International Full Size Jeep Association
Home Forums Reader's Rigs Tech Library Trail Stories FSJ-List
International Full Size Jeep Association  

Go Back   International Full Size Jeep Association > Tire Kickin' > Off-Road FSJ Tech

Thread Tools Search this Thread Display Modes
Old 02-18-2009, 01:28 AM
trcooperone's Avatar
trcooperone trcooperone is offline
Grease Monkey
Join Date: Feb 23, 2007
Location: Rexburg Idaho
Posts: 492
Dana 20 doubler

There was a pervious post that sparked this idea, has anyone ever used this doubler kit that uses a np203 range box and mates to a dana 20.

What do you think? opinions?
1976 Cherokee Chief w/401, SOA and chevy 63" springs in the back, Dana 60 in the front and Dana 70 rear welded, dana 20 twin sticked, and 38" TSL's
Reply With Quote
Old 02-18-2009, 04:58 AM
4x4fEvEr's Avatar
4x4fEvEr 4x4fEvEr is offline
Master Mechanic
Join Date: May 25, 2005
Location: abingdon, va
Posts: 803
I wouldn't waste my time using a 20, there's so many other and better cases. If you are gonna use a 2:1 case you should atleast use one that will take abuse like a NP205
77 cherokee chief 360/435/205-60/60-42's
Reply With Quote
Old 02-18-2009, 08:20 AM
ncjeepers ncjeepers is offline
Gear Head
Join Date: Dec 18, 2002
Location: Locust, NC (near Charlotte)
Posts: 709
A D300 with a 4:1 kit would probably be cheaper and make for a much lighter and more compact package.
Tony Casey
Reply With Quote
Old 02-18-2009, 08:40 AM
elbastardo elbastardo is offline
Gear Head
Join Date: Oct 04, 2005
Location: wa
Posts: 507
Im a BIG fan of the 20. But i went to the 205.
Reply With Quote
Old 02-18-2009, 10:21 AM
Posts: n/a
Outside the 205, I don't know of that many factory cases better than the 20. Cast iron box, gear-to-gear transfer of power, compact, and upgradable without a bunch of trouble. One downside of must OEM aluminum cases is breaking the case with trail obstacles hitting it.

For a lot of guys running autos, the easiest way to double your crawl ratio is to switch to a T18/19, 465,435, or 420 tranny.
Reply With Quote
Old 02-18-2009, 10:44 AM
Randyzzz's Avatar
Randyzzz Randyzzz is offline
258 I6
Join Date: Mar 03, 2008
Location: Redmond, OR
Posts: 351
Use a D300, not a D20. The D20 is a good case, just not ideal for a doubler.

Biggest problem with using a D20 as the second box is front bearing retention. The D20 bearing and gear ride on the output shaft of the 203, making it critical that the 203 output is machined perfectly with attention paid to gasket thickness and other variables. Plus the machining required on the 203 shaft includes a surface for the bearing to press onto and then a threaded area.

A D300 has a captured, sealed front bearing. All that's needed on the 203 end is a splined shaft. No real critical lengths the standard NP front bolt pattern on a 300 is much easier to build an adapter for- the D20 texas pattern always seems to have a bolt in the wrong place.

I designed a D20/203 adapter...then redesigned for a D300, much easier. Then I got a 241OR case cheap, and gave up on the doubler idea all together. Still have a 2" thick aluminum plate sitting in the cabinet...
Randy S.
It's not what you Buy, it's what you Build.
1987 J20 SOLD
1966 Waggy SOLD
1970 Waggy SOLD
1982 Scrambler SOLD
1981 Scrambler - Current Project/Keeper
Reply With Quote
Old 02-18-2009, 05:57 PM
orangecherokee's Avatar
orangecherokee orangecherokee is offline
Join Date: Aug 17, 2002
Location: Kingsport, TN
Posts: 5,414
yeah but you alos will need to upgrade the output shaft. I have no issue with the D20 except that. I've seen too many people stranded or broken down because of it including yours truly. if anything I'd go with the 300 if I had to.
Places to Wheel in the Southeast

Originally Posted by Topgun2mo
I would think boxing would limit the amount the frame could flex over obstacles which I think IMO would be a bad thing. I would think you would want all the articulation possible.
Originally Posted by johnny019
I'm not saying lockers don't improve the performance of your rig, just that they're overrated.
Reply With Quote
Old 02-18-2009, 09:21 PM
SCscoutguy's Avatar
SCscoutguy SCscoutguy is offline
Gear Head
Join Date: Jul 25, 2005
Location: Florence SC
Posts: 692
That kit is for use with a Ford pattern Dana 20 which is much harder to find than the Jeep/IH 5 bolt Texas style Dana 20's.
Reply With Quote

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -6. The time now is 11:52 AM.

Powered by vBulletin Version 3.5.4
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
corner corner