ZF with a NP205 or D20?

[Ranchtruck]

What's the main advantage to keeping the D20 when swapping to a ZF 5spd? The much lower 1st gear in the ZF should more than make up for the 0.5:1 loss in low range between the D20 and the NP205, right?

If I'm building a crossmember for the ZF, I might as well add a support for the 205 at the same time, so that's not much of a bother. There's a 50lb difference between the D20 and the 205, but it's mounted low and central in the truck so it shouldn't have an effect on how it drives.

The ZF case has to get notched for the NP205 shift rail, but I'd be building custom shifers no matter what transfer case I used, so again, not much extra work there.

It seems like spending $400+ on an adapter to keep the D20 isn't worth it to me.

The 3spd 1st is 3:1, the D20 is 2.5:1, and the 9" is 4.11:1 for a total reduction of 30.75:1

The ZF 1st is 5.72:1, the NP205 is 2:1, and the 9" is 4.11:1 for a total of 46.9:1.

With the D20, that's lowered to 58.65:1.

So if I kept the D20, it would have twice the reduction, if I swap to the NP205, it would have 1.5 times the reduction of stock.

It's not going to ever have big tires, 32" at the most, or do insane rock crawling. It's a utilty vehicle that spends time on the highway, on mountain trails, and towing hay or water to the cattle year round. I'm also a little worried about the D20 holding up to the 351w with careless drivers. Everyone in the family uses it, and some of them are pretty rusty when it comes to operating a clutch.

 

[Ethansdad73]

I have asked the same question and i cant find my post with the answers i got. but you have your thought process right on track. most will keep the 205 easier and cost effective. The dana 20 will hold up to a 351 all day so strength is that there if you decided to keep it.

 

[thunderbolt]

Im in the middle of the same swap. I figured the same thing, that the difference of the transfer case ratios is more than compensated for by the zf's first gear. Just gonna go with a free 205 and adding twin sticks. Still have to make a crossmember and collect the rest of the parts though! The other thing is before I grind the tail housing of the zf, i need to figure out if its worth clocking the 205 for extra ground clearance. Some guys are just drilling new holes halfway between the existing ones

 

[camomog]

Go with the 205, it is stronger and if you find the gearing needs to be lower you can get a set of gears to make the 205 a 3.0 to 1 for a little over your 400 for the adapter.

 

[broncnaz]

Some of the advantages of keeping the D20 is that its a smaller package, less total lenght, and the slightly lower gears. I wouldnt worry much about a D20 holding up behind the 351W your not doing anything extreme and your tires are relatively small so you'd really have to be beating on it to hurt it.
While yes the ZF first gear does more than make up for the loss of gearing in the t case a lot of people want all the lower gearing they can get. I dont believe there are any low gear sets availible for the ford NP205. Even the so called lower 205 gears that are out there require a new case so there's really not just swapping gears.

Either way you should be fine with a 205 for what your doing. You should be able to pick up a np205 for less than half of what a D20 adapter kit costs. Might need to scrounge up a rear yoke in the correct size at the most. But over all in your situation it will work out cheaper.

 

[Ranchtruck]

Good to hear. I hadn't seen much on using the 205, so it's good to see other people using it to.

As far as abuse goes, I cracked my head on the back window pretty hard when my cousin did an accidental 4k rpm clutch dump in 4 low. We were in a bit of a tricky spot on a trail, and the feathering the clutch while not stalling it wasn't working out so well. So I have to build it with driver inexperiece in mind.

 

[RustyShackelfor]

I would just use the 205.

 

[trtlsoup22]

I can't give you any advice on the 205... I got my ZF for free, so spending some money on the adapter for the d20 was fine... I love my set up... 4:56 gears and 36" tires. Drives great!

 

[rcmbronc]

One thing about the ZF, there is a pretty decent split between 1st and 2nd. I dont find myself using 1st in low very often, but mostly 2nd. I would not want any higher TC gearing, so I used the Dana 20. I really like the combo with 36" tires, 5.13 gears and the Dana 20. Also like the compactness of the D20. It was worth the cost of the adapter for me.

 

[Bronco73]

Since I have a 205 I will use it. If I had both the 205 and an adapter for the D20 to choose from then I would probably go with the D20 just because I don't plan on doing anything to kill a D20.