Rebuilding the Dana 20 Transfer Case

[Hedgehog]

After cleaning and rebuilding Rusty, a T18a, I was feeling confident about doing the same with it's forever partner the Dana 20 Transfer Case , with the addition of a set of low gears (this has been debated, decided and are on a big brown truck heading my way). In preparation I'm reading up on rebuilding a Dana 20 Transfer Case . Now my confidence is slipping a little.

Transmissions are fairly straight forward, gears, slip thingies, forks, needle bearings, top shifting units, all have their little quirks, mostly manipulating weight along with fine adjustments. These transfer cases seem entirely different, tap this, push that, end play adjustments everywhere.

Have you rebuilt a Dana 20 , is it really as tricky as it looks or is most of it simply smoke and mirrors? Would I be better off to take it to a rebuilder and pay the man?

I was nervous before with the T-18 , now I simply don't know.

 

[CJ]

All you need are basic hand tools. I started a writeup here -->> Dana 20 Rebuild. - Jeep-CJ Tech. Articles (not finished .)

You can see more images here -->> Dana 20 Rebuild - Jeep-CJ Gallery

If you don't have a dial indicator to measure end play you can use feeler gages.

 

[Hedgehog]

Thank you for you quick response. I've got the tools from setting up my ring and pinion so the tools shouldn't be a problem. And of course the Terra Low gears will require grinding the case. Setting up end play always makes me nervous, why I'm not really sure, it's never come back to bite me.

 

[Hedgehog]

Nice beginning to a write up on the Dana 20 . Even as short as it is I did learn a few things.

 

[Lumpy Grits]

HH-You have set up R&Ps and rebuilt a tranny.
YOU can do the t'case.
The only caution I would add-You may well have to 'clearance' the case in places for gear placement/engagement.
I for one(IF, you want to)would love to read a write-up of the t'case rebuild with the TL kit.
LG

 

[tarry99]

Easy to do.........the key to the rebuild is getting the best parts to rebuild it with............IE; bearings, seals , shims and the 1.250" main shaft......Novak has done a pretty good job of putting together those pieces including supplying there own shafts that are built in house..........make sure you push the main shaft out the right direction as it has a slight taper on one end. Some early cases do need grinding but the later cases have clearance.

 

[Hedgehog]

My internal parts are coming from Advanced Adaptors, they had the gear kit for less than everybody else, even though it will be drop shipped directly from Terra Flex (Terra low). Other parts are coming from NOVAK

 

[BusaDave9]

Rebuilding the Dana 20 is easier than rebuilding a Transmission or differential. I did just what you are doing. I put in the Tera Low kit during the rebuild.
You have to make sure the output bearing shims (#8 in the picture below) are very clean but I had a leak. It was easy to address.

Reuse the shims. Don't use any type of silicon based sealant such as Form-a-Gasket. That is the same as having thicker shims. Not good! You can't measure the silicon and even if you could it can move after assembly.
Here is what you use: Thread sealant. It will compress down to nothing and it still seals.
Here's what I used and it did the trick. It's not just a thread locker it's also a sealant:

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[Hedgehog]

I recently reread your "Here's my CJ" thread and noticed that you did the Terra Low gear set in your Transfer Case . I know that many here would prefer the 4:1 gears available for the Dana 300 over the 3.19:1 in a Dana 20 . What is your opinion of the gearing, was is a significant improvement, would you do it again?

What makes me nervous about this rebuild is experience with the T-18 . There were many blind alleys while putting it back together. Essentially reassembly had to be done in a certain order. The back main bearing was installed and removed 5 times. Believe me on this one, the main shaft and input shaft won't go together at all with a main bearing installed. Other transmissions will, the T-18 won't. Luckily when the instructions, when finally read they said exactly what needed to be done. The one shop manual available with Dana 20 instructions reads like this.: Take this off, remove that, put it back together, pay attention to the end play here and there. Naturally it is a little more in depth, but not much more. I'd like to avoid the pit falls and dead end alleys hit in the T-18 rebuild. ........ Hmmmm come to think of it Rob at Willys Works will allow me to copy the instructions from a jeep shop manual. I do have a Jeep Shop manual, it's for a 1980, but has served me very well for many years. However it doesn't have anything for a Dana 20 in it.

The thread sealant idea is great.

 

[BusaDave9]

The Terra Low was well worth it. It made off roading much more enjoyable with that low gear. Sure it would be nice to have a Dana 300 with 4 to 1 gears but that's too much trouble.
Rebuilding the Dana 20 is easy. I say go for it. It'll be rewarding when your are done. You could have a shop do it for you but I never find it rewarding to give my money to someone else.

 

[Lumpy Grits]

HH-Couple of folks I 'jeep' with all the time have the TL kits in their '20s'.
They both say it was well worth it and money well spent.

LG

 

[BusaDave9]

This is also a good time to add twin sticks if you haven't already.

 

[Hedgehog]

Like all things internet when thinking about going with the low gears I posted on it, many posters really didn't believe it would be worth the cost for such a small change in gearing. They all had sound reasoning, but I like to ask someone that did the switch about their experiences with the gears.

Busa & Lumpy - thank you for the positive responses. It would have been bad if you'd come back with, "The worst waste of money ever, the gears broke and cracked the case within a couple months." That was really what my original post on the Terra Low gears was fishing for, bad experiences that is. Nobody seemed to have those, it was a cost vs gain thing for most. With the 3.31 road gearing I put in on purpose I figure the low Transfer Case gearing will compensate off road. That is along with the known qualities of the T-18 ahead of it.

Twin Sticks, well by golly I've been running Twins with the pills for a couple years now. The new sticks for the long T-18 are in the mail. My real dilemma now is to pull the pills or not. Have you done it (anybody is welcome to answer this)? Somebody must have cross geared Hi and Low did it actually do any damage? If you are not horsing hard I imagine you would know before the mistake would cause any real damage. With me being a bit of a klutzes it will only be a matter of time before I did/do it. Also, with the pills in place there is a feel for when it snaps in gear, without the pills is it a hit/miss situation or is being in gear something positive you can feel in the stick?

As with all my CJ project I'll end up doing this myself ... along with a better manual that is.

 

[Lumpy Grits]

Never much cared for a twin stick setup. I'm still run'n the one stick, in my 4:1 D/300 t'case.
I look at the one stick deal as KISS...........
LG

 

[BusaDave9]

My real dilemma now is to pull the pills or not. Have you done it (anybody is welcome to answer this)? Somebody must have cross geared Hi and Low did it actually do any damage?

I say pull the pills as long as you have it apart. It helps with a tight turning radius. At times you can almost pivot. Not often I admit but it's easier if you have a hill on one side of the trail when you turn around. Once (maybe twice) I cross gears with the front in high and the rear in low (or vise versa). I really don't know how you can do damage like this. The problem is it seems to jam if you do this. It takes a bit to get one shift into neutral then the other come easy. It's not like you get cross shifted and out of curiosity try giving gas and releasing the clutch. And if you try shifting while you are moving, even slowly you'll never get it cross shifted. I think you'd just grind gears although I'm sure their is some idiot out there that has proven me wrong. The only reason I got cross shifted is because I carelessly reached for both levers and pulled back. One lever slipped out of my hand and I was in both high and low at the same time. Now I make sure to shift into neutral before going to low. That way if you slip, no problem, correct it before going into low.

 

[Hedgehog]

If the set up in the 20 were as good as it is in the 300 I had I wouldn't be considering the change now. But there is something uncomfortable about the excessively long throw of the 20. Bark your knuckles going into 4wd low and smash your fingers going into 4wd high. I like the quick short snap into gear the sticks offer in my 20. It should be the same in the new/replacement 20. Even with the pills in place the idea of 2wd low appeals to me, honestly why I don't know.

Busa - Pretty much as I expected. Gears bind but don't break. A nice anti theft measure. How does removing the pills effect feel as in when in high, then neutral then in low. Also when in gear are they solidly in gear with no slipping out?

Yeah there is always someone there to prove you wrong. I'm understanding that Lumpy guy more and more all the time.

 

[BusaDave9]

The change from 2.03 to 3.15 gears may be a change of only 1.12. That may not seem like much but when talking about gear ratios you need to think in percentages. As a percent going from 2.03 to 3.015 is like changing your axle from 4.11 gears to 6.4 gears! No one makes 6.4 gears for jeep axles because the pinion would be so small that it would shatter. Another advantage to the low TCase gears is it only affects you when in 4WD low. On the highway you still have tall gearing.

 

[Hedgehog]

I am generally a UPS fan. They are efficient and speedy. But not all the time. Got home yesterday to find a note on the door. They can't leave the package ($1,000 worth of gearing) without a signature from someone 21 or older. They will resend the next business day, darn it, I take today off to receive the package. Then notice that even with the "Deliver Tomorrow" box checked there is something about deliver to access point. What access point? Then reading more closely I can track my package using a number on the note. Tracking says: 1201pm nobody home ... 1211 readdressed to Access Point .... 613 delivered .... this morning "Out for Delivery" ..... Out for delivery where? I call the "Access Point" listed on the tracking page. They haven't got the package, but the driver is unloading a pile of packages as we speak. I leave number, a few minutes later they call back from the "UPS Store" the package is here. Honestly, if I didn't check the on line tracking information I would have had no clue as to where my $1000+ delivery was. As far as I'm concerned this was a FAIL on UPS's part and I'm a big fan of the big brown truck.

 

[Lumpy Grits]

Just be happy that UPS didn't turn it over to USPS to deliver. That alone adds 1 to 2 days to the wait.
Glad you got it. I don't 'wait well' either.......
LG

 

[Hedgehog]

It's not really the waiting, it came quicker than expected, it's the confusion that shouldn't have happened.