3rdgenstm

The trans won't shift until it hits 5500-6000 RPMs at WOT. I can feel it gaining speed until it hits 4500rpm then it feels like it hits a wall. It will shift out of 1st and into 2,3,4 just fine.

I also don't get a good downshift, I have to go to WOT to get it to do a 3-2 downshift and it is very weak at that. Another 89 I drove recently has a very nice crisp downshift response at half throttle.

I have planned to install a B&M shift kit and 3.23's, but I know this won't help the problem and I would rather have the problem fixed before I install everything.

I have done a f/f change, added fluid and adjusted the TV cable. Neither seemed to help any.

165K on it, 30 over 305, 2.73 gears.

TurboGM1

Does your car diesel at all when coming off the line, like it's still in a higher gear and never shifted back down to 1st? Your tranny is doing what mine does at times, otherwise it drives fine until it's time to stop or slow down and mine also seems to hold 2nd and sometimes 3rd for a while until hitting up near 5,000 rpm's, to higher at times. I have no clue what it is on mine and looked up your post hoping to find and answer. Anyone have any ideas on this?

3rdgenstm

No, it just doesn't want to shift out of first until it hits the 5500 mark at WOT. All other shifts are fine. It will chirp the rear tires in 2nd. If I progressively open it to WOT it shifts better, just when I really get into it does it not want to shift.

C&DPerformance

How did you adjust the tv cable? Did you open the throttle with the pedal or the throttle body. Sounds like you need to go in a clickor two on the tv cable. Move it a click and drive it.

3rdgenstm

I'll re-adjust the cable and see how it does.

I was also looking at these parts. Do you know if they do anything??

B&M 'downshift kit'- it is pretty much the Corvette valve. I have heard this helps.

Jet servo kit- says it holds the band at a greater force to improve the 1-2 shift.

B&M governor recalibration kit- allows to change the shift points.


The car didn't run when I bought it 3 years ago, so I don't know if it is something I have done with the engine that has made it do this or if it is purely the trans.

Thanks

Supervisor42

I can shed some light on the B&M governor recal kit. It is helpful for changing part and full throttle shift points up or down together. I like this kit. Really. When they say "with the possible combinations of the different weights and springs in the hundreds, your combination is there, it just requires some trial and error". They ain't kidding. Some tips I have learned thru much, much experimentation: 1. The springs & weights effect the 2-3 & 3-4 shift more than 1-2. (ie: move the 1-2 up a little, the rest move up a lot) 2. Changes to the governor effect part throttle shifts and WOT shifts at the same time. (ie: raising the WOT shifts will raise the part throttle shifts too)
I have the opposite problem that you do. My engine makes power from 2500-6500. I got little from 1000-2200. When it hits 4500 it really begins to pour it on thru 6500. I can't get the 1-2 WOT shift higher than 5500 without the 2-3 part throttle shift delaying past 3000 (a real drag for driving around town). I can't floor shift it because it tachs up so fast in first it goes past 6000 to 6500 in less than a tenth of a second. I know what I have to do. Just have to do it.