Let’s face it—the stock 9” drums and pitifully small single well master cylinder Jeep put on these old CJ’s were fine for the agricultural use they were marketing the Jeeps for at the time.  But they’re unsafe for any sort of average road use in today’s world. 

After years of double-pumping the brake pedal, hoping that a lazy wheel cylinder wouldn’t cause an unexpected lane change, I decided to upgrade the brakes.  There are a number of options available to the early CJ owners - junkyarding for later model Jeep parts, disk conversions, etc.  I elected the kit of new parts approach and bought the 11” drum kits available on the aftermarket.  Going into overkill mode, I also decided to convert the head-end of the braking system to power and convert to a firewall mounted dual master cylinder.  After much deliberation of donor vehicles a friendly Jeeper suggested a late-model CJ.  Duh!

The Junkyard Trip
Donor was a mid-80’s CJ7.  I bought the M/C, boost unit, proportioning valve, pedal hanger and pedals for $125 - but this was around 1992. The price may or may not have been great - I was just happy to find the parts since *any* CJ parts are scarce in Michigan.

The Master Cylinder
I pulled the stock “placebo heater” and using cardboard made a pattern for a metal firewall patch. The best mounting spot turned out to be on the engine side as far inboard as possible without interference between the boost unit and V6 dipstick. On the interior side this put the pedal hanger so it butted up to the steering column on the inboard side. Using the holes in the pedal hanger as a pattern I marked the cardboard and took that to a sheet metal shop for fabrication.

The Pedal Hanger
Note that I only installed the CJ7 brake pedal, the clutch setup on the CJ5 remains stock. The pedal hanger bolts to the firewall on the front, and on the back I just made up some metal straps that reach from the hanger to the bottom lip of the dash.

The Brake Pedal

The mounting location for the pedal hanger made the CJ7 pedal hang left of the stock CJ5 clutch pedal. The CJ7 pedal was also quite long and wouldn’t swing as needed. I took a piece of coat-hanger wire and bent it into the shape pedal I thought would work - basically coming down from the CJ7 pedal hanger, turning right for about 7 inches (to clear the steering column), then turning back towards the floor with a slight bend up. I took that wire and the stock CJ7 pedal to a fabrication shop - one of those great 2-3 guy operations without a computer in sight. They cut the CJ7 pedal and using the top bushing and 3” or so, added the metal from there down to match the shape of the wire. It took a couple of fittings to get it just right but the guys at the shop were great and wouldn’t take my $$ until it worked.

The Proportioning Valve
I mounted the ‘87 proportioning valve right where the stock ‘66 master cylinder mounted.  The bleeding instructions called for some special tool, but unable to find that I just bled away and things worked out.

The Results
This was all done at the same time as installing 11” drums all around. Performance (with dry brakes) has been great - hardly a 1/2” pedal travel to stop on a dime. With wet brakes...well...just that rollover thing... The only gotcha? I have a 1-pc ‘glass front end, and did all this work with it pulled off. When I went to put it back on, I suddenly realized that the boost unit and M/C stuck out quite far...farther than the V6 does. The front clip wouldn’t clear as it swung down...so out came the jig saw and now I have a big hole in my inner fender…