AROCA Sprints - Sandown

14th February 2015

Sandown - Valentine's Day Edition. The day started with a very wet track, having rained throughout the whole night and into the morning. The rain eventually subsided by the track dried up by around 11:00 after a few sessions worth of cars taking the racing line. The day then became very warm and humid, with ambient temperatures around 30 degrees Celsius.

The new parts in the car's setup were:

• RDA slotted front brake discs
• Project Mu HC+800 front brake pads
• 18 x 10J front wheels with 285/30 Hankook Z221 semi slicks (C70 compound)

The RDA disc brakes were great and held up well in combination with the brake pads in the hot temperatures. The most notable difference is how the car now handles with the wider tyres up front (up from 265/35R18). Now with 285 wide tyres all around, I noticed that the larger amount of front grip translates to feeling mid-corner where the rear of the car is seemingly at the limit of grip but then follows the front around the corner.

Below are the lap times for the day. Unfortunately, I did not beat my previous best time of 1:27.69 but I did learn that the potential of a faster time is now greater with the car's new setup.

Practice - Untimed
Session 1 - 1:59.0989 1:56.1098 1:51.6517 1:50.1842 1:54.0665 1:43.3011
Session 2 - 1:39.1209 1:37.8309 1:36.7610 1:34.9352 1:36.2855 1:38.3492
Session 3 - 1:37.2765 1:35.8748 1:36.1227 1:32.6068 1:34.9488 1:31.6475 1:33.3968
Session 4 - 1:30.4820 1:35.0791 1:32.2845 1:30.7166 1:28.6187 1:30.0778 1:28.2480
Session 5 - 1:32.6736 1:29.8638 1:28.2622 1:28.1247 1:27.9774 1:28.5248 1:32.4355
Session 6 - 1:32.8446 1:34.3082 1:29.5302 1:28.0986 1:27.7601 1:29.9723

As can be observed by the speed graph, I didn't beat my best time because I was let down by my top speed on the two straights.

What is interesting though, is that I drove faster through sectors 2, 4 and 5. Could this be attributed to the wider front tyres? Whatever it is, I'm happy there is plenty to be gained in the current setup as the theoretical lap time is now a low 1:26.

I'm looking forward to returning to Sandown when it's not so hot.

RDA Slotted Rotors

It's time to replace the front rotors on the Z. This time I'm working with a smaller budget, so I thought I would try out the rotors from RDA (Part number RDA7685S for 350Z with Brembos).

Here is a comparison of mass for all the brake rotors that I have tried:

Dixcel DAV FS: ~9.5 kg

RDA Slotted: ~8.5 kg
DBA 4000: ~8 kg
DBA 5000: ~7.5 kg
X3E Motorsport: ~7.5 kg
Project μ SCR-Pro: ~7 kg

Along with the rotors, a new set of Project Mu HC+ 800 pads find their way into the brake setup (thanks Kam). I have also treated the Z to a fresh set of OEM wheel studs and lug nuts, the old set have served the car well over the past 8 years.

The proof will be in the pudding when I test out these brake pads and rotors next week at Sandown. I am anticipating some hot conditions, being at the height of summer; so it will be a good workout for the brakes.