Back in January of this year I posted a three part thread describing the installation of the set of used front and rear Brembo GT kits I snagged on Craigslist.org. At the time, the rear discs were still of sufficient thickness, so I installed them in used condition on the car. A few weeks ago I measured them again and found that they had finally worn down below the minimum specified thickness.

I order a pair of replacement drilled discs from polepositionusa.com/. This shop sells the full line of replacement parts for the Brembo BBKs and the best pricing I’ve found so far. The discs showed up earlier this week, so this weekend seemed like a good time to do the replacement.

The rear discs have a minimum specified thickness of 27mm. Mine had worn down into the 26+ mm range. Here’s a shot of the specification on the new disc:



Brembo requires that you install new replacement attaching hardware every time you do a disc replacement. I’m not sure why some of the fasteners couldn’t be reused, but since the brakes are a primary safety system on the car, I sprung for the new mounting hardware. Here’s a shot of the various bits and pieces after unpacking it:



The first step in the replacement process is to deactivate the SBC. I removed the connector had the SBC unit under the hood. Next step is to remove the old disc from the car. As anyone who has ever done a brake job knows, this is a pretty straight forward task – remove the wheel, tap out the retaining pins, press the pads back (I recommend opening the bleeder screws at the rear calipers for this step), remove the pads, unbolt the caliper from the bracket, loosen the disc retaining screw, and lift the old disc off.

With the disc on the workbench, you then must remove all of the old fasteners. Here’s a shot of the disc bell following removal of the fasteners and old disc:



After cleaning up the bell, it was time to install the new disc. On the rear discs, the retaining springs are installed every other bolt hole. All fasteners are torqued to 62 inch pounds. Here’s a shot of the new disc mounted and torqued to the disc bell:



With the disc fully assembled, it’s time to remount it on the car. I cleaned up the disc retaining screws, installed some Locktite Blue, and torqued them to 10 nm per MB specs. Here’s a shot of the replacement disc reinstalled on the car. The caliper can be seen hanging from a piece of wire I used to keep any stress off of the stainless steel brake line.



With the disc remounted, next step is to reattach the caliper to its mounting bracket. Here’s a shot of the lower bolt being torqued to specification:



With the caliper back in place, it was time to do a little cleaning and the reinstall the brake pads. I debated whether to just install new pads with the new discs, but decided to cheap out since the existing pads were in excellent condition with most of the friction material still there.. I cleaned the brake dust off the pins and pad retaining spring using brake cleaner. Here’s a shot of the clean parts as used on the Brembo GT kit:



Next step was to wipe the existing lubricant off the pad backing plates and give them a fresh application of CeraTec (see Part 1 in the DIY thread for more info on this great product). Once the pads are slipped back into place, the retaining spring and pins are reinstalled.

Before bleeding, it’s necessary to reactivate the SBC system to have the caliper pistons press the pads against the new disc. After reconnecting the SBC harness, I activated the system by opening the driver’s door. Once the pads were pressed up against the disc, I deactivated the SBC again and bled the rear calipers using fresh MB DOT 4+ brake fluid. Done. Reinstalled the wheels, lowered the car, and went for a drive to bed the pads to the new discs. Brembo GTs; awesome brakes.

 

did you actually feel and stopping difference between these and stock?

 

When I test drove an SL65 it had the OEM 390mm disc setup and the brakes on that were much better than on my E55....

I think generally it will be more resistant to fade under continuous hard braking, but in everyday use would not imagine a big difference - especially with SBC.

If I hit the jackpot this will be my next and final mod.

 

Yes, definitely more stopping power under all conditions. The weight savings over the stock cast iron calipers is significant too; this was discussed in one of the earlier threads.

 

Finding a complete used front and rear set was hitting the jackpot for me.

 

Man I can't believe you didn't clean up your calipers one can of break cleaner and they would look brand new Great setup though I have the same on my CLS63...

 

I did clean them up after installing the pads and finishing the bleeding. Guess I should have taken an "after" picture too. My bad.