Andy Duffins New ENDLESS Brake Kit

Written by Mike Cullingford

I’ve known Andy for a while now. He’s a good bugger. Down to earth – but boy oh boy he can drive. It's amazing to work with drivers/teams that are open to suggestions and information. We met during his 2014 GTRNZ campaign when he was gunning for GT2 champion – which he accomplished!

Andy did really well on his standard brake kit when the FD was only using the 13B engine. But with the new 20B PP engine from the Green Brothers, the brake kit was really struggling to keep up. Andy had plans to go to WTAC (Time Attack) at this stage, so an upgrade was really required. After plenty of discussion, we chose the RacingMONO4 kit with 345x32mm discs to keep weight down.

Now that the 3 Rotor Racing RX7 has continued to mutate towards it’s current form, the engineering circle has come around full loop. More power, more aero, more tyre, more grip. David Higgins from Kinetic Simulation increased the downforce massively, which makes the brakes need to work harder than ever to keep up with the grip levels generated. For WTAC the current Mono4 kit was great. Lightweight and extremely capable. Andy is looking to compete with GTRNZ again this season, with some endurance racing (1-hour and/or 3-hour) on the horizon. So we needed bigger!

I looked at all of the options and the RacingMONO6 kit with 370x34mm kit was the way to go. ENDLESS normally makes this disc with a 21mm airgap. But I specially requested this with an 18mm airgap to make the disc heavier. The cooling potential is still excellent with the 84 curved vane disc structure. Having a disc with enough thermal mass is really important to keep the peak temperatures down, and reduce the temperature variation with each stop. This helps to reduce cracking, and makes everything last longer. Endurance racing is really hard on brakes, so it’s always better to over-engineer this system.

The ENDLESS RacingMONO6 caliper uses a thicker 25mm pad (RacingMONO4 was 18mm), which gives great value and thermal insulation. The brake pad compound acts as a thermal insulator – so less heat reaches the caliper. The Mono6 is the big brother of the Mono4, in every aspect - they are made with the same design and manufacturing principles. Made from forged aluminium alloy (ENDLESS proprietary grade) with as little post forging machining as possible. Something a lot of people forget is that machining after forging has an affect on strength because you’re “breaking” the grain structure. In some area’s it’s not that important, but for overall strength is better to have the forging as “raw” as possible. Complex forging is generally more expensive than going down the “billet” route, and it takes a lot longer. Proof of concept prototype and testing pieces will often be made from Billet.

Something cool that ENDLESS incorporates in their bleed nipples is an o-ring. This means when you crack the bleed nipple when you’re bleeding your brakes, the fluid wont seep past the threads. Simple and clever!

The ENDLESS caliper kit comes with everything needed to bolt on and go. Calipers, Pads, Discs + Bells, Brackets, Bolts/washers and Brake Lines. ENDLESS has a huge range of these kinds of kits, specializing in Japanese models. They have a range of Euro cars also. But sadly no Australian models (Holden/Ford) are available.

Once Andy had installed the caliper kit, he called me and gave me some feedback. Andy reported the brake pedal was even firmer that previous, which was interesting with the increased piston area (approx. 10% bigger area). We could only put this down to the super rigid caliper. With the bigger disc and larger piston area, I specced a longer lasting and lower friction pad over the S33O he was using previously. I chose ENDLESS T43A for it’s semi-endurance capability. This has a similar friction range to N35S, but it’s designed for longer life and heavier duty conditions.

Andy was testing earlier in October at Taupo to shakedown the car after it had been rebuilt by Green Brothers Ltd. Chris and Richard are big on preventative maintenance and making sure their customer’s always finish their races with reliable equipment. Andy sent me some pictures of the discs once he had been through the bed-in process and to make sure there was no issues. You can see in the picture below that the disc has a nice matte layer on it – the compound is doing it’s job. Streaks are OK.

Andy reported that there was definitely more front brake bias with the larger pistons area and disc size, even though we had “stepped down” the compound. To summarise – he was stoked with the brake performance. I think Andy wasn’t expecting that much of a difference!

Andy talking about his ENDLESS Brakes - https://www.youtube.com/watch?v=ZLqlThhlYz8

That’s all for now – more info to come once Andy has really driven the new setup in anger. Prosport Auto has supplied new Yokohama slicks for the 3 Rotor Racing RX7, so Andy will have all the grip he needs!