Shift Problem ?

Red line is last year 2018. Green line is this year first time out. Same trans and convertor from last year. Got progressively worse over 2 days and this is the last run (green line). Shift Output (electric solenoid shifter) was on for approximately 0.20 seconds all runs 2018 – 2019.

4.9x dragster. Spragless Convertor.

Opinions…..

Change you electric solenoid on the shifter.

Issue occurred at the same spot each pass. Grid shows shift output time same all passes but car does not complete the shift in the same duration

Same fluid? Trans temp?

You can try a run where you manually shift to see if it is a shifter or transmission problem.

Same fluid, no idea the trans temp however this just carried over the next day as getting progressively worse meaning the first run sunday was a little more aggressive of a spike vs the last run Saturday so i doubt its heat related..

Have you checked the shifter cable? Maybe it's gotten sloppy and is having trouble finding/engaging high gear. Park and low are easy to find, but the middle gears can be a challenge when the cable is worn.

I have checked the cable in 1sr/2nd gear and park. I also put it in gear and cycled the solenoid and then checked the cable again. There is some slop but how much is too much? 1/4” play or 3/4” ???

Make sure the shifter is not getting sticky. In both the cars we race I removed the detent spring that hold roll pin in the notches between gears. Makes moving the shifter thru gears much easier but still functions fine and safe.

Secondly make sure your power supply is good and strong. What is the voltage run to run saying in logs? You should be so you know be able to overlay them as well. Mine is just a blip in voltage on shift. Check that and see if the solenoid is laboring, drawing more.

Sounds like you got that covered then. Trying to make sure its not something easily overlooked.

As far as how much is too much? Depends on a lot of variables. I have seen some shifters that have a lot and work fine, others that won't shift right with a little. (that probably didn't answer your question though)

Any chance it's spinning on the gear change?

Its a 4.90 dragster so not spinning.... i would hope not. The battery voltage goes from solid 17.8v and during shift drops to 16.4. This is consistent on all runs

I was told, this trans was removed and replaced with a spare trans and tested on stands. Has not been track tested yet.

This trans removed was disassembled and nothing out of the ordinary found with 120 runs on this trans. It still appears to be new inside.

Here’s my question. Given that all the DA rpms look to be smooth prior to and after the shift was completed, is there any possibility that the convertor could cause this?

Can you put car in first and trigger solenoid with test function in grid to see how quickly it pushes shifter. It should be nearly instant. On cars I've seen the solenoid labor and move it slowly. The above fixed it. This would rule out several things.

I have tried that but not running. The test function is activated when ignition is triggered on

Update: found a broken sealing ring on the servo just now. This applies the band so that makes sense here.

Glad you found it please let us know after you track test to verify.