998 VS AW4 ?

[Nightpath]

I've been thinking about my upcoming drivetrain swap, and the options keep on rolling.

Would there be any benefit to keeping the 998 + 119 in my Eagle as oppsed to switching to the AW4 + 231 when I swap my 4.2L for the 4.0 HO engine? I know I'd have to either buy the Hesco CPS relocator or tap a hole for it in the bellhousing, and I'd need to grab something else that I can't remember.

So would there be any benefits besides not having to fab up the floorpans and invent linkages for the AW4?

[DaemonForce]

The benefit to keeping the A998 is that you get the same lightweight drivetrain with powerful takeoff speeds. To me the AW4 is a major complication when you're already using the A998. I believe a rare flexplate, crank position sensor, extremely rare engine computer, uncommon wiring harness with secondary donor pieces, and possibly the OEM transmission crossmember and a few small support pieces would need to be swapped. THAT is too much work even to me. I've been rather patient in a rebuild that has gone on for over a year now.

I'm doing it anyway.

The main and ONLY benefit I see with the AW4 is a modest overdrive and slightly more appropriate shifting mechanism. Since I'm replacing the 258 with a 285, I think most would see the immediate issue there. I plan on reusing the Torqueflite just for the sake of being able to use the car while I can scavenge for other now extremely rare parts. When I swap in an overdrive transmission it's going to be a 6 speed. I would rather swap in a flywheel, bell and clutch mechanism than deal with the electronically controlled mess of an AW4. The Torqueflite is treated like a manual transmission anyway so it makes my job exponentially easier when the time comes to bolt in the clutch.

[Nightpath]

I can find just about anything around here...lots of parts cars and huge junkyards.

[eaglefreek]

What is your intended use of the vehicle? My main reason for wanting to go with the AW4 was so I could install a lower gear. I hated when I would go up long hills and it would either rev to the moon in 2nd or bog in third and start slowing down. The electrical part isn't really that bad. there are only a few wires to hook up and if carbed, a TPS needs to installed on the carb and a mount for the TV cable needs to be fabbed. I'm currently working out of town 20 days on and 8 days off and sometime in the near future plan on doing a detailed write up of the AW4 install. After installing the AW4, I wouldn't want to own a 998 equipped Eagle. It is a very reliable transmission, but since I take trips cross country and go offroading, the AW4 allows me best of both worlds for gearing choice. I get to use a lower axle ratio that helps when off road and OD which drops my RPM to an acceptable level while on the highway.
I personally wouldn't want a NP231 in an Eagle since it is a part time case, but that is just me.

[Nightpath]

I'm just viewing my options with the parts I currently have. I won't be taking it to do any serious offroading, but dirt roads and the like are travelled, and snow wheeling. w00t

I know the 998 works with higher gears like 2.73 and so forth, and that gave me decent highway mileage, but the AW4 is newer and has OD which is nice.

I used this site to check gear ratios and tire options : http://www.grimmjeeper.com/gears.html

I think I might be able to get away with the 4.0HO, AW4, 3.07gearing and 27.5-28" (P225 70 r15)tires. RPM's seem to hover around 2400 in 3rd, and a bit above 1800 in 4th.

If I stick with the 3.55 I can run near 30" tires (P235 75 r16) which are common around here as well and be just above those RPM by 100rpm or so.

I think that the 3.55 may end up being more attractive due to the look of the tires. Smaller tires on the Eagle look crappy...having the option to rock out with 30" tires and not worry about having too low RPM's is very attractive.

Is there anyone here that has done the full drivetrain swap from an old Eagle with higher gears to the XJ drivetrain with lower, like I'm looking at? I'd really like to know if the Eagle's body VS XJ provides better MPG overall.

And does the Eagle drivetrain weigh more than the XJ? Seems like it would.

[carnuck]

You can get a 999 from a 4.0L Wrangler (or even just use the 999 case, converter and flexplate with the 998s internals) to put EFI in the Eagle more easily.

[DaemonForce]

You can get a 999 from a 4.0L Wrangler (or even just use the 999 case, converter and flexplate with the 998s internals) to put EFI in the Eagle more easily.

Really, I'm under the impression that that's the only way to do it without aftermarket pieces. The existence of the A999 is what makes compatibility a lesser nightmare. The flexplate is the super rare piece that's so important for any of this to work. Oh, and the computer. Wherever I'm going to find one for this.

The ultimate advantage to the A998/A999 is that I don't feel like rebuilding an AW4. Sure they have a great lifespan in comparison but my paranoia about this car stranding me is pretty high. I've already dropped more than $10000 into it because it lets me down.

[carnuck]

Flexplate isn't so rare. '94 to? Grand Cherokee with 4.0L and 42RE trans uses the same flexplate and converter as well as CPS (I'm pretty sure from seeing the one I have and selling lots of JGC ones) The 42RE is longer than 32RE (999) so it's not a good fit and it is WEAK. Usually last only about 50,000 before needing replaced and they use more fuel.