In a message dated 4/10/99 6:29:41 AM Pacific Daylight Time,
<< I'm on your side Bill. Just not 100% sold on pressed in liners. Have heard
the stories of slippage as well but don't know anybody who has had it happen
to them. >>
I wouldn't hesitate to try it on the street cars, but I have enough on my
mind as I mentally weigh the exact moment to nail the brakes at speed, going
into a downhill hairpin, without nagging doubts about the brakes.
Maybe the reason that I am a little gun-shy is that some years ago, I was in
just that situation, going into a corner at close on 130 mph, and nailed the
brakes. So far so good, but what happened then was a little annoying. The
Twincam brake pistons use an aluminum seal retaining plate that is held to
the piston by two screws which are locked by little conical lockwashers. One
of my screws had worked out as the lockwasher had fractured and fallen off.
The screw was held between the back of the calliper bore and the piston by
the tight clearance, until the pad wear reached a point where under extreme
braking, the screw fell out and lodged behind the piston.
Net result was that when I let off the brakes, all but that cylinder
released. I might have been able to control it, except for a friend in a
Morgan, who was right in front of me. I had to let it spin, probably at only
about 50 mph, and wound up backward against an Armco barrier with one door
torn off and a slash in my seat 2 inches from my arm.
Ever since, I refuse to race with anything other than the later pattern
Dunlop pistons, with the backing plate pressed/peened onto the piston. It may
not make much difference, but I swear I can go just that little bit deeper
into the corners knowing that I have eliminated at least one of the things
that can screw up.
It strikes me about the linered pistons, that you are introducing another
variable that may or may not be significant, but that it is better in
principal to avoid such uncertainty, at least in the systems essential to
life (mine and the car's).
I am copying this to the MG list as some of them might be interested in
Dunlop brake stuff.
I would add that I have never done the hard chroming on small cylinders like
the master (I use a tandem cylinder and balance bar), so I don't know if it
is possible to do on small diameter stuff. The result on the calliper halves
was quite thick, and required regrinding to size - the same effect as liners,
except that the metal is electroplated instead of being glued.
A friend who is a crack machinist once made up some new stainless calliper
halves that used a Datsun seal kit, with stainless pistons for his E type.
Beautiful work and very effective. When Lofty England was out here and saw
them he just harrumphed and asked why he bothered! Different strokes, I guess.