T18/NP435 swap info

[9.3x62]

So, an '80 Cherokee with 4.2/t176/np208 has landed in my lap. Its a delightful truck as is, but...Currently contemplating mods for the distant future, one of which would be dumping the t176 for a big granny trans, for the sake of durability (gonna be running at least 35s at some point), and improved crawl ratio. I've searched around for info on swapping in either a t18a or np435. Seems I'd need a rare t18a from a 80s j20, cuz why?? And that the np435 would bolt up with the t176 bell housing, but the actual stick shifter is going to end up coming out under the dash? How does one deal with that?
I do like the np208, would it bolt up to any ford np435?
Thanks for your patience in advance, amigos.

[tgreese]

Depends on the engine.

Most of these trucks came with a V8, and its transmission is long. The 258 transmission is the same length as the one in the CJ-5 and Ford trucks. Big difference.

You understand that you are limited to transmissions from 4WD trucks, or 2WD transmissions that are converted to accept a transfer case using an aftermarket adapter, (ie Advance, Novak).

https://www.novak-adapt.com/knowledge/t ... ons/manual

The Ford NP435 from a 4WD truck may work in a J10, and possibly not in a Wagoneer/Cherokee due to fuel tank placement. I expect the Ford transmission has the long tailshaft adapter like other Ford pickups. This combo will be way too long on the back end for a CJ, but may be ok in the Jeep truck.

If you go to the Novak web site, they describe the various Ford truck 4-speeds. Their market is mostly short-wheelbase Jeeps and there are likely combos you can use that they do not address.

This is the 1980-on Jeep truck T-18 used with the NP208. All these trucks have V8s, except maybe some export models. This combo only appeared in the J20 1980 and later:



You can see that it is long. The front adapter is made for the FSJ with a V8, and is peculiar to V8 Jeeps only. This places the V8 engine forward and retains the shifter positions used with the six.

Pretty sure the rear adapter is the same as Ford from the same era. Conceivably you could use any Ford truck 4-speed from the era that came with a NP transfer case; T-18, T-19, NP435. I know the output spline on the above Jeep T-18 is different from the Ford, but your NP208 may match the Ford transmission. Something to investigate - the Novak site may cover that if you read the articles there.

More pics of the 1982 J20 T-18 here viewtopic.php?t=10473

[SJTD]

That adapter looks about the same length as the Advance Adapters OD/UD. Could use it as an adapter?

[Yeller]

That adapter looks about the same length as the Advance Adapters OD/UD. Could use it as an adapter?

That adapter only applies to V8’s the 6 cylinder doesn’t use it. But yes if you can find one the ranger box from AA would work fine. Last I checked they were discontinued by AA.

[9.3x62]

A am I right in my understanding that I need an 80s j20 t18 because I'm using an np208, and that the 70s jeep t18 had a d20 behind? In that case, a Ford t18/np208 would work just as well for me as one from an 80s j20? Or am I missing something? The only reason I'd go with a np435 would be if I couldn't find a compatible t18.

[Yeller]

I always get confused on the break year….. if the front is drivers drop you can use the Ford transmission and matching transfer case.

[tgreese]

The break is 1979 to 1980.

A am I right in my understanding that I need an 80s j20 t18 because I'm using an np208, and that the 70s jeep t18 had a d20 behind? In that case, a Ford t18/np208 would work just as well for me as one from an 80s j20? Or am I missing something? The only reason I'd go with a np435 would be if I couldn't find a compatible t18.

Yes, approaching 1980, Jeep used the Dana 20 exclusively and those are all passenger-side-drop. In 1980 Jeep went to the New Process transfer cases for FSJs like your NP208, and the FSJs (like your Cherokee) went drivers-side-drop.

The '80s J20 T-18 does not help you if you stay with the inline six. These transmissions are both scarce and for the J20s with V8s only. This is the only Jeep T-18 that drops on the driver's side, uses the NP transfer cases, and was available in the USA.

With a 258, you may be able to use the Ford transmissions (T-18, T-19, NP435) that drop on the driver's side. I believe they use the same long transfer case adapter you see in my picture above - the part that looks like a rocket engine nozzle. This extends back far enough that it may interfere with the gas tank. Works ok with the more compact J10/J20 gas tank, but maybe not the coffin shaped tank in a wagon.

Also, beware trying to bolt your Jeep NP208 to the Ford transmission. The splines may match, or might not - I don't know.

[9.3x62]

Do you toss the long adapter when attaching to a I6, since the 6 is longer?

[tgreese]

You can't toss it, because the input shaft and bearing retainer are proportionately longer to match it. Look at the rest of my thread that I posted above.

(Added) Plus the transmission is Jeep pattern and the front of the adapter is Ford pattern. It's an "adapter" in that sense. Won't bolt up. The sixes-to-T-18 use a thin plate adapter to one of a few bell housings, depending on the year.

[9.3x62]

Ah, ha. Thank you

[Stuka]

I think there is a bit of confusion here. It sounds like 9.3x62 is talking about the t-case adapter on the back. And tgreese and Yeller are talking about the input shaft spacer on the front.

The front spacer has to be there. No way around that.

The adapter on the back has to be there unless the rear output shaft was changed, as it runs through the full length of that t-case adapter.

You can use a ford NP435 (with the correct bell housing), but you will need to custom bend the shifter as it will be 5" farther farward then where they normally are with the long input shaft. So it ends up kind of under the dash, but can be made to work if you have an acetylene torch.

[tgreese]

...
you will need to custom bend the shifter as it will be 5" farther farward then where they normally are with the long input shaft. So it ends up kind of under the dash, but can be made to work if you have an acetylene torch.

The OP has a 258 in his Cherokee. The long engine-to-transmission spacer only applies to V8 applications.

Seems like he got conflicting advice regarding the J20 T-18/NP208, since all of these J20s and most of these Jeeps have V8s. The situation for sixes is different.

If he keeps his original engine, the Ford NP435 shifter should come up in pretty much the same place as the existing shifter.

The original design of these trucks was for one engine, the OHC 230 inline six. V8s are roughly 6" shorter overall than inline sixes. If you keep the transmission shifter stalk in the same place, and the front of the engine in the same place, there will be a 6" gap when you replace the six with a V8. The engine-to-transmission adapter and long input fills this gap.

[Stuka]

...
you will need to custom bend the shifter as it will be 5" farther farward then where they normally are with the long input shaft. So it ends up kind of under the dash, but can be made to work if you have an acetylene torch.

The OP has a 258 in his Cherokee. The long engine-to-transmission spacer only applies to V8 applications.

If he keeps his original engine, the Ford NP435 shifter should come up in pretty much the same place as the existing shifter.

The original design of these trucks was for one engine, the OHC 230 six. V8s are roughly 6" shorter overall than inline sixes. If you keep the transmission shifter stalk in the same place, and the front of the engine in the same place, there will be a 6" gap when you replace the six with a V8. The engine-to-transmission adapter and long input fills this gap.

Ahh, I glossed over him having a 258. In that case he's fine for shifter placement.

[tgreese]

...
Ahh, I glossed over him having a 258. In that case he's fine for shifter placement.

I'm sure you understand this. I added some detail because the question comes up a lot, and it might help some future reader.

To the OP - NP - glad if I could help.

[9.3x62]

Yes, tgreese, I thank you. I think I finally get it. Sounds like an np435 would be a better than a t18. 70s t18 uses passenger drop d20, 80s t18 was only behind v8s and probably would be to long behind a I6. All good, the np435 sounds like an awesome tranny. Gracias, amigos.

[Stuka]

The next step above the 435 would be an NV4500, then you get an overdrive. But their prices have gone through the roof sadly.

[9.3x62]

Yeah, but I think I like the ultra low granny of the np435. Most of my off roading experience is with tractors, so I've been spoiled on great crawl ratios.

[Stuka]

Yeah, but I think I like the ultra low granny of the np435. Most of my off roading experience is with tractors, so I've been spoiled on great crawl ratios.

The NV4500 has two versions. One with a granny low, and one with a first gear that is lower than most, but not to the extent of the T18/NP435/SM465.