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gm 400 trans

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401harry View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 401harry Quote  Post ReplyReply Direct Link To This Post Posted: Jul/17/2017 at 6:16pm
Originally posted by jlswaggers jlswaggers wrote:

do I have to make up my own kit? how do you make converter? cut two in have and make one


Actually a custom converter is the easiest solution. Have no idea what it would cost but I would call Turbo action in Jacksonville or JW and at least ask. They are pretty helpful. The kit from American performance is not listed on their website but i remember it had spacers and need the converter mounting pads machined down and it was like $250 bucks and you still need a converter. I would not use the later Jeep TH 400 as it has a unique angle built in to clear the transfer case. If I was going to run a Turbo I would use the Ultrabell but I like my TFs
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304-dude View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Jul/17/2017 at 6:36pm
The angle of the Jeep TH400 is minor. Like 5 degrees. Has no effect In installation and is the simplest to install. The only concern is speedo gear mounting, as the case has the provision but is not fully bored.

Until some one proves a Jeep case fails because of a change of angle at the pan, I see no reason for such claim.

71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pit crew Quote  Post ReplyReply Direct Link To This Post Posted: Jul/17/2017 at 9:38pm
FYI. I run a Jeep TH400 in my 73 Hornet with no issues. Just changed the output from 4WD to 2WD and carved out the speedo mount.

73 Hornet - 401EFI - THM400 - Twin Grip 20
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401harry View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 401harry Quote  Post ReplyReply Direct Link To This Post Posted: Jul/18/2017 at 6:43am
Originally posted by 304-dude 304-dude wrote:

The angle of the Jeep TH400 is minor. Like 5 degrees. Has no effect In installation and is the simplest to install. The only concern is speedo gear mounting, as the case has the provision but is not fully bored.

Until some one proves a Jeep case fails because of a change of angle at the pan, I see no reason for such claim.



I made no claim regarding the strength of the late jeep 400 case. As I stated I think a custom converter and a amc case TF is the easiest solution to the posters problem without pulling the motor. In the case of a mild 343  I would look at using a 904/998/999. Lighter, less parasitic loss and if you get a lockup model you can get highway performance from it. Just like all the other suggestions you will still need a converter
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Jul/18/2017 at 7:14am
Originally posted by 401harry 401harry wrote:

Originally posted by 304-dude 304-dude wrote:

The angle of the Jeep TH400 is minor. Like 5 degrees. Has no effect In installation and is the simplest to install. The only concern is speedo gear mounting, as the case has the provision but is not fully bored.

Until some one proves a Jeep case fails because of a change of angle at the pan, I see no reason for such claim.



I made no claim regarding the strength of the late jeep 400 case. As I stated I think a custom converter and a amc case TF is the easiest solution to the posters problem without pulling the motor. In the case of a mild 343  I would look at using a 904/998/999. Lighter, less parasitic loss and if you get a lockup model you can get highway performance from it. Just like all the other suggestions you will still need a converter

No problem, just sounded a wee sharp about the angle being a concern over any other TH400 option.

Actually both TF and TH trannies do very well, though each has strengths and weaknesses. I would've chosen a TF for better downshift for engine breaking, but for my check list of options, the TH400 ended up being my choice.

The OP wanted to know about TH400 adaption, and will find it is not going to be simple, without machining the crank. There are a couple of threads on machining the torque converter snout, and nothing has clearly come of it, as for outcome. 

71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Jul/18/2017 at 7:53am
The Novak adaptor is designed to work with the later 72 on Torqueflite style crank flange and will allow you to use a GM TH transmission rather than the AMC (Jeep) specific one. Perhaps they can make up separate crank spacer that works with the early crank to go with their kit if you ask, otherwise that is something you will need to get machined up yourself.

As I understand it, on factory AMC TH equipped engines, there was a spacer ring pressed into the later Torqueflite crank to accommodate the slightly smaller diameter of the GM convertor snout. This is similar to the crank adaptor supplied by Novak.

If you go with the custom convertor option for either TF or TH transmission, it is something you will have to have made yourself as there is no off the shelf option. Any decent performance convertor shop should be able to pretty much build a convertor from scratch to suit any application, but they will probably need some measurements to work with.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote shootist Quote  Post ReplyReply Direct Link To This Post Posted: Jul/18/2017 at 12:36pm
I would also agree with a custom converter with being the way to go. However, like any custom made order don't be surprised if you are staring at a bill near the 1k mark for a custom converter. Coan, Hughes, Turbo action, TCI just about all of them would likely be willing to make one but again price may get prohibitive pretty quick since it truly would be a one-off and then with a one-off there could be trouble with it. Be sure that if you are going the custom converter route you have it very specifically measured for what you need or you could get stuck with something that doesn't work for you.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Jul/18/2017 at 1:01pm
What I would do... Is get an adapter kit, and have a machinest make a steel centering dowl to fit the crank with an over sized head to fit the crank spacer and use a what ever TH tranny you want.

Though I would go with a thick tranny adapter as to allow the crank spacer enough room for the centering dowl.

This way nothing gets messed up and can be sold later to whoever without any issues or limitations on how to install.

As for crank end... you may have to pull the bushing if a manual tranny was installed. This will give some extra diameter to the centering dowel.
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ramblinrev Quote  Post ReplyReply Direct Link To This Post Posted: Jul/18/2017 at 1:02pm
Originally posted by FSJunkie FSJunkie wrote:

It's probably easier to simply get a 727 Torqueflite from a post-1971 360 or 401 AMC. If you get the trans, flexplate, torque converter, driveshaft, mounts, etc. it would drop right in.

Using a Turbo-Hydramatic 400 is the hard way. Post-1973 Jeeps have a TH-400 that bolts directly to the AMC engine. Jeeps before that used a Buick Nailhead TH-400 with an adapter plate. 


Matt,
A 727 does not bolt up to the earlier cranks without and adapter or machining
74 Hornet Hatchback X twins (since 1977)
62 American Convertible (still worth the $50 I spent in 1973!) AMCRC #513, AMO #384
70 AMX 360 4-speed (since 1981)
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