Brake Upgrade Part 1 - Rear Disc Brakes and Beam Upgrade

Going fast is not only all about building horsepower. A car will also need to be able to stop as well if it is not to turn into a flying coffin. By some strange logic TC decided to equip the second or arguably the fastest Sentra variant in Bolehland with rear drum brakes. Drums are cheap to manufacture and the brake shoes are even cheaper. However they're mostly useless for hard and performance driving on something as big and heavy as the Slowtra. I decided to upgrade the rear brakes to disc brakes as the first part of my brake upgrade.

The rear beam on drum braked N16s do not come with the mounting bosses for the disc brake caliper so to upgrade to rear disc brakes one has to either try and weld the bosses on the beam itself or source for a used beam complete with rear disc brakes. I did try the third option which was to buy everything new but TC wanted to charged me in excess of three thousand smackers just for the beam alone and we haven't even started talking about the calipers, rotors, etc. Clearly going for a used beam is the only economical option. Oh and here's what you need for a rear disc brake upgrade:

1. Rear Beam from an N16 variant complete with disc brakes (caliper, brake rotor/disc, pads, brake hoses), axles, hubs, etc. The complete assembly. Even the dust boot on the drum is different from the disc brake so hardly anything cept the some bolts are reusable. I've decided to upgrade my brake hoses to PRO-RS items. Everything else is stock Nissan
2. Rear handbrake cables. The drum and disc brakes use different handbrake cables.
3. About 1 litre of brake fluid. I'm using Motul RBF600

It took me quite some time, ok more than 2 years in my case to finally find a decent condition rear beam.  Blame that on other life priorities. TCEAS in Bayan Baru did managed to source for me a beam two years back but that didn't really fit my grade. The calipers and pads are all stock items. No point going for performance items yet as I'm on stock front brakes and upgrading to rear pads with a higher coefficient friction will just spoil the braking balance. Besides I have part two, three, etc. to write :)

Pix below of my rear beam after unpacking. Even the service centre manager helped to unpack the goods. Thank You Sir! The beam has been repainted and likewise the calipers. I choosed silver for the calipers for the oem look. Don't really dig ricey red. The long dangling things are not "tentacles" but are the handbrake cables.

I also had my "works engineer" who sourced me the beam to upgrade the stock bushes on the beam trailing arms to Superpro items. Thank You Ah Tiong (Hoong Hooi Motorsport). Ah Tiong even painted the calipers when his regular painter declined due to "too much work". The stock bushes cannot be physically removed from the beam as its shell had to be reused for the Superpro. This means using a burner or welder to burn away the bush. The shell was then spot welded to the trailing arm and the Superpro bush fitted. Pix below of the Superpro rear beam trailing arm bush.

So why all the hassle on the bushes? Picture below of the stock rear bush tells the whole story.

The stock soft bush is great for NVH as it allows for lotsa movement in all planes but this detrimentally impacts handling during hard braking and side load (cornering). The Superpro minimizes this. There is also the harder 90 durometer Superpro bush if one aspires to build and all out race car like the Dog III. I'm using the standard variant part number SPF1942K. The harder variant is SPF1942-90K. If you're interested in the bushes please contact me.

It took most of the morning to remove the stock beam. The exhaust heat shield had to be removed to access the handbrake assembly.

The PRO-RS rear braided brake hose installed to the caliper first. The mech managed to install the hose at the wrong side despite clear labels marking which side and which end. Luckily I spotted the mistake.

 
These are the ABS sensors for the rear wheel. Since the Slowtra does not have ABS these were removed. Per my TCEAS technician my beam's JDM as these use a different sensor compared to the MYDM N16 Sentra. There are two sensors (one per side) and part of the cabling is secured via brackets to the beam trailing arm.

The sensor goes here if  you're curious. I just grabbed a socket wrench quickly to help the mech to remove.

Picture below showing the drum brake beam vs the disc brake beam

The disc brake beam actually has a larger diameter compared to the drum brake beam. 65mm vs 55mm. IMHO the disc brake is able to generate more load and stress to the beam hence the need for a stiffer and stronger beam .

Picture of below of the beam installed on the Slowtra together with brake hoses.

Rear caliper and rotor.

All MYDM N16 and USDM non-Brembo equipped B15 variants run a 258mm diameter X 10mm thick solid rotors with same pad shape and size. Rear caliper has a single piston of 33.96mm. Compare this to the drum with a 203.2mm inner diameter and 17.45mm single piston. Clearly my stock 7/8" master cylinder is maxed out! Luckily brake pedal travel is not compromised and pedal feel is excellent with the PRO-RS braided brake hoses. Took quite some time to properly bleed all the brakes as I also had my front brake hoses upgraded to PRO-RS items. These might not stay too long on my car though as I have other plans for my front brakes.

Here's how the rear disc brake looks behind the wheel. Took the entire day to install and bleed the brakes. I also installed my braided clutch hose and changed the Slowtra's engine oil and oil filter.

Driving back home the improvements were immediately very obvious. The rear end felt more firm and planted. The brakes were so much better in terms of feel. Better stopping power was also noticeable. I'm not done though. I have a DBA 4000 series rear disc on order which should be arriving from Down Under in January. Have not decided on what rear pads to use yet. There's plenty of choices avail from EBC to Hawk to Carbotech so no worries there. And why am I only talking rear brakes when an FF car requires 70-80% front braking action? What about the front brakes? My front brakes pads are on its last legs but I'm not changing coz I'm planning to revamp my entire front brake config. And I mean it. Please be patient for Part Two and Three. I promise it won't take two years :)