Twin stick dana 20 interlock removal

[Built Not Bought]

How hard is it to make Dana 20 to where I can operate front axle in low only with my jb twin stick shifter

 

[Reddrig]

It's been covered a lot on several forums. I'm looking to do the same thing. You will need to pull the Dana 20 and open it up, then remove the internal interlock pills. Do a search under Dana 20 interlock pills and you should get enough info to tackle the project. I'm going to wait until I rebuild the unit since I need to drop it anyway.

I'm sure your aware of the dangers of a high low implosion should you have a brain fart. Anyway it's probably a fairly easy project from the research I've done, just requires some time.

 

[Posi]

Twin sticking a CJ Dana 20 isn’t a very popular option because there is no real benefit besides ease of shifting. Unlike the FSJ Pickups, Cherokees, and Wagons, that have a u-shape shifting pattern are able to use the front and rear axles independently. An added benefit on the FSJ and Bronco Dana 20 is the slightly larger case so there is no need for grinding to install the larger 3.15 gears.

To gain independent use of the front and rear axles an owner of a CJ-Dana 20 would need to remove the shift rail interlock pills (looks like 2 Tylenol pill) or be lucky enough to have worn pills. By removing the pills you stand the chance of binding and damaging the Transfer Case by accidentally shifting the front in low and the rear in hi or vice-versa (the interlocking pills keep that from happening).

If I was going to twin stick I wanted the use of both axles independently but also wanted the safely of not binding the Transfer Case especially when letting others wheel my Jeep. I decided to modify one of the shift rails enabling me to use the axles independently hi/low and still retain the pills.

Below are the two shift rails, detent springs and balls. I used a set of fuses to simulate the interlock pills. If you were looking down on the Transfer Case the rails, springs, and balls would be at the bottom.



I marked the rear shift rail where I plan to remove some material.



I used a bench grinder and finished with a drumel.



I re-installed both rails in the shift housing without the detent springs and balls and there was no interference with the interlocking pills. I could now get low and hi in each axles independently with no fear of binding.

 

[Hedgehog]

If you want to drive in rear 2 wd only all you have to do is install the twin stick and leave your pills/rails alone.

Left stick controlls the rear axle ... back = 2wd high ... middle = neutral ... forward = 2wd low

There is a concern about using 2 wd low in high torque situations. The Transfer Case gears are designed to hold the load or torque of all 4 wheels in low range. Essentially the load is split between two gears. When put in 2 wd low all the torque is placed on one gear that is designed to take only 1/2 the torque available from the engine/Transmission .

If you want to run just the front axle you need to remove the pills or modify the shift rods as shown above. I have a Dana 20 with a twin stick conversion and have left the pills and the shift rods alone. Having a positive and short throw between gears along with having rear wheel low lonly is benifit enough for me.

 

[mopar440cu]

Hedgehog, Your saying without removing the interlock pills or grinding the rails that I can still be capable of using 2wd low or high? I really don't care about the front wheel drive thing for running in the swamps. lol

 

[Hedgehog]

Oh my, an old thread. By going with the Twin Stick conversion and doing nothing else you gain the ability to run in just rear high or low range. I've heard that in rear low the gear might not b able to hold the power. Remember the Transfer Case is designed to split power between 2 axles while in low range or having 50% going to each axle. With 100% going through one low range axle you might have a problem. But remember that is only something I heard. Lots of folks have blown a drive shaft and gone many miles essentially doing the same thing.

I like my Twin Stick a lot for what we are talking about and the short throw of each stick. No more barking your knuckles up front or in the back. A quick snap in and out. You do have to think about what your are doing though. ALWAYS shift the rear in first, then the front in the proper power band IE rear low - front low. Going the other way front -neutral, then rear neutral to high, then front high. A real shuffle act if you are stressed or in a hurry. But knowing how it's done makes the jeep all yours. I know it would be ugly for me to remove the pills, I'd blow it sooner or later. A nice way to keep your jeep from being stolen though. Park it in a high/low situation and all but the most experienced thief wouldn't know what to do.

 

[mopar440cu]

Hedgehog, Thanks for the response. I went with leaving the pills in and NOT grinding the shift rails, again due to I myself will never use front wheel drive alone in the swamps.
The Dana 20 rebuild was made easier with my 10 ton press and another set of hands. As for the needle bearings, what a pain. I had to give up and let the wife do that while I watched and drank a beer to calm down. lol

 

[mopar440cu]

Actually I have to say that rebuilding a T-18 is a whole lot easier than doing a Dana 20 . Funny the wife is right here shaking her head agreeing with me, because she helps me with the Transmission work.

 

[Hedgehog]

You are a fortunate man to have a partner that shares this level of mechanical work with her husband. Keep her happy, keep her around......