[NewMuscleGT]

Will I need to retune, Brenspeed custom tune for CAI, after a bump from 3.31 to 3.73 gears in an Auto?

Or will I just need to manual adjust the ratio from 3.31 to 3.73?

Anyone have personal experience? Thanks

[Bullitt5339]

In my SF3/X3, you can just go in as long as the tuner left user adjustability turned on and change the gear ratio manually.

[stlwagon]

You'll be able to do it with a Brenspeed tune. Just make the change and reflash the tune.

[GT John]

Originally Posted by NewMuscleGT

Will I need to retune, Brenspeed custom tune for CAI, after a bump from 3.31 to 3.73 gears in an Auto?

Or will I just need to manual adjust the ratio from 3.31 to 3.73?

Anyone have personal experience? Thanks

Changing of the gears in the x2 or x3 will only allow the speedo to read correctly.

Here are two screen shots for automatic tranny truning. (wish they could have read more clear)
The first screen shot is where the "axle Ratio Switch" must be turned off.
The second screen shot shows the shift points for a stock rearend gear.
With the stock gears at a pedal position of 540 and 44mph the engine rpm will be 5991. The reason is at 49mph your engine rpm will now be 6751rpm at a pedal position of 540 this has to be done for each upshift and downshift.
It will be necessary,for proper upshifting and downshifting to ratio the table (mph vs PP) upwards for the new gears. The same thing will have to be done to the torque converter table.

Not changing the shifting will feel like the car is shifting sooner at like 39mph at a pedal position of 540. It may not bother you though......your call. Give your tuner a call let him know your changing gears..............he will send you a new tune.

[NewMuscleGT]

So. With a Brenspeed custom tune already...if I upgrade from 3.31 gears to 3.73 will all I need to do is adjust the options to reflect the new gears? Or by doing this will it throw off everything else...and will I then need a completely new tune?

[stlwagon]

Originally Posted by NewMuscleGT

So. With a Brenspeed custom tune already...if I upgrade from 3.31 gears to 3.73 will all I need to do is adjust the options to reflect the new gears? Or by doing this will it throw off everything else...and will I then need a completely new tune?

That's all you need to do. Won't affect anything else.

[eyeeatrice]

if you have an sf or x 3 just go to program vehicle to your customs tune then go to adjust options then go to saved options then scrool down to gear ratio and select 3.73 and just select continue...the tune will not change anything else its just gonna let the car know the gears so your speedo will be correct.

[ski]

Suggest that you contact Brenspeed to see if your car needs either the current tune to be updated, or a new tune.

Here's what Doug from Bamachips says about changing gears with his auto tunes:
"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."