I have a 61 Mk2 sprite, and have been trying to upgrade to the later double
acting piston brake system. I bought a used differential housing from
about a 68 midget and took the brake backing plates off and installed them
on my car, with the other brake hardware. When I put the drums on, they
hit the backing plates. Around 1/16" was ground off the drums, which
allows the car to go straight, but when I go around a corner the drums
scrape the backing plates near the bottom 1/4 of the backing plates. The
drums are deep enough to be contacting the backing plate on corners. I
checked the backing plates with some others, and they seem to be identical;
there is nothing bent or defective. I then measured the differential
housing on my car (quarter eliptic) with the one I took the brakes from.
It turns out that my car allows the bearing and hub to slide in about 1/8"
further than the newer differential housing. The part that stops the hub
from going all the way in to the center is about 1/8" longer on the new
car. The old original backing plates were curved towards the center of the
car, so the drums would not contact them. But the newer backing plates are
not curved as much, and so the drums hit the backing plate. I've thought
about simply putting a spacer between the drums and the axle, but would
prefer to do things right and figure out what went wrong. I know several
people have done this conversion without trouble. I did take the backing
plates off of a wire wheel car, but I thought all of the later backing
plates were the same. I'm using my original hubs, and also put new wheel
bearing in. I'd sure appreciate any help on this; I've spent a LOT of time
trying to figure out what went wrong.
Ric Otte
otte@cats.ucsc.edu
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Richard Otte
Department of Philosophy
University of California, Santa Cruz
Santa Cruz, CA 95064
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