Subject: Time:12:59 PM
OFFICE MEMO 120 discs, MGA calipers Date:10/20/93
William Woodruff wrote:
>I am working on a friend's XK 120. He is interested in
modifying the brakes. I guess it is common to use the disc brake
setup from an XK 150. As far as I know, the 150 has a four wheel
disc brake system. Does anybody know what is involved in this
conversion? Is it worth changing the rear over to discs? My
feeling is to only modify the front. Would I have to get some
sort of a biasing (sp?) valve to get the correct front/rear
braking pressure if I only convert the front? How about the
master cylinder - does it have to be changed? Any idea of the
costs involved?
Talk him out of it. The drum brakes in my 120 are fine if properly adjusted. He
only needs discs if he is going racing. To convert to 150 discs you also need
the power assisted master cylinder, a vacuum source in the intake manifold, and
I think the entire rear axle. Not worth it unless you get the parts car real
cheap. The early 150 discs with round pads are a pain to change. The later cars
had square quick change pads.
MGA calipers with stuck pistons: drop them in a bucket of diesel fuel for a
week, maybe a month. Yes, I said a month! Then you need three things: patience,
more patience, and even more patience. If you can't find any of the above, try
a penetrating oil called "KROIL", our shop has had good luck with it. Heat up
the outside of the caliper around the piston and drop ice cubes or liquid
nitrogen in the cup. Eventually the piston should loosen up so pressure from
air, brake line, or grease gun should get it out. Don't separate the halves
until you've tried everything else.
|