c4 trans

I have a 91 mustang that i switched to a C-4 tranny i re-used the c-6 torque converter using a spline adapter from PA trans.

also hardened input shaft and -re-inforced drum upgraded servo


anyways, first time at the track with the new trans, car went 12.2 at 105 and 10.92 on the bottle at 121MPH

but the flair up between 2 to 3rd is HORRRRRRIBLE i'm woundering how much speed im loosing to the flair up,

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I have a 91 mustang that i switched to a C-4 tranny i re-used the c-6 torque converter using a spline adapter from PA trans.

also hardened input shaft and -re-inforced drum upgraded servo


anyways, first time at the track with the new trans, car went 12.2 at 105 and 10.92 on the bottle at 121MPH

but the flair up between 2 to 3rd is HORRRRRRIBLE i'm woundering how much speed im loosing to the flair up,


Did you switch from a c6,if so what was your times compaired to the c4.
thanks

You need an H-servo or preferrably a C-servo.

Is it a fresh rebuild C4? What clearances ? What servo?