11" Drum Upgrade - Can You Do Just Front?

Hello,
I'm upgrading the brakes on my M38A1. It has the 4 cylinder engine, 5.38 axles, stock diameter tires. I'm getting an overdrive this winter.
Is is possible to upgrade the front brakes to 11" drums and keep the rears at 9"? I remember from auto class that the front brakes do 80% of the work. I'm not sure if the expense of upgrading the rear brakes would have any real benefit.
I have a functional transmission brake so I don't need a parking brake for the rear wheels.
Thanks,
Ken

 

Front 11s and rear 9 is better than all 9s.
But you may consider front disk and put those 11s on the rear...
(I hate eccentric 9s they never come out even)

 

That's how mine is set up right now, made a huge difference

 

That would be a good reason to upgrade the rear...self adjusting brakes. If you can find the 11" backing plates, the cost is not that much.

 

Hi Ken -

In hard braking, the rears are mostly tasked with keeping the rear wheels from coming around and putting you into a spin. Most of the braking force is applied by the front wheels. When you have 11s front and rear, the cylinders of the fronts are larger by 50% so that front and rear tend to lock up at the same time. Jeep later (ca 1974?) added a proportioning valve for the rear wheels, which adds even more front axle bias in hard braking.

One additional reason to go to the 11s in the rear is parts cost. The Bendix 11s were used on millions of vehicles, including the F100 Ford pickups. There's still a good market for these parts, and multiple brand-name suppliers. With the 9s, the market is limited to a few unmodified CJs still on the road, and you have few suppliers with little incentive to keep the price down and quality up (ie Omix).

 

Parts availability on the 9's was a problem for me and one of the reasons I went with 11's all around.

 

I did 11" fronts. Big difference, easy job.

 

Parts availability and cost are why I went 4 wheel disk. caliper brackets are a lot cheaper and adjustment is pretty easy. It's a grind however getting the calipers to clear the knuckles. Now I need 3 point seat belts to keep myself from kissing the windshield.

 

The problem is not you kissing the windshield. It's the windshield kissing you back. Just saying.