One of the first parameters to work on when tuning a chassis is front carriage width. Because of Hackerman’s angles front width regulation generates strong effects on front grip. Increasing front grip offers better speed entering curves, but can be an obstacle exiting them. It is always a matter of balancing your kart to shift vertical force generated by weight from front to rear tyres and vice versa.
On a very technical track in Rome (Pista d’Oro), first Italian track to be built, maybe the hardest track to race in because of physical challenge (no long straights to rest) and technical difficulty, we decided our test of the day. Just see how much and in which way front carriage width variation acts on behaviour of the chassis and final lap time performance. Circuit runs clockwise.
We started with a base front carriage width of our Tony Kart Exprit chassis, which I must say is generally very well balanced on all tracks with the standard setup. Still we know that track conditions and specific track conformation may require changes in the balancing of the kart.
So we ran out first laps with Le Cont LH 03, the same ones we did our long test drive with and which incredibly had still something to say! Rubber on the tires still present on all the thread, but with limited quantity in the internal part close to the chassis, especially on rear tyres.
First laps to warm up a little and then a good run of eleven laps with best time set on the 9th lap at 50.07 sec, second best at 50.22 sec on lap 8. Kart behaviour was good, but even though not much rubber was on the track the feeling was of good entrance in corners, but some traction difficulty exiting the bends. Along fast curves also the rear of the chassis tended to slide too much.
The choice was to try to achieve some improvement along fast curves widening front carriage, which should give generally greater front grip especially at mid curve and at high speeds, while loosing something in the very first moments entering corners. We so took off a 1 cm ring from front hubs and reduced front carriage width of total 2 cm.
A session of 10 laps was ran and my best performance was 50.10 on lap 7 and 50.14 on lap 8. So no overall improvement and the feeling was great difficulty to improve previous session times. The kart in fact was not much better along fast curves, but lost a lot in slower and narrower turns. The entrance in the bends did not improve, but exiting was somehow tougher, with the front tires sticking to the asphalt all the way when exiting the corner generating a loss of grip on rear tires. Possibility to accelerate was retarded and final lap time was negatively impacted by this, even though I was warming up, so final lap time was similar to previous session.
Third and last run
We then decided just simply to try the opposite of the previous run and reduced front carriage of 1.5 cm, taking away a 1 cm ring and a ½ cm ring. Now what could happen was to heve reduced grip on front tires entering corners and along fast curves.
The feeling while driving was instead simply a much freer kart exiting curves and no rear tire sudden grip loss and sliding as in previous sessions. No real difficulty entering curves, even though our driving had to be partially adjusted anticipating turns so to avoid being too wide along the bends.
Well our feelings were quite correct and it was incredible to verify how instantly and easily my lap times decreased, with a 49.93 sec at lap 5, and 49.80 sec on lap 6 and finally a best lap at 49.75 sec on lap 7.
After that, no real improvement, but constant lap times around 49.90 sec. No doubt, kart was behaving better, a 0.32 sec improvement compared to previous two sessions just by varying front carriage width. Also kart was easier and less tough to drive.
So we confirmed how important it is to just act on front carriage width. We will see in next issues rear width and other parameters very simple to very and how they act on performance and lap times.
Just remember that not always an easier to drive setup gives better lap times. It worked this time, it might not always be the same.