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Dual Diaphragm Power Brake Booster Conversion Kit w/ 1 in. Bore (91-95 Jeep Wrangler YJ)

Item J12007
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Market Price $555.99 You Save 17% ($93.00)
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$462.99 (kit)

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      Product Information

      Features, Description, Reviews, Q&A


      • Dual Diaphragm Power Brake Booster Conversion Kit
      • Cast Metal, Brass Plates
      • Natural Finish
      • Matches OEM Materials
      • Designed as a Heavy-Duty, High Quality Conversion Kit
      • Converts a Single Diaphragm Brake Booster to a Double-Diaphragm
      • Requires 18 Inches of Engine Vacuum with Warm Engine Idling
      • Reduces Required Pedal Pressure, Boosts Stopping Power
      • 1 Inch MC Bore Size
      • 18.6 lbs (8.45 Kilograms)
      • Includes Booster, Master Cylinder
      • Warranty Until Installation
      • Fits 1991-1995 Wrangler YJ Models


      Specs. The Dual Diaphragm Power Brake Booster Conversion Kit, provides an excellent upgrade to your Jeep Wrangler's brake system. You will need to apply less pedal pressure to brake strongly after installing this kit, and your Jeep's stopping power will be noticeably raised for increased safety. The materials are the same as those found in the OEM single diaphragm booster, including cast metal and brass.

      Construction. A booster and a master cylinder comprise these Dual Diaphragm Power Brake Booster Conversion Kit, which weighs in at 18.6 pounds. This kit is a heavy-duty upgrade that converts the factory single diaphragm booster to a dual diaphragm system developing more brake force. With a 1 inch MC bore size, this brake booster requires 18 inches of engine vacuum in a warmed engine at idle. The warranty lasts until installation in recognition of high working stresses.

      Application. Fits 1991 - 1995 Wrangler YJ models.

      Fitment: 1991 1992 1993 1994 1995 Details

      MPN# DDB2

      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 (5 answers)

      5 Top Rated Questions

      I converted a 1988 yj to rear disc from terraflex and stainless lines from classic tube. braking still not the best. question it says it wont work for my year but with the rear conversion will it work?

      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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