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Dual Diaphragm Power Brake Booster Conversion Kit (91-95 Jeep Wrangler YJ)

Item J12006
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$462.99 (kit)

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      Product Information

      Features, Description, Reviews, Q&A


      • Power Brake Booster Conversion Kit
      • Converts Single Diaphragm Brake System to Dual Diaphragm Setup
      • Creates More Braking Pressure with Less Pedal Effort
      • Reduces Stopping Distance and Increases Off-Road Capability
      • Heavy Duty Design for Extreme Off-Road Use
      • Comes with Master Cylinder and Power Brake Booster
      • 1 1/8 Inch Master Cylinder Bore
      • Requires 18 Inches of Vacuum Pressure at Idle
      • 12 Month / 12,000 Mile Warranty
      • Designed for the 1991 - 1995 Wrangler YJ Equipped with 4-Wheel Disc Brakes or Aftermarket Axles


      Specs. If you want to improve your YJ's braking capability both on and off the road, then you need this dual diaphragm power brake booster conversion kit from. It provides significantly more vacuum assist than your OE single diaphragm brake booster, which translates to more brake line pressure with less pedal effort. This will reduce your stopping distance out on the road, and improve your vehicle placement out on the trail.

      Construction. This conversion requires that your Wrangler create 18-inches of vacuum pressure at warm idle. We recommend upgrading your Wrangler OE brake lines to stainless steel brake lines since they resist brake line expansion which will help you to take full advantage of the added brake line pressure.

      Application. This conversion kit works with 1991 - 1995 YJ Wranglers.

      Fitment: 1991 1992 1993 1994 1995 Details

      MPN# DDB1

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (4)

      Write a Review

      Ratings Summary

      3 out of 5 overall rating from 4 customers

      • December 13, 2018

        1 2003 Wrangler - Leoner

        The fit was fine but...

        The fit was on par with the stock one, however, I installed it and it was leaking, I took it to a shop to fix it because, well, at this point, why not. They took it apart and put new seals in it. Also, the product image is not even close to what I got. I should post a picture of the one I got to show the differences. I'm honestly really disappointed.

        Helpful (13)
      • February 28, 2018

        2 1999 Wrangler - StevenM

        Fitment isn’t exact (99 TJ)

        Im in the middle of installation. So far, old brackets havent matched up to the new studs on the booster so I have to do some cutting. Also, it doesnt mention in the kit that you literally have to special order parts for 2 new brake lines that YOU have to custom make yourself. Thankfully they provide the part numbers.... towards the end of the instructions.

        Helpful (15)
      • January 26, 2017

        4 1989 Wrangler - Jking

        Significant difference

        Got this to completely rehab a brake system on my yj and boy did it! Braking is now really noticeably better and quicker! Install went pretty well and quick but removal of the old one was a challenge

        Helpful (18)
      • January 11, 2017

        5 1997 Wrangler - Justin

        Improved braking

        Really improved my braking.probably vut my braking distance in half

        Helpful (15)

      Questions & Answers (4 answers)

      4 Top Rated Questions

      Does this master cylinder have the same 1/2 and 7/16 port as the stock master cylinder

      • Yes, this item would have the same 1/2 and 7/16 ports as the stock master cylinder.

      Helpful (0)

      Hello. Does this come with the proportioning valve as pictured?. Is this a direct fit for a 2004 LJ or are modifications needed?

      • This does not come with a proportioning valve, you would re-use the existing one.

      Helpful (0)

      Will this conversion work with rear drum brakes and is it simple bolt on replacement? Thanks so much, Aaron

      • The Crown Automotive Dual Diaphragm Power Brake Booster Conversion Kit is designed for the 1991 - 1995 Wrangler YJ Equipped with 4-Wheel Disc Brakes, so unfortunately it would not work with rear drums. The install is also on the Advanced level of skill to install this conversion kit, it is not a simple bolt on install.

      Helpful (0)

      What is the size of the booster in inches

      • The Crown Automotive Dual Diaphragm Power Brake Booster Conversion Kit will have a 1 1/8" Bore master cylinder, however they do not have a listing of the booster diameter for this kit.

      Helpful (0)
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      Will It Fit My Wrangler

      • YJ Wrangler 2 Door - 91, 92, 93, 94, 95

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