Quick question. Is there a TH440 or 4T60 that's available with a quicker gear ratio than the GX3 / 3.33:1 final drive?
Or, is there one that has a quicker 1st and 2nd gear? Since it's already got an overdrive, I'm thinking the quickest acceleration possible from a dead stop is probably the most important aspect for me if I want to do a swap.
If you go with the 3.33 differential gear and the 33/37 sprocket set, I believe that you will end up with a 3.73 final ratio. There is also a combination that will yield 3.42s, but I forget what the combinations are. (Perhaps 33/37 with 3.08 gears. But don't hold me to it.)
Those ratios are in 3rd (1:1) gear. 4th gear is still overdrive.
I believe the highest (numerically) geared trannies came with the 3.4 DOHC.
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11:19 PM
82-T/A [At Work] Member
Posts: 25834 From: Florida USA Registered: Aug 2002
If you go with the 3.33 differential gear and the 33/37 sprocket set, I believe that you will end up with a 3.73 final ratio. There is also a combination that will yield 3.42s, but I forget what the combinations are. (Perhaps 33/37 with 3.08 gears. But don't hold me to it.)
Those ratios are in 3rd (1:1) gear. 4th gear is still overdrive.
I believe the highest (numerically) geared trannies came with the 3.4 DOHC.
Thanks Raydar, I appreciate it a lot! What exactly do you mean by sprocket set? Is that something I can easily change on the transmission?
I don't even have a 4T440 yet, but I figured I would start looking for one. I may decide to just order a good rebuilt one with a warranty and see what happens.
I posted some pages with gear ratios, sprocket combinations and torque converter stall across several different years for the 125 and 440, which should have included which cars they came in, but I can't find the thread. If you know how to work the search engine on the forum well, you should be able to dig it up. It will provide much more detail than the link listed above.
[This message has been edited by Joseph Upson (edited 12-03-2008).]
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05:53 AM
engine man Member
Posts: 5355 From: Morriston FL Registered: Mar 2006
I have a 33/37 sprocket set that will someday go into my 3.33 4t60 that will someday go into the car! It was not the easiest thing to find and even harder to get the right one. I think it took 3 shipped sets from 2 different guys to finally get the right one, most said they just didnt have it. Although I believe I heard you can still get them new from GM? (that was the last place I thought of looking)
Jason
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06:28 PM
Lilchief Member
Posts: 1763 From: Vevay,Indiana Registered: Feb 2004
I have a 3.42 in my 4T60 and love it. I get 30 mpg highway. Shifts into 4th at 45-50 mph. I used the middle size sun gear ( one for the 3.08 ) and a 33/37 gear set. And I still have a 33/37 gear set for a TH125, it won't work in a 4T60 though.
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85 GT 3.4 14.9 @ 90 1.9 60' Old TH125/3.06 Unknown New 4T60/3.42
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09:04 PM
engine man Member
Posts: 5355 From: Morriston FL Registered: Mar 2006
It was not the easiest thing to find and even harder to get the right one. I think it took 3 shipped sets from 2 different guys to finally get the right one, most said they just didnt have it. Although I believe I heard you can still get them new from GM? (that was the last place I thought of looking)
