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Are gear ratio's fixed when building 4l60e or 4l80e

This is a discussion on Are gear ratio's fixed when building 4l60e or 4l80e within the Automatic Transmission forums, part of the Drivetrain category; Can someone educate me on the internals of automatic transmissions. I'm wondering if the gear ratios are fixed or if ...

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    Are gear ratio's fixed when building 4l60e or 4l80e

    Can someone educate me on the internals of automatic transmissions. I'm wondering if the gear ratios are fixed or if a custom shop that is building a beefed up trany could also swap some other ratios in there for me.

    I believe the answer is yes for 1st and 2nd, based on what I see in the TCI 6X, but I could be wrong, and even if I'm guessing correctly, I'm still wondering if 3rd (ie 1:1) and overdrive can also be changed?

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    Moderator Firebirdjones's Avatar
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    I'm not aware of any other gear set available for the 4L60,,,if there were I'd take that stinking 3.06/1.62 combo out of there.

    There are however gears made for trannies such as the turbo400. You can switch the 2.48 first gear for a 2.75. Been a while since I had to look into this, they might offer more now.

  3. #3
    There is a 2.84 first gear set for the 700R4/4L60E, expensive though. $1200.00 or more just for the gear set alone. And in my opinion a good torque converter would be a much better choice for far less money. For the TH400, there is 3.00 & 2.75 gear sets. I would assume they will bolt in the 4L80E, but I would talk to John Kilgore who makes these gear sets for the TH400 or Jakeshoe who specializes in the 4L80E.

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    Ok, so it sounds like choices are pretty limited. I don't have much experience with transmissions, but when I started looking at thier ratios I realized that most of them seem pretty randomly spaced.....by that I mean, when you hit the 1-2 shift your rpms my drop down to 3275, then when you hit the 2-3 shift your rpms will drop to 3950 and on the 3-4 you hit at 4350.

    Perhaps there is a reason for that, perhaps its just what we have to settle for. I was just wondering if an aftermarket trany could be built that hit all the gears at a similar rpm. . . . but it would seem not. (At least not with an auto - The 6 speed manual from a Z51 corvette, hits its first 4 gear changes at a consitent rpm, the 5th change is steeper, but that is the double overdrive)



    One final question, there are a few optional 1st and sometimes 2nd gear ratios for the 4l60e and 4l80e, but are there any options with the overdrive?
    Last edited by Intrepidman; 02-09-2011 at 11:09 AM.

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    LSX whore allbaugh_04's Avatar
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    Have you looked into the 6L60E?

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    Moderator Firebirdjones's Avatar
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    Quote Originally Posted by Intrepidman View Post
    Ok, so it sounds like choices are pretty limited. I don't have much experience with transmissions, but when I started looking at thier ratios I realized that most of them seem pretty randomly spaced.....by that I mean, when you hit the 1-2 shift your rpms my drop down to 3275, then when you hit the 2-3 shift your rpms will drop to 3950 and on the 3-4 you hit at 4350.

    Perhaps there is a reason for that, perhaps its just what we have to settle for. I was just wondering if an aftermarket trany could be built that hit all the gears at a similar rpm. . . . but it would seem not. (At least not with an auto - The 6 speed manual from a Z51 corvette, hits its first 4 gear changes at a consitent rpm, the 5th change is steeper, but that is the double overdrive)

    Well that's exactly why you take that 3.06 first gear out of the 4L60. So the rpm drop isn't so drastic on the 1-2. Going to the 2.84 first gear as about a 7-8% drop, which brings the rpms closer on the 1-2 and more in line with the 2-3 drop. So you are getting a similar rpm spread that you are looking for.
    Take a look at the 2004R's,,,,they use a 2.75 first gear, and that's what makes them so popular.

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    Quote Originally Posted by allbaugh_04 View Post
    Have you looked into the 6L60E?
    I can't really find any good information on it, other than that it perhaps has the same gear ratios as the 6l80e. At the moment I'm not even sure a 6l60e exists, google turns up a ton of hits on the search, but there is no information in them; just people asking questions, or subjects that turn out to actually be about the 6l80e.


    As for the 6l80e, I hear its HUGE, rather expensive, and apparently a royal pain to tune...other than that a 6 speed auto would be great, especially if its first gear wasn't 4.0x (which is massive!) and if its double overdrive was a bit longer than 0.67
    Without doing the math to confirm the #s, I would guess that a first ratio of roughly 3.4 and a sixth ratio of 0.55 would make it a fantastic unit for both racing and cruising.

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    Moderator Firebirdjones's Avatar
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    I personally don't care for the steep first gear ratios in the new trannies.

    That 4.02 first gear in the 6L80E drops to a 2.36 for second gear That's a 1.66 difference,,,and it's even worse than the 4L60E drop.

    4L60E = 3.06/1.62 for a 1.44 drop.

    The only good reason for these steep first gears are for cars with engines that lack low end torque and run a 2.73 rear gear And that's why manufactures are using them, so they can run numerically lower rear gears for better mileage and still have some form of acceleration in first gear.
    Otherwise they are useless in my opinion.

    For a performance application, I'd rather see less first gear in the trans, which will give you a closer gear spread throughout, and then just gear the car accordingly.

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    Senior Member JaycenK's Avatar
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    Quote Originally Posted by Firebirdjones View Post
    I personally don't care for the steep first gear ratios in the new trannies.
    X2 The trans was made for a couple of reasons.
    1. Towing fuel efficiency, and power off the line
    2. New engines are easier on fuel below 3000rpms so the close ratio's allow them to conform to the Fuel mileage standards. even though the weight on a modern truck is way more than 10 to 15 years ago.
    3. Variable valve timing.

    The new trans is a great cruiser. It's a problem as old as the car it's self, how to match great performance with great fuel efficiency... Answer= has not happened. Variable valve timing and the extra 2 gears has gotten them closer but the problem is weight keeps increasing on modern cars and trucks.
    I say a good stall and some good rubber are a cure all for the 4l60-e ratio problem.


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