CJ brake upgrade, part two

I posted this earlier today in the forum for the Jeep club I'm in and wanted to include it here.

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I came to another roadblock while re-wiring Mongo today. The optimas and the dual battery relay haven't come in yet, so there isn't much more I can do on the wiring harness. I wanted to get in a few hours worth of work, though, so I went back to the brake system.

recap: Mongo is a 75 CJ-5, 304, t15 transmission, manual steering and manual brakes. I've mounted the vacuum brake booster from a 1995 Grand Cherokee. The next step is to add the master cylinder from a 1985 Ford E-350 van. I chose this MC because I anticipate installing a disk brake conversion on the front brakes far sooner than the rear conversion and the rear chamber is significantly larger than the front. Once I do the rear conversion I'll switch to the master cylinder from a 1969 Stingray.

 

In this picture, you'll note that I've clamped the MC in a standard bench vise. remember when your Dad would yell "do as I say, not as I do!" when you were a kid? This is the same principle. The body of the MC can be distorted if you clamp it too tightly. Since my drill press isn't large enough to handle this MC, I cheated and clamped it in the vise. Whatever you do, don't clamp it around the cap as this will distort the metal before you've tightened the vise enough to hold the MC still for drilling.

Select a drill bit that is larger than the hole you're drilling out. It's a matter of personal preference here, as the holes only require a slight enlargement. If you run the drill in reverse, it won't get stuck (as it may running forward). Once you've got the new hole started, you can put it back in forward and apply greater pressure.

This picture was taken after starting the right hand hole. You'll note a small difference between the hole on the left and that on the right.

 

Once the holes are drilled out, you can see that the MC mounts flush against the brake booster with no additional grinding required. It is possible that, in other combinations, you'll need to grind the flanges outside the bolt holes. If this had been necessary, I would have hit it on a bench grinders wheels a little at a time. When you are trying to make a mounting surface flush, Take as little as possible of it at a time. It's a lot harder to grind the entire surface down to flatten it if you take off too much while grinding the edge of the flange.



This picture is another angle of the test mounting, now it's time to bench bleed this guy!

 

This is just a 1/4 inch extension from a ratchet/socket set. Use this to push the piston in.



This angle shows the extension inside the piston. The MC is again held in the vise used to hold it during drilling.

Fill each cylinder of the MC reservoir half full of new brake fluid. Push the socket extension in 3/4 to 1 inch within the piston and hold it for 20 seconds. Slowly, release the pressure, which allows fluid to be drawn into the channel and wait 20 seconds, which will allow air to bubble up to the top of the channel and into the reservoir. Repeat the process until all of the air bubbles are free. Gradually, the depth you are able to depress the piston will decrease to about 1/8th of an inch. Once there are no bubbles returning to the chamber, you've finished. Now, mount the MC on the vacuum booster, connect the brake lines (as quickly and neatly as possible.. the air you introduce here has to be bled out at the tires), and bleed the system. All done!

 

Another great addition. I look forward to the rest of your write-ups.

 

I'll keep them coming, sissy chrome valve covers and all