Adding Rear Disc Brakes

Rear Disc IconThe Scirocco 16v came with rear disc brakes – it was the only A1 that had them stock. Upgrading for looks? Better braking? Here’s how to do it.

Special thanks to Brendon Porter (AKA VWralley on VWVortex) Patrick Buearu (ATS Technotes) and Rob (AKA Mk1scirocco1980 on VWVortex) for pieces of this technote. This is a combonation of of those, plus a few more pieces added by me (Timbo).ALL Sciroccos are A1s (Mk2 roccos are still A1 as well) – And this will also apply to any Rabbits, Cabriolets and 80-84 Jettas. The first car being shown is a Mk2 1985 Scirocco, the second is a 1980 Mk1 Scirocco.
A2 conversion is similar.

By far, the easiest way to to this is to find a 16v Scirocco in the Junkyard. Get the whole back axle. Maybe Buy the parts off of eBay or Scirocco classifieds. The 16v Scirocco has 8.9″ Disc brakes in the back. Keep in mind that they weigh about 5 more pounds per side, and that’s un-sprung weight too.

A new Master cylinder is not necessary unless you are also doing 10.1″ front brakes, because these disc brakes move less hydraulic fluid than drums. If you need to swap master cylinders, check the Technotes for that.

VWralley adds, The Proportioning valves are VERY important. If you don’t put them in, your rear wheels will lock and cause your car to fishtail everywhere and it is very dangerous, especially in the rain.the stock rear beam mounted prop valve properly adjusted for a lowered ride height or aftermaket adjustable valves available through Jegs, Summit racing, etc…I have HAD to change pad compounds in my car AND run the inline valves to make it even safe to drive, and it STILL locks up under heavy braking at freeway speed. any less and you will have SEVERE rear lock up issues with any hard braking. anyone who has experianced this once (and believe me it only takes one time!) will wholeheartidly agreeParts List

  • New Scirocco 16v Parking brake cables (one for each side)
  • Stainless, or stock 16v rear brake lines
  • brake fluid for your system
  • New or used calipers, if you get used, make sure the parking brake section is not frozen
  • Caliper carrier brackets
  • New or used stub axles for parking brakes
  • bolts for stub axle, caliper
  • brake pads (new)
  • brake discs (new)
  • brake dust shield (optional, really)
  • Disc wheel bearings
  • New grease seals – don’t reuse the old ones
  • wheel bearing grease
  • new grease caps for the bearing (might come with a bearing kit depending on where you buy)
  • 16v Scirocco Brake pressure reducers (inline at the master cylinder)
  • Adjustable Proportioning Valves

Useful Part Numbers

Scirocco 16v Rear Discs: 357 615 601
Scirocco 16v Rear Caliper (left): 191 615 423 AX
Scirocco 16v Rear Caliper (right): 191 615 424 AX
Scirocco 16v Proportioning Valves: b 533 612 151 A
*Jetta GLI and GTI with Rear discs have the same part numbers for these*

Removing the Drums

First, jack the car up, and properly support it. Take the rear wheel off, and remove the dust cover in the center of the drum with a pair of Channel-Locks. Inside, you will find the nut. Remove the cotter pin with a pair of needle nose pliers, remove the nutlock thingy, and remove the 24mm center nut and washer – it should be very easy to come off – less than 10 ft/lbs.

Removing the DrumMake sure the parking brake is off. If you can remove the drum, great – rip it right off. If not, simply put the wheel back on, put a couple of lugs in, and use that to remove the drum. Easy!!

Next, disconnect the brake line from the back. it should be an 11mm nut.

Removing the Stub Axle NutsRemove the 4 bolts holding the drum to the axle. They should be 15mm.

Clean the area up if you wish, paint it with some rust eating paint or whatever.

Remove Parking brake cables

Next, remove the parking brake cables from the car. You need different ones for the disc brakes. You may find that this step is easier if you remove the passenger’s seat. The nuts are 10mm.  Now is a good time to optionally swap the lever for a later A2 lever, which is a bit stronger and better looking.

Assembling the rear disc brakes

Stub AxlesThis picture shows why you swap the hubs – the disc hub has the ear to hold the caliper. Also, the bearings are a bit different.

Clean up the stub axle as best you can, and make sure it doesn’t rust. WD-40 is a water disipator – hence it’s name. Spray it on.

Brake PartsHere is a layout of parts for the brake conversion. Also shown is the dust shield. You can also see the Scirocco 16v parking brake cables in the bag.

Bearing RaceThere are many ways to slip the wheel bearing race into the disc, you can use a Starter bolt, and gently tap around the racer to slip it in. you do NOT want to gouge them for OBVIOUS reasons. The picture at right is to show you how far you have to go, if you notice there is still a space below the racer and the final edge where it should sit. continue to slip it in until it sit completely on this inner edge.

Rear Bearing RaceProceed to insert the inner bearing race into the rear of the rotor, again the race is to be pushed in all the way until it seats on the inner edge.

Now, back the bearing chock full of bearing grease. Get it in all of the needle bearings. It’s real messy – but this will last years if you do it throughly.

Grease SealPut the inner bearing into place, and then put the new inner grease seal on top.

Brake LinesThe only major issue in doing this conversion was to change the current brake line (hard line) from atop the axle to below the axle, So this picture shows the location of the first rubber line that needs to be disconnected (which I replaced with the dual female ended stainless line later, and then straightened out the line (be careful not to kink or fold it…)

Brake LineThe picture at right shows the routing of the Stainless Steel brake line on the axle beam. You can use fuel line rubber hosing, slit on one side to provide additional anti-friction for the hard line against the rear axle. Re-close the clamp on the upper end of the axle to hold the line in place.

Bolt the new spindle into the same location as the old spindle with the dust shield (the big old black thing) in front of it. The bolt pattern is such that you cannot do it wrong. The four bolts get 50ft/lbs of torque.

Slide on the brake disc. BEFORE doing anything else, make sure you bolt the carrier down to the spindle with the brake disc in the carrier, the two carrier bolts get 25 ft/lbs of torque. Then you can put the outer bearing on, washer, nut, nut locker, and cotter pin. The 24mm spindle nut only gets FINGER tight.

Stainless Brake LineAttach the other end of the stainless brake line to the calipers. Install the pads into the carrier with included shims and clips (if any), then Bolt the caliper onto the carrier.

Parking Brake Cable for DiscsThe Emergency brake cables run along the top side of the axle and slips through the mounting hole, slip the slip on at this location on the cable, push the rubber end a bit. Push on the spring and slip the ball end into it’s final resting place. Run the lines through the body holes, and attach the other end to the parking brake lever inside the car.

Repeat all operations for other side of the car! (ha-ha! 😉 )

Disc Brakes DoneGet all of the air bubbles out of the brake system by bleeding it out. Use new fluid. Here is the final product once you are done one side..

An important step with rear brake bleeding is to “gravity bleed” the rear calipers. With the brake line attached, the rear caliper should be removed from the carrier and suspended in such a way that the bleeder nipple points skyward so that it is the highest point of the caliper, then loosen the nipple and allow the air to escape and let the brake fluid fill the piston.

Initial brake bleeding with the caliper installed can leave an air bubble in the piston as the bleeder is not at the highest point. After the initial gravity bleed, future bleedings can be done as usual unless the rear brake line is removed from the caliper again.

The Bentley manual states, press the brakes 40 times after bleeding system to reset the parking brake adjustment. I have found that the  parking brake is still “soft”, I was advised by others that this is normal, and can take up to two weeks for it to catch completely tight. This is pretty standard for any car with rear disc brakes. Remember to park in first gear in the meantime!   Also – those one-man pressure bleeders are well worth it. Get one!

That’s it!