Re: Brakes / ISV

[ti@bazooka.amb.org (Ti Kan)]

Jeremy R King writes:
> Just ordered a heap of stuff for my Quantum - paying long overdue
> sacrifices.  BJ had a bright idea while looking at prices on drums for the
> rear of my car.  He checked some part numbers and had me double-check.
> Seems the rear DISC brake setup for the Jetta's and Golf's is a DIRECT
> BOLT ON in place of my current rear drums.  I'm getting his "kit" and
> putting it on my Quantum in the next week or so.  Is this too good to be
> true?  Is the line pressure to the rear enough to push calipers?  I'll
> have to figure out something for the parking brake.  Anything else I need
> to be aware of?  Anybody ever done this?  If it works, it will also work
> on the 4ks and the non-turbo Coupe GT.  

Yes the rear 8.9" disc brakes from VW GTI/Jetta-GLI/Scirocco-16V cars
will bolt on to the rear of the the Quantum and the 4000 and Audi Coupe.
I have done so to my 4000.

You will need to replace the stub axle with the proper unit that has
the disc brake caliper mount flanges (the one from the GTI/GLI/Scirocco-16V
will work fine).  You will also need fabricate a bit of hard brake
line (with flared ends) to replace the piece that goes from the flexible
hose to the brake drum slave cylinder, and add an additional flexible
line to go from the hard line to the caliper (BTW This is a good time
to upgrade to stainless steel braided brake hoses).  You will need to
route the new line to somewhere close to the caliper, and mount the
line such that is secured to the suspension beam.  You can observe the
factory setup on the GTI to see how it's done.  The stock emergency
brake cable should hook right up to the rear caliper, but you will probably
need to loosen up the adjustment to make it work properly.  Also,
you may need to fabricate a little brake cable cable guide to prevent
the brake cable from rubbing on the "ring" part of the caliper frame
where the factory rear disc brake e-brake cable would have a guide
(there was never a FWD 4000 with rear disc brakes so there is no
factory replacement e-brake cable for this purpose).

Lastly, you will need to adjust the brake proportioning valve
(connected to the rear axle via a spring) so that the rear brakes
don't lock up before the fronts.

It is not too difficult a swap but I think it will be worth your
while to upgrade the front discs to the 10.1" vented rotors
if your car isn't already so equipped (I did that to my 4000 too).
The front brakes do most of the braking on these cars and that's
where you can get the most improvements.

-Ti
-- 
    ///  Ti Kan                Vorsprung durch Technik
   ///   AMB Research Laboratories, Sunnyvale, CA. USA
  ///    Internet: ti@amb.org
 //////  UUCP:     ...!uunet!bazooka!ti
///      URL:      http://sunsite.unc.edu/~cddb/tikan/