Example shift tables wanted

[fairmont50]

Everyone,
I would like to see some working shift tables for a 4l80e if anyone has them. I am running an LQ4 v8 (6 liter) with the 4l80e in a ~3400 lb car with a 3.08 rear. Any examples would be appreciated. I am having trouble figuring out where to place my bins.

Thanks

Chris

[Bernard Fife]

Chris,

The default table is what I ran in my Corvette with a 4L60E and 3.08 gears, 6500 rpm redline, and 26" tires. The problems with using someone else's table is that the table doesn't account for the different redline, axle ratio and tire diameter.

I have been meaning to do up a javascript shift table calculator (sort of like the VE table calculator here: http://www.useasydocs.com/theory/vetable.htm) to create an initial shift table based on the gears and tire diameter. I will work on that and post something in a few days.

Lance.

[fairmont50]

Lance,
As always, thanks for the response. Not sure why but I have not been happy with the default shift table. It seems to shift late at low load. May have something to do with the different ratios in the 4l80 compared to the 4l60 or the fact that the engine is not completely tuned yet. Has anyone looked into a 16 x 16 shift table? It would be nice to be able to put more bins on the low load and speed areas of the table without losing any on the top end. Probably just lack of trans tuning experience but it seems like it would be nice.

Chris

[Bernard Fife]

Chris,

I think the table depends a lot on the type of driving one does, as well as ratios, converter, etc. It also depends on your driving style (I like my Corvette to shift late, so it's always ready to go when I punch it).

Have you tried moving the shift point around at low loads? If you put 2's where some of the 1's are now, the 1-2 upshift will happen earlier. And similarly, put 3's where some of the 2's are. On the same for 3rd/4th.

So you might change this:

Capture1.JPG

to this:

Capture2.JPG

I have had a few people ask about larger tables. I know it is counter intuitive, but this actually makes tuning harder, because with larger tables it becomes increasingly difficult to avoid creating situations where the trans hunts between gears as the load and speed change. When I first started the code, I even considered 4x4 tables to avoid that.

This is entirely unlike the VE table. With the shift table, you only need to specify the shifts; so any in the middle of the table column that has all the same gear in it will be wasted, essentially.

Lance.