|Tech Article Title
|Rear Big Brake Upgrade
I started investigating doing a BBK - Rears in the Fall of 2006 and compared products, procedures, hardware, everything I could read and study about upgrading the rear brakes. I finally decided to go with Alex at STaSIS since he helped me out so much with my front BBK.
Here is why I wanted to go to a BBK - Rears; they are so much bigger than stock!
That is an S2 245mm x 10mm on the left and STaSIS 298mm x 22mm on the right!
I started collecting the parts to do the BBK - Rears in January 2007. Since STaSIS did not have anyone they knew of who had done an install with their Kit on a B4 Audi, I had to solve one problem after another. It took from January to May to solve each of the problems I encountered.
1. The first parts I needed were 2000 Audi S4 rear calipers with parking brakes. I ordered a set from a junk yard and I test fitted these along with a 2000 Audi S4 rear rotor onto my setup(1 year ago I had swapped out my 4 lug hubs for 5 lug hubs). In the process of test fitting these on my car, I realized I needed to off-set the rotor somehow.
2. I finally figured out I had to move the rotor toward the outside of the body by 8mm. I settled on putting an 8mm spacer in between the axle face and the inside rotor hat.
I started with 8mm thick wheel spacers made from 6061 Billet Aluminum/Magnesium alloy CNC'ed (which I purchased) with dimensions of: 155mm Outside Diameter and Center Bore Diameter of 57.1mm. I machined that down to: Outside Diameter of 132 mm and a Center Bore of 74 mm.
Here you can see the 8mm spacer (silver in color), between the axle face & the inside of the rotor hat.
3. Now that I knew the S4 Calipers were going to work, I ordered a re-manufactured set of complete 2000 Audi S4 Rear Brake Calipers.
4. I ordered Speed Bleeders for the rear calipers so that I could bleed the brakes by myself.
5. I then ordered the STaSIS Rear Brake Kit (STaSIS Part #KB01.5001.00)
2 - Alcon Rotors, 298mm x 22mm, vented, gas slotted
2 - STaSIS Rotor mounting hats, directionally vented
2 - STaSIS Carrier mounting brackets
1 - set Ferodo DS2500 brake pads
All the associated hardware & bolts.
5. During several test fittings of all the parts and pieces, I realized I needed to order custom Stainless Steel lines, with 1 end a banjo fitting.
Here you can clearly see the banjo fitting on the caliper in position.
6. I then bead blasted the calipers and painted them black with high-temp brake caliper coatings from Eastwood.
Here you can see one of the Carrier mounting brackets(gold colored metal).
7. I replaced the front Hawk HPS pads with Ferodo DS2500 pads.
8. When I went to install the right rear caliper, I realized there was a problem with the re-manufactured caliper because I could not get the piston to move in. I ordered a replacement and installed it when it came.
This picture shows the difficulty in getting to the parking brake adjusting nut.
9. To get to the parking brake adjustment, I dropped my exhaust system, heat shields, and even the 1 piece drive shaft I had installed in February.
9. I bleed the entire brake system using the new Speed Bleeders, which allows me to bleed the brakes the old fashioned way of pumping the pedal, and doing the whole job myself, with no helper needed.
10. I then bedded in the pads & new rear rotors.
Completed right side with unpainted caliper.
Completed left side with painted caliper.
So, how does it brake?
Better than before, but I have not gotten into a tight situation to really test them out. In my final runs of bedding in the pads & rotors, I really jumped on the bakes and it slowed down very rapidly. Brake bias does not seem to be affected, even though the rears are almost as big as the fronts (S6 V8 Front Rotors 314 x 30).