DeTomaso Mailing List: April 99, Message #163

All,

A big thanks to everyone who gave me advice on my brakes.  I've finally got
them to work after a combination of standard pumping foot
pedal/gravity/return tube back to master/MityVac bleeding.  The car now
stops really well even with light pedal pressure.  However, if I push down a
little harder, the pedal still feels springy, so I'm convinced there's still
air in the system.  I took the car to a brake specialist but he couldn't do
any better.  Jerry at PIM where I bought the new master cylinder said that
it has a large enough swept volume for the four piston Wilwoods I've got.

So, should I just expect springiness in the pedal, or should I persevere
with the hard pedal Holy Grail?

Also, the 'brake specialist' put DOT4 in the system.  Is this going to cause
seal perishing problems as some people have suggested before?  He said that
if a system is DOT3 compatible then DOT4 is fine too. 

Thanks

Max 

		-----Original Message-----
		From:	Max Watson [mailto:MWatson@alphablox.com]
		Sent:	Tuesday, March 23, 1999 12:11 PM
		To:	Multiple recipients of list
		Subject:	Brakes - a g a i n !

		Hi 

		Some of you might remember from some time back that I wrote
to the list
		describing a brake failure I had (75mph, traffic, no parking
brake - thank
		god for engine braking!) and that I was having trouble
fixing the
		problem(s).  I had bought and fitted a new master cylinder,
removed the
		proportioning valve and replaced with a T section, bought
and fitted a
		second hand differential valve (the old one was cracked at
one of the "well"
		designed 90 degree internal edges - read stress
concentration!) and bled the
		brakes.  This was all done in my company parking lot, but I
found the new
		master cylinder to be defective.  Bummer.

		Well, I finally towed the car back from work and into my
garage, got another
		new master cylinder, bench bled it and then bled the system
using a MityVac
		- and still no joy.  The pedal travels straight to the floor
with little
		resistance.  There appear to be no leaks anywhere in the
system.  I've
		tested the master cylinder by fitting a couple of blanked
off tubes and the
		pedal is rock hard, so I presume the booster and m/c to be
ok.

		So, what the heck am I doing wrong?

		I figure if a seal was blown in one of the calipers, I'd see
fluid leaking
		out.  Is there some trick I have to do with the pressure
differential valve
		to enable bleeding (I've heard other people talking about
problems with
		this)?  Could there be an air pocket trapped somewhere?
Help!

		Thanks in  advance,

		Max
		(Pantera-full, but haven't driven it in months.)