Posted by Iain Litchfield on 18th March, 2021 in Chassis Setup, Dyno Tuning, Engine, Exhaust, McLaren
We are working on an increasing number of Mclarens for both servicing and upgrades. Now the prices are becoming more affordable and customers know we can look after them we are seeing a number of our good clients from BMW, GT-R and performance car owners in general moving into them as an exhilarating weekend car.
We initially purchased a 720s which we really enjoyed but once we finished our engine tuning work we decided to moved on to more in depth work on a popular Sport series model. We then managed to get a great deal on a 19 mile pre-registered 570GT and this particular car had all the options including the normal S suspension and steering rack which is slightly quicker.
Often the point of a demo car is to demonstrate what we are capable of doing purely in measurable performance terms. However this McLaren was very different, brilliant in each individual area however our 570GT, like our previous 720S, never really felt like it came together as a whole.
As we lived with the car and in particular began to use the car on track the issues of cohesion became more obvious and frustrating. A trip to the Nurburgring in 2020 with its bumps and changes in tarmac confirmed it. We felt the cars core ingredients were capable of so much more.
On our return we reset our goals with the aim of improving each aspect of the car and ultimately make it more enjoyable to drive on road and track. It also allows us to demonstrate to fellow owners we understood each aspect and could offer cost effective solutions that the customer can cherry pick to suit their usage.
Clearly the most important part of the cars ability to utilise its performance comes from its chassis and here we were able to make positive improvements with relatively simple changes.
One of the complaints we have seen is that owners find many of the Mclarens twitchy on the road and particularly at higher speed. When we received our Mclaren fresh from the dealer the wheel alignment was some way out. Like a race car the Mclaren geometry for camber uses shims to space the suspension arms to the required settings. As you can imagine this is quite a long winded process to get the car aligned properly and even if you know the approximate alignment change, each shim will make it will be a least a 3-4 hour job to get the chassis lined up perfectly. It was no surprise then that our car, like most of the Mclarens we see, had no suspension shims fitted from the dealer and was running on the original factory settings, that whilst in tolerance, left it with a setup that was far from ideal and made it feel nervous on the road. After some time on our aligner and then some additional fine tuning we now have a setting that gives the right balance between crisp turn-in and high speed stability. We strongly recommend that all Mclaren owners have their geometry checked as it is one of the most cost effective improvements they can make to the car and the improved chassis can be enjoyed at all speeds. – Mclaren Geometry setup cost is typically £250-400+vat depending on the time needed to adjust. Once adjusted it should only need a tweak as part of the yearly service
To compliment the alignment setup we have also produced our own wheels spacers (11mm front 13mm rear) which are specifically designed for the Mclaren hub and wheel. The wider track further helps stability and helps the car track more purely and responds to driver inputs more faithfully. The spacers also improve the appearance of the standard wheels within the arch, especially if the car has been lowered as the wheel can look a little lost in the arch. Our wheel spacer set costs just £295+vat
Our GT is fitted with the 570S suspension and steering rack which work very well but we felt they could be optimised further so we installed a new spring kit. This upgrade included new springs all round that have a slightly more progressive design than the originals. The very first movement is marginally softer than standard which helps with the ride and traction but then it firms up and ultimately has a higher rate than the original springs. The spring kit also has an adjustable platform to allow us to move the ride height down and corner weight the suspension which further enhances the chassis balance and allows us to tailor the setup for each customer.
Combined with our other chassis changes the spring kit provides benefits in traction and composure without affecting the ride quality.
Our adjustable height spring kit is £1,151+vat
Rear Limited Slip Differential
Our trip to the Nurburgring was really interesting, showing the inconsistencies in the chassis as the circuit would upset the rear of the car as the e-diff struggled to clamp the rear brakes correctly with the car trying to find traction through undulating bends and changes in tarmac. All road going Mclarens have an open rear differential and use the rear brakes to simulate a traditional diff, by clamping the inside wheel to reduce its speed. We found that whilst this might work in theory on standard cars driven sensibly on the road, when driven harder or with more power the e-diff would start to unravel. You start to second guess the e-diff and would question what its response would be, not ideal for driver confidence around the ‘Green Hell’. Mclaren will argue that not fitting a rear diff saves weight and the electric version can perform the same but it can’t and this is why their weight sensitive track cars run a mechanical diff.
Whilst the suspension upgrades and modified engine will be the most obvious changes to our 570, the real difference and missing link is the mechanical differential.
The original open rear differential was replaced by a Limited Slip differential with 8 drilled and lightened clutches that have been specifically setup to account for the intervention of the e-diff and provide good road manners. This new diff gives much better traction and a more a more predictable break away when coming out of a bend. The confidence in the car is transformed as you can now get a consistent response from the chassis when turning in and apply power. Because it is mechanically maintaining the wheel spin the e-diff doesn’t have to interfere too much but is still there when required and when the Mclaren VDC systems are left on. It only adds 2.4kg compared to the original open diff and is similar to the system already used in Mclaren race cars. As all the Mclarens use the same gearbox and open diff this upgrade is applicable to all the other models from the early 12C to the Senna – £2,995+vat
If you would like to improve the way your Mclaren drives both on the road and track give us a call and we can talk through the options in more details
In the next blog post we’ll talk about the power upgrades we applied to our 570