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Unread 02-18-2013, 12:09 AM   #1
vinnyabs
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Dana 20, rebuild or swap for 300?

I have been researching and want to see what the factual reasons behind either route would be. My current 20 is leaking from speedo gear (which needs updated for new 35's) and pan or just find a 300 rebuild and install. I do trails and beach (the 35's are overkill for this and maybe I am compensating so hold your comments rock crawlers and mud buggys) so not trying to climb vertical. Bt very interested in everyone's take. Also still running stock 2.73 so if you want to add a gear suggestion I would be open. I'm thinking somewhere between 3.73 and 4.11. I know 4.56 or 4.88 are on the charts but if you suggest that please give good reason for my use. I saw BESRK uses 3.73 with 35's so there! Really appreciate everyone's help!

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Unread 02-18-2013, 05:29 AM   #2
nshefbuch
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What was beserk's tranny first gear ratio? This matters. I was running 33's with the same axle gears you have but I have a t18a so first gear negated any axle ratio you could throw at it. Didn't matter what tire size I had. Now I'm using 4.10 on 37's and still have no issues. Tranny gearing makes a world of difference and is often over looked.

Me personally I hate the d20. The d300 is the best tcase jeep ever made. You would benefit if you swapped to the d300 for its 2.65 low range compared to d20 2:1 low. With all this said, you will need different axle gears as the 2.73 gears were meant for an automatic tranny and high way driving. If you are getting by now then do what you want but once you hit some hard trails you will easily see the downside of those gears.

If I had to rebuild a d20, I would spend the coin on an adapter and use a junk yard d300 instead.

The only bad thing about the d300 is its stock rotation hangs low. Here is mine with a clocking ring I clocked flat gaining like 5" ground clearance. Don't let many try and talk you into redrilling the case for a cheap clock. It needs a beefy ring and new input shaft to compensate for the spacer.
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Unread 02-18-2013, 09:09 AM   #3
BlueRubiconrich
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think about this the JeepT18 bolts to a Dana 20 the dana 300 does not.
but if you use a Scout Dana 300 it will bolt to a T18.
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Unread 02-18-2013, 10:18 AM   #4
Davis77Cj
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for simplicity i would stay with the dana 20. they are great a t-case, strong and is a plenty for what you do. this case shares many of the same attributes for which the dana 300 is revered. personally i would instal the teraflex low range kit to drop the low range down to 3.15. onto the gearing of your axles i would highly recomend a re-gear. 3.73's are good but what i would recommend is go to a ratio calculator and play around with it to determine what you would like. also nshefbuch is correct you need to determine your t-18 first gear ratio. jeep produced them with a stout 6.32 first gear and a 4.02 close ratio.
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Unread 02-18-2013, 10:21 AM   #5
Truck633
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Quote:
Originally Posted by nshefbuch View Post
What was beserk's tranny first gear ratio? This matters. I was running 33's with the same axle gears you have but I have a t18a so first gear negated any axle ratio you could throw at it. Didn't matter what tire size I had. Now I'm using 4.10 on 37's and still have no issues. Tranny gearing makes a world of difference and is often over looked.

Me personally I hate the d20. The d300 is the best tcase jeep ever made. You would benefit if you swapped to the d300 for its 2.65 low range compared to d20 2:1 low. With all this said, you will need different axle gears as the 2.73 gears were meant for an automatic tranny and high way driving. If you are getting by now then do what you want but once you hit some hard trails you will easily see the downside of those gears.

If I had to rebuild a d20, I would spend the coin on an adapter and use a junk yard d300 instead.

The only bad thing about the d300 is its stock rotation hangs low. Here is mine with a clocking ring I clocked flat gaining like 5" ground clearance. Don't let many try and talk you into redrilling the case for a cheap clock. It needs a beefy ring and new input shaft to compensate for the spacer.
Your shaft is longer than mine. Seriously though, I just installed the 4:1 kit and the input shaft just bareley slips into the seal in the rear of the transmission. I didn't get the clocking ring, but I may later, the only thing I would have done different with my 300 is the longer input shaft!
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Unread 02-18-2013, 12:46 PM   #6
nshefbuch
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Quote:
Originally Posted by Truck633

Your shaft is longer than mine. Seriously though, I just installed the 4:1 kit and the input shaft just bareley slips into the seal in the rear of the transmission. I didn't get the clocking ring, but I may later, the only thing I would have done different with my 300 is the longer input shaft!
Lol, every inch matters. At least I'm told that

I used JB conversions clocking ring kit and it's top notch. Only bad thing is it doesn't come with the shim needed for new input shaft. Clearance is very tight and many don't need a shim at all. I had to go to a local axle shop to get a shim on mine.

On the d300 scout all I know is they have the Texas bolt pattern and are very unique so read up on that before searching for one.

Lastly, by swapping to a d300 and getting a lower gear range you may like the improvement off road compared to your d20 and it might buy you time on axle gear swap.
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