Tuning a Camaro 3.45 differential in a G8 GT?

[Allmachtige]

What tuning adjustments to the TCM are required to swap out the stock 2.92 diff for a 3.45?

I currently have a custom dyno tune for a custom cam, 3600 stall, headers, exhaust, etc.

How involved is it to make the proper adjustments myself after install the new diff, if any?

[c.u]

Go to speedo-Gear/tire calc. Enter tire size and new gear. Hit commit it will rescale the trans settings for the new gears.

[Allmachtige]

Go to speedo-Gear/tire calc. Enter tire size and new gear. Hit commit it will rescale the trans settings for the new gears.

Is it really that easy?

[Allmachtige]

For the Tire Size am I just entering the diameter in inches?

[alextremetj]

Correct. I always go to the tire manufactures web page to get the exact diameter.

[c.u]

Dia or tire heght yes. If you open the scanner and click on unit conversion. In the top right cornner just input the tire you have and it will give you what needs to be inputed.

[Allmachtige]

Dia or tire heght yes. If you open the scanner and click on unit conversion. In the top right cornner just input the tire you have and it will give you what needs to be inputed.

Thanks. I was clicking around and eventually found that nice conversion table.

My current setting for tire size is 26.22, but even stock tires (245/40/19) are larger than that. I'm currently running 275/30/20's, but is there a reason the value from a G8 PCM is incorrect?

[c.u]

I don`t know if it is the way HP reads out the stock OS or if was just the GM calc. Most are about .5 out. I always set to what the unit conversion comes up with. Have not seen any problems setting up like this.

[Allmachtige]

Thanks. You've been helpful.

[Russ K]

Correct. I always go to the tire manufactures web page to get the exact diameter.

No, using the advertised tire dia will cause the speedo to read high. The formula is; new tire advertised dia/old tire advertised dia*old tire advertised dia and enter that into the new tire size field in the editor.

Russ Kemp

[Russ K]

For the Tire Size am I just entering the diameter in inches?

If your tire dia is stock, then leave the tire dia field the same as stock.

Russ Kemp

[Allmachtige]

No, using the advertised tire dia will cause the speedo to read high. The formula is; new tire advertised dia/old tire advertised dia*old tire advertised dia and enter that into the new tire size field in the editor.

Russ Kemp

So to clarify:

(New/Old) * Old

?

[Russ K]

So to clarify:

(New/Old) * Old

?

Yes.

Russ Kemp