Hi all. I'm new hear. Just signed up so that I could join this conversation.
Glad to see there are others out there that are having fun with the F103GT.
I just recently started racing mine at the local outdoor track. I really enjoy tuning this chassis and wanted to add that I am using the pivot ball T-Bar mounting system (without tweak screws) in conjunction with the white damper plates and hard damper springs. I am currently using 32mm wide Tamiya super grip radials on the rear and 26mm front. I have an exceptional amount of traction and can accelerate from the Apex with aggression and no spin. Due to the increased rear traction and the soft Tamiya tires I have now got some really bad under-steer or (push) as they call it. Before the end of my last race day I tried some 1 deg camber uprights and that decreased the under-steer. This weekend Ill be using 2 deg for the next test. Hopefully the over-steer/under-steer balance will be closer to neutral as the 1 deg helped a lot. I will also be using stiffer front springs if needed in the future.
On a side note, I tried some old TC 24mm tires. (LRP VTEC 36) No under-steer at all with these and the rear traction wasn't too bad but certainly no where near what the 32mm Tamiya tires provide. The car did spin a few times trying to accelerate from tight 180 deg corners. Other than that there was plenty of traction and steering response through the high speed sweepers and just backing off the the throttle into the slow turns without any unwanted tendency to spin.
I'll also be testing some other tires in the future, foam 37-SH/26mm-F, 35S-H/30mm-R, Sorex 24s all round and Tamiya super slicks 26mm-F & 32mm-R.
I used to have the original O-ring T-bar mount system in the winter at night racing events when I first started driving this chassis. I was using HPI X pattern tires back then as my other were on order. Was on a concrete surface and really cold. Was very difficult to get traction. Had the screws on both mounts just about at full loose to get maximum rear pod roll. Wish I had the Sorex 20s back then and the pivot ball system.
I was still learning about tires and tried a set of Sorex 36 but it was like driving on ice. Couldn't even move forward in a straight line. Not even the diff setting could help.
This chassis is a lot of fun to drive and I find it more enjoyable than 4wd. I currently use the HPI RX7 shell but will be using the JC Concepts Layla in the near future.