Dana 20 Rebuild

[DanHall]

while I've got it out for an engine and transmission swap I decided to rebuild the TC. Nothing wrong with it I just have no idea if it had ever been done and it is already out. Getting it back together now and set the front output shaft shims based on end play and it turns with free. The rear output shaft is back in now too but seems to be a little stiff. It turns smothly but takes a little more force than I feel like it should - with no basis other than it is stiffer than the front. I used the shims that came out thinking that would be good. I didn't find a spec for end play or any other measurement for the rear.

Should I pull it again and add a thin shim to get it loosen up a bit or is the rear supposed to be a little stiffer than the front? I certainly don't want it to damage the bearings and have to do this over again only because I was too lazy to do it right this time.

[horseplay]

I believe there's a rotational inch Lbs spec not at the shop so I don't have it handy.

[DanHall]

Just measured as best I can with a torque wrench and it looks like I'm at 19 in-lbs.

Is the front output supposed to be set with a preload as well? I set it by end play at the lower end of the 0.001-0.003" spec that I found and it has no measureable preload.

[Viperwolf1]

The end play spec is the same as the front but I like to set them both up a little tighter. For example get it down to .002-.003" end play then remove a .005" shim. That should give you about 10 in-lbs.

[DanHall]

Thanks! I'll play with the shims to get to about 10 in-lbs on both.

[DanHall]

I finally got it all back together with both output shafts very close to the 10 in-lbs recommended. Now I'm having a hard time getting it to shift properly. When it is in the correct positions it is smooth.

The problem is when I tighten the detent for the front shift rail it seems to lock it up on the front side. I loosened the detent retainer and it shifted okay until I went from 4 lo back through into neutral on the rear and then into high on the rear and stayed in low on the front (I have done this a number of times and the problem only occurred once but that is enough). That put me in a bad place if I were driving. I'm wondering if I didn't lose one of the inner pins between the shift rails but I wouldn't think that would cause both problems. I did shift the rails by hand before putting anything else back and they felt fine and seemed to hold at the right points.

Am I missing something or am I just gonna have to tear it back down?

[Viperwolf1]

Is it a T or J? J only has one pill and you can shift any combination.

[DanHall]

T shift

[Viperwolf1]

Stock shift rails or have they been modified? The modified rails will allow one bad combination.

[DanHall]

Stock rails.

I'll probably just pull it apart again, double check the pills and rails and if I don't find anything just pull the pills and twin stick it. Just bugs me that it is happening.

[DanHall]

Yep, only had one of the pills in it. I pulled the one that was in there and have a JB Fab twin stick sitting on the bench. I'm going to try a limiting bracket like this https://youtu.be/PgfoN99zc5c and see how it works. Basically just replaces the shift flag with a piece of steel with oblong holes to limit the offset between the shift rails so they can only be even or one step apart eliminating the low/high combo.

[Eck]

Yep, only had one of the pills in it. I pulled the one that was in there and have a JB Fab twin stick sitting on the bench. I'm going to try a limiting bracket like this https://youtu.be/PgfoN99zc5c and see how it works. Basically just replaces the shift flag with a piece of steel with oblong holes to limit the offset between the shift rails so they can only be even or one step apart eliminating the low/high combo.

Have you done this modification yet? I will be looking to Twin Stick my T case as well and don't want to have to have the lo/high combo be an issue either. I saw this option (http://www.wt4x4.com/tech/twinstick.htm), but removing the pills completely and using this type of bracket from that youtube clip seems much much simpler. Interested if you have tried it and how it has worked for you.

[DanHall]

I gave it a whirl and cut the slot a little long on my first attempt so it will just barely get into the hi-low combo. I will probably give it another try before I install the TC. It is sitting on the bench right now while I have been tearing down the Mounty for the "new" engine and tranny. I will have to get through the harness mods and rebuild the heater before I get back to the TC.

I saw that thread too but for whatever reason (I probably lost the other when tearing down the first time) I only had one pill so the grind and weld option was out for me.

[sykanr0ng]

One thing this writer (http://www.wt4x4.com/tech/twinstick.htm) is not aware of is that the Scout (and Jeep?) 26 spline front output shaft that he says there is not a lot of yokes for is the same size as the yokes used on the:
Dana 300 TC front and rear
NP231 front yoke (some are double cardan)
D30
D35
D44
D50

Maybe more.....
some Ford Explorer fronts ( '91 - '01 )
and the Jeep Dana 20 rear output (some front)

[Eck]

I pulled my Dana 20 apart today and have a few questions.

I pulled one of the shaft seals and it had a part number of 540644. I quick Google search gave me a cross reference to a NATIONAL 472635 (which on O'Reilly's site does not have a compatibility with a FORD.) Also, the output shaft bearing has a part number of TIMKEN 14131 which appears to be correct for FORD.

The D20 serial # is 1307540 and the B/M #300777-3. It also had only one pill in it (which is fine because I am removing them). It is also missing ONE detent spring and ball. I know WH sells them so I will probably get them replaced.

Can someone that has rebuilt a Dana 20 please help me figure out which seals I need to get? I already have the gaskets and don't plan to order a complete rebuild kit for $130+.

Thanks!

[Viperwolf1]

Seals:
Input shaft seal (double lip)-CR #517383,Napa #NOS 18676, CR #18676 (good seal) (Do not use Timken #473179)
Output shaft seals-Timken #450185
Shift rail seals-CR #6204, Timken #471466
Yoke o-ring-1-1/4"OD x 1-1/8"ID x 1/16". Danco happened to be the brand at the hardware store and it is their #29.
Speedi-sleeve for yokes-SKF99155

Bearings:
Input- SKF #307NRJ
Rear output-Timken #25877 (inner), Timken #15117 (outer)
Front output, J shift-Timken #14116
Front output, T shift-Timken #14131

Cups:
Rear output-Timken #25821 (inner), Timken #15245 (outer)
Front output-Timken #14276 (both T and J)

The pill in the front hole typically gets stuck in there because the hole doesn't go all the way through. It's there, you just need a small magnet to get it out. There is no ball/spring under that front plug.

[Eck]

Seals:
Input shaft seal (double lip)-CR #517383,Napa #NOS 18676, CR #18676 (good seal) (Do not use Timken #473179)
Output shaft seals-Timken #450185
Shift rail seals-CR #6204, Timken #471466
Yoke o-ring-1-1/4"OD x 1-1/8"ID x 1/16". Danco happened to be the brand at the hardware store and it is their #29.
Speedi-sleeve for yokes-SKF99155

Bearings:
Input- SKF #307NRJ
Rear output-Timken #25877 (inner), Timken #15117 (outer)
Front output, J shift-Timken #14116
Front output, T shift-Timken #14131

Cups:
Rear output-Timken #25821 (inner), Timken #15245 (outer)
Front output-Timken #14276 (both T and J)

The pill in the front hole typically gets stuck in there because the hole doesn't go all the way through. It's there, you just need a small magnet to get it out. There is no ball/spring under that front plug.

Thanks. So there are only 2 springs for the 3 holes then. Good to know. I thought stuff was missing.

[DanHall]

I did the same thing, had to go back to the diagrams to figure it out.

[akaFrankCastle]

Let me know if anyone needs a page zoomed in on.

[Viperwolf1]

One common mistake is putting the main drive gear on backwards. Don't do this or you will be pulling the tcase back out.

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