|[an error occurred while processing this directive]||Short Cuts|
By: Terry L. Howe - 9/2001
|The master cylinder and booster attached to the firewall|
|A front view of the chopped swing arm pedal|
|A side view of the chopped swing arm pedal|
|The proportioning valve mounted below where the master cylinder is mounted.|
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. I wanted to have a dual cylinder master cylinder and disk brakes up front. I also wanted power brakes because I was planning on running an automatic transmission.
The first step in the brake swap was to convert to a swing arm brake pedal. The stock CJ-2A uses a pedal through the floor and the pedal is mounted to the frame rail. Pedals that are mounted through the floor can bind up if the frame and body get twisted up, I didn't want this. I bought a swing arm brake pedal from a CJ-7 with an automatic transmission. I wanted the donor to have an automatic transmission so that I would get the wider pedal making it less likely that my foot would slip off the pedal.
It turned out that the distance from the firewall to the dash on a CJ-2A is less than the distance on a CJ-7, so I had to shorten and modify the part of the pedal swing that mounts to the dash. Engine clearance and clearance from the gas pedal forced me to mount the swing arm to the left of the steering column. When there was clearance for the master cylinder and booster, the pedal itself was too long, at the wrong angle, and too far left. I cut the pedal and welded it back together with a piece of 2x2 square tubing to readjust the pedal angle and length. I wanted to be sure that I could get a full throw on the pedal in case I needed a full throw to stop. This puts the pedal in a pretty awkward place, but I have gotten used to it.
On the dash side of the swing arm pedal, I shorten the swing and drilled some holes through it. To attach it to the dash, I welded a piece of angle iron to the back of the dash with some holes through it. The pedal swing is bolted to the firewall and to the bracket welded to the back of the dash. This keeps it very securely attached.
The master cylinder and power brake booster needed a flat surface to mount to that would clear the engine and hood. I placed it about as close to the hood as I could and in the end, it doesn't rub at all. I bought the master cylinder and power brake booster from a CJ-7 thinking this would make it easier to use it with my swing arm pedal. I was kind of wrong on that.
The CJ-7 uses a bracket to relocate the power brake booster and I could not use the bracket. The other complication was the bolt pattern on the two sides of the bracket were different. I welded up the old holes in the pedal swing and redrilled it for the booster bolt pattern. Next, I took the push rod from the swing and the push rod from the relocation bracket. I cut the two push rods and welded them back together to get the two halves that I needed.
The Buick 231 V6 came from a donor that had power brakes, so it was a simple matter of hooking up the vacuum hose to the booster. I ran brake lines from the master cylinder to the proportioning valve which was pretty tight on the hood, but it clears.
The proportioning valve is actually from a late 70s Scout II. It was just a vehicle I was parting out and it had a nice proportioning valve. The Scout II drum cylinders and calipers are about the same size as the ones I was using on the CJ-2A. I mounted the proportioning valve just below the master cylinder to keep it out of the way. Since the brake lines from the proportioning valve go to the frame rail, I put a spring shaped loop in both lines to absorb flex between the body and the frame.
Disks and Drums
When Pieces and Parts was finally ready to hit the trail, it had drums in the back from a '78 Cherokee and disks up front from the same vehicle. The drums are big 11"x2" drums which are much larger than stock. I didn't see the need to go with disks in the back, the drums have been fine and they are a lot less expensive. The disks up front use the large calipers and fat rotors found on late 70s Cherokees. The stopping power is excellent for such a light vehicle.