[356speedster]

How does it behave without the guide spring? A Too strong guide spring could lift the car as it tries to lean over into the front tires at entry.

Narrow cars often need the front wheels as "outriggers" to avoid tipping over at entry, so try to eliminate vertical slop in the front axle and keep the front tires barely touching the track by adjusting the guide height/load with shims or different guide spring strengths.

Weight down low will help, but try to make it run as good as possible before adding any, as it will only mask the real problem.

 

[356speedster]

Very long and narrow, but should be great for long power slides once sorted

Looking at the guide, it seems very close to the front panel, have you checked that it turns freely when the spring is fully compressed?

I would also try to replace the spring with a styrene tube to seat the guide and transfer more weight onto the guide, the spring often leaves too much weight on the front tires and if they grip the track at entry it will flip over since it's so narrow.

I think this car wold run better if most of the front-end weight is on the guide (tripod setup), but with coated front tires that barely touch the track to support the car through the turns.

Tore

BTW: it looks great!