TH400 or TF999 with a 4.0

[brp0830]

I'm not sure the best way to pose this question, so here we go. Later this year, I'm going to convert my scrambler to an automatic and dump the T5. I'm undecided on what transmission to go with, but wanted y'alls input. I currently have a 4.0 out of a 94 XJ and it's great. Easy to work on and reliable as you all know.... BUT, not a lot of power. My current setup is a dana 60 rear, dana 44 front with 456 gears and 37's with 4:1 dana 300.

I guess my question is, if I stayed with the 4.0 & didn't go with an LS and went to either a TH400 or TF999, would the ratios in the transmission be too high and cause me to need to regear my axles to 488 or 513? I believe the T5's 1st gear has a 3:76 ratio, whereas the TH400 is 2:48 and the TF999 is 2:74.

 

[sdsupilot]

The 999 would be the easiest and cheapest path. If considering a GM transmission the 700R4 is a fine option. It has a 3.06 first which is great for crawling and a .70 overdrive for highway. My knock against the 400 is the lack of overdrive and its first gear. Your 4:1 transfer case may make up for that though. I also have a 60 rear, 44 front. I run a TBI 4.3 and a 700R4 with 4.88 gears on 35" tires.

 

[brp0830]

Any driveshaft clearance issues with the 700r4?

 

[bigwalton]

AW4, do not pass go, do not collect $200. No contest. Done and done. Thank me later.

Overdrive, bolt-on, very stout, runs forever. Grab one of the aftermarket controllers, add a switch and get both manual and automatic control. That's precisely what I have and I LOVE it. Full auto 99% of the time, flip the switch and I get complete control of the gears with a controller on my rollbar beside the steering wheel.

This is the newer version they make of the one I have, there are other options too:

Rail Controller

www.radesignsproducts.com

 

[brp0830]

AW4, do not pass go, do not collect $200. No contest. Done and done. Thank me later.

Overdrive, bolt-on, very stout, runs forever. Grab one of the aftermarket controllers, add a switch and get both manual and automatic control. That's precisely what I have and I LOVE it. Full auto 99% of the time, flip the switch and I get complete control of the gears with a controller on my rollbar beside the steering wheel.

This is the newer version they make of the one I have, there are other options too:

Rail Controller

www.radesignsproducts.com

What are your thoughts on this write up from Novak?

 

[ag4ever]

AW4, do not pass go, do not collect $200. No contest. Done and done. Thank me later.

Overdrive, bolt-on, very stout, runs forever. Grab one of the aftermarket controllers, add a switch and get both manual and automatic control. That's precisely what I have and I LOVE it. Full auto 99% of the time, flip the switch and I get complete control of the gears with a controller on my rollbar beside the steering wheel.

This is the newer version they make of the one I have, there are other options too:

Rail Controller

www.radesignsproducts.com

This! DO NOT try for an A999 (TF6 or 32RH or A904) unless you have a good one with a good torque converter! Parts are a nightmare to find. The TH400 will also be a unicorn to find. I think those cases will be out of a late 70’s CJ or J truck. I think the transfer case bolt pattern might be different as they had Dana 20 transfer cases, not the Dana 300 used in the 80’s.

The AW4 is 4 speed with an overdrive. You can gear down for low crawl ratio and still have nice highway rpm’s.

Just go the easy route, find an AW4 in a Cherokee from a wrecking yard and bolt it in.

 

[brp0830]

This! DO NOT try for an A999 (TF6 or 32RH or A904) unless you have a good one with a good torque converter! Parts are a nightmare to find. The TH400 will also be a unicorn to find. I think those cases will be out of a late 70’s CJ or J truck. I think the transfer case bolt pattern might be different as they had Dana 20 transfer cases, not the Dana 300 used in the 80’s.

The AW4 is 4 speed with an overdrive. You can gear down for low crawl ratio and still have nice highway rpm’s.

Just go the easy route, find an AW4 in a Cherokee from a wrecking yard and bolt it in.

Sounds good, I’ll have to do some research. My scrambler is not a highway Jeep. It’s primarily for wheeling now and weekend drives

 

[ag4ever]

If you were able to keep a T5 alive wheeling on 44‘s/60’s, the AW4 will be more than up to the task. The AW4 is indestructible compared to a T5. Also, the AW4 was used in many Toyotas (A340), so parts are easy to find. There are even custom builds with modified gear ratios if you don’t like the Jeep ratios. There is a shop in Cali that specializes in the A340 version, can’t recall their name.

 

[brp0830]

Very cool and great to know. My 60/44 swap was just finished this March and my first trip out, my clutch linkage failed on me. With the kind of wheeling I want to do now, an auto is the way to go.

There’s always the option of LS/4L60E, but there’s nothing wrong with my 4.0

 

[bigwalton]

Dude, I BOMB my Scrambler around the Silver Lake Sand Dunes with basically no mercy (we have a place up there so I go a lot every summer). I’ll give the Jeep a break if the engine gets too hot, but I trust the trans and have never had a problem.

I’m talking repeated uphill runs in sand literally bouncing the 4.0 off the rev limiter (which is possible because I use the manual controller every time I’m in the sand). I BEAT THAT THING SILLY. Rockcrawling, by comparison is pretty damn easy on a trans. With a torque converter in the mix and off-road gearing the trans doesn’t end up doing much work.

I also do multi thousand mile highway trips towing my camp trailer all over the country.

If I haven’t cooked this thing, they can’t be cooked IMO.

 

[brp0830]

Dude, I BOMB my Scrambler around the Silver Lake Sand Dunes with basically no mercy (we have a place up there so I go a lot every summer). I’ll give the Jeep a break if the engine gets too hot, but I trust the trans and have never had a problem.

I’m talking repeated uphill runs in sand literally bouncing the 4.0 off the rev limiter (which is possible because I use the manual controller every time I’m in the sand). I BEAT THAT THING SILLY. Rockcrawling, by comparison is pretty damn easy on a trans. With a torque converter in the mix and off-road gearing the trans doesn’t end up doing much work.

I also do multi thousand mile highway trips towing my camp trailer all over the country.

If I haven’t cooked this thing, they can’t be cooked IMO.

You make a good point

 

[Mistrornge]

I went with a t18. It is a thing of beasts. The older Jeep ones may be hard to find. Mine is out of a Ford with the 6.8 low gear

 

[bigwalton]

You make a good point

Let’s just say this: AW4 over a 999 all day.

I went with a t18. It is a thing of beasts. The older Jeep ones may be hard to find. Mine is out of a Ford with the 6.8 low gear

He wants an auto.

 

[brp0830]

Let’s just say this: AW4 over a 999 all day.

He wants an auto.

AW4 with a doubler on my 300 with 4:1 would be a sweet combo

 

[Chamba]

I vote for keeping the T5 in your 8 and buying a Prius to scratch the automatic itch. That way you get the best of both worlds with no need to castrate a Jeep. 😜

 

[ag4ever]

I vote for keeping the T5 in your 8 and buying a Prius to scratch the automatic itch. That way you get the best of both worlds with no need to castrate a Jeep. 😜

I love a manual as much as anybody, but reality is for hard core rock crawling, an automatic with the slip and torque multiplication of the converter wins every time.

Still not near as fun as a manual though, but no matter what, for hardcore off-roading, that T-5 needs to go. Way to fragile for hard off road use. In no world does a T-5 belong in front of a D60 or behind a D44.

 

[Chamba]

I agree.. that's why I put an AX15 in mine. It was between that and the nv4500 for me.

I've wheeled a lot in Moab over the last 35 years, mostly in manuals. I have wheeled in autos a couple times. I do agree they are smoother, but I simply love the challenge of manuals on the rocks. Likewise in snow, I find manuals far superior.

I got to wheel a marlin crawler-equipped FJ45 with an H55F 5 speed years ago at Cruise Moab. As I recall it was over 100:1. That was absolutely stunning on the rocks. I rarely had to push the clutch in in first gear, but it red lined at about 1/2 mile per hour or so.

 

[sdsupilot]

AW4 with a doubler on my 300 with 4:1 would be a sweet combo

To be honesty with your 4:1 300 I don't think a double would be necessary. The converter will give you a much better crawl ratio with the auto than the manual. In my wheeling group we have a magnum 205 behind a TH400, a 2 speed atlas with 11.7:1 combined behind an AX15. I am not a manual guy but the doubled atlas/ax15 does work well in the tough stuff. Same for the magnum 205 with the TH400. The 400s first gear really isn't deep enough for tech rock crawling - at least coupled with the 1.96:1 low range in the 205.

All that said, the above rigs are neat and work well. I haven't found a situation where my 3.06 first gear and 2.72 700R4/NP241 haven't worked just fine. I think you would be in the same place with the AW4/4:1 Dana 300.

 

[brp0830]

To be honesty with your 4:1 300 I don't think a double would be necessary. The converter will give you a much better crawl ratio with the auto than the manual. In my wheeling group we have a magnum 205 behind a TH400, a 2 speed atlas with 11.7:1 combined behind an AX15. I am not a manual guy but the doubled atlas/ax15 does work well in the tough stuff. Same for the magnum 205 with the TH400. The 400s first gear really isn't deep enough for tech rock crawling - at least coupled with the 1.96:1 low range in the 205.

All that said, the above rigs are neat and work well. I haven't found a situation where my 3.06 first gear and 2.72 700R4/NP241 haven't worked just fine. I think you would be in the same place with the AW4/4:1 Dana 300.

I found a guy with a recently rebuilt TF999 out of a CJ. He said the early models dont use an ECM and are all hydraulic? Does anyone know about the bolt and spline count/length & compatability with these? For what it's worth, my 4.0L is out of a 94XJ.

 

[Chamba]

I agree with Mike: either are infinitely capable. I really don't think automatic transmission rigs are 'more capable ' than and well set up manual. It really is just personal preference. I've wheeled both and I simply prefer the added challenge/control of the third pedal. I've used my starter in first before and climbed rocks I had no business climbing. Likewise, I've let a torque converter pull me up rocks while I contemplate the clouds and scenery.