How do you determine 4T60E final ratio (2.73, 2.97, 3.33)?

[EngineerBill]

My ATSG transmission manual shows the broadcast codes from the 4T60E transmissions and lists the corresponding final drive ratio / rotor as well as the drive sprocket / driven sprocket teeth such as:

2AYW - 3.33/31 35/35
2ABW - 3.06/30 37/33
3AMW - 3.33/31 37/33

but a '92 Seville for instance had either a 2.97 or a 3.33 and a '92 Deville had either a 2.73 or a 2.97, yet those type of numbers are not in the transmission manual. Does anyone know either the formula to calculate this from the sprockets and final drive numbers or is there some code either embedded in the VIN or on the Transmission somewhere?

[Night Wolf]

the '92 DeVille... if it was a regular DeVille (most are) it is a 2/73... if it is a Touring Sedan (rare) it is a 2.97

for the '92 SeVille.... well, only the 4.9 was offered... as the NorthStar was in 1993.... but, I am pretty sure the base version got the 2.97 while the STS got the 3.33...... '92 was the only year that you can get the newer style ('92+) Seville (or Eldo) in the STS/ETC trim....

[EngineerBill]

Thanks!

I finally got a formula to know how it is figured. I will post it here in case anyone else ever wants to know. Here are some examples. You need to know the final planetary drive ratio as well as the chain sprockets drive / driven teeth such as:

planetary drive/driven
3.33 35/35
3.06 37/33
3.33 37/33

First you divide the drive by the driven and get a number. Then you divide that into the planetary and that value is the final drive ratio for the car.

For the above examples:

3.33 / (37/33) = 3.33 / 1.12 = 2.97 final drive

3.06 / (37/33) = 3.06 / 1.12 = 2.73 final drive

3.33 / (35/35) = 3.33 / 1.00 = 3.33 final drive

and now we see the published numbers for final drive and how they are gotten from the transmission sprockets and planetary.

Hope this helps somebody. It sure helped me because I have two transmission from a junk yard and they told me both were 2.97 and it turns out that one was a 3.33 and that is the one that I just put in seals and filter and now it is the wrong one! Hopefully I can just change out my ECU chip to one that works with the 3.33.

Thanks again.

[N0DIH]

Thread back from the dead!

Anyone ever find out much more on what Cadillac offered? I know Buick had the 3.33's in the 91 SSE and Cadillac had them in the 91 Deville Touring Sedan. Probably killed them for mpg....

Originally Posted by Night Wolf

the '92 DeVille... if it was a regular DeVille (most are) it is a 2/73... if it is a Touring Sedan (rare) it is a 2.97

for the '92 SeVille.... well, only the 4.9 was offered... as the NorthStar was in 1993.... but, I am pretty sure the base version got the 2.97 while the STS got the 3.33...... '92 was the only year that you can get the newer style ('92+) Seville (or Eldo) in the STS/ETC trim....

[Cliff8928]

There's a few other combinations you could use too... I know the 3.4 DOHC cars got some fairly aggressive gearing with a good FDR. There's also some custom options too.

[N0DIH]

Yup, found something where they got the 3.43's, which are 3.06 diff with the 33/37 gearset....

[Rodya234]

Not trying to thread jack, but if anyone who knows about changing the FDR in a 4T60-E wants to help an adventurous young man, could you visit this thread: http://www.cadillacforums.com/forums...do-i-need.html (Changing the FDR: What do I need?)

Thanks.

[Cliff8928]

They'd probably be better off on a W-Body forum to be honest. The 4T60-E was a primary transmission in those.