Re: When an Engineer… Part 2

Ah yes,.. as the sun sets on yet another day of track side entertainment, the PT cools off and I endevour to enlighten all about the project thus far…in order to improve endurance the Tomy motors(green end)were replaced with the low resistance but short lived xtrek original (unsupported comutator)type and much removal of excess weight from what ever I could(only 1 gram.. down to 25). A severe vibration was evident with the starboard gearbox and the crown wheel inner support shaft was found to be eccentric so a complete new crown wheel was more carefully made, however some vibration is still there and probably caused by the 6 tooth motor pinion, it must have had some effect though,as the power balance adjustment is just left of neutral. The pcb was moved forward 1.5 mm and more clearance made around the motor wiring to reduce binding of the front suspension strip. I am begining to have some doubt about the trailing arms torsional strength as high speed cornering is not ideal, even though c of g is as low as possible the rear tyres lose grip easily and me thinks the loading on the outside tyre is high enough to bend the arm until a point is reached that it flicks back causing the tyre to break away….hmmmm. New tyres made from blue “absorbathane” were fitted, (closest thing to gindable glue I’ve found) batteries charged and track dusted down. I decided to go for only single charge attempts in view of motor issues’ and the turning circle was set for minimum move ment, the new tyres made an impact and average speed steadily increased from 3.4km/h to 4.6km/h with 43-47-49-48-48 laps recorded (didn’t break the magic 50..doh!) speed is well down on the Enertecs 5-5.5km/h but the Chrysler rarely made contact with the wall. The minimum speed jumped from 1km/h to 1.9km/h and top speed went up to 9.6km/h measured over a 2 metre section with 1.5 metre run up, wheel dia is 13.5mm and 4400 rpm on full power with the motors churning over 35000rpm, there was less than 200 rpm difference between the wheel speeds on full power. Strangely, I prefer to drive the car very slowly around the course with a goal of not making contact and managed 15 laps at an average of 3.2 km/h. Where to now with the outstanding xtrek?