Re: 10.1 brake question--The Truth! (long)

[Mash <type53@yahoo.com>]

--- Dave Ewing <rabbit16v@prodigy.net> wrote:
> I upgraded my rear discs and 10.1" brakes before
> doing the master cylinder
> and didn't have any problems.

What year and model car?

  I did upgrade to the
> bigger master soon after
> that and the pedal did seem better but not
> dramatically.
> 
> I also disagree with the proportioning valve ideas
> on the list.  The
> proportioning valve restricts the amount of
> fluid/pressure going to the rear
> so as not to create an out of control rear lock up
> situation.  On earlier
> cars (and some later) they have a level sensing
> proportioning valve

Some have none - 1975-1980 Sciroccos . . .

Are you sure that these are level sensing? My Bentley
specifically says "This proportioning valve is not
load-sensitive and cannot be adjusted" (ignoring any
Rabbit or Pickup applications).

 which
> will limit the amount of pressure/fluid going to the
> rear brakes based on
> the load in the car/truck.  I have seen the small
> cylidrical looking
> proportioning valves on everything from Rabbit
> pickup 85 and newer golfs, 85
> and newer sciroccos, foxes, etc with no rear discs
> so there are different
> proportioning valves.

yup . . .

  IF you are doing the upgrade
> on a Rabbit, use the
> Golf valves, if you are doing it on a scirocco, use
> the 16v valves.

Why the difference? Same chassis, same weight
(roughly) . . .

Dem 16V prop valves are rare and pricey and presumably
take into account those 10.1" front discs . . . If you
are doing the 10.1 front + rear discs then of course
the Scirocco 16V props are the only way to go (my
opinion)

> Different valves on different cars have to be
> calibrated for different
> weights

yup.

<snip discussion on pickups>
  
> Another thing I don't agree with is that you DON'T
> have to have the 16v
> pedal assy for this swap.

Are they different than the 1985 & up Scirocco pedals?

  The 22mm master doesn't
> have an extra spot for
> the pressure switch usually used on older VWs for a
> brake light switch.

Does not this also apply to the 1985 & up Scirocco?

> Instead, it is an electrical switch on the pedal
> assy.

Yup.

> Be careful when upgrading to rear discs that there
> are two different kinds
> of calipers.  There are A2 calipers that have the
> parking brake cable
> mounted at the bottom of the caliper and the
> Scirocco 16v calipers have them
> mounted on the top.  The best way to tell is note
> where the bleeder screw
> is.  Obviously the Scirocco 16v calipers are the
> nicer ones to upgrade to
> since the cables fit perfectly on all A1 cars
> (except pickup which is a
> breed of it's own) so you don't have to hunt or have
> some made.  IF the
> bleeder is NOT ON TOP, THEY WON'T BLEED OUT!!! 
> Don't ask why I know about
> this one!

Problem with the design used on the Scirocco 16V and
early A2 cars is that the e-brake fails.

> 
> When upgrading to the bigger master you WILL need
> the bigger booster.

If you don't already have it (1985 & up) :-)

  The
> "BIGGER" part that everyone is talking about is the
> bore, this means more
> fluid, more pressure so you couldn't use the smaller
> bore booster that your
> smaller bore master just came out of.  

  Don't be fooled either,
> I believe that all A2s
> have the bigger master and booster so don't pay a
> butt load of money for
> this from someone else when they are a dime a dozen
> in the Pick A Part
> yards.

True.

 
> Mostly just use your common sense.  Realize that if
> there are prop. valves
> on 2000lb cars and 3500lb cars that they must be
> different!!  They aren't
> all the same.  Second, when getting "Suggestions"
> from someone, even on the
> list, question the source for reliability.

Absolutely!

  I think
> we should voice our
> proof when answering a question like this too.  I
> would trust someone that
> works at a dealership on VWs or a German auto shop
> more than I would trust
> someone who dabbles in their back yard
> (certifications help too) although I
> have known the backyard mechanic to be right before
> the Dealership mechanic
> also.

Seen that too!

  And last but defineately not least, Bentley,
> Bentley, 

I love Bentleys but they don't help here :-)

=== message truncated ===

I guess that really was long!


=====
Mark Peele
1985 Scirocco, 1982 Scirocco, 1981 Scirocco, 1978 Scirocco, 1987 Golf GT
http://www.scirocco2.de/mark.htm
Direct Mail: SCIROCCO_GTX@YAHOO.COM
Need parts? try http://www.parts4vws.com/ (Potterman)
or http://www.germanautoparts.com/ (Adirondack)
or http://thescirocco.com

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