Idea of Using a Bronco Dana 20

Dawnpatrol

Jesse Higgins
Joined
Apr 25, 2016
Location
Raleigh
In discussing pros and cons of different transfer case options, a friend and I questioned the use of the Bronco Dana 20 in a Jeep (YJ/TJ) application. I've read where people have trouble with flipping Dana 300s and keeping them from leaking, so that lead to why not a bronco Dana 20. I'm not very familiar with the Dana 20's so looking for the pros and cons of using this transfer case in the following setup: 4.0/AX15/NWF Ecobox-i/bronco Dana 20.

At first glance it looks like a cheap solution to a 4 (basically a 3) speed case. Seems that the Dana 20 has similar strength to the Dana 300, with the rear output being the main weak link.

What are others thoughts?
 
They are tough cases. I’d be afraid of parts availability. Not sure if if has provisions for a vehicle speed sensor in it or not.

Probably easier to buy a used atlas.


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Dawnpatrol said:
In discussing pros and cons of different transfer case options, a friend and I questioned the use of the Bronco Dana 20 in a Jeep (YJ/TJ) application. I've read where people have trouble with flipping Dana 300s and keeping them from leaking, so that lead to why not a bronco Dana 20. I'm not very familiar with the Dana 20's so looking for the pros and cons of using this transfer case in the following setup: 4.0/AX15/NWF Ecobox-i/bronco Dana 20.

At first glance it looks like a cheap solution to a 4 (basically a 3) speed case. Seems that the Dana 20 has similar strength to the Dana 300, with the rear output being the main weak link.

What are others thoughts?
Click to expand...
I have j shift pattern Dana 20 out of a Bronco. It was mated to a C4 if interested.
 
Depending on tire size and power plant, a member on here broke one in a V8 YJ.
 
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NickMaul said:
They are tough cases. I’d be afraid of parts availability. Not sure if if has provisions for a vehicle speed sensor in it or not.

Probably easier to buy a used atlas.


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I think the upgraded rear output has a gear driven speedo that's optional (similar to the D300).

The rebuild kits seem reasonably priced and looks like there are a few cases locally for cheap.

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Don Custer [@Granny], ran either the Bronco 20, or the gear set, in a D20, when he had His CJ, T-18, 258 6 cly. He built the twin stick for it! The main reason he went with it, was for the 2.72[?] low range. Never had a problem. Hope he sees this!
 
Dawnpatrol said:
Wouldn't happen to know what broke? I've heard of the rear output being the weak link. Curious to hear the person's setup and what part broke.

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I wanna say rear output, but spring wrap may have been a factor. 4.8/4spd/20/tons/40s
 
After you upgrade the output shafts the weak link becomes the case itself. It can get pretty thin in some areas but if you can get one cheap then go for it.


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NickMaul said:
After you upgrade the output shafts the weak link becomes the case itself. It can get pretty thin in some areas but if you can get one cheap then go for it.


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I might try and grab one to at least take measurements and inspect in person since I'm not too familiar. There is some aftermarket support, but not like the D300. I have a bronco friend that has one that has held up to a 302/np435 other than the rear output. Interested to hear others experience.

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Dawnpatrol said:
I might try and grab one to at least take measurements and inspect in person since I'm not too familiar. There is some aftermarket support, but not like the D300. I have a bronco friend that has one that has held up to a 302/np435 other than the rear output. Interested to hear others experience.

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Click to expand...

This guy local to me wheeled with success. His TJ is pretty light though.


7/8ths Ton TJ


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They are decent case no really big issues with them. The rear outputs can go out with high horse power, but they make a HD version which is very similar to an atlas 2 output. You can basically get all the parts to rebuild them really easily thanks to bronco guys rebuilding them. The J shift style actually have lower gear ratio that Tshifts FYI. Both units can be twin sticked.

Dana 20 Transfer Case - WILD HORSES Early Ford Bronco Parts
 
I ran one in a v8 cj on 38’s. Bronco gears in a Jeep case for the deeper low range. Had to do a bunch of grinding on the case to get it to fit. It held up well in both @cabtruck YJ and my CJ. I ended up breaking it though. Stripped bunch of teeth off of the intermediate shaft and cracked the case all in one shot.
 
As said, the rear output shaft is the weak link. If running leaf springs, a traction bar would go a long way to help reduce the chances of it failing due to axle wrap. They are not terrible to rebuild and kits are available for them. I wouldn't hesitate to run one as long as the adapter kit isn't ungodly expensive. They use a gear driven mechanical speedometer. A few places were making a gear drive unit with a Ford type VSS sensor tied to it. No idea if that would work for you.
 
Rnuovrcj5 said:
I ran one in a v8 cj on 38’s. Bronco gears in a Jeep case for the deeper low range. Had to do a bunch of grinding on the case to get it to fit. It held up well in both @cabtruck YJ and my CJ. I ended up breaking it though. Stripped bunch of teeth off of the intermediate shaft and cracked the case all in one shot.
Click to expand...


Never had a output shaft problem it was behind a t18 had 37”tires with leaf springs
 
Also have a T18/D20 combo and it will be in front of a set of tons and 37's and/or 41's. Not worried about it for moderate wheeling. The HD output isn't awful expensive for them either. Like others have mentioned, traction bar will help it live as well.
 
rodney eppes said:
Don Custer [@Granny], ran either the Bronco 20, or the gear set, in a D20, when he had His CJ, T-18, 258 6 cly. He built the twin stick for it! The main reason he went with it, was for the 2.72[?] low range. Never had a problem. Hope he sees this!
Click to expand...

Swapping gears from a Jeep Spicer 18 and Bronco Dana 20 into a Jeep Dana 20 will change the low-ratio from 2.0 to 2.46 which worked out well for me. Twenty some years later, coupled with other options I would wonder if it would be worth the effort. Anyway, from the archives here is what I have. Hope it helps someone. :)

Lower Gears For a Jeep Dana20 Transfer Case (2.46:1)

You can change the low range ratio from 2.03:1 to 2.46:1 using
parts from an early Jeep Dana/Spicer18 and an early Bronco Dana20.

The following gears are needed.
The numbers should be stamped or cast on each gear.

#18-5-9 (18T)(39T) intermediate gear
from a 55/71 Jeep Dana/Spicer18 or 66/72 Bronco Dana20

#18-8-22 (33T) front sliding gear
from a 55/71 Jeep Dana/Spicer18

#18-8-23 (29T) transmission input gear
from a 55/71 Jeep Dana/Spicer18

#18-8-24 (29T) front output shaft gear
from a 55/71 Jeep Dana/Spicer18 or 66/72 Bronco Dana20

#18-8-58 (33T) rear sliding gear
from a 66/72 Bronco Dana20 (see paragraph about numbers)

The Bronco Dana20 transfer case is easy to identify. It has the shift rods located in the top-center and has a flat bottom cover plate. It's really an odd looking thing.

The Bronco rear sliding gear has at least five different numbers for the same gear. #18-8-37, #18-8-39, #18-8-58, and #18-8-65 are all common numbers, and there are a couple others. Just make sure the gear has 33 teeth and 15 splines. If it does, you should be OK.

The Jeep Dana/Spicer18s use different diameters of intermediate shafts. If you're going to use an intermediate gear from a Jeep Dana/Spicer18, make sure it has a 1 1/4" intermediate shaft diameter!

The Bronco Dana20s should all have an intermediate shaft diameter of 1 1/4". If using it, you should not encounter any problems.

You will also need an input gear to match your particular transmission. The #18-8-23 listed above is the most common one used. It has 6 splines with a 1 3/8" spline diameter. These gears are commonly found on Jeep T-90 (3-speed) transmissions used from 41/71.

If you have a T-150 transmission, the #18-8-23 (29T) gear will have to have a surface machined for the bearing retainer seal, 7\16" x 1.750".

Some cases require a little grinding for clearance of the larger gears.

A power-take-off will not work without special gears!
 
Thanks for all the info @Granny!

I am slowly moving forward with the gathering the parts for a doubler with the bronco dana 20. The NWF EcoBox-i will allow for the adaptation directly form the Dana 20 to the 23 spline AX15 without any additional adapters and only adds a little over 5" to the length. I was able to pick up a J shift Dana 20 (shout-out to @WARRIORWELDING for the sweet deal). This will put my low-low ratio at 6.38:1 which is more than enough. Now I just need to scrounge up some NP231/NP241 parts order the bigger ticket items and start assembling.
 
Dawnpatrol said:
Thanks for all the info @Granny!

I am slowly moving forward with the gathering the parts for a doubler with the bronco dana 20. The NWF EcoBox-i will allow for the adaptation directly form the Dana 20 to the 23 spline AX15 without any additional adapters and only adds a little over 5" to the length. I was able to pick up a J shift Dana 20 (shout-out to @WARRIORWELDING for the sweet deal). This will put my low-low ratio at 6.38:1 which is more than enough. Now I just need to scrounge up some NP231/NP241 parts order the bigger ticket items and start assembling.
Click to expand...
No problem and that @Granny. Fella was the expert I was talking about. You need to meet him. Rarely a more patient, gracious, and inteligent wheeler out their. Deffinatley the old school cool.
 
If you do the nwf doubler I would suggest building your own cable or linkage shifters. I ponied up and bought the expensive triple shifters and it tool a lot of messing around to get them to work right
 
Also if you need any help with the doubler...I just did a econobox to 205 and it's still fresh on the brain.
 
1stgenxxx said:
If you do the nwf doubler I would suggest building your own cable or linkage shifters. I ponied up and bought the expensive triple shifters and it tool a lot of messing around to get them to work right
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I was thinking about buying the twin stick shifter kit from wild horses (https://www.wildhorses4x4.com/product/17830/Bronco_Dana_20_Shifters#pdf) and extending the linkages. Now that I look at it more closely i wounder if I could extend the shifter pivot arm and add in another lever for a triple stick. Does the eco box allow you to connect the shifter linkage to either the driver side or the passenger side (i.e. dealers choice)?

I may hold out on the shifter until I see how everything is going to line up. I maybe able to copy the wild horses design with some angle iron, flat plate, and some tubing. This is all new to me, so is there any good place to get the parts to build a triple stick shifter, for instance the small heim linkages, or a cheap one that could be modified?
 
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