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The Road To Race Car Handling

BNR34

The Road To Race Car Handling


The Quest For Perfection

I guess it comes with the territory, but one question I’m often asked is ‘what’s the best car you’ve ever driven?’

It’s a great question to be asking a guy in my position, and my first reaction is always the self-realization of how ridiculously lucky I am. Not only do I get to sample many of the most exciting new cars that hit the market, but I’m often thrown the keys to modified machines of every type.

Let’s get back to the question at hand though, of which the answer is quite simple. To some of you it might sound like a load of bullsh*t, but the best car I’ve ever driven is the car I’ve owned since 1999, my BNR34 Nissan Skyline GT-R.

You see, aside from the fact that the final RB26DETT-powered GT-R happens to be one of the best platforms to create something very special on, I’ve been very slowly fine tuning mine to my personal taste. Having the car sit in a perennial state of improvement gives it this exciting aura. I get the tingles every time I look at it as I know it’s my baby; it’s so good, feels so special and is constantly being improved. ‘Step by step’ is my motto, feeling all the upgrades as they are fitted and learning how the car reacts.

Which brings me to this update on Project GT-R. The handling.

For quite a while now I’ve been running Nismo S-tune coilovers in my car, which as the name implies is oriented towards fast ‘street’ use more than anything else. It’s a great upgrade if you intend to have the best of both worlds and don’t ask too much of your car. If you want something more focused you will find it a tad unresponsive, as it’s dialed in towards safe understeer and is quite inefficient at controlling body roll, pitch and dive.

That brings me to KW, who I’ve been talking to about my car for years now. I’m a great fan of how much KW has achieved in the motorsports world, and how that knowhow has been translated to the street; the V3 coilovers I run in Project Drop Top are testament to this.

But for the GT-R I wanted more. The guys at KW took that as a challenge. and said, ‘give us a few months and when we are done we’ll send you what we’ve come up with’.

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The wait was due to two things; first that KW doesn’t have an off-the-shelf kit for the BNR34, and secondly that they knew I wanted to take full advantage of the available technology but not render the car unusable on the street. I spent the best part of three months wondering how the car would drive with a serious suspension setup, and the day I find out is getting very close now.

First up, however, was the delivery of the finished products, which was brought right to my door step by the efficient guys at FedEx Japan. The delivery guy gave me a weird look when I raced out of the house with a DSLR in my hands, but I told him, “I’m really sorry, I’m very excited about what’s in those boxes, so if you don’t mind.”

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He gave me an understanding look, probably thinking ‘damn weird otaku gaijins‘, made me sign for the packages, and then headed off to his next delivery.

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The resident mini Speedhunter was just as excited as I was; together we get to test out every improvement on the ‘Gee-Aayaa’, as he calls it.

The Urge To Unbox

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I quickly brought boxes inside and cut off the nylon straps that held them tightly packed for shipping.

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Talk about Christmas coming early!

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You might laugh at me, but I had a little peek at the middle section of the box by lifting the padding and then closed it immediately like I had seen something I shouldn’t have. Then I giggled.

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The more I peeled away the packaging, the more was revealed.

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What makes these coilovers rather special is that they are custom-built for Project GT-R and are based on KW’s 2-way adjustable Competition dampers yet have Clubsport settings. It’s like having the best of two worlds; they were built by the race department at KW but taking into account the sort of driving I’d be doing: a mix of mountain roads, highway runs and of course the odd track day.

KW researches and develops its dampers on the famed Nürburgring Nordschleife and that means they’re subjected to a vast array of tests, from differing surface changes, imperfections, mid-corner bumps and extreme extensions and compressions. Doesn’t this sound like the sort of stuff you have to deal with on normal city and mountain roads? Bringing race technology to the street means you still have a compliant sort of damping for normal road driving, but one that can be adequately stiffened up when you hit the track. That’s something specific to KW as it’s always been of the opinion that searching for the ultimate mechanical grip requires softer spring rates and outstanding shock technology.

To say I’m rather excited to find out what this translates to on the street, as well as the track, is an understatement!

Built around lightweight aluminum housings (KW lets race teams to choose between aluminum when weight is a concern or steel for the highest structural strength) allows the whole ensemble to shave a little unsprung weight from each corner of the car. Project GT-R’s dampers run twin tube technology with an 18mm diameter rod for strength and compliance with the damper being adjustable in 15 positions on the bump stroke and 18 separate positions on the rebound stroke.

Let’s take a closer look at the front dampers. The aluminum top mount, anodized in KW’s signature purple, is mounted onto the damper via a pillow ball, already something very different to the S-tunes on the car, which run a rubber bush to attenuate vibrations and make things a little more comfortable. But the metal-on-metal link will now not mess around with chassis feedback, be it through the steering or the seat of your pants. This goes for the lower pillow mount too.

The KW hex key that’s included in the kit will slot into the top of the damper and allow me to adjust the rebound setting. The springs are linear race components, measuring 130Nm/mm (13.2kg/mm), which is just over double the stiffness of the front springs on the S-tunes (58.8Nm/mm or 6kg/mm), that are mated to helper springs that ensure that the damper performs its best over road imperfections.

Lastly, but of great importance, you might have noticed that each damper runs a billet aluminum cup. These are the lifting units that make up KW’s Height Lifting System (HLS), cups that extend when pressurized hydraulic fluid is pumped through them. With these mounted above the spring perch on each damper, the R34 will be able to rise up 45mm instantly at the press of a button. This will allow me to run an aggressive ride height and accurate geometry without the need to sacrifice my front and rear diffusers. It all fits in beautifully with the main idea to modernize my 17-year-old GT-R and bring it on par with performance cars of the 21st century.

The rears, aside from the obvious difference in shape and length, sport the same characteristics as the fronts. There are rose jointed top mounts, 90Nm/mm (9.17kg/mm) springs – compared to the 65.7Nm/mm (6.7kg/mm) rates of the Nismo S-tunes – a helper spring and HLS cup. You can also get a better look at the purple rotary dial which allows you to select through the 12 bump settings on each of the dampers.

HLS To The Rescue

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So with the four coilovers neatly presented in their box, you would be correct in assuming that the second box in this special delivery from Germany contains the necessary hardware to make the HLS work.

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Let’s have a look inside…

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The first thing I pulled out was the neat little KW-branded tool box that contains the two wrenches necessary to adjust the spring perches on the dampers to set the desired static ride height. Also included is the purple hex key I mentioned earlier.

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Then we have the largest part of the ensemble, the hydraulic servo pump which pumps pressurized fluid to each of the cups.

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The whole system is actually pretty compact compared to say an air suspension solution which employs an air tank. In fact, everything adds less than 5kg to the car which is totally negligible. I just have to figure out where to hide it away; hopefully there is enough space in the rearward sealed section of the trunk where the ATTESA ETS-Pro ECU, battery and other electronic trickery is positioned. We are only talking about a few kilograms here, so not a big impact. I could counteract it by getting off my rear end and losing some weight!

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KW includes everything you need for the install, including the appropriate hydraulic fluid, braided lines, wiring, mounting brackets even enough zip-ties to tuck anything away that needs to be.

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The system may look daunting in its laid-out-on-the-floor complexity, but once fitted it will simply all be operated by this stainless steel button. Press it once and the HLS unit extends 45mm on both axles and the red backlight will come on. Hit it again and the car will lower. Depending on the application, this 45mm expansion may translate to up to 55mm of actual lift, dependent of course on the damper/wheel ratio and the length of the front and rear ends, and how far things like diffusers hang down from each corner. The HLS will also get connected up to the car’s speed sensor so that at 60km/h it will lower automatically.

Now it’s on to the fitting and set up of both the HLS and the actual dampers. I will first run the dampers as they are and then figure out if I need to add stiffer sway bars. I’m also looking at roll center adjusters as well as adjustable links, but those additions will all come later on.

Project GT-R continues to evolve, slowly but surely and forever improving along the way.

Dino Dalle Carbonare
Instagram: speedhunters_dino
dino@speedhunters.com

KW
More Project GT-R stories on Speedhunters



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