What are all the options?

[DaemonForce]

I've been thinking about finally updating parts in my Eagle and one of the things that has been bothering me is that I can't seem to find a comprehensive list of all Automatic and Manual transmission options for the entire AMC Eagle series.

Mine is currently rocking the Torqueflite A904 and while it's a great transmission, I've had to tear apart the shifter, linkage, dipstick tube and several other stupid things due to circumstances beyond my control(In short: Someone touched my car when I wasn't there >.>).

For a while I've thought about going straight to the T-5 manual OD transmission since I follow the elitest mindset that any worthwhile OD transmission is going to be a purely mechanical thing. However, I am recently seeing reports of people using the TH700R4 and various others that I overlooked. I know it would be a lot of work to go from Auto to Manual but that's an individual thing. Is there any list of compatible transmissions for the AMC Eagle on here or do we have to start it here? I think it would be a great help to anyone having transmission problems or flat out considering a new transmission. Especially with the way things seem to be these days. For the past three months I've finally been commuting to work in excess of 30 miles every morning and it involves screaming across the freeway at 70MPH at 3AM. It would be nice to have that overdrive option so I'm not burning as much as 3 gallons every day of the week. If this somehow helps anyone that seems to be headed in that direction, so much the better. Thanks.

[Gil-SX4]

OK. Just cause I'm a great guy I'm going to add to your options.
Today 08/13/2011 on Power Block Blog Buggy Part 2 / Low Dollar Wheeler IV they showed a automatic transmission to manual conversion kit from Monster Transmission.
It switches the gears to P R N 1 2 3 manual shift.

[eaglefreek]

Eagles came with a TF998 auto (very similar to the 904),  and SR4, T4 and T5 manuals. I believe the 4 cyl. used the TF904 auto. A Jeep AW4 auto will bolt up to the engine but will require mount and driveshaft modifications along with wiring in the transmission computer. Any other auto OD transmission will be a custom job using adapters.

[DaemonForce]

A Jeep AW4 auto will bolt up to the engine but will require mount and driveshaft modifications along with wiring in the transmission computer. Any other auto OD transmission will be a custom job using adapters.

I'm expecting my next swap to require some minor modifications but I didn't expect mention of the AW4. It looks like I'll have to think a bit more on this. Thanks.

[captspillane]

Your 5 speed options are as follows:
1) T5 transmission rated at 265 ft/lbs. This is the five speed original to Eagles and CJs. It is a very small casing and prone to breaking in a bunch of ways. It shifts very nicely and doesn't weigh much, but its really just intended for cars. Don’t get a T5 if you’re going to tow with your Eagle.

2) "World Class" T5 transmission. These are common in Ford Mustangs but do not adapt to our transfer cases easily. Some people take the Jeep T5 and swap in most of the "World Class" parts, but it’s not even remotely worth your time. When they're finished the case is still prone to warping under torque and it is still considerably weaker than an AX15 or NV3550.

3) AX15 Transmission rated at 285 ft/lbs: This is found behind the 4.0 in Wranglers and Cherokees from around 1990 to 1998. I forget the exact years. This transmission shifts very nicely and is also very strong. It’s very common and is the easiest transmission to find at a junkyard. Early AX15s had an internal slave cylinder and later ones are external. Either one works fine, but I would prefer the internal slave cylinder because it has a normal 3/16 double flare input versus the crazy pin and o-ring input the external slave cylinder has. You must use a 4.0 flywheel with this transmission because the 4.2 flywheel is a quarter inch thicker. The T5 clutch is the same, but the pilot bearing is different for the AX15 and NV3550. Instead of a brass plug the AX15 and NV3550 have a thin roller bearing pressed into an aluminum spacer that in turn is pressed into the end of the crankshaft. Make sure you get the roller bearing and aluminum spacer together, since you can’t remove the bearing without damaging the spacer. I first bought mine at Autozone and only the roller bearing part came. I then bought it at Advanced and the two came together for the same price.

4) NV3550 rated at 300 ft/lbs: This is the strongest five speed found in factory Jeeps. It replaced the AX15 around 2000 until 2004. Advance Adaptors sells the external slave cylinder with a stainless mesh flexible input line and the brass adaptors it needs. With that kit you just need to make a short piece of double flare brake line from your Eagle clutch master cylinder to the flex line. You must use the correct fluid or you’ll damage the synchros.

If you’re installing it behind a 4.2 or 4.0 you should retain the NV3550 bellhousing and 4.0 flywheel so that your fuel injection has a place for the crank sensor. If you’re installing it behind an AMC V8 you cannot use a 4.0 flywheel because V8s are externally balanced. In that case use an Advanced Adaptors kit that mounts between the NV3550 and a T5 bellhousing (Its basically a 3/4 inch thick spacer). That retains the bigger flywheel and all the original shift linkage.

5) NSG370 6 speed transmission rated at 272 ftlbs: This replaced the NV3550 in Jeep Wranglers. They’re very rare but not impossible to find. Only a NSG370 from a 2005 or 2006 4.0 Jeep Wrangler has the AMC bolt pattern. They still use the NSG370 today in Jeeps, but the bellhousing cannot be removed from the transmission so 2007 and newer Jeeps have a Chrysler bolt pattern and are useless to us. This transmission has a 4.46 first gear and a 0.84 overdrive in contrast to the 3.83 first gear and 0.79 overdrive in an AX15. This means that you should use 3.07 gears with a NSG370 to get the same shift points you would have with an AX15 mated to 3.55 gears.

6) AX5 transmssion: Its a very weak transmission easily confused with an AX15. Don't use it. Only 4.0 Jeeps have the AX15.

7) NV4500 rated at 460 ft/lbs: This is a true truck transmission. It’s literally twice as heavy as a T5, it shifts clunky like a truck, and it is easy to adapt to our engines and transmissions but it’s not easy to fit under our Eagle floorpan. This option should only be considered if you have a 401 in front of it and a custom Dana 60 axle behind it.

[captspillane]

For Automatics, you have some options:
1) Change gear ratios and put larger tires on. This is actually the best option. I used to have two identical station wagons. One had 3.07 gears and got about 20 mpg on the highway. The other had 2.72 gears and it got about 25 mpg on the highway. I liked the 3.07 gears better because it accelerated much faster, but the difference in RPM at 75 mph was huge. I also convert all of my Eagles to the standard Jeep Cherokee tire size of 235/75R15. I do not trim any externally visible parts of the fender, but it does require trimming up under the fender.
For reference if your engine is at 2500 RPM with 205/75R15 tires and 3.07 gears you’re going 63.66 MPH. Changing to 2.72 gears you’ll be going 71.85 at the same 2500 engine RPM. Changing to 235/75R15 tires you would be going 67.82 MPH with 3.07 gears and 76.55 MPH with 2.72 gears.

2) AW4 conversion: This transmission is relatively weak and has a reputation for overheating easily and being very inefficient for fuel mileage. In my opinion the fuel savings of having an overdrive does not make up for the fuel that is lost in overheating with this transmission. The transmission is also much more complex, prone to failure, and considerably harder to rebuild than a TF998. I believe you will be grossly disappointed by this conversion if you decide to do it.

They hold up fine in 4.0 Jeep Cherokees that are driven as daily vehicles, but they do not hold up to large tires or aggressive driving. They are computer controlled and you should only install one if you also install the fuel injection to go with it. The computer harness is tied into the fuel injection harness and there is a cable that goes from the throttle body down to the transmission that is meant to work with the fuel injection manifold. The best plan is to buy a whole 4.0 Jeep Cherokee 1991 or newer and transplant the entire drivetrain and wiring harness into your Eagle. The transmission is about 4 inches longer and you will have to contend with changes to your driveshafts.

3) TF727. This transmission is rated at 450 ft/lbs and is strong enough for even a well built 401 V8. It is found behind AMC 360 V8s in full size Jeeps and Grand Wagoneers. The case is fatter around the middle but otherwise looks identical to our TF998s. All the linkages and shift levers from the TF998 will work with it and the transfer case output is identical. It has a similar gear ratio for first and the same 1.00 third gear as the TF998. It’s a great upgrade for an Eagle, but not necessary. A TF998 is plenty strong enough for a 6 cylinder Eagle.

4) TH400: This transmission was found in 77 to 79 CJs and Full size Jeeps with special offset rear axles. It has an AMC bolt pattern but it has a crazy long output shaft and strange bolt pattern that will not work with our transfer cases or easily adapt.

5) 700R4: This is a GM transmission, only available with a GM bolt pattern. It’s the modern version of the TH400 with an overdrive added. It can be easily adapted to our transfer cases and adaptors to Jeep engines are available through Novak adaptors, but there are driveline length issues and flexplate issues that make this a very complex conversion.

6) 42RLE: This is the transmission I have in my 2006 Rubicon. It is computer controlled. It has a very high 4th gear at 0.69 overdrive. It is a modern variation on the exact same TF998 that we already have in our Eagle as indicated by the “2” as a second digit. The first digit “4” means four speeds. The V8 Grand Cherokees were the only Jeeps to get a modern TF727 equivalent, called a 45RE. The “5” means 5 out of 5 strength. Those transmissions only exist with a Chrysler bolt pattern and couldn’t easily be installed in an Eagle. Any Wrangler 4.0 transmission could be put in an Eagle if you had the wiring harness and computer and lots of money and patience.

-Dave Spillane-