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gm 400 trans
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jlswaggers View Drop Down
AMC Apprentice
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Joined: Dec/22/2008
Location: hudson, nc 2863
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Points: 187 		Post Options Post Options   Thanks (0) Thanks(0)   Quote jlswaggers Quote  Post ReplyReply Direct Link To This Post Topic: gm 400 trans
    Posted: Jul/14/2017 at 9:55am
I have a 68 rebel 343v8 with bw11 trans.  thinking about a novak adter kit to put a gm 400 in it.  what issues will I run into doing this swap? 
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72AMX View Drop Down
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Joined: Aug/07/2007
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Points: 476 		Post Options Post Options   Thanks (0) Thanks(0)   Quote 72AMX Quote  Post ReplyReply Direct Link To This Post Posted: Jul/14/2017 at 12:01pm
Keep in mind, Jeep had a AMC bellhousing specific version of the TH400 in some models, if you can track one of those down it would be a direct bolt in without having to use the Novak adapter.

If you plan to use a true GM trans, then you will probably going to have to deal with some or all of the following:
  • Driveshaft Length
  • Trans Yoke
  • Trans Mount & cross member
  • Trans to radiator cooling lines
  • New flexplate or flexplate to torque convertor attachment issues

My two cents, if you are going to the trouble of converting to a GM trans, you ought to consider one of the overdrive  versions like the 700r4 or 200r4 instead of the TH400.  

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tufcj View Drop Down
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Joined: Jul/10/2007
Location: Watkins, CO
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Points: 4097 		Post Options Post Options   Thanks (0) Thanks(0)   Quote tufcj Quote  Post ReplyReply Direct Link To This Post Posted: Jul/14/2017 at 12:55pm
Even with the Jeep version TH400, you'd need an adapter because the flat crank on the 343 won't accept the TH400 torque converter. The other option would be to remove the crank and have it machined to fit the TH400 torque converter.

I'd go for the Jeep version, and have it converted to 2WD by swapping the tail shaft, and get the adapter for the crank. Cost would probably be about the same as the Novak adapter. I'd also check with Novak to be sure their adapter is compatible with the pre-72 crank.

Bob
tufcj
69 AMX
74 Javelin AMX
67 Rogue

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jlswaggers View Drop Down
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Joined: Dec/22/2008
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Points: 187 		Post Options Post Options   Thanks (0) Thanks(0)   Quote jlswaggers Quote  Post ReplyReply Direct Link To This Post Posted: Jul/16/2017 at 11:03am
is there anyway to use a gm or 727 trans in my car without reworking  the crankshaft 
68 rebel sst
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72AMX View Drop Down
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Points: 476 		Post Options Post Options   Thanks (0) Thanks(0)   Quote 72AMX Quote  Post ReplyReply Direct Link To This Post Posted: Jul/16/2017 at 11:17am
Is this what you are looking for?

http://www.bulltear.com/catalog/product_info.php?cPath=21_35&products_id=237
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jlswaggers View Drop Down
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Joined: Dec/22/2008
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Points: 187 		Post Options Post Options   Thanks (0) Thanks(0)   Quote jlswaggers Quote  Post ReplyReply Direct Link To This Post Posted: Jul/16/2017 at 2:45pm
there are the magic words, requires crankshaft machining.  and that is what I don't want to do.  i'm looking for a way to change transmissions without doing machine work
68 rebel sst
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FSJunkie View Drop Down
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Joined: Jan/09/2011
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Points: 4742 		Post Options Post Options   Thanks (0) Thanks(0)   Quote FSJunkie Quote  Post ReplyReply Direct Link To This Post Posted: Jul/16/2017 at 3:09pm
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. 
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1966 Marlin
1972 Wagoneer
1973 Ambassador
1977 Hornet
1982 Concord D/L
1984 Eagle Limited
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WesternRed View Drop Down
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Points: 5808 		Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Jul/16/2017 at 5:34pm
Exact same problem with the 727, still won't mate up with the early crank. You can get a bolt on adaptor for the crank along with spacers for the trans or you can get a convertor made like this to go between the TF or TH trans and the flat crank:



And associated bits:
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jlswaggers View Drop Down
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Joined: Dec/22/2008
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Points: 187 		Post Options Post Options   Thanks (0) Thanks(0)   Quote jlswaggers Quote  Post ReplyReply Direct Link To This Post Posted: Jul/16/2017 at 7:50pm
do I have to make up my own kit? how do you make converter? cut two in have and make one
68 rebel sst
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mramc View Drop Down
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Points: 3223 		Post Options Post Options   Thanks (0) Thanks(0)   Quote mramc Quote  Post ReplyReply Direct Link To This Post Posted: Jul/17/2017 at 5:15pm
Novak and Advance adopter have kits. Novak gives you a flex plate in the kit. Assuming your street driving the car , if your  going this way you might as well do a 700R4 instead of the 400 and get over drive in the bargain. LRDaum
LRDaum
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