Auto needs retune for gears???

[KILLER06GT]

Im not much of an auto guy and i never really payed attention to the posts about the autos. My brothers car is an auto and has 373s, obviously its tuned out with a vortech and nitrous. I want to put 410s in it, Im pretty sure the shift points would need to be retuned to shift at the correct rpm. Am I correct, or does the tranny shift off rpms and not speed(i think it shifts off speed).

Im hoping it dips into the 10.20's on 16 psi, spray and bogarts.

 

[BlackSnakeMoan]

yes u will need to have new tune for the 4.10s. you'll love the resuts

 

[Error404]

not really a retune I think, but if you have a tuner, just plug it in and change the gear ratio. I don't think anything else needs to be changed? I could be wrong.

 

[Charlie Sheen]

not really a retune I think, but if you have a tuner, just plug it in and change the gear ratio. I don't think anything else needs to be changed? I could be wrong.

He is correct.

 

[KILLER06GT]

not really a retune I think, but if you have a tuner, just plug it in and change the gear ratio. I don't think anything else needs to be changed? I could be wrong.

Edit: geuss i read that wrong the first time. Hope to get more feedback on that being correct...

 

[SixtySix]

It's not really clearcut. It'll depend on the amount of tuning the tuner did to the auto.

Here's a quote from Doug at BamaChips on that very issue:

As I'm sure you know if you have my automatic tunes my shifting is entirely different then that of the stock tunes or even the SCT or Diablosport base files. The shift points are set mainly by MPH instead of RPM, except at WOT.

Now when you update your gear ratio this changes everything for the shifting as the MPH points remain the same but the engine RPM at that MPH point is different. So now your transmission shifts faster, depending on the new gear ratio how much faster.

When you update your tunes using the user options on both SCT and Diablosport products it is simply changing the Speedometer settings and correcting this part of the equation. This works fine on the stock tune or even most SCT base files but not on my tunes.

For example say you went to 3.73 gears from the stock 3.31's, at 55mph you used to be doing around 2300 rpm's but now with 3.73's your doing nearly 2600 rpm's. So now you can see why changes need to be made. Also with the converter lock up rates, there again using my tunes.

Feel free to check with your own tuner for required changes using someone elses tunes.

So, if you have gearing changes and you have my tunes that I've not adjusted for and you are feeling faster shift points or the that the transmission isn't shifting properly then just let me know and I'll take care of it for you. This is all covered under my free tune updates for minor bolt ons for the ownership period of your car.

So, it's really going to depend on how far the tuner(person) went with regards to altering parameters on the automatic, if you're going to need a tweak beyond just changing the ratio on the handheld unit.

I say change it, then see how it feels. If it's funky, you'll know it!

 

[Steedman07]

yes u will need to have new tune for the 4.10s. you'll love the resuts

+1^^..I love the way mine shifts with a custom tune, even though its an auto..

 

[ixtlan]

It all depends on the tune options you have.
If your Ratio settings are open the change them to the 4:10.
Then raise or lower your shift points to your need.
I found that the shift points are based on WOT and proportional to that setting below WOT.
The PCM controls the shift points and firmness and uses adaptive learning to adjust it.
So it will learn your habits and adjust to fit them.
The tune will overide the baselines that the learning mode will compare too.
It would be a good idea to disconnect the battery to erase the adaptive learning. Then adjust your tune to suit your patterns.
I have mine adjusted to my everyday driving. But overide the firmness to +5% and raised the shift points 2 to 5 mph depending on the gear shift 1-2, 2-3, ect..
Exception is the 4 to OD shift at 0% firmness and + 5mph increase over baseline.
At WOT it holds the longest.

 

[racevert]

The shift points will be fine, they are by RPM.. The only thing affected will be your speedo.
Why would youi need a tune?? You can adjust the gear ratio in the user setting of the handheld tuner if need to correct the speedo.

 

[SoundGuyDave]

Not necessarily true. The Bama tunes are MPH-based, not RPM, and that will be all out of whack by the time you do gears... Speedo cal is definitely a flash-tuner fix, but depending on how the tune is set up, you may need a re-tune.