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  1. #1
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    Default 3.36 to 3.70 gears

    Will this have much of an effect on acceleration if I make this change? My car feels like it runs out of gear and is a dog off the line.
    thanks

  2. #2
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    Corvette(s)
    1989 Black Z51 Coupe

    Default

    A little more information would be helpful. Are you running stock-size tires, undersized tires, or oversized tires? A 3.36 rearend ratio was common on C3's with a wide ratio 4-speed. Is that what you have? Has your engine been tuned recently? (Don't want to swap gears if a tune up is all that is needed.)

    Both of my LT-1's came stock with a close ration 4-speed and 3.70 rearend gears and would smoke the tires coming off the line so swapping to a 3.70 should get you in the red zone a whole lot quicker, but your cruising RPM's are going to be much higher. (Here's a link to Summit Racing's gear ratio calculator that allows you to plug in your rearend ratio, tire diameter, chosen RPM, to obtain your MPH.) If you do have a wide ratio 4-speed, a better choice of ring and pinion gears would be the 3.55 ratio.

    Hope this info helps!

  3. #3
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    Yes- I have the stock tires size and Close Ratio 4 speed manual. Engine has been tuned.

  4. #4
    Member GTR1999's Avatar
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    1969,1972,1975

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    If you truely have a close ratio 4 speed then it will be a dog with a low torque sb and 336 gears. BB torque would drive it but the CR trans had a 2.20 first gear vs the 2.56 of the WR trans. CR trans are really a road racing trans setup to keep the RPM's "close" in the power band during up/down shifts. They were usally matched with a 370 or 411 rear gear. The WR was matched to a 336 gear in sb and 308 or 336 in BB cars. 79's didn't have BB so the question is do you have a CR Muncie as linked which was not offered in '79 or what should be a BW ST-10? You probably would have had to order the L82 to get it and I would be surprised if many were sold.
    If you plan on changing you would be better off with a 373 over a 370 or 355 gear. The jump in RPM will be about 400 higher on the highway.
    Gary
    GTR1999

  5. #5
    SVO
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    Corvette(s)
    1972 LS-5 Coupe, 1972 LT-1 Air Convertible

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    Not sure how it affects the discussion, but if the OP has a '79 with the factory CR Super-T10, then it has a 2.43 first gear. If he has the factory WR Super T-10, then it has a 2.60 something first gear (don't remember the exact ratio). But the 2.43 close ratio box was only available with the L-82 engine and a 3:70 rear gear. There was also a third manual transmission option available with a deeper first gear and a 3:36 ratio only with the L-48 engine.
    I used to be with it, then they changed what it was. Now what I'm with, isn't it and what's it seems weird.

    NCRS Member 1071

  6. #6
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    Yes - I have an L-82 w/ the BW ST-10. It used to have 3.70 gears but I lost my brain and put 3.36 in

  7. #7
    Technical Writer for Internet & Print Media
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    71 95 04 12

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    Put the 3-7s back in.

  8. #8
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    Orange Park FL USA
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    Corvette(s)
    1970 Marboro Maroon Convertible

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    Gary, please explain why the 3.73 is a better choice than the 3.70. Thanks

  9. #9
    Member GTR1999's Avatar
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    Quote Originally Posted by sharkcar71 View Post
    Gary, please explain why the 3.73 is a better choice than the 3.70. Thanks
    The current availble 370 ratios are imported. The 373 has more teeth on the gears and Tom's are USA made.
    Gary
    GTR1999

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