Pontiac Repair: 1991 Chevy Lumina APV Late Shifting, chevy lumina apv, 1991 chevy lumina

Question
Hi Todd,
I have a 1991 Chevy Lumina APV Van that has an automatic trans that shifts late.  It starts off in low gear and revs quite high before shifting into second gear and again revs high before shifting into drive.  I put some transmission treatment into the trans and that seemed to free it up a bit, but it still shifts late. Is there anything I can do to fix this?
Secondly, the speedometer is reading is not accurate.  You drive 55 and the speedometer reads 80.  I tried replacing the speed sensor on the trans, but it didn't make any difference.  Is there anything that I can do?
Thanks for your help.
Rick

Answer
Hey Rick:

I'm not a transmission expert but I'll try to help you out. You have 1 of 2 things going on here. Either the governer is bad for the transmission of the gear for the governer is stripped out causing your speedo issue as well The governer is under the speedo drive. the valve may be hanging up in it or like I said the drive gear is messed up. The other thing may be the throttle valve cable may be out of adjustment. That is the cable that attached to the throttle body assembly on the engine and goes down into the transmission. Good luck :0