Thanks for the replys!

supafastsupra2 did you grind away the lip on the shock collar to sit on top of the traxxas insert or did you dremel away enough room for the lip to fit inside of that piece? Hope that question makes sense...

no grinding needed, the traxxas uppers fit perfectly over the lip....

I have an old school B4 FT (not a 4.1). What would I gain with the new 4.1 worlds that would be useful for local club racing?

yes it will make a big difference in handleing, stable!!!!!!!

It really all depends on the track. Personally I prefer the Old Car and I am faster with it. but I have only tried others B4.1 WE and not my own.

Most importantly you will have a new car!

There has been alot of changes since the b4 I would just buy the Worlds kit and have all the updated parts, +8mm chassis etc.

Does anyone know the lowest tooth count that will fit (pinion and spur teeth added together)?

The biggest thing is the longer chassis:
http://kriostasis.com/store/index.ph...f1d76dfebea7e0

proline MC suburbs

The Traxxas collar is slightly larger ID than the OD of the bottom of the threaded associated collar. No dremelling required

Why would you want to know this?

I'm running 69 spur and 31 pinion. I really dont think you could get a smaller spur. The slipper pads are right at the edges, but the 31t pinion is the size of a nickel. But it sure runs great with a 13.5

I know a 20/84 is cutting it close.
My t4.1 runs 20/84 and the motor is all the way forward and is at the min amount of gear mesh I would want to run.

What parts do I need to get to convert my b4.1 to the worlds edition?

I'm surprised to see so many people running the MC compound, they seem to hard to me..