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We recently had a MK5 Supra with us for some product development. With their surging popularity as track cars, particularly in the United States (USA) and United Arab Emirates (UAE) we have had them high up our development list for a while. Our good friends and UAE Trader Mission Motorsport got in touch recently too in order to push the Supra up our development list as their demand for upgrades was so large. Following a great conversation on the requirements they were inundated with for track and fast road suspension upgrades, we set to work.
Ultimately a BMW chassis with a supra body (and all the better for it in our opinion) we had plenty of data and product knowledge to start with from our extensive development work that we have already carried out with the BMW chassis and implemented within our product range.
The underside of the car is a very similar platform to that of the BMW M240i G42 with many components resembling those fitted to the G8X platform too. Most notably the uniquely designed top mounts on the front shock absorbers. Although they are different to those fitted to the bigger cousin on the G80 M3, they share some defining features allowing us to implement some of the key geometry development that we discovered whilst working with Century Motorsport and their BMW G82 M4 GT4 Racing cars.
With the Supra on the ramp we got straight to work stripping down the suspension and scanning in a multitude of suspension components. With the OEM components scanned in we are able to reverse engineer the standard part and begin adding in adjustment and geometry alterations within the design to maximise grip and steering feel and feedback from the chassis.
Two key areas that we have been told by customers with Supras that use them on the roads and the track are a lack of steering feel leading to a lot of mid corner understeer and issues with rear traction and stability on corner exit when applying the throttle aggressively. Being no strangers to these all too common symptoms we set to work implementing some design changes to maximise performance and make the Supra handle much more like its infamous predecessor, the Castrol TOM’s Racing car! Okay well maybe not quite to that level but as close as we can get with some bolt on upgrades!
Toyota Supra Camber Caster Top Mounts
The first product to gain our attention was the camber plates on the front axle. This is because as standard, the Toyota Supra MK5 doesn’t have any camber adjustment at all and has a very limited stock setting of around -1.5 degrees of camber which is not enough to maintain front axle grip at speed. With our extensive development with the GT4 racing cars we know that the perfect blend of caster and camber can have huge effects over understeer and make the tyre work properly with the tarmac to get as much grip out of the contact patch as possible. Therefore, we increased front caster to sharpen steering response and increase steering feel for the driver, making the front end much more direct and intuitive. Next we added in the camber adjustment to allow front camber to finally be adjusted and set to a position that uses the full width of the tyre through the corner. This not only reduces the understeer but improves tyre wear if you like to drive hard.
Improving tyre wear might seem unexpected with the addition of more front camber but due to the low amount of front camber as standard, the outer edge of the tyre starts to wear away much faster than the rest of the tyre. With the camber increased, more of the tyre is used effectively throughout the corner, leading to a more even tyre wear and an increase in grip.
Toyota Supra Rear Toe Arms
With front axle grip increased and understeer fully addressed, we switched our focus across to the rear toe arms. A very common issue we find at the rear axle on many BMW chassis’ is a lack of toe adjustment. The rear camber and the rear toe is adjustable on the Supra but still falls into the same issues. When enough camber is installed at the rear axle (usually around -2 degrees) it is no longer possible achieve toe in at the rear wheels which is critical in maintaining grip and stability at the rear axle.
Therefore we have designed our adjustable rear toe arms to offer a much larger adjustment range into the chassis to ensure that no compromises are required at the rear axle anymore. They allow optimum camber to be set using the OE adjuster and the adjustable toe arm can then set the toe-in back into the rear of the car.
The OEM rear toe arms also feature rubber bushes at both ends. During hard cornering such as when driving fast on the roads or on track, these rubber bushes flex as they are loaded through the corner. As they flex, the rear toe angle is changed, altering the geometry at the rear wheels whilst the car goes through the corner. This can lead to an unpredictable feeling at the back of the car. Therefore, our arms feature rose joints that don’t flex as they are loaded. Not only do they not flex, keeping the rear stable and planted through the bends, but they also don’t increase any noise or harshness making them a perfect upgrade for the road and track.
Toyota Supra Rear Solid Control Arm Bushes
Whilst we are on the topic of the rear axle flexing through the corners, its not just the toe angles that are affected. The rubber bushing in the rear lower control arm (or coffin arm) that the spring and damper sit in at the rear axle also flexes through the corners. Not only does this flex alter the camber and toe angles as the car goes through the corner, but it also caused a slight delay in chassis response. Chassis response is how fast it takes for the chassis of the car to move after an input is put in by the driver. In this case the steering wheel is turned, load is carried through the tyres and the rubber bushes flex as the tyre force pushes against it. Once the bush has finished flexing, it moves the chassis and the car changes direction. If the rubber bushes are removed and replaced with a solid bush such as ours, then the chassis response is immediate leading to much more driver feedback and responsiveness which improves driver trust in the chassis allowing both the driver and the car to drive faster.
Couple this effect with the fact that the geometry is also no longer shifting and changing as the car goes around the corner and this further compounds the effects to give much more driver engagement and trust in the chassis to push harder and have more predictability in the car.
Toyota Supra Front and Rear Drop Links (End Links)
The final products to be produced on our development day were the front and rear drop links. Fixed length drop links are good for standard ride height vehicles that don’t have any ride height adjustment or haven’t been lowered. As soon as the Toyota Supra is lowered, the front and rear anti roll bars (sway bars) are rotated away from their standard resting position. This puts an increased load on the anti roll bar bushes due to them being bonded to the bar. This increased load on the bush can lead to premature failure and cracking of the bushes which will allow anti roll bar movement and flex which will reduce its effectiveness over the chassis.
With the adjustable drop links fitted, the bar can be set back to its oem position after lowering to take the load off the bush and provide its original longevity and life span.
Further to this, if your Supra has coilovers fitted then you unlock the ability to corner weight and align the car. This is where you can fine tune ride heights to distribute the mass and balance of the chassis around the car to get optimum grip levels at each tyre. To achieve a perfect corner weighting the ride heights often end up being slightly different by a few millimetres at each corner of the car. This results in the anti roll bar being loaded at all times when driving straight. This means that when the car corners left for example, the bar is loaded in that direction and has immediate effect over the chassis. However, when the car turns right, the bar needs to unload and then load up again which makes the car feel very soft on turn in and then immediately stiff as it enters the corner which can lead to understeer or oversteer depending which anti roll bar is being affected.
The adjustable drop links can solve this issue by being fitted at the front and rear of the car. Once corner weighting is completed, the drop links can be adjusted to be different in length to take the load out of the anti roll bars. This accounts for the difference in ride heights after corner weighting and resets the anti roll bar loads making for a much smoother and predictable drive.
Our drop links also feature motorsport high load rose joints to improve the responsiveness of the anti roll bar, making the chassis more direct and respond even faster to inputs.
Coming soon….
After a great development day with the Toyota Supra chassis we haven’t finished yet. Coming soon we will have even more suspension products including but not limited to:
- Toyota Supra Solid Front Control Arm Bushes
- Rear Camber Arms
- Rear Traction Arms
What else can you install to your Supra?
Aside from our geometry altering products that extract as much potential from the chassis as possible you could install a set of lowering springs or coilovers to the car. We installed a set of KW V4 Clubsport Coilovers to this Supra as it was intended for track use. Coilovers add a lot of chassis adjustment into the car as they allow the alteration of damping rates, ride heights and corner weights as well as providing a stiffer spring to reduce body pitch, yaw and roll. If you would like to see more options for your Supra click the link below and see how you can improve your handling substantially.
