CJ3A Front and Rear brake Wheel Cylinders interchangeable ??

[patrickt]

 It's like 10pm over here,  so I will just take off I drum tomorrow  and send a pic of what it looks like inside. Though here is a picture I took from the internet of the back portion of a CJ2A, which looks exactly like mine.

[Rus Curtis]

...using a bigger bore master cylinder than stock normally results in less pressure output.....and results in less pedal travel since a bigger bore can push a greater amount of fluid with less movement of the pedal.

.........I understand as well that an undersized m/c will do the opposite, create a higher pressure output, which is nice of course, but result in a longer pedal travel, because of the smaller bore of the m/c, which takes longer to fill up the wheel cylinders......

.....the jeep in fact only had an extremely undersized 3/4-inch m/c ! .....And this was with the 1-inch wheel cylinders on all four drums......

 .....the rear wheel cylinder of the CJ3B that looked like mine, and that the fronts were totally different looks wise.......The pistons for the front by the way didn't seem to have the notch for the brakeshoes to mate with. Whereas the CJ3A wheel cylinders I saw had notched pistons for both front and rear, as well as the exterior looking identical to each other.

I follow your fluid mechanics and believe that is accurate.  Correct sized parts will certainly help. 

Oldtime has more hands-on than I do AND more reference material too!  My library is just a few books so far (all I have on Mitsu's is just pictures and the 3B Page).  I wouldn't think much difference between the 3A and 3B brakes (mostly the engine change over) and am speculating that the notch "may" be a manufacturer thing vs. what will work.  I've seen the notches (and smooth pistons) but (again, speculating) don't believe them to be that important to actuate the brake shoes.  Your shoes are still anchored the same way and travel is still limited within the drum.

On posting, you can use 3rd Party, i.e. Imgur or Flickr, or attach directly.  There's supposed to be a gallery here but haven't used it yet.

[oldtime]

The wheel cylinder pistons with a notch are 1941-1953 design.
Front wheel cylinder = A-1484
Rear Wheel cylinder = A-6110
Master cylinder = A-556

You can also use  1953-1958 parts essentially the same excepting the flat piston head design.
Front wheel cylinder = 807356
Rear Wheel cylinder = 807357
Master cylinder = 805223

After 1958 they use L=R wheel cylinders at the front.

I have those available for sale OEM NOS from the 1960's.
See: https://stlouis.craigslist.org/atq/d/saint-charles-willys-jeep/7007697619.html

[patrickt]

RUS and  OLDTIME - I will get back to you both, have to run to work (morning over here). Here's pics of my wheel cylinder.

[patrickt]

Pics

[patrickt]

another pic

[patrickt]

last pic of wheel cylinder

[patrickt]

           Okay, just to be on the very safe side, i decided to take exterior measurements of my wheel cylinder using a simple vernier caliper. Obviously not as precise as a digital one, but good enough for my needs.
            So may I ask if anyone who has access to his CJ3A (or 2A if you have one) 3/4 - inch rear wheel cylinder, can please check the same areas I measured on my wheel cylinder ? I would hate to order the wrong one, and have to pay international shipping fees, as well as restocking fees to return it to the seller (if they would even accept returns). I hope you guys understand... Thanks again ! Patrick

[oldtime]

#807356 = 1" Left + Right = Cast # FD 7228 (early 9" front)
#803639 = 1" Left = Casting #FD 9006 S2 (late 9" front)
#803640 = 1" Right = Casting #FD 9006 (late 9" front)
#807357 = 3/4" Rear = Casting #FD 7544 (all 9" rear)

The 1953-1958 CJ's used front cylinder #807356 with "S" tubes

All 1959-1971 CJ front axles with 9" Bendix brakes eliminated the "S" tube at the wheel cylinder.
Instead they use 11" flex hose attached at both sides of front frame.
The hoses thread direct onto the "rear ward angled" front wheel cylinder ports.
Hence RH and LH part numbers for the front cylinders only.

All 1953-1971 CJ's with 9" Bendix brakes use rear cylinder #807357

Got that ?

[patrickt]

Finally took off rear-right brake drum. Pics first, text to follow in a bit.

[patrickt]

I decided to include the axle shaft and hub flange.

[patrickt]

Drum off

[patrickt]

3/4 view

[patrickt]

Top view

[patrickt]

Adjusters