[Healeys] Brake issue

[Michael Oritt]

In yesterday's fiasco after a few miles of driving the brakes went to full
lock with no play whatsoever in the pedal, an d I had to pull off the road
and wait about 30 minutes until the pressure let off enough so that I could
make it back to the shop.  The consensus opinion, both on this forum and on
the Healey autox email list, is that there was not enough free play in the
master cylinder pushrod, thus preventing the MC piston to go past the
return hole and relieve pressure.

Earlier this afternoon, with everything cool, I put the car up on jack
stands and while under the car I actuated the brake while spinning the left
front wheel.  Whatever free play I had--or thought I had--last put into the
pedal linkage had disappeared and with no free play the slightest bit of
pedal movement brought about brake activation.  So after loosening the lock
nut I rotat the shaft about 1/4"-3/8" until there seemed to be the
appropriate amount of free movement and, again using moving the pedal from
under the car and spiing the left front wheel, there seemed to be some
gradual brake actuation.  So I locked the shaft down and went out for the
proverbial test ride.  At first all seemed good but as the engine warmed up
and after using the brakes several times with different degrees of
pressure, etc. I could again feel the brakes begin to drag and by the time
I got back to the garage the pedal height had changed with all free play
having disappeared.

I can't help but feel this phenom is--at least partially--related to heat
transfer into the MC.  It is very warm here in MD and, with the same pedal
shaft adjustment as yesterday, prior to temperatures going up there did not
seem to be any issue.  Then again maybe there has been some deterioration
within the MC and/or debris within the cylinder itself.

Anyway, I will make another attempt at adjustment tomorrow morning and
report back.  In the meantime thanks for the many helpful suggestions.
However it appears that more work needs to be done.

Best--Michael Oritt

On Sun, Jul 28, 2019 at 2:25 PM <warthodson at aol.com> wrote:

> Michael,
> You are correct in pointing out that there is known problem with the 100
> master cylinders. In addition, inadequate free play adjustment of the 100
> master cylinder could also cause similar symptoms. Adjusting the free play
> seems like the easiest thing to check first.
> Gary Hodson
>
>
> -----Original Message-----
> From: Michael Salter <michaelsalter at gmail.com>
> To: warthodson <warthodson at aol.com>
> Cc: Michael Oritt <michael.oritt at gmail.com>; Oudesluys <
> coudesluijs at chello.nl>; healeys <healeys at autox.team.net>
> Sent: Sun, Jul 28, 2019 9:11 am
> Subject: Re: [Healeys] Brake issue
>
> Regarding pushrod free play.
> Unfortunately the known problem with 100 master cylinders is internal to
> the cylinder itself and is not resolved by ensuring that the push rod has
> free play.
> Roger Moment wrote an excellent, and of course exhaustive,  article on the
> subject many years back after he encountered difficulties when using
> silicon fluid.
>
> M
>
> On Sun, Jul 28, 2019, 9:42 AM warthodson--- via Healeys, <
> healeys at autox.team.net> wrote:
>
> I still suspect the lack of proper free play in the brake pedal & this is
> the easiest to check. Simply adjust the free play, temporarily, such that
> there is excessive free play & go for a test drive.
> Gary H
>
>
>
>
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