Transmission swap ideas

[millerguy76]

I'm restoring my 84 J-10. While I have the engine out, I was going to get the trans rebuilt as well. I'm starting to have 2nd thoughts about rebuilding the trans and maybe going to something that would provide better highway performance. My thought is 5 speed automatic.
Does anyone know of a transmission swap that would marry up to the J10 without having to modify? I'm not interested in modifications.
Any thoughts or knowledge on what trans would be a good candidate are appreciated.

Thanks

[Stuka]

First, what transmission do you have now?

The only 5sp that ever came in an FSJ with the T5. It only came with the 258, and even at that it did not last and was prone to early failures. But even that transmission would require mods. Even if you currently have a manual 4sp now, you would still need new drive shafts at a minimum.

An AX15 or something is a great swap for medium duty usage, but it too, will require some mods. There is just no such thing as a swap without any mods.

[cone]

I install a NV4500 manual 5-speed in my 87 Grand Wagoneer and 87 J-20 and am happy with it. I got the adapter bellhousings from Advanced Adapters. I was able to use the original transmission crossmember just moved it back a couple of inches. The frame already had holes in it from the factory to mount to crossmember that matched up. I don't know why Jeep had the hole there but they matched up perfectly.

[millerguy76]

Thanks for the options.
I'm ok with making a change or 2, like changing out the driveshaft or getting getting an adapter to make it fit. I just don't want to get into fabricating or welding this or that into place or cutting out a notch here or there.

I will look into these options...If any others come up, please share. I'm going to stick with an automatic tranny

[Stuka]

I install a NV4500 manual 5-speed in my 87 Grand Wagoneer and 87 J-20 and am happy with it. I got the adapter bellhousings from Advanced Adapters. I was able to use the original transmission crossmember just moved it back a couple of inches. The frame already had holes in it from the factory to mount to crossmember that matched up. I don't know why Jeep had the hole there but they matched up perfectly.

Different engine and transmission setups have different lengths. V8's tended to use the front holes, while i6 tended to use the rear holes.

[Stuka]

Thanks for the options.
I'm ok with making a change or 2, like changing out the driveshaft or getting getting an adapter to make it fit. I just don't want to get into fabricating or welding this or that into place or cutting out a notch here or there.

I will look into these options...If any others come up, please share. I'm going to stick with an automatic tranny

Ahh ok, that makes it more doable. Still be good to know what transmission you have now.

The AX15 was common found in XJs and TJs behind the 4.0 HO. They are pretty easy to find, and your current t-case (most likely an NP208) will bolt up to it.

The NV4500 is a fantastic transmission. It is larger, stronger, and more rare. As it needs to be from behind a gas engine (not the diesel version). And as noted above, you will have to purchase the adapter.

EDIT: I just noticed you asked for a 5sp automatic, not a 5sp manual. There is no 5sp auto that will work with an AMC engine. But in the post below, you can see there are 4sp options like the AW4.

[tgreese]

... I'm not interested in modifications. ...

Note that any transmission except the original equipment will require modifications. There are transmissions within the Jeep family that could be less work than others. I don't know of any "5-speed automatics" that are compatible with your original engine. Kinda suspect you don't appreciate what's involved here.

If you want that overdrive gear and want to keep your original engine, I think your only options might be the Aisin AW-4 from an XJ Cherokee, or a 42RE from a 4.0L Grand Cherokee. Both of these were paired with the inline 6, and you'd need to deal with the different balance between the V8s and 6s, and whatever electronic control might be needed. Of course, neither of these appeared in a J10 ever, so you'd need to change the mounts; driveshaft lengths, transfer case compatibility, etc. But they would bolt to an AMC V8 engine.

https://www.novak-adapt.com/knowledge/t ... automatic/

You can go with one of the GM automatic overdrive transmissions, but it would need adapting at both ends and still involve plenty of modification of the mounts, driveshafts, etc. The usual swap would be to take everything from a Chevy pickup or such and get a Chevy small block along with its multiport fuel injection. That combo will give you somewhat better fuel economy and more power, but it's a major transplant. Skips adapting the engine to the transmission though, and the transmission contol can be carried across from the donor.

I would sit down with pencil and paper and work out what I expected in terms of savings and investment for this swap. Kinda seems to me like it's not practical for a hobby car - you will spend way more in money time and effort than you will ever get back.In terms of "highway performance" the main advantage aside from economy will be reduced noise (you can also reduce noise with quiet tires and more insulation). The engine will be fine at highways speeds, and you won't get more performance from an overdrive transmission. Replacing the transmission might give you better ratios for acceleration, but you'd need to work that out in advance using the ratios from the replacement transmission and your existing axle ratio.

[millerguy76]

... I'm not interested in modifications. ...

Note that any transmission except the original equipment will require modifications. There are transmissions within the Jeep family that could be less work than others. I don't know of any "5-speed automatics" that are compatible with your original engine. Kinda suspect you don't appreciate what's involved here.

If you want that overdrive gear and want to keep your original engine, I think your only options might be the Aisin AW-4 from an XJ Cherokee, or a 42RE from a 4.0L Grand Cherokee. Both of these were paired with the inline 6, and you'd need to deal with the different balance between the V8s and 6s, and whatever electronic control might be needed. Of course, neither of these appeared in a J10 ever, so you'd need to change the mounts; driveshaft lengths, transfer case compatibility, etc. But they would bolt to an AMC V8 engine.

https://www.novak-adapt.com/knowledge/t ... automatic/

You can go with one of the GM automatic overdrive transmissions, but it would need adapting at both ends and still involve plenty of modification of the mounts, driveshafts, etc. The usual swap would be to take everything from a Chevy pickup or such and get a Chevy small block along with its multiport fuel injection. That combo will give you somewhat better fuel economy and more power, but it's a major transplant. Skips adapting the engine to the transmission though, and the transmission contol can be carried across from the donor.

I would sit down with pencil and paper and work out what I expected in terms of savings and investment for this swap. Kinda seems to me like it's not practical for a hobby car - you will spend way more in money time and effort than you will ever get back.

I appreciate the conversation in info on this.
Its not that I don't appreciate the degree of involvement, I just don't want to veer onto a bunch of customization. This truck is completely factory and as solid as you will find. I went back and forth whether or not I should upgrade the complete powertrain. At the end of the day, I decided to stick with the 360 thats in it and just do a refresh on it. As for the trans, the last few times I ran it on the highway, it was a beast...running high and hot. I just thought it'd be nice to get something that would run a bit more efficient while not altering the truck. The trans would be the only thing on the truck that is not original.
I do not know which trans I have yet, aside from its a J-10 3 spd auto with a 360ci in a 1984 Laredo, tfer case is a shift bar on the floor.
I'm learning as I go...

[tgreese]

An '84 360 J10 got a A727 automatic. This is a Chrysler Torqueflight 727 with an AMC case, meant to match the AMC engines. The 727 is a sophisticated, smooth, durable and reliable transmission, though these legacy automatics are not very efficient. I would look into a quality rebuild, and explore some shift mods if you want something with a little more performance feel. I don't know much more about these sorts of mods, but the 727 is very popular with hot rodders and muscle car owners, and I'm sure there is plenty of knowledge, experience and support out there to get the transmission to perform more to your liking. I kinda think there's no reason not to like this transmission, except for the economy issue.

I also added a little more to my above post about noise and such. I suggest you read the TSM for your truck to learn more about your transmission. The '82 TSM is online and you could read there, if reluctant to purchase the '84 TSM. Same wrt the transmission.

[will e]

What is your use case for the truck? Daily driver? Highway? Towing? Off roading?

What axle ratio and tires are you running?

[millerguy76]

Thank you tgreese

This truck will be fit car shows, cruises and sunday drives. So just looking for efficiency and mileage. Sorry, hearing car shows and cruises probably makes some folks think "that poor jeep truck". I'm building this for my son, who is only turning 6 this week but will be something I want to pass down to him.
Thank you guys for the detail. I also educate myself more on the specifics

Here Is the 'before' pic.... It'll be a while before I have the 'after' pictures

[will e]

That's a solid looking start!

For your use case I wouldn't worry too much about keeping the original transmission. You're not going to put a lot of miles on it. It's the original configuration so it's fine for wear and tear and it would take a while to recoup the extra cost of a swap from improved gas mileage... at least for now.

Best bet would be to keep it simple and keep it at 65 mph and under. The slower you go the better the gas mileage by far.

[millerguy76]

That's a solid looking start!

For your use case I wouldn't worry too much about keeping the original transmission. You're not going to put a lot of miles on it. It's the original configuration so it's fine for wear and tear and it would take a while to recoup the extra cost of a swap from improved gas mileage... at least for now.

Best bet would be to keep it simple and keep it at 65 mph and under. The slower you go the better the gas mileage by far.

I found that out. I was on the interstate for a mere 20 mins at 75, just keeping up with traffic. I think I could see my gas gauge moving, not to mention my temp gauge was just about borderline red....guessing the higher RPMs was something she was built for :\

[tgreese]

Nice. I'd guess you're going to do something with the stripes. Maybe factory-type graphics or such?

Mmm. Kinda think you can't blame the temperature on the transmission. The transmission does contribute to the engine operating temperature, but it should not be an issue on the highway if everything operates properly. An auxiliary transmission cooler is sometimes added, but that's more for trailer towing or hard-and-slow going on big rocks trails. The factory transmission cooler should be fine for the use you describe.

I would be more inclined to blame the condition of the original radiator for overheating. That's the usual problem. It's just old.

75 mph should be no sweat for that truck. No '84 docs to look at, but the '80s factory axle ratios are 2.73 with 3.31 optional. These are tall tall tall for a Jeep - '60s J-trucks came with 4.88s; my '77 and '82 are 3.54 and 3.73 resp. My '73 CJ-5 had 4.27s. Most 4-cylinder Jeeps in the '50s had 5.38s. You have tallish tires too, more than 30" diameter. That gives 2300 RPM with 2.73 gears, and 2700 with 3.31s (trailer towing package). Not a problem. How many Jeeps have you owned? You may not be accustomed to the noise an older vehicle like this will make. Fan noise, tire noise, wind noise... all will be higher in an older vehicle like this, and Jeeps are noisy as a group. More insulation in the floor, quieter tires, quieter fan, etc. It's a Jeep.

[will e]

Your engine shouldn't run hot at 75 mph. Like Tim said, probably the radiator.

If you know your rear end gears you can try out grimmjeepers.com gear ratio calculator. http://www.grimmjeeper.com/gears.html

It will give you engine RPMS for various speeds and various speeds for given engine RPMs. He calculates it based on transmission, tire size and axle gear ratio. It's arguably the best calculator out there.

For reference. I run 4.56 gears with 37" tires and the standard TF727 transmission. At 75 I am tooling along at about 3300 RPM.

[millerguy76]

Thank you. I made an assumption because I never had an overheating issue before. The time I take it on the interstate it runs hot.
Either way, I started to disassemble for the restoration. I'll eventually be removing the powertrain so I will investigate the radiator then. I'll go from there [fingers crossed]

[dyermullet]

You have a radiator/cooling system problem.

OD is way over rated in my opinion. We swapped an ax15 into our j10 not to get over drive, swapped it to get a reliable Trans after t177 failed twice.
I haven't personally worked on a 727 but they are rugged transmission that was used in cars up to 1 ton trucks. Just keep the 727 it will be fine. Especially if your truck is all a stock it will have a highway gear ratio in the differential.

Like was stated above find the gear ratio and tire size we can help you calculate the rpm at highway speeds.

Looks like a cool project you have. Post more pictures as the work progress.

[OldFarmTruck22]

A 3.54 rear ratio with a Turbo 400 and 31.5" tires at 70 mph is clipping along at 2700 RPM.
By going to a 700r4 you can reduce your engine rpms by 800.

Just sayin

[230ohc]

The Mercedes 5 speed automatic is in 2010 grand Cherokee and others. Those are pretty cheap for a whole vehicle cause people got fed up with 3.7 v6

[sierrablue]

You might consider the 42re out of the '93-95 ZJ. You'd want to take the whole harness too, BUT those have a transmission computer separate from the engine/body computer. It would take a lot of patience with the wiring, but if you could get it all hooked up, it would bolt right in, have all the advantages of an electronically controlled transmission, and would have an overdrive. They have a little bit of a rep for being weak, but number one if you're sticking with a relatively stock 360 it shouldn't be a problem, and two it's basically a 727 with an overdrive inside so it can be made to handle plenty of power.

The overheating/struggling at 75 could be the radiator, but if the engine's questionable and you're pulling it, I almost wonder if that's just all the engine's got, and it's not running right so the extra energy from the fuel is being turned into heat. Just a theory.

Otherwise it's a pretty common thing to swap in a 700r4 (or related electronic transmission) with an adapter or an AW4.