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72 Dana 30 Disc Brake Swap

Discussion in 'Early CJ5 and CJ6 Tech' started by Seadiver5, Jun 30, 2017.

  1. Jul 17, 2017
    Seadiver5

    Seadiver5 New Member

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    One more question related to this swap and that would be the best combination/proportioning valve to use. I've read a lot of conflicting information. If anyone can enlighten me on the best and why and the part number I would very much appreciate it.
     
  2. Jul 17, 2017
    Focker

    Focker That's a terrible idea...What time? Staff Member

    WA
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    Are you wanting an adjustable one?
     
  3. Jul 17, 2017
    Seadiver5

    Seadiver5 New Member

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    What are the slight differences in outer axle shafts that you mentioned and would it be better to swap spindles or reasonable to just run the newer spindles with the old axle shaft?
     
  4. Jul 17, 2017
    iharding

    iharding Quitter

    Tacoma, WA
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    Feb 24, 2013
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    I bought D30 u bolts and spring plates with the dual shock mounting pins. I cut off the pins on the wrong side, and had to grind off some spot welds to drive off the spacers on the remaining pins. Then I needed to improvise spacers for the outside of the shock since the pins are "too long". I can take some pics if this doesn't make sense.

    I did not use a proportioning valve. I did remove the internal check valve on the front circuit and added a 3 lb residual pressure valve. The rears lock up first and it stops really well so I'm happy.
     
  5. Jul 17, 2017
    Focker

    Focker That's a terrible idea...What time? Staff Member

    WA
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    I used 2 RPV's.

    Brake Conversions
    [​IMG]
     
    Muzikp likes this.
  6. Jul 17, 2017
    Seadiver5

    Seadiver5 New Member

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    Not particularly but what's the good argument for one?
     
  7. Jul 17, 2017
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    The rear axle gets really light on severe braking. Most of the braking is done by the front axle anyway, but the weight transfer increases with severity of braking (which increases with increased capability). You don't want the rear axle to lock up before the front - this will make the back end come around if you are turning, and put you in a spin. Ideally you want the front and rear to lock up at the same time... an adjustable proportioning valve is a way to dial this in. You could also change the cylinder diameter of the rear brakes and experiment till you have the performance you want.

    I presume there is a safety advantage to having even braking power front and rear, regardless of braking severity. That would be the most controllable on all surfaces.
     
  8. Jul 17, 2017
    Muzikp

    Muzikp Active Member

    Sacramento Ca.
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    Focker you are running a 10lb on the rear and a 2lb on the front? I was just looking through your disc brake thread and didn't see the 10lb one. I thought you were using a 2lb on the rear only. Assuming after the initial install you found this to be a better setup?
     
  9. Jul 17, 2017
    Focker

    Focker That's a terrible idea...What time? Staff Member

    WA
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    I had to add a 10lb to the rear when I installed a new MC. The new one didn't have it built in.
     
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