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Swap 3:36 unit for a 3:70 unit

 
Old 02-16-2019, 06:46 PM
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Mike65
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Default Swap 3:36 unit for a 3:70 unit

If I decide to swap my 3:36 differential unit for a 3:70 differential unit would that be a direct bolt on?


Thanks

Mike
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Old 02-16-2019, 06:55 PM
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Vette5311
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Year of car? Trans type?
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Old 02-16-2019, 06:56 PM
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Originally Posted by Vette5311 View Post
Year of car? Trans type?
65 Coupe with a M20 close ratio trans.

Last edited by Mike65; 03-04-2019 at 01:17 PM.
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Old 02-16-2019, 07:00 PM
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Should not be a problem unless u joint size is different. I don't think it is. The close ratio trans will like the 3.70 a lot better.
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Old 02-16-2019, 07:02 PM
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Originally Posted by Mike65 View Post
If I decide to swap my 3:36 differential unit for a 3:70 differential unit would that be a direct bolt on?


Thanks

Mike
They use the same carrier so it will fit without a problem. However, if you go any lower you would have to switch carriers.

Last edited by 68hemi; 02-16-2019 at 07:04 PM.
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Old 02-16-2019, 07:03 PM
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M20 is a wide ratio gearbox.....3.36 is a much better gear most of the time if the car sees any freeway use.
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Old 02-16-2019, 07:04 PM
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Originally Posted by Vette5311 View Post
Should not be a problem unless u joint size is different. I don't think it is. The close ratio trans will like the 3.70 a lot better.
Thanks for the reply Vette5311! That's what I was thinking as well.

Last edited by Mike65; 02-16-2019 at 07:04 PM.
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Old 02-16-2019, 07:08 PM
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Originally Posted by GTOguy View Post
M20 is a wide ratio gearbox.....3.36 is a much better gear most of the time if the car sees any freeway use.
That is true but most people are changing to a 3.70 or more low end grunt. The wide ratio gearbox that comes with the smaller h.p. cars std. also have a deeper 1st gear so it amplifies the stump pulling take off.

Last edited by 68hemi; 02-16-2019 at 07:09 PM.
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Old 02-16-2019, 07:10 PM
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oy
Originally Posted by 68hemi View Post
They use the same carrier so it will fit without a problem. However, if you go any lower you would have to switch carriers.
Thanks for the reply 68hemi. I wouldn't go any lower than a 3:70...I have a 3:73 in my 68 Camaro and I really like that combo.
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Old 02-16-2019, 07:13 PM
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Originally Posted by 68hemi View Post
That is true but most people are changing to a 3.70 or more low end grunt. The wide ratio gearbox that comes with the smaller h.p. cars std. also have a deeper 1st gear so it amplifies the stump pulling take off.
I forgot to mention I have the L76 365 horse motor. I do believe I have the close ratio trans.

Last edited by Mike65; 03-04-2019 at 01:18 PM.
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Old 02-16-2019, 07:16 PM
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Originally Posted by Mike65 View Post
I forgot to mention I have the L76 365 horse motor. I do believe I have the close ratio shifter.
If it is still the original trans then yes it would be the close ratio and another good reason to go with 370 gears. You will like the combination.

Last edited by 68hemi; 02-16-2019 at 07:17 PM.
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Old 02-16-2019, 07:22 PM
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Originally Posted by 68hemi View Post
If it is still the original trans then yes it would be the close ratio and another good reason to go with 370 gears. You will like the combination.
Yes sir, it is the original trans.
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Old 02-16-2019, 07:28 PM
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Originally Posted by Mike65 View Post
Yes sir, it is the original trans.
Not many 365 h.p. Cars sold with anything less than 3.70 gears, the close ratio trans has a taller 1st gear and you really need 3.70s or lower to realize the full potential of that engine.
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Old 02-16-2019, 07:37 PM
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UOTE=68hemi;1598891902]Not many 365 h.p. Cars sold with anything less than 3.70 gears, the close ratio trans has a taller 1st gear and you really need 3.70s or lower to realize the full potential of that engine.[/QUOTE]
I agree. The dealer I bought car from told me it has the 3:36 gear. I just bought the car in December so maybe I should verify it actually has the 3:36.

Last edited by Mike65; 02-16-2019 at 07:41 PM.
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Old 02-16-2019, 07:50 PM
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I just did the identical swap a couple weeks ago. I have a T56 Magnum with a 2.66 first gear and the 3.70 still makes a huge difference taking off from a dead stop. I swapped the entire differential, and it was quick and easy.
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Old 02-16-2019, 07:56 PM
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Originally Posted by Mike (Naples) View Post
I just did the identical swap a couple weeks ago. I have a T56 Magnum with a 2.66 first gear and the 3.70 still makes a huge difference taking off from a dead stop. I swapped the entire differential, and it was quick and easy.
Thanks for the reply Mike. The vendor that I am thinking about buying the differential unit from is asking If I have a 3 3/4 or the 4 1/4 yoke. Do you know the yoke size?
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Old 02-16-2019, 08:29 PM
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Originally Posted by Mike65 View Post
I do believe I have the close ratio shifter.
Close RATIO or wide RATIO refers to the gearing of the transmission itself. I think what you are getting at is that you have the shifter adjusted for the short-throw setting. The lever does not travel as far forward or back as when it's in the long-throw holes. Is that right?
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Old 02-16-2019, 08:43 PM
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Originally Posted by Railroadman View Post
Close RATIO or wide RATIO refers to the gearing of the transmission itself. I think what you are getting at is that you have the shifter adjusted for the short-throw setting. The lever does not travel as far forward or back as when it's in the long-throw holes. Is that right?
The close ratio 4 speed muncie had a 1st gear 2:20 and the wide ratio Muncie had a first gear of 2:56 (L75). The L76, L78,L79 & L84 had the close ratio Muncie trans.

Last edited by Mike65; 02-16-2019 at 08:48 PM.
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Old 02-16-2019, 08:54 PM
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Originally Posted by Mike65 View Post
The close ratio 4 speed muncie had a 1st gear 2:20 and the wide ratio Muncie had a first gear of 2:56 (L75). The L76, L78,L79 & L84 had the close ratio Muncie trans.
Right. I was addressing your statement you had the close ratio shifter. The shifter has no idea which transmission it is bolted to, and the stock shifter is the same for either close or wide ratio.
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Old 02-16-2019, 09:00 PM
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Originally Posted by Railroadman View Post
Right. I was addressing your statement you had the close ratio shifter. The shifter has no idea which transmission it is bolted to, and the stock shifter is the same for either close or wide ratio.
Yes Sir. Thanks for the reply. My beer assistant is in over drive right now.

Last edited by Mike65; 02-16-2019 at 09:33 PM.
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