A lot of questions...

[Wagoneer-ing]

Ooooookay..I'm semi-new to FSJs. I have a 1985 Jeep Grand Wagoneer. It currently has the 360, 727, D44 front and AMC 20 rear. I bought a fuel-injected 401 for a pretty good price and I plan on putting it in my Waggy. I was also wanting to get a D44 with disc breaks. I plan on making this Waggy a DD with occasionally wheeling, but nothing crazy. I've been looking at gear ratios(which make me feel like I'm 6 feet under the water). I do plan on using this Waggy to tow occasionally. (Lake trips with the boat. ) I may make no sense and be asking some really dumb questions. Basically I'm trying to find a good gear ratio. My axles are set at 2.73. I don't want to burn anything up by going too small, but I also don't want to have acceleration issues on the highway because 90% of my daily commute is a 30 minute highway drive. Also are there any better auto transmissions that will bolt up without modifications that might be better than the 727? Mine only has three gears and it takes a bit for it to shift with the 360 in it right now. Any help is appreciated.

[wewillsurvive]

Ooooookay..I'm semi-new to FSJs. I have a 1985 Jeep Grand Wagoneer. It currently has the 360, 727, D44 front and AMC 20 rear. I bought a fuel-injected 401 for a pretty good price and I plan on putting it in my Waggy. I was also wanting to get a D44 with disc breaks. I plan on making this Waggy a DD with occasionally wheeling, but nothing crazy. I've been looking at gear ratios(which make me feel like I'm 6 feet under the water). I do plan on using this Waggy to tow occasionally. (Lake trips with the boat. ) I may make no sense and be asking some really dumb questions. Basically I'm trying to find a good gear ratio. My axles are set at 2.73. I don't want to burn anything up by going too small, but I also don't want to have acceleration issues on the highway because 90% of my daily commute is a 30 minute highway drive. Also are there any better auto transmissions that will bolt up without modifications that might be better than the 727? Mine only has three gears and it takes a bit for it to shift with the 360 in it right now. Any help is appreciated.

I would lean toward a gear set in the area of a 3.55. It's about as middle of the road as you can find.

The 727 is a great trans. I would keep it personally, but I'm a MoPar guy so....

[tgreese]

If you want rear disk brakes, why don't you convert the AMC 20 to disks? It's arguably as good an axle as the 44, and different from the 20 that is used in CJs. No reason to replace it with an equivalent axle.

Regarding gear ratio, the higher numerically the better (for a trail Jeep). Figure out what your tire size will be, how fast the engine will turn on the highway, and how fast you want to drive, and calculate the ratio. For example, if you want to go 70 at 3000 RPM with 33s, that's roughly 4.10s. With 3.73s you'd be turning ca 2650 RPM. The engine will be fine at those speeds - it's simply a matter of how much engine and drive train noise you can tolerate. Mileage will be lousy regardless.

There are plenty of gear calculators on the net - from simple http://www.novak-adapt.com/knowledge/gearing.htm to elaborate http://www.grimmjeeper.com/gears.html

As mentioned, the 727 is a very rugged and durable transmission. If it's not shifting right, there is something wrong with it. The main criticism of it (and the TH400 used before 1980) is efficiency - it consumes a lot of power just to operate. There's no easy swap there. Possibly an AW4 from an XJ would work... but there's no V8 application for the AW4, so you'd have to sort out a convertor and flex plate that would work with the 360. More common to go all-Chevy, with a modern GM automatic and engine. But it will take a looong time to make back the investment, if ever.

[carnuck]

I'm doing an AW4 (you need '91 up for 23 spline) to the 304 in my Honcho. Use the stock converter (it would be slightly higher stall than a V8 one anyways) and get the 4.0L flexplate balance matched tot he 401 plate (did the shop zero balance the motor when it was built?) AW4 is 3" longer than the 727 and the mount is further back. At least with the V8s a crossbar is easily modded from the OEM one by moving back one set of holes. (requiring ebrake cable mods) I ran out of frame length on the shortbox J10 when I put my 4.0L in but now I have an adapter plate from the Comanche I just parted that will move it forward again.
You need a 1" spacer between trans and FSJ tcase or run a NV242 HD (or mod a regular 242 with the internal parts from a 242 DHD. IE: Wider chain and gears) You need to hook up a TVS cable to the carb or throttlebody and throttle position sensor so you can wire in the shift computer or use Radesignsproducts.com manual shifter (or build your own. Lots of youtube vids on that)

You would want 3.73 gears unless you go taller than 31" tires.

[haminawag]

You're looking for a better tranny than a 727?? Good luck! A 2.72:1 gear ratio is a bit tall for towing, and definately not the best for quick accelleration, however Walter Chrysler gave you the option of using that transmission in 1st & 2nd gear, you don't have to drop it into "DRIVE" every time you go someplace, don't be afraid to use your shift lever, just don't over-rev the engine or be abusive toward anything. For towing a boat? What does the boat and trailer weigh? And since tire size and gear ratio are directly related to one another, it would help if you tell us what tire diameter you're wanting to use. Until fairly recently I was running 2.73:1 rear gears in my 1967 Plymouth DD since it was new, AND pulling a 30 foot Airstream trailer twice monthly between Albuquerque and Carlsbad, NM, I got good gas mileage and the 727 Torqueflite never missed a beat, but for a 4x4 I can see why you might want a lower ratio.

[FSJunkie]

For stock 29" tires, I find 3.31 works very well. Of course, I am biased because that's what my Jeep has. It cruises the highway all day long at about the same fuel economy it gets all the time (11-15) and torque off the line is nice. I actually have to be careful in dirt driveways.

In off-road situations the torque is great. The only times I want deeper gearing is when I am going through rocks and need speed control, because low range is only 2:1. Lots of torque, just doesn't crawl very slow, but being an automatic, you can always ride the brake with your left foot and throttle with your right and make up for it.

In low range locked in 1st gear it idles (700 RPM) at 3 MPH. I actually am careful in low range, because with all the torque I'm afraid if I give it too much throttle that I'll break driveline parts or mounts.

[serehill]

yeah. I do everything you do & I have a healthy 360. The 3:31 do me good. want some grunt off road??? That's what low range is for. $10's are too low for me. I can tow my 21' fish n ski with a tandem axle trailer & a 250 horse motor with out issue. I's about 3500 pounds.
I agree mostly with Time but by the time you do all the adaptation to get a 700R4 or aw4 you might as well do complete GM solution.

Overdive would push you to a 3:90 to 4:10 gearing to get it happy. $$$$$$$$$$$$$$$


You have no idea of the cost. You can not run an OD tranny with the 2:75. Overdirve would be useless in normal driving.

[carnuck]

underdrive maybe. (Brownie go that way too)