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Old 12-10-2004, 01:17 AM
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closed/open ratio

Hello. Im more of an engine person, I know next to nothing about transmitions and rear ends. I just know the basics. Could someone please tell me the difference in a closed ratio gears and open ratios? And which is better for a 450hp daily driver. Thank you much.
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Old 12-10-2004, 04:58 AM
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An open rear is one that does not have a posi/locking unit in it. The wheel with the least traction gets the power.

Posi units give the rear end the ability to put power to both wheels.;
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Old 12-10-2004, 06:38 AM
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Poncho is correct. To elaborate a little.... you can drop the "ratio" from the term since the actual gear ratio has nothing to do with whether or not the rear end is open or "closed". You can have the same ratio in an open or posi rear end. The difference is as Poncho described. The "closed" or Posi rear transmits power to both rear wheels where the open transmits power only to the the wheel with the least traction which is usually the passenger's side. For a 450 hp daily driver I would definitely suggest a posi rear. Otherwise you'll have a lot of problems getting that power to the pavement.

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Old 12-10-2004, 07:00 AM
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Cool

the thought I came up with is perhaps he was talking about close or wide ratio manual trannys?
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Old 12-10-2004, 07:05 AM
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Quote:
Originally posted by Crosley
the thought I came up with is perhaps he was talking about close or wide ratio manual trannys?
Suppose that's possible..... Guess we'll just have to wait for him to post again to find out.

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Old 12-10-2004, 07:21 AM
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me too

Quote:
Originally posted by Crosley
the thought I came up with is perhaps he was talking about close or wide ratio manual trannys?
Crosley, when i saw the title thats what came to my mind also.....

To the orginial poster,
This term is used mainly in the muncie transmission world. They made 2 different ratio transmissions ( excluding the 63 to 65 models)

The 66 to 74 M20's were 2.52 / 1.88 / 1.46 / 1.00

All M21 and M22's were 2.02 / 1.64 / 1.28 / 1.00

The debate on what trans is better / stronger can go on for days. It usually comes down to a preference. Neither will give a huge benifit from the performance standpoint.... but needs to be matched to the rest of the combo and driving style...

Keith
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Old 12-10-2004, 08:05 AM
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Wide ratios work better with numerically low (3:31, etc.) rear gear ratios while close ratios work better with higher (3:73, 4:10, etc.) rear gears.

tom
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Old 12-10-2004, 08:17 AM
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Quote:
Originally posted by machine shop tom
Wide ratios work better with numerically low (3:31, etc.) rear gear ratios while close ratios work better with higher (3:73, 4:10, etc.) rear gears.

tom
Tom speaks with straight tongue. Drag racers love close ratio trannys 'cause they keep the engine turning in a narrow rpm range. By definition, racing engines have eliminated a lot of the compromise that makes a grocery getter easy to drive in favor of max power. Engines are constant series of compromises and when you eliminate them, that really narrows the power band to a small rpm range. Conversely, wide ratio trannys are great for Granny's Olds 'cause her engine is designed for a wide power band and she doesn't have to shift as much as Hot Rod Harry as she accelerates.
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Old 12-10-2004, 11:32 AM
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Thank you all for the replies. Sorta funny tho, I was asking about the transmitions...but now that yall did post about rear ends, i remembered I was going to ask something about that eventually. Hah, thanks, and take care.
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