _Dylan_, Apr 14, 2013.

  1. _Dylan_

    _Dylan_ STAY FROSTY

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    How to swap out the squishy brake pedal for a firm brake pedal. The OBS trucks are known for a horrible squishy brake pedal.

    -NBS 1500 series master cylinder (mine was from a junkyard truck, IIRC it was a 2001)
    -AGS BLF 26C brake line adapter (I got mine at autozone)
    -DOT 3 brake fluid
    -master cylinder bench bleeding kit

    The OBS master cylinder has different sized ports. One is 9/16-18, the other is 1/2-20. The NBS master cylinder is 1/2-20 on both ports. This is why you need a 9/16-18 female to 1/2-20 male adapter. AGS makes an adapter #BLF 26C that I got at autozone. It was behind the counter, so ask for help. The bench bleeding kit was also behind the counter.



    I first attached the adapter.

    Then I bench bled the master cylinder. There are plenty of videos on youtube showing you how. In my case I used the kit and cycled the piston with a 3/8" socket extension against a tire stop. :lol:

    A77CB675-5586-4D67-B827-50D149F29306-1967-000007CF71281AA8_zpsee829e54.gif

    Then I removed the 2 brake lines and removed the 2 nuts holding the old master cylinder on the brake booster.

    picture of old master cylinder:
    1DC09C94-7CBF-4FFC-944D-0EF64BA39933-1967-000007CF62F17238_zps8bbb2c5b.gif

    Bolt the new cylinder cylinder on with the 2 nuts. Then gently bend the brake lines to reach the holes. The NBS master cylinder is shorter than the OBS master cylinder.

    Only thread the nuts back on just a little, enough to let brake fluid and air leak past.

    Inside the truck use an object to press down on the brake pedal and hold it down. This may get brake fluid spray on the surrounding area, cover with a rag to catch any spray.

    If the lines haven't leaked, loosen up the nuts just a tad on the brake lines to let out any air and let some fluid drip out. Then tighten all the way up.

    Release the brake pedal after both lines are tight.

    Very little air should be in the system. If you think there still may be air, go ahead and bleed the brake lines.

    Finished product:
    6779432A-FDC1-4664-B773-89E48A202169-1967-000007CF787CF2E0_zps2a172af8.gif

    Enjoy the firm pedal your truck should have had. :D
     
  2. SunlitComet

    SunlitComet OBS Jedi-Do Good

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    you did not just find out about this upgrade did you?
     
  3. _Dylan_

    _Dylan_ STAY FROSTY

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    uhhh yeah I did. About a week ago.

    Get off your high horse.:emotions34:
     
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  4. Gzes

    Gzes the drifting 2dr

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    Lol. Yea alot of us knew about this mod for a good while just i didnt do it because my dad was giving me bs when i got the new one so i had to get the obs one. You should have done a brake test for both.
     
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  5. _Dylan_

    _Dylan_ STAY FROSTY

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    The brake reaction time is much faster. The firm pedal begins braking after maybe a inch of pressing down. The original one didn't start braking until my foot was halfway to the floor.

    I don't think that many people know about it either. I don't know why sunlitcomet is bashing a how to thread. Keep everyone in the dark buddy. :emotions34:
     
  6. SunlitComet

    SunlitComet OBS Jedi-Do Good

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    just wondering it was in a few threads this year as well as the booster upgrade. thought you knew already. at any rate if you go hydro their will be some modding to the booster needed to make a nbs fit.
     
  7. slipping

    slipping Full Access Member

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    I didn't know, will be looking into this. Don't usually see NBS at my yard though.




    Do you have thread handy? I'll look for it later tonight. Being lazy right now.
    Found it.
     
    Last edited: Apr 14, 2013
  8. _Dylan_

    _Dylan_ STAY FROSTY

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  9. Monstar_est87

    Monstar_est87 Full Access Member

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    Sweet write up Dylan... Ive heard of this swap b4 but I thought it was only meant for the hydro boost... Either eay its gonna help alot of people out there...
     
  10. slipping

    slipping Full Access Member

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