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Month: September 2015

CMS Nissan R33 Skyline GTS-T

Corby Motorsport Nissan R33 Skyline GTS-T

The Corby Motorsport Nissan Skyline showcases our range of products and allows us to test new products before we offer them to our customers. It is also bloody good fun to drive round any track!

The car started life with us as a lightly modified example the R33 Skyline GTS-T. It came with a T38 Stage 3 hybrid turbo, (unbranded) front mount intercooler, a large cone air filter and HKS big bore exhaust so probably making around 270bhp weighing roughly 1500 Kg including its standard interior. A cheap set of Daiyama coilovers and basic Jun body kit completed the package.

The Big Idea

Add a bit more power and add lots of adjustable suspension parts to show that you don’t need to spend a fortune of silly bhp, just need to add adjustability to maximise grip and traction so you can use the power you have properly.

So, we have not modified everything on the car at once preferring to evolve the car over time in the same way most of our fast road and track day customers modify their cars. We have built the most adjustable chassis we could within a reasonable budget to maximise the available grip and traction for a faster car without spending a fortune.

We have added a bit more power – around 400bhp now, a CG Motorsport clutch that can stand the abuse, brakes that actually stop the car and a roll cage (Cobra seat and racing harness) for safety and we stripped the interior to add free performance by making the car lighter.

The car was first tested in October 2014 but had a few issues which were fixed over the winter of 2014. The idea for 2015 is to run the car on track days through 2015 whilst playing with the suspension geometry and damping rates to get the car dialled in to our drivers style and lapping quickly, whilst fixing any problems that may crop up (the car is 25 years old after all!).

If all goes to plan, we should have some fun in our dedicated track day car and compile a list of modifications to improve the car for 2016 based upon how the car performs over the year.

2015 Engine Modifications

Under the bonnet has been kept fairly simple for reliability. Simple stuff like a remap, Z32 AFM, bigger injectors and fuel pump and a rise in boost has released more power. We now have around 400bhp to play with. Not huge headline power but certainly enough to be more entertaining given the R33 GTS-T Skyline is quite a heavy car.

2015 Suspension Modifications

Suspension parts are our main focus as a company and hence a lot of parts have been upgraded within the suspension to give us as much adjustability as possible. The reasoning behind this is that if we can use the adjustability to set the geometry up to use all of the available grip, we will have a faster car than if we relied on just simply chucking a set of coilovers at it and hoping for the best, then thinking we need to add more power to make it faster. Not so! In our view, adjustability in the suspension is critical to setting up the car properly for faster lap times and is often cheaper than simply adding more power.

To this end we have installed……

BC Coilovers – BR Series with WHAT spring rates and race damping
Hardrace rear camber adjustable upper arms and rear adjustable traction rods
•Driftworks HICAS to adjustable toe conversion kit
•Cusco camber adjustable front upper suspension arms
Front strut brace

We can now adjust the camber and toe at the front and rear. Our drivers bottom will know whether the car is understeering or oversteering and where and using our trusty heat sensing gun after a session on the track, we will be able to see where the tyre is hot and where it is cool so we can adjust the geometry to even out the tyre temperature to get grip across the full width of the tyre (check out our tuning guides to understand grip, reduce understeer and reduce oversteer).

We have left the front and rear bottom suspension arms alone on grounds of cost, we don’t believe that many of our customers will go to the expense of replacing their bottom arms and we seem to be able to dial in the camber we want with the much cheaper upper arms that are available.

We have not fitted uprated anti roll bars as yet, preferring to see if the spring rates and race damping will negate the need for them. So far so good, we may fit them in 2016 as a test to see whether they will offer increased lateral control despite our high spring rates.

With so many of the new arms having suspension bushes already fitted, we have not yet replaced the rest, again, this will happen in 2016 as the car evolves as will renewing the engine and gearbox mountings for uprated Vibra Technics parts.

2015 Brake Modifications

We killed off our old Nissan 200SX factory brake system in less than 5 laps at Rockingham Raceway in Corby so rather than wait, we have fitted a KSport Brake Kit with 356mm grooved rotors (which clean and refresh the brake pads on every application) fitted with Pagid RST3 pads which are becoming very popular in Time Attack cars as they come up to temperature very quickly and maintain perfect performance every time we hit the brake pedal. Not ideal on the road as in our experience they don’t get hot enough in normal everyday road use and hence are a bit on/off but warmed up for track use they give great feel and massive bit albeit they can be a bit noisy (brake squeal) in use. Ferodo DS2500 would be quieter but we felt we should give the RST3 a go and we are so impressed we will live with the noise!

We have fitted Pagid RST3 rear pads in OE callipers at the rear and will decide if the rear need upgrading through the 2015 season. As most braking is done at the front end, the rear end will stay relatively standard unless we decide we can improve lap times with more rear stability under braking if it becomes a problem.

Braided brake lines at the front have been changed as they came in the KSport kit. As yet we have not changed the rest of the brake lines but will be doing so in the winter of 2015 as well as fitting an Optimum Balance Brake Bias Pedal Box on the grounds they are not that expensive, superb quality and will help us define how the car turns in under braking – we will be able to dial out understeer or oversteer for a more neutral and stable chassis under braking which should reduce our lap times.

2015 Transmission Modifications

We have fitted a CG Motorsport clutch as there was no way the factory clutch was ever going to cope with the torque output of the R33. It’s a bit on or off to use but it doesn’t slip and the pedal is not heavy so happy with that!

Our Skyline R33 GTS-T still wears the factory LSD but you would never know it as its worn out! This is one area we are very keen to improve as our R33 losses traction very quickly and converts forward motion to fire and brimstone as the tyres light up, the unloaded rear wheel spinning up as we try to accelerate around the bends. Not cheap but a limited slip diff is one of the best traction aids money can buy! Other than that, the gearbox, propshaft and rear end are coping at the moment!

2015 Body (In / Out) Modifications

So with the idea of building a track focused car within a similar budget as our customers and pointing out the best parts to change for added improvements, spending out on the Rocket Bunny body kit was pure vanity! The kit adds over 100mm in width at the rear and a similar amount at the front and we think it looks great but be warned, you will need to remove a lot of metal out of the OE wheel arches and weld it all back together, fit the kit then use a fair amount of paint to get it all back to one colour.

You will also need some wide wheels. We went for 10 x 18” Rota Grids. Tyre choice was Toyo Proxes T1 Sport as they are sold as an all weather tyre. It has to be said they are stretched a bit (265 rear and 245 front) but in our experience they offer zero traction in the wet and overheat quickly in the dry. Maybe its the stretch of the tyre, the power of the car or the weight or a combination of these, either way, we wont be running theme again and we will replace them in 2016 for some track day semi slicks. Then we will think about what we will do if it rains!!!!

We have raised the bonnet at the rear edge to let hot air escape more easily (common mod on turbo cars as the under bonnet temperatures are generally far higher than in normally aspirated cars) and we have changed the boot lid for a fibreglass item which weighs a lot less than the OE lid (and hence adds free speed!).

We will in 2016 be looking at replacing more panels with lighter versions, bonnet, and doors will all be considered before we start thinking about what testing what aero packages such as air dams, splitters and diffusers might make the car faster in terms of cornering grip (of course you loose some top speed as your shape is no longer slippery but more pushy into the ground but that’s all a way off yet!!)

For safety and lightness, we have added a full weld in roll cage with cross diagonals and cross door bars into a stripped out interior with just a single Cobra racing seat and Safety Devices 6 point harness.

One of our own R33 GTS-T through bonnet” front tow bracket, a rear tow hook and an Aztak In Car Camera (to record our on-track exploits) complete the 2014 build of our Skyline R33 GTS-T. Now we will run the car at some track days and see how we get on, testing and playing with each part to maximise the performance of what we have……………

Gripper LSD – Lifecycle

The Gripper LSD itself will go on forever. They are set up with a certain preload (dependant upon use) by selecting correctly sized clutch plates which can wear over time. The wear in reduced in Gripper diffs as the clutch plates have minute grooves machined into them which pumps a microscopic layer of LSD oil in between the plates (this also reduces the plate chatter noise associated with plate type diffs, making Gripper diffs almost silent in operation). Plate wear is caused by mechanical stress as the plates lock together when the diff is in operation (when different wheel speeds are detected as in cornering) and is governed by the type of use the car gets i.e. a road driven car will wear plates more slowly than a car driven exclusively on race tracks using slick tyres as the cornering forces are far higher on track.

Generally, apart from oil changes (we suggest every 6 months), unless the diff has stopped working properly, we would suggest leaving it alone!

Clutch plate kits are readily available as are all the internal parts (most of which will be covered by the Gripper Lifetime Warranty) so running a plate type Gripper diff in your road or race car is simple and cost effective given the huge increase in cornering grip you will enjoy.