98 Z-28 4L60E downshift question

**Bakerman** · 07-30-2009, 08:50 AM

I have a 98 LS-1 Z-28 with a 4L60E tranny. I autocross race this car and need to have the car shift down from 2nd to 1st at up to 27 mph upon hard acceleration with the shifter in the 2nd gear position. The car currently runs just fine but will not shift down from 2nd to 1st gear upon hard acceleration above 18 mph. Can the PCM be programmed to change this shift point? Or do I need a shift kit??? Appreciate any recommendations - Thanks !!!

**shady milkman** · 07-30-2009, 10:09 AM

1 gear is sooo steep that i believe it tops out at around 12-15 mph...so that is why it wont downshift to first..so you don't grenade your trans

**c5z28** · 07-30-2009, 11:05 AM

it runs out of juice a little over 30mph, I have roll raced from 25mph once and never again. Your car can definatley be tuned for it and a shift kit would be nice to-get a tranny cooler! I like autox and am still very new-talking to people on there 3rd 4l60e's slowed me down a bit.

**Bakerman** · 07-30-2009, 01:21 PM

I have a 98 Z-28 (4L60E tranny) that I race in autocross. I normally run the entire course with the gear selector lever in 2nd, allowing the car to up-shift and down-shift itself. I'd like to change the downshift point from 2nd to 1st gear to about 27 mph (or slower) upon hard acceleration. It currently downshifts at about 18 mph (or slower) at full throttle.

My question is will a PCM tune change the tranny shift point for me to do this ? or will I need to put in a shift kit ? I'd appreciate any help anyone can share. Thanks !!!!!

**c5z28** · 07-30-2009, 01:23 PM

a tune will change it-talk to frost about a mail order tune.
not that you need a third thread but this should go in the drivetrain section.

**Bakerman** · 07-30-2009, 01:27 PM

Thanks for your help !!!

**lovedrvr** · 07-30-2009, 01:42 PM

buy a diablosport predator (the slp7196 version)
has alot of tranny settings that will work great for autocross
and the best part is you can change them anytime you want
with a tune you are stuck with youy settings

**Bakerman** · 07-30-2009, 01:58 PM

Will definetly check it out !!!! Thanks !

**0rion** · 07-30-2009, 09:55 PM

you can change your shift points with tuning

moving to the tuning section

**Bakerman** · 07-31-2009, 09:10 AM

Thanks guys !! I'm getting alot of great info here. Your right about getting close to the redline at a little over 30 - 33 mph in 1st. Things happen pretty fast in autoX and I don't need to be back in 1st gear very long until its shifts back into 2nd (probably wouldn't get to the redline before it shifts into 2nd) - but the time lost lugging in 2nd (at 20-30 mph) until the speed picks back up again is significant relative to the "stick cars" . So being able to downshift into 1st for even a short while would be a great help !

Thanks again for your guidance!!