Dana 20 Swap - Auto to Manual

[rguest3]

I currently have a Bronco C4 / Adaptor / D20 and want to take off the D20 and install it to a Top Loader 4-Speed that already has the Adaptor and AA Shaft installed.

Is there anything internally in the D20 I have to change out, or is it as simple as a new gasket and re-bolting it on?

 

[Broncobowsher]

Keep your transfer case input gear. Don't loose any of the 13 bearings that will want to fall out.

 

[rguest3]

So, there is no difference between the Input Gear/Spud Shaft wether connected to a Manual or Auto transmission?

 

[Broncobowsher]

The input gear (I think) has to match the gear ratio in the transfer case, and there were 2 ratios over the years.
The spud shaft has always been part of the transfer case adaptor. But I have never owned a C4 either.

 

[mrdrnac]

According to Tom's Bronco Parts web site the spud gear is the same for all 66 to 77 Broncos, but I'm not sure either what all changes with the different gear ratios?

 

[Broncobowsher]

OK, I couldn't remember if the change in ratio was done in the helical or the straight cut gears in the transfer case.

 

[Viperwolf1]

Input gear is the same, input shaft is different length.

 

[Broncobowsher]

Input gear is the same, input shaft is different length.

The spud shaft? The one that goes over the transmission output shaft? About 6" long? 28 spline female to 6(?) spline male?

That shaft?

 

[rguest3]

The Top loader has the AA adaptor kit installed and the Ford Adaptor (mid housing) with the input shaft seal and bearing installed. There is no Main Drive Gear or snap rings installed. I will transfer these when I separate the transfer case from the C4.

Once I Install the Bearing Snap Ring, Main Drive Gear and Gear Snap Ring I should be ready to install Transfer Case with a New Gasket. Correct?

Anything else needed?

 

[Viperwolf1]

The spud shaft? The one that goes over the transmission output shaft? About 6" long? 28 spline female to 6(?) spline male?

That shaft?

Yes. The auto spud shaft is exactly 7 3/8" long. The manual shaft is a little longer, maybe 7 3/4". The extra length of a manual shaft on a C4 will cause it to bottom on the governor before the adapter mates to the C4. Some manual shafts have deep enough inner splines that they can be cut down to work on a C4. Some don't.