Scirocco 16v Disk Brake Conversion

The Scirocco 16v is arguably the pnnacle of the A1 line as far as performance is concerned.  Sure, later cabriolets had such nifty things as Digifant fuel injection and driver's side airbags, but they are slooooowwwww.  Since the 16v Scirocco was manufactued up to three years after the roll-out of the A2 platform, it has many A2 parts, such as (obviously) the 16v engine, and a brake system based on A2 calipers.

Although the GTI has good brakes in its stock vented 9.4" form, we're all about modifications here, and if there's a possibility for improvement, then it should certainly be considered.  Case in point is the brakes that came with the Scirocco 16v from 1986 to 1988.  The rears on these vehicles were discs as opposed to drums, and the fronts were 10.1" discs instead of the stock 9.4" on the GTI.

REAR DISKS

 Many people perform the rear disk swap because of the "coolness" factor, although quite frankly we all know that the fronts are the ones that do the real work.  I started out wanting the rear discs and started looking for the appropriate parts.  The best way to make sure you've procured everything you need is to grab the entire rear axle beam from a donor 16v Scirocco.  That way you can swap out the entire axle beam if you are so inclined.  Beware of so-called "kits" that are often seen for sale on eBay, as they are often missing major components that are necessary for the swap.

Here's what you need for the rears:

• Stub axles
• Rear dust shields
• Backing plates
• Rotors
• Calipers
• Caliper carriers
• Emergency brake cables
• Bearings and hardware
• Rubber brake lines (or braided if you've purchased those as well)
• New brake pads!
• Scirocco 16v proportioning valves (Without the rear proportioning valves, the rears will lock up easily, and this could result in loss of control).

Scirocco 16V rear axle, and left side after removal and cleaning

After a good amount of cleaning, I painted the calipers orange and prepared to install everything.  For a later model A1, it truly is a bolt-on project.  You can get a pretty good feel for what needs to be done by looking at the European Car article from November 1991.  Here are a few tips:

• The brake lines at the rear can be hand-bent to meet up with the rear disks and will still look good.  Be sure to gently bend the lines, since if you aggressively bend them, they could kink and break.
• Older cars may require some slight grinding on the rear axle beam so the carriers will bolt on.  Westmoreland Rabbits should not require this step.
• The most frustrating part of installing the rear calipers will be feeding the new emergency brake cables up and into the guide tubes inside the car, as they'll want to slide underneath the emergency brake handle, rather than up to a point where they can be attached.  Keep working it, they'll fit.  Swearig in German is recommended.
• The proportioning valves screw into the bottom of the stock master cylinder.  You'll find this to be a problem, since they protrude down an extra 3" or so below the m/c, and this in turn interferes with the shifter linkage (it even gets close to touching the transmission housing!).  You'll have to bend the rear brake lines an uncomfortable amount to make everything fit without any clearance issues.  I ended up buying new metal lines and bending them to fit.  It is possible to screw them into the side outlets of the master cylinder, although this would mean swapping the order of the break lines - fronts where the rears used to be, rears where the fronts used to be.
• Once you've finished installing everything and have the brakes bled, you'll be very disappointed in how the brake pedal feels.  It will be very spongy and lack the firmness that is usually associated with VW brakes.

The last item is the rub.  Once you've gone through all this trouble, you'll find out that those folks that have been telling you to get the 22mm 16v master cylinder are absolutely right.  The stock master cylinder on your Rabbit just isn't big enough to push an adequate amount of fluid.

So, I left my car in this condition for a few months, until a 1987 16v showed up at a local salvage yard.  It still had the complete brake system, including the master cylinder.  The salvage sold me everything I needed to do the front brakes and change the m/c for $75.  What a deal.

A Note About Proportioning Valves

Westmoreland Rabbits have a "block" proportioning valve located at the bottom of the driver's side firewall.  It also has an electrical connection on it for the brake failure warning light.  Any proportioning valve installed on your car, other than the adjustable proportioning valves mounted by the rear axle on some German-made cars should be removed.  This is becasue drum brake proportioning valves hold residual pressure, which is necessary for the proper operation and adjustment of rear drums.  These valves will cause your rear disks to drag, which will be a drain on pad & rotor life, and will decrease the fuel mileage of your car.  In my case, the residual pressure section of my block proportioning valve was shot, so I went ahead and left it in.

22mm MASTER CYLINDER

The 22mm m/c will not fit on Westmoreland rabbits, since the Scirocco booster,etc. is made by ATE, the Rabbit by Bendix - the bolt patterns are different.  You have to pull the entire m/c assembly, including the brake booster and the linkage to the brake pedal.  Anyone that has removed a brake booster from an A1 car will vouch for the fact that it's a real pain.  The bolts are very difficult to get at, and the factory has seen fit to put thread locking compound on everything.  Often the bolts are rusted on.    However, when you see the Scirocco m/c, you'll see how those proportioning valves are supposed to fit.  The brake line fittings on the 22mm unit point at an angle upwards, rather than down and to the sides like the Rabbit m/c.  Make sure you get the brake pedal linkage, as the linkages are different between German and US manufactured vehicles, and the Bendix linkage will not work with an ATE booster.

Changing the booster and m/c is straightforward, but difficult due to the location of the bolts, and the fact that you'll have to get underneath the dash to disconnect the old linkage and reconnect the new.  Tip:  it may be easier to remove the old linkage by completely removing the brake pedal from the car.  There is a circlip at the end of the pedal assembly that when removed, will allow you to remove the clutch and brake pedals.

10.1" FRONTS

So, I have my 22mm master cylinder, booster, etc.  So I figure why not change out the front brakes to the 10.1" rotors and calipers while I'm at it?

The fronts bolt right on with no modifications or grinding.  You need the calipers, caliper carriers, and rotors, just unbolt the old, bolt on the new.   Be certain to use thread locking compound on the bolts that secure the caliper carriers onto the front hubs and torque them to specification.

Once you've accomplished all of this, you will be rewarded with brakes that are (in my estmate) about 20% better than what you have stock.  This is a noticeable difference, and the stopping power is truly phenomenal.

For those interested, here is a scan of the upgrade procedure from the November 1991 issue of  European Car:  Page1, Page2, Page3.