904 slipping from 2nd-3rd (with video)

I had a flare problem on my 904. I double checked and triple checked everything. Tried 3 different valvebodies, rebuilt the front clutch 3 timed. A member here told me to take out the outer front servo spring. Works good now.

Sounds like you have an overlap problem, in 2 gears at the same time. It's common for a 904. My Trans Go TF-2 kit instructions said not to put the orifice plug in the case of a 904, and I didn't in mine. You have a shift timing problem, so maybe you need the plug. I would try the plug and see how it shifts. You can change the size of the hole to adjust you shifts.

If all else fails, you could always call Trans Go's tech line and see what they say. But make sure you have all the pressure information for the trans or they won't even talk to you. Don't ask me how I know this.