flattusmaximus78

iTrader: (1)

I have a 02 z28 with a 4l60E. It has the above kit. I also has the 3-4 z pak, diff drum, and I believe a diff swervo. fti 3000 stall, super tight. I'm new to autos and I didn't set up the trans. I just have left over instructions and the old parts that came out.

My question is: The hd2-C instructions says gear command. Does this mean if I can manually up-**** the car from 1-2-3 and manually 3-2-1 if I want?

Or

Does it mean if I leave it in first it stays there, if I put it in 2nd if will start in first... go to 2nd and back to first? Same thing with third.

Or

Does it do both.

My converter is tight so I want to get spirited sometimes I'll come to a complete stop and go wot from 1-2 then get to speed and pop it up to drive. Just want to make sure I'm not doing any damage.

mrvedit

I have installed the HD2 kit, but did not install the "gear command" valve as I don't want to risk overrevving due to a mis-shift.

Normally the PCM completely control the shifting. The "gear command" valve forces the trans to be in a gear no higher than what you have selected. However, if the shifter is in e.g. [D3], the trans will not upshift into 3rd until the PCM tells it to according to its programmed speed. In other words, when you move the shifter to a higher gear, the trans will not necessarily shift then. However, if you move the shifter to a lower gear, the trans will immediately downshift.

Here is how Transgo explains it:
"Back shift to any gear at your command. Holds the gear you select to any rpm."
It is NOT the same as a full-manual valve body.

Most people here will concur in my opinion that there is no reason to manually upshift. Let the PCM do it. If you mod the engine, you should should not only tune the PCM for those mods, but perhaps also tune the trans shift points for best performance.
I run a high duration/lift cam and at WOT I program my trans to shift at 6900 RPM with a rev limit of 7000.

RevGTO

iTrader: (12)

There is one good reason to have this feature enabled, I think. I have it set up this way with my Transgo install. For example, if you're involved in some street action and start to spin when you take off in first, the transmission will upshift to second, and then when the tires grab, it'll downshift back to first. It makes a mess out of getting up to speed and must be hard on the transmission.

With this feature, you put it in first and it will not upshift until you do so. You can manage your traction situation much more effectively.

mrvedit

Good point and addition. I run drag radials and don't spin too much on clean dry streets. I also tune so that a 2-1 downshift can only occur below 10 mph; just too extreme otherwise.

RevGTO

iTrader: (12)

I run Nittos also on the street and they are good, but they can break loose. I have mine tuned the opposite - to allow 2-1 downshifts at fairly high speeds, but it's both hands on the wheel and pay close attention. That being said, I'm only at a bolt-on power level.

flattusmaximus78

iTrader: (1)

Thanks for the input guys! Rev put it better then I could. I have a pretty big 232/239 .617/624 cam. It will spin down low very bad, so when it up shifts due to tire spin, my 3.27's don't help and it bogs a little before it does anything else.

I would never downshift the car while rolling. At the track I have radials and wouldn't do this. Just for situations like above. Sometimes I'll drop if into the lower D while rolling. My converter is tight and unless I'm at the perfect mph it doesn't always rip.

Just wanted to know if those occasional 1-2-3's would hurt something.