musclecar70sfan

iTrader: (1)

Hey guys, I have a 1991 T/A 'vert with the LB9 engine (305 TPI) with the 700r4. I noticed that this thing won't (sometimes it will but it hesitates) downshift into 1st at anything above 20-25 mph. A full-throttle start from a standstill makes it shift into 2nd at around 40-45 mph so I figured that at the speed mentioned above there is plenty of room to downshift into first. Since when I'm driving at around 30 mph and decide to gun it, the thing kicks down only into 2nd at at that speed/gear the car feels sooo lethargic and kinda boring. My 1994 GMC Jimmy will kick down into 1st (4 speed auto as well, I'm assuming 700r4?) at 35 mph or below when floored.

So is the car supposed to do that or do I have a sensor or something that's out of whack? However the car shifts very smoothly and drives great (I think the tranny was rebuilt not too far back, according to the previous owner).

BTW I noticed that at full throttle my car shifts at 4500 rpm, which the yellow line. Can I make it shift at 5000 rpm which is redline? Do I want it to do that?

cIaRmOaCrZo

there is a tv cable or better known as "kick down" cable that attaches to your throttle body lever. you can make adjustments with that to change shift points and kickdown sensitivity. look on the bracket bolted to the side of the plenum, where the throttle cable and sometimes cruise control cable go through,,the other cable is the tv cable. there is a "button" type thing you have to push in to pull the cable forward or backward. pushing cable forward will make it shift SOONER, and more difficult to kickdown. pushing cable backward will make it shift LATER, and more sensitive to kick down. just tincker with it and make many test drives till you have found that spot you like. and shifting at 4500 is GOOD on a stock lb9. the hp power band is right at 4000 rpm. anything later than that, it just waste time and speed for the next shift. so you WANT that 4500rpm shift. and your torque band is at its highest at 2900 rpm. but if you just want that kickdown, then pull it back (youll end up shifting late as ****) but u may get it kickdown below 20mph like u said u want

Atilla the Fun

Trying to get what you want from the TV cable isn't the correct way. There are shift kits that specifically address this. If you leave your engine stock, then 4500 is fine. But if you do stuff like cam, headers, et cetera, then you'll want the 5000 rpm upshift, or even 5500, depending on what mods you do. To do that requires changing the governor. B&M sells a kit to modify the governor you already have.

Atilla the Fun

BTW, your '94 has a 4L60E, so that's why it behaves differently.

musclecar70sfan

iTrader: (1)

Ooohhh gotcha. Thanks guys!

musclecar70sfan

iTrader: (1)

Oh btw how much does a shift kit usually go for?

cIaRmOaCrZo

im not completely for sure, but a "shift kit" isnt actually any type of component or part you actually install. basically what you buy is DIRECTIONS on what to DO to your valve body to make it perform a certain way. you can just save your money and ask a automatic transmission expert which holes to drill out, and block off, ect. Because that is ALL a "shift kit" sells you. And yes there are wrong and right ways of doing those precedures for bumping main line pressure.