Brake System Modifications

As owners of VW's, we are blessed with a braking system that's pretty good right out of the box.  Of course, being those same VW owners, we like to make things just a little bit better.  There are, as usual, modifications that run the gamut from mundane to radical.

Here are some excerpts from the FAQ listings regarding brake modifications:

General Information from the watercooled vw technical faq.

Brake Upgrades:  Generic brake upgrade information from the watercooled vw performance faq.

Front Brakes

Front rotors for the A1 cars come in three sizes:  9.4", 10.1", and 11".  All 8V A1 cars come stock with 9.4", while the Scirocco 16V came with 10.1" rotors. Most aftermarket suppliers sell 11"  Corrado upgrade kits, but they are expensive and require at least 15" wheels with 33mm offset.

The front brakes on 1983/84 GTI/GLI and 82 and up Sciroccos  8V are 9.4" vented rotors.  This setup works pretty well, and any major gains in braking performance will cost bucks.  If your A1 is not one of these models, you most likely have solid rotors that can greatly benefit from swapping to the vented setup.  This will require the calipers and rotors from a later model A1, but the installation is a straightforward bolt-on.  

The front setup from a Scirocco 16v is an excellent way to get 10.1" rotors on the front of your car.  This change is a direct bolt-on, and if you can find the parts in a salvage yard the change is highly recommended.  If you have 13" wheels, these brakes WILL NOT fit, so you'll need to upgrade to 14" or 15" wheels.

Before I upgraded to Scirocco 16v brakes, my car still had the stock sized 9.4" rotors, but I did install cross-drilled rotors and Mintex brake pads.  When considering cross-drilled rotors, read the Brake Upgrade FAQ and think about whether this is truly the way you want to go.  Cross-drilling rotors reduces their overall strength, and the holes will crack over time.  I bought my rotors from Autotech, but before I did, I made sure that the holes were radiused (not chamfered) for stress relief - this reduces cracking problems.  Unfortunately, these rotors developed a strong vibration after some use, which I attribute to warpage of at least one of them.  The Mintex pads were excellent and demonstrated none of the cold braking  fade problems normally associated with high performance pads. 

Brake Upgrade Table

Stock	Stage I	Stage II
9.4" Solid Rotors	9.4" Vented GTI Rotors (requires GTI calipers)	10.1" Scirocco Rotors (Requires Scirocco calipers and carriers, 14" wheels)
9.4" Vented Rotors	10.1" Scirocco Rotors (Requires Scirocco calipers and carriers)	11" Corrado Rotors (Requires Corrado calipers, carriers, and special adapter plate, 15" wheels

Obviously there are even more radical upgrades, such as Wilwood calipers, but these are completely unnecessary and quite expensive.

Rear Brakes

Face it, on a front wheel drive car the front brakes do most of the work.  If you're like me, however, the sight of drum brakes on your car makes you cringe. This is why I've upgraded the rears to disks from a Scirocco 16V.  This is not too complicated, but on a scale of 1-10, this job looks to be about a 5.  The cheapest way to go is to buy the parts from a salvage yard, although the parts can be found new on the internet for a fairly steep price.  Autotech sells a complete kit, or a smaller kit that contains much of the parts that wear out, such as grease seals, etc.  Reference Autotech part number 10-698-410K (although at $900, it is much cheaper to look through the salvage yards).  Supposedly, the rear disks from any A2 platform will fit on any A1 platform, but the Scirocco setup requires fewer modifications and bolts right on.  To do the job right, you will need the master cylinder from the 16v Scirocco, as it is larger than the stock one on your Rabbit and can push more fluid through the lines.  Many people have complained about a spongy brake pedal after upgrading to rear disks, and this will correct that problem.  It is also a vital upgrade if your convert the front disks to 10.1" rotors.  If you drive a US (Westmoreland) made Rabbit, you will have to change the brake booster as well (US made Rabbits came with a Bendix booster, while all the cars from Germany came with ATE), and while the swap is straightforward, it is not particularly easy as many of the bolts are in a difficult to reach location and often rusted on.

The Brake Upgrade FAQ makes some mention of this upgrade, but a good reference for the entire process can be found in the November 1991 copy of European Car (gee, has it been that long since that mag was worth reading?).  For starters, you'll need the rotors, calipers, stub axles, bearings, backing plates, and e-brake cables from the donor car (your best bet is to call German Parts Warehaus and tell them what you are doing - they know what parts are needed).  

It is very important to note that US manufactured cars will require new proportioning valves for the rears.  These go between the master cylinder and the rear brake lines, and screw directly into the master cylinder.  If you do not install these, the rear brakes will lock up under even moderate braking and you could go into an uncontrollable skid.  I know many people have skipped this step, but for your safety I recommend spending the extra money and adding the valves.   The proportioning valves are also available from Autotech at about $99 each (two required), although the last time I checked they were out of stock and Autotech didn't know if they would ever have them available again.  I often see them in pairs on eBay, so keep looking if you didn't secure these from your donor car.

Master Cylinder

In general, any German manufactured Rabbit will have an ATE booster and master cylinder.  Any Westmoreland assembled Rabbit will have a Bendix master cylinder and booster.  The ATE booster will accept the larger 22mm Scirocco 16v master cylinder, as well as the 22mm Corrado (non-ABS) master cylinder.  If you are upgrading to 10.1" or larger brakes, you will greatly benefit from a larger master cylinder, especially if you've upgraded to rear disks as well.  The stock MC will handle the larger brakes, but your pedal will more than likely feel mushy and will not provide the feedback you've become accustomed to.  The problem with Westmoreland Rabbits is the Bendix booster.  To accept the larger MC, you'll need the booster from a German-built car, preferably a Scirocco 16v.  This means completing the painful task of removing the old booster and installing a new one.  The bolts that secure the booster are difficult to reach, and are usually rusted on.  The connections to the 22mm master cylinder also are angled upwards (as opposed to sideways on the stock 20mm unit), so some bending of brake lines will be necessary - first to meet up with the new connections, second to meet up with the proportioning valves. 

Brake Lines

I have braided stainless-steel brake lines on my car, mostly because they look pretty cool on the fronts.  These lines don't flex outward under pressure like the stock lines do, and you will notice a firmer pedal feel after their installation.  Some are concerned that they will wear quickly and spring a leak due to grit working it's way into the steel braiding, but I have not heard of this happening to anyone.  The older versions are not DOT approved, but the aftermarket has come to the rescue with DOT approved lines that are of course more expensive.   This is one of those upgrades that really isn't necessary, but I did it anyway.

Brake Maintenance

Everyone knows when to change brake pads (when you see metal shavings, right?), but few people do the maintenance required to keep your braking system in optimal shape.  Really all you have to do is replace the brake fluid about once every 24 months.  I use Castrol LMA, which is a dot 4 fluid that will mix with any dot 3 or dot 4 fluid.  Stay away from dot 5, since this is silicone based material that will not mix with other fluids, and has erratic compressability properties over the temperature range associated with even normal driving.

The FAQ at the beginning of this page has some excellent information relating to brake fluids.  If you haven't read it, do so now.