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

["Dave Ewing" <rabbit16v@prodigy.net>]

> --- 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?
77 Rabbit but basically the same as an MK1 as far as stock parts are
concerned.
>
>   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).

I haven't done the upgrade on an MK1 or MK2 (yet anyway, I have a MK2 to do
soon) but my Rabbit had one, the Rabbit pickup had one and they are mounted
to the body with a spring going from a moving arm in the level sensor to the
rear axle.  Couldn't be for anything else!

>
>  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) . . .

That is just it, it is 'Roughly' the same weight, and in my opinion, isn't
close enough.  But, even though I use used parts and have a habbit of being
cheap I am still somewhat of a perfectionist so when possible would
reccomend swapping parts from "like" cars.

>
> 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)
>

It is actually irrelevent whether or not you do the front disc conversion
since the prop valves are only on the rear brake lines and by limiting the
amount of press. to the rear so as not to lock up the rear brakes does not
put more pressure to the front brakes.  Prop valves are merely to limit the
pressure to the rear discs to keep them from locking up since they actually
create an uneven bias to the rear.  It is "cool" to have the rear discs but
in all actuality, are unnecessary since this creates an overbraking problem.
Drums are sufficient in most cases and doesn't throw brake dust on your
$2000 wheels but they are lower maintenance since there is no adjusting and
no cleaning out the dust from the drums.  I have heard that the better
upgrade for the A1 VWs is the 200mm drums brake systems on newer VWs.  But,
since I had the parts, I did the upgrade and since it is "talked" about so
much everyone else wants to do it too so I sell the parts and do the work
for people.  Now if you are planning to RACE you car (street/strip/road
course/etc.) then the rear discs are nice to have BUT to make use of them
they need to be set up correctly.  That is why I reccomend the different
prop valves because I HATE to do a bunch of work and not have a huge
difference from stock.

> > 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?

No, as far as I know they are the same (unless the 85 and up has the little
spring thing for the clutch which makes it feel really nice, almost like a
hydraulic clutch) but what they don't have is the eye hole thingy for
mounting the brake light switch since it is activated by the pedal position
and not by brake fluid pressure.  AFAIK, there was a bigger difference
between 85 and 86 then 84 and 85 isn't there?  Does the non 16v 86 Sciroccos
have the brake switch mounting hole?

>
>   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?

AFAIK, all the 16v Sciroccos have the different pedal cluster.  Plus, even
though I haven't been able to verify this yet, I have also heard that the
cluster is heavier duty that the earlier one.

>
> > 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.

I am not sure yet of the cause of this but could actually be a problem in
installing new pads and not pushing the piston back correctly.  This is
actually an industry wide problem with rear discs with the p.brake
integrated into the hydraulic caliper, not just VWs.  Hopefully they will
fix this problem with newer calipers.  Should of used the other european
design of having the p.brake in the hat of the rotor and not integrated into
the caliper, but that would be more weight and more money.

>
> >
> > 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.

Someone commented on the "pressure" subject on this statement and it may not
have MORE pressure than the original system but more fluid does demand the
same or higher pressure whether the bore is 20mm, 22mm, or 44mm.  It also
depends on the throw of the piston too.  But for now, the pressure would be
the same or greater depending on the rest of the system (obviously if SS
lines create a harder pedal, then this would equate into a higher pressure
and a higher pressure you would send to the calipers by pushing on the
harder pedal).

>
>   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 :-)

They can help if you have Bentleys for the vehicle you got the parts from
and one for your own car.  Integrate them or make copies of diagrams and lay
them side by side. Works great for doing wiring upgrades (fuel systems,
ignition, etc.).

This is all things that I have learned by working as a VW tech/German car
tech and doing a lot of upgrades professionally.  I don't claim to "know it
all" like Chris D. does (kidding, it is very nice to have someone on the
list with your knowledge!!).  I take a very common sense approach to
everything I do and I also plan and take my time (mostly).  When swapping
parts, almost ANY part, you can run into problems and most swapping is
experiemental unless there has been a kit made commercially and even then
you can run into problems when considering that other human beings designed,
packed, made the parts for, and sent the kit to you.  There is a S. African
2.0L inline 4 kit with Mono-motronic for the watercooled vanagons.  I have
done two of these conversions (w/ A/C, P/S, Cruise, etc.--the worst) and
have found atleast 15 mistakes throughout the entire swap.  Wrong
directions, misleading directions, wrong parts, missing parts, etc.  So keep
in mind that when swapping anything it is all experimental and allow
yourself extra money and time for every swap!!!  HTH someone!

Dave




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