Hydramatic?

[DaemonForce]

I'm so disgusted with these weak Torqueflite transmissions that I'm not going to bother rebuilding them anymore. If anything, I'd rather give it to some poor shop mechanic and bleed him dry through a warranty but I'm not that diabolic right now. What do you guys think of bolting a GM transmission to an AMC 6cyl? I'm thinking of getting a TH400 and it might be strong enough to survive my simple distance trips until I can find a manual to put in here. Is there anything I should specifically look for besides the 4WD model?

[standup650]

My dad has a 79 blazer with a stought 355 and a built th400. he bought it in 93 did the motor and had the local shop do the th400 with a coupel of aftermarket improvments. He pounds on this thing still today and the only thing he has done to the 400 is normal mantinance.

[DaemonForce]

All I really ever do with this Eagle is long distance freeway trips over flat pavement and minor hills. The transmission blows up whenever I pass through Vancouver and I'm sick of going through a total panic whenever this thing kills the engine in Portland traffic. I've found a few listings for a AMC/Jeep TH400 on craigslist and I've even found a wagon with one of them but it's bolted to a 360. Will this easily bolt up to an Eagle or will I have to modify something?

[IowaEagle]

The AMC 360 and the 258 share the same bell housing pattern.  We seldom hear of catastrophic 998 failures -- mainly its the weak thin-wall torque converter input shaft that causes issues.

[mudkicker715]

A misadjusted kickdown rod will cause all sorts of problems

[captspillane]

The TH400 with AMC bellhousing had a unique tailshaft that only worked with the Borg Warner quadratrac transfer case. You will need a different tailshaft and an adaptor, along with a transmission rebuild to install it, in order to bolt it to the New Process bolt pattern. You will likely have driveshaft issues because of the length. You will also need a different flexplate. Pretend its a Quadratac 1979 CJ7 with 258 for the flexplate.

One cool thing about the TH400 is the kickdown. Its an electronic switch. On some FSJs there was a switch similar to the one that controls your brakelights except on the gas pedal, to let it know when to downshift. On my CJ7 its a cable jobber off the throttle plate to the switch. That makes the installation more flexible.

The TH400 is exactly as strong and reliable as a TF727. A TF727 is much better than your old 998 and it uses all the old linkages, and it can be purchased for less than the cost of the fancy TH400 tailshaft adaptor. Generally installing a TH400 is a waste of time and money, but that's your decision to make.

[carnuck]

Do a Grand Wagoneer 727 swap or go with an AX-15 and be done with it. (wish I knew for sure what needs modding to put a Jeep AW4 and NP208 in)

[DaemonForce]

Okay so it's too much work. Would it be possible for me to send the 904 off to a shop as a core and ask for a 998 or 727? None of the shops will help me because of this transmission.

Do a Grand Wagoneer 727 swap or go with an AX-15 and be done with it. (wish I knew for sure what needs modding to put a Jeep AW4 and NP208 in)

This is what I've been desperately trying to do but the picking yards crush every wagon I pick from less than a week later. This is a horribly frustrating and stupid way to do business and it wastes my time and fuel.

[carnuck]

Where are you at? (re-read. I thought it was Portland) I have a core 998 (converter snapped but it still moved until it dumped all the oil) for $50 here in Seattle. Sea-Tac trans here knows what to do with them.

[Jurjen]

Novak conversions has some interesting stuff:
http://www.novak-adapt.com/knowledge/th400.htm

[BenM]

If I were going to move from a 998 or 999 (Found in wranglers, a 998 can be built up to a 999) I'd go to a 700r4 or AW4 for all the drive line effort. Both are not too bad. Lots of AMC-ers going to the AW4, and lots of Jeep-ers going to the 700r4.

But a 999 build should handle just about anything short of heavy towing.

[DaemonForce]

Where are you at? (re-read. I thought it was Portland) I have a core 998 (converter snapped but it still moved until it dumped all the oil) for $50 here in Seattle. Sea-Tac trans here knows what to do with them.

I saw that listing. Looks like a good idea. I'm staying out of Seattle and Bellevue for now though. My truck only gets 5MPG and I'll be in Seattle and Arlington in early April so I might be able to check it out(if I can afford it). Both of my TF904s are junk and the current issue is probably thanks to the torque converter. I would use an AW4 if I could find one. I need this car running within the next two weeks, period. I will pull out my ancient NP435 and order every adapter if need be but that's a very last resort. I don't have two weeks to spend looking for a clutch and bearings. This is my daily driver and it has to work or else I won't.

[carnuck]

Turnaround on the 998 at Sea-Tac is 2 days

[standup650]

Do the AMC th400 and Chevy th400 have the same guts?

[carnuck]

Yes. I think the TH400 is a bigger case than 727 (longer too) You could probably use '88 up Chev TH400 4x4 parts to go driver's side drop NP241 or others if they aren't too long.