6-speed 6T70 6T70 vs 6T75E: Almost Identical, but Better Gear Ratios in the 6T75E

[ThatSlow.W204]

Hey everyone,

I wanted to share some insights into the 6T70 and 6T75E transmissions, as they are often confused, and you might be wondering whether they can be swapped out for one another. Spoiler alert: Yes, they are very similar and can be swapped, but there are a few important differences, especially when it comes to gear ratios and final drive options.

Similarities​

The 6T70 and 6T75E are both 6-speed automatic transmissions developed by General Motors. They share a lot of common components and designs, and both are used in similar GM vehicles. Because they come from the same family of transverse automatic transmissions, swapping one for the other is typically straightforward, as long as you're working with compatible models.

Key Differences​

While the 6T70 and 6T75E share many common parts, the main difference lies in their final drive ratio options. The gear ratios for the 6T70 and 6T75E are actually the same in the 1st and 2nd gears, with the key distinction being in the final drive options. The 6T75E offers slightly more aggressive final drive ratios, which translates to better performance, particularly in acceleration and power delivery.

Here are the correct gear ratios and final drive options for both transmissions:

6T70 Gear Ratios:​

• 1st: 4.48
• 2nd: 2.87
• 3rd: 1.84
• 4th: 1.41
• 5th: 1.00
• 6th: 0.74
• Reverse: 2.88

6T75E Gear Ratios:​

• 1st: 4.48
• 2nd: 2.87
• 3rd: 1.84
• 4th: 1.41
• 5th: 1.00
• 6th: 0.74
• Reverse: 2.88

Final Drive Ratio Options:​

• 6T70
  The 6T70 typically comes with the following final drive ratios:
  • 2.44
  • 2.77
• 6T75E
  The 6T75E offers these final drive ratio options:
  • 2.77
  • 3.16
  • 3.39

Performance Benefits of the 6T75E​

As you can see, the gear ratios in the 1st and 2nd gears are identical between the 6T70 and 6T75E, so both transmissions will offer similar performance in terms of acceleration at lower speeds. The key difference is in the final drive ratios.

The 6T75E’s higher final drive ratio options (especially the 3.39) provide more aggressive gearing, which can offer improved acceleration, particularly for heavier or more performance-oriented vehicles. On the other hand, the 6T70’s lower final drive options, such as 2.44, may provide slightly better highway cruising efficiency and fuel economy.

However, both transmissions perform similarly on the highway, particularly in 6th gear, as both share the same 0.74 ratio in this gear. The biggest performance difference will be felt in city driving and acceleration, where the 6T75E’s higher final drive ratio options provide an advantage.

Conclusion​

In summary, while the 6T70 and 6T75E are nearly identical and can often be swapped with little modification, the 6T75E has a slight edge in terms of performance, particularly due to its more aggressive final drive ratio options. If you’re looking for better acceleration, particularly in low-speed or city driving conditions, the 6T75E is the better choice. However, if highway cruising and fuel economy are your priorities, the 6T70 with its lower final drive ratios will still perform very well.

Let me know your thoughts or experiences with these transmissions!

 

6-speed 6T70  Step-by-Step Guide: 6T70 vs. 6T75 – Similarities, Differences, and Swapping

[ThatSlow.W204]

Hello everyone,

I wanted to discuss the transmission options in the 2012-2016 W-body Impalas, particularly the 6T70E that came standard in these vehicles. While the 6T70E is a reliable transmission, it is equipped with a final drive ratio of 2.44, which many find underwhelming in terms of performance, especially in acceleration.

There have been some rumors suggesting that the police versions of the Impala (often referred to as the "police package") came with a 2.77 final drive ratio. However, based on my research and experience, I believe this is inaccurate. It appears that all of the 12-16 W-body Impalas, including the police variants, were equipped with the 2.44 ratio in the 6T70E.

For those looking to upgrade performance, the 6T75E with its 3.16 final drive ratio would be a much stronger and more responsive transmission choice. The 6T75E provides significantly better acceleration, especially from a standstill, while still maintaining good highway performance. The increased final drive ratio of 3.16 allows for quicker power delivery, improving overall driving dynamics without sacrificing fuel efficiency on longer trips.

Upgrading to the 6T75E would be a noticeable improvement, especially for anyone looking for better performance and acceleration without compromising on highway driving.

 

[ThatSlow.W204]

Side Note: If you proceed with this swap, it is essential to retain the TEHCM (Transmission Electro-Hydraulic Control Module) from your Impala. Additionally, ensure the vehicle is properly tuned to accommodate the updated gear ratios for optimal performance and functionality.