Consider this a draft post that I’ll be expanding.

Jim mentioned in one of his emails to me that he once test drove (and purchased) a CJ-2A with stock brakes that stopped so fast, it surprised him.

Jim wrote, “The old guy I bought this sweet (seen to the right) all original 2A from laughed at me when I test drove it. I hit the brakes and about put my face through the glass, not normal for a Willys right? I asked what he had done, I had already looked underneath and knew it had stock drums. He laughed and said youll figure it out young man. Master cylinder was stock, brakes were stock but this thing would stop on a dime like no willys I had ever seen. Under the passenger side, I found a 1950s era huge vacumn powered brake booster, done so well it looked like a factory item, just brilliant!”

That got me looking around the internet and found a great page on the CJ-3B site about some power boosters that were offered as early accessories on CJ-3Bs. To the right is an image of a brake booster from the CJ-3B site.  These boosters were used along with the stock 9″ brakes.  There’s debate on the CJ-3B site about the wisdom of using the boosters with the 9″ brakes due to heat build up issues.   It’s an interesting solution if you only use your jeep occasionally, but probably not the best solution if you are going to use it often.

The JP website has a nice historical look at jeeps and brakes.  As 4x4wire.com puts it, “The stock brakes on a CJ-2A are frightening by modern day standards. They use a single cylinder master cylinder that has no redundancy and small drums all around. ”  So, there’s good reason to update those older brakes if you plan on seriously driving your older jeep.  There’s a variety of web page “how to’s” on upgrading brakes on older jeeps.   I’ll have to do some web searching to find the good ones, but here’s a draft list of options (and the options could vary depending on the front and back housing you run):

1. STOCK BRAKES: Stick with your stock brakes, stock pedals and stock master cylinder.
2. BOSTER PUMP: Add the booster pump.  Here’s info about the booster pump.
3. SINGLE TO DUAL MASTER CYLINDER: Change your single master cylinder to a dual master cylinder
4. 10″ BRAKES: Upgrade to 10″ brakes.  I had 10″ brakes on my Dana 44 that I pulled off a mail jeep.  I’m not sure where you find 10″ backing plates from the front.
5. 11″  BRAKES: Put on 11″ brakes.  You have a couple options, you can use 11″ backing plates from a 60’s J-10 or redrill later-model backing plates (such at CJ-5 or CJ-7 backing plates from mid 70s).  Here’s a discussion of both options from the CJ-2A site.
6. HYDRO-VAC: Install a Hydro-vac unit.  I ran across this as part of the sale of a jeep.  Apparently, these little devices were used on Trucks and Buses to improve hydraulic pressure. Here’s an image of one and more info.
7. EARLY DISC BRAKES: Put on disc brakes from a mid 70’s chev truck. Here’s more information on it.  & Here’s a great overview from a Pirate 4×4 installation of disc brakes on a ’47 CJ-2A.
8. LATER DISC BRAKES: Put disc brakes on the front from a late 70’s early 80’s CJ-5 or 7 (if you are running a dana 30).  Though the knuckles for a Dana 30 from a drum and a disc might look similar, they have slightly different outside bearings and slightly different knuckle shapes.  So, if you use a disc brake setup on a knuckle designed for drums, you’ll need to grind a little off the back of the knuckle.  Here’s one link on the subject.  Here’s another Dana 30 drum to disc swap discussion.

Here’s some additional links

• This discussion at Pirate 4×4 looks useful, though I haven’t thoroughly vetted it
• Here’s  discussion about converting a Dana 27 to disc brakes
• Here’s a detailed look at putting Chevy Disc Brakes on an early Bronco
• Here’s a great, detailed look at changing early Dana fronts to Discs at the earlyCJ5.com website.  It also includes links to other websites that discuss brake issues.
• At Jeep Forum there’s a number of blown up images of Dana 30 CJ-5/7 disc brake schematics
• Early jeep brake conversion from Jp Magazine

(Willys Brakes — Jeep Brakes — Upgrading Brakes)