The 2018 BirelART S9 is the latest chassis from the famous Italian manufacturer, we tested the 2018 model thanks to Jade karts who sell the chassis with Andy Cox Racing (ACR) being the sole importer.
Birel, now BirelART as of a few seasons ago, have always been one of the most popular chassis manufacturers, especially on the European and world stage. They have had a lot of success with drivers using their chassis, most recently with Oliver Hodgson who in 2017 finished 2nd in the British X30 championship, won the British Kart Grand Prix in senior OK, and became IAME international champion in senior X30 as part of the team PFi on the BirelArt S8 chassis.
To test the 2018 chassis Jade provided a race ready kart in senior X30 trim at Whilton Mill on a beautiful spring day, perfect to get a feel for how it handles on circuit.
The most obvious thing that is different about the BirelART is the new for 2018 front nose cone. Closer resembling a wing than a bumper it is designed to be aerodynamically efficient and creates downforce in higher speed corners increasing front grip without disturbing the air to the brakes and airbox.
Jade put the kart down on their stock setup and immediately it felt great. My first impressions were that the kart has a positive front end and the steering felt precise making it very intuitive to drive. Taking the difficult Christmas corner at Whilton is done with no more than a hint of steering, and the kart glides effortlessly through the corner.
The Free-line braking system on all BirelART models is very good, full floating disk as standard means you can be sure of consistent braking at every corner. The feel of the brakes is very solid, as the pads pinch the disk the brake pedal stiffens and any further pressure gradually increases the braking force applied to the rear axle. I found myself being able to threshold brake and hold the pressure right to the apex even at the notoriously difficult downhill off camber Ashby hairpin. This ease and positivity on the brakes will I’m sure make overtaking and big lunges down the inside feel like second nature.
Away from the circuit there were some very neat and clever additions to the chassis which I particularly liked. The steering column on the BirelART has an ingenious parallel tube and clamp system meaning adjustment of the steering wheel height is as easy as loosening and tightening two bolts, and the number of positions for steering wheel is much higher than usual meaning the chassis will suit any driver from Mini X30 all the way to the tallest Senior driver.
After close inspection, I noted another very clever addition, on each rear bearing carrier there are the standard four bolts to locate the axle bearing in the chassis, but the BirelART also had an extra optional bolt hole at the bottom of the carrier, which when inserted adds an extra stiffness to the rear of the kart for use on a green surface or in wet conditions.
Comparing the BirelART to other chassis I have driven, it felt a little stiffer than most which contributes towards the precision of the front end. There was no bouncing or ‘pogo-ing’ that you can sometimes experience with a softer chassis and personally I liked that it was that little more solid. The stiffness gives a very neutral and stable base especially in the higher speed corners, and the chassis responds well to precise driving. The only potential issue I found because of the stiffness was that the kart didn’t glide easily over kerbs, for example using the kerb into the boot at Whilton mill makes for a bumpy ride. As a senior driver this is only a minor issue and very manageable as you can use your body to absorb the energy, it just may take a bit of getting used to for a smaller or junior drivers. Despite this the kart handles the bumps of Whilton mill very well, with the attitude of the kart not being affected by the bumps in the corners.
Due to the chassis’ inherent front end grip the kart rotates well in the middle of corners and therefore releases very well off the corners. Throughout the day as the track temperature rose and the rubber went down I experimented with the setup a little as the rear tyres began to go off just a little towards the end of a session. After lowering the rear ride height the kart settled down and began to conserve the rear tyres over a stint, and the braking stability also improved.
Every setup change we made had a noticeable and direct effect on how the kart handled which will make taking this kart to new circuits easy. According to Jade, everywhere they take the kart the setup is almost identical with minor caster adjustments using the asymmetric caster ‘pills’ normally being all that is needed to get the desired attitude through each corner.
By the end of the test day I felt comfortable in the kart and driving it felt natural, I was able to lap with just a few hundredths over a session proving how easy it was to get to grips with.
The BrielART S9 is without doubt one of the best chassis I have driven, and would definitely be in my short list of favourite chassis. Jade karts are the UK importers and will be happy to answer any questions about the chassis, or anything else. The BirelART TKM chassis has taken off with a large proportion of the Super1 TKM grid now using it to great success, I can see this X30/OK/Rotax equivalent doing something very similar in the coming months/years.
Thanks to Jade Karts for supplying the chassis and Engines for the test.
Photos courtesy of BirelART, and Chris Walker
Written by Piers Prior