1. Brake & Wheel Systems
  2. Manual Brake Conversion

Why convert to manual brakes? Reduced engine bay clutter, eliminate a possible source for vacuum leaks, and especially less weight. The vacuum booster weighs ~8lbs. If you're building a drag car, that's a lot of weight.
I started off with the Mopar Performance manual brake conversion kit for the V8 cars. This comes with an adapter plate, a pushrod, and a master cylinder. The adapter plate won't work on our cars, and the M/C is the same as our power M/C anyway. And, the pushrod is too long. So, basically, I had to modify everything.

1st, I sketched what would be needed for an adapter plate and pushrod:
(the sketch is wrong, the tapped holes are M8, not M6)

CONFIG


The 4 outer holes are studs on the original booster (at least on my Daytona). I put M8 studs into them and just used the original nuts on the inside of the car (brake pedal bracket). I guess they don't have to be tapped, but then you'd have to have a buddy hold the wrench in the engine bay while you crawl under the dash to tighten the nuts.


FABRICATION

Here's the nearly finished pics. The adapter plate fits nicely. The studs I found (at the local Ace hardware) aren't exactly what I wanted. They're to long to bottom out on the adapter plate. So, I locktite'd them in place.

The Mopar Performance manual pushrod fits the Daytona brake pedal pivot perfectly, but it's way too long (~7"). So, I ran a die the rest of the way down the pedal end (it was only threaded about halfway) and cut 1-1/2" off of it. But, it was still ~1/2" too long. So, I took 3/4" off, then put it on the belt sander to re-make the spherical end. And also added a groove for an o-ring to keep the pushrod in the MC. Originally, the MP pushrod/MC kit came with a rubber ring that fits into the wide, deep groove on the pushrod (the groove can be seen in the pics above), that's meant to keep the pushrod from pulling out of the MC and causing - well a very bad situation. I think a simple o-ring will work just as well, though. And much easier to cut into the pushrod.

CONFIG
CONFIG


OK, so I finished the pushrod and assembled the adapter plate, master cylinder and pushrod to the car.

CONFIG


The brake pedal seems to fall a little further back now (closer to the driver), but it's not uncomfortable at all.

With just the manual M/C conversion, the brake pedal effort was too high. Stopping the car was no problem, but staging the car was nearly impossible. Any load on the converter and it would roll through the beams. So, I had to convert to a 20mm (manual brake Omni) master cylinder, Minivan 60mm front calipers to get decent brake pedal feel. I can now hold the car on the line and stall the converter.

I would only recommend this conversion for race-only vehicles where every single pound is important. It's too important a system for the street to risk compromising braking performance.

One final note: There were Omni's made with manual brakes up to ~'85. If you can find the parts from one of these, it would probably make for a simpler conversion. But, they're probably getting difficult to locate.
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