Is 4.09 the functional equivalent of 4.10? -
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post #1 of 5 Old 03-17-2007, 09:53 AM Thread Starter
Vacant Stare
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Is 4.09 the functional equivalent of 4.10?

I've been looking at gear sets for my Dana 30 front and Dana 44 rear. I find that a 4.09 is available for one, and a 4.10 the other in many cases. Can you use a 4.09 on one end and a 4.10 on the other without ill-effects?

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post #2 of 5 Old 03-17-2007, 09:58 AM
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Yes you can. An oldtimers trick is to run a point or two higher in the front, keeping the front pulling slightly. I run 4.09's in the front and 4.10's in the rear.
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post #3 of 5 Old 03-17-2007, 10:41 AM
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That is how my set came..4.09 front (d30) and 4.10 rear (d44)..
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post #4 of 5 Old 03-17-2007, 12:55 PM
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Yes that is normal, that is because of different ring gear diameters.

Originally Posted by Kerndone
Manufacturers really don't do has to do with the size of the R&P. Different diffs have different sizes of ring gears and pinion heads and that comes through in the gear ratio. Anything within a 1% difference isn't anything to worry about (general rule of thumb).

'98 Sport, 4.0, AX-15, D44, 3.73, stock w/ 10k original miles

Gone - 2000 Sport, 1987 YJ, 1997 SE, 1998 XJ
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post #5 of 5 Old 03-21-2007, 09:56 AM
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Originally Posted by SecondTJ
Yes that is normal, that is because of different ring gear diameters.
actually it's normal because the 4.09 gears are 11 teeth on the pinion 45 on the ring and 4.11 gears are 10 pinion/ 41 ring.
fords were notorious for this because the 9" gears were different than dana gears. 4.09/4.11 is way close enough.

I install gears!
lots of gears
gears that make you go, gears that make you slow.
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