Master cylinder push rod - ran out of travel.

Hi,

I have a super, and am thinking of changing my Master cylinder. With
my current one, I have run out of adjustment on the pushrod, it is out
as far as it will go, and I still have excess travel ( more than 1/2
inch) before it contacts the plunger in the master cylinder.

THe only thing I can think of as to what would cause this, is that the
spacers between the body walls were lost and the previous owner
compressed the walls when putting on the new master cylinder(?). I am
thinking I have to replace the master cylinder as I cannot get this
adustment correct. What else can it be?

Thanks

Matt S

Matt S wrote:

> Hi,
>
> I have a super, and am thinking of changing my Master cylinder. With
> my current one, I have run out of adjustment on the pushrod, it is out
> as far as it will go, and I still have excess travel ( more than 1/2
> inch) before it contacts the plunger in the master cylinder.
>
> THe only thing I can think of as to what would cause this, is that the
> spacers between the body walls were lost and the previous owner
> compressed the walls when putting on the new master cylinder(?). I am
> thinking I have to replace the master cylinder as I cannot get this
> adustment correct. What else can it be?
>
> Thanks
>
> Matt S
>

The adjustment isn't made at the pushrod.
There is a bracket bolted to the floor
which acts as a "stop" for the pedal.
The stop can be moved fore and aft (if the bolt will loosen)
to adjust the free play.

Speedy Jim
http://www.nls.net/mp/volks/

The adjustment must be done as a combination of moving the pedal assembly
forward or back, where it is bolted to the tunnel and adjusting the position
of the stop plate. The face of the brake and clutch pedals need to be
vertical and there must be 190mm of brake pedal travel (before the pedal
hits the front cross panel), for safety reasons. Once this has been
achieved, the pushrod can be adjusted to give the pedal the correct
free-play with the master cylinder.

Be aware that pushrods fitted to late model Mexican Bugs are shorter and
should not be used, unless with the corresponding master cylinder.

>"THe only thing I can think of as to what would cause this, is that the
> spacers between the body walls were lost and the previous owner
> compressed the walls when putting on the new master cylinder(?). I am
> thinking I have to replace the master cylinder as I cannot get this
> adustment correct. What else can it be?"

If your suspicions are true you should be able to crawl up under the
wheel well and see if the MC is sitting up tight against the outer wall
of the cabin. If it is not, then you should remove the bolts and see if
you can get the spacers out of the body(assuming the last person to
change the MC dropped them into the body. If not, you'll need to obtain
some replacements.

Tightening down the master cylinder without the spacers will compress
the inboard 'skin' of the body, and I've seen the metal fracture around
the bolts as a result. Every time you press on the brake pedal with the
thing incorrectly assembled, the force of your foot gets carried by the
thinner panels on the inside of the car body. The spacers are designed
to put the clamping force on the OUTER skin where the metal is thicker.
The other thing that you might be dealing with is rust on the outer
layer of the body. You should be able to see what is happening very
easily by removing the pedal cluster and removing the master cylinder
bolts. The spacers are critical. Both of my bugs were missing the
spacers, and I was able to find some by talking to Mario @ vintage auto
werks. Might want to give him a call if yours are missing.

Chris

> wrote in message ...
> Tightening down the master cylinder without the spacers will compress
> the inboard 'skin' of the body, and I've seen the metal fracture around
> the bolts as a result. Every time you press on the brake pedal with the
> thing incorrectly assembled, the force of your foot gets carried by the
> thinner panels on the inside of the car body. The spacers are designed
> to put the clamping force on the OUTER skin where the metal is thicker.

The thickness of the metal on both the inner and outer walls, where the
master cylinder is mounted, is the same. However, you can't torque the
bolts properly, through a box section. With the spacers installed the inner
wall simply acts as a positioner which resists any tendency for the m/c to
deflect under the magnified foot pressures. As a further caution, the holes
in the inner wall are almost as large as the bolt heads (so as to accept the
spacers), so it is possible to eventually push the bolts through the holes
completely!