New member with a 71 SST doing a 360 swap

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   The speedo gear on a Jeep TH400 is in the transfer case, the main trans case isn't machined to take a speedo gear -- it's not in the output shaft housing but the main case. That's why the mod posted by AMXFSTBK390 is needed. You also have to change the output shaft from a standard GM 2WD model TH400, which means the trans has to come apart, so it needs to be rebuilt to convert to 2WD. 

I don't know about the Jeep 727. It still has to come apart (rebuilt) to be converted to 2WD (from common Mopar 2WD parts). But I don't know if the case needs modifying for the speedo gear. I don't think so -- the speedo gear is in the output shaft housing and on the output shaft on the 727, so it should be speedo ready when converted. 

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farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19686	Post Options Post Reply Quote farna Report Post Thanks(0) Quote Reply Posted: Aug/28/2019 at 6:38am
	The speedo gear on a Jeep TH400 is in the transfer case, the main trans case isn't machined to take a speedo gear -- it's not in the output shaft housing but the main case. That's why the mod posted by AMXFSTBK390 is needed. You also have to change the output shaft from a standard GM 2WD model TH400, which means the trans has to come apart, so it needs to be rebuilt to convert to 2WD. I don't know about the Jeep 727. It still has to come apart (rebuilt) to be converted to 2WD (from common Mopar 2WD parts). But I don't know if the case needs modifying for the speedo gear. I don't think so -- the speedo gear is in the output shaft housing and on the output shaft on the 727, so it should be speedo ready when converted.
	Frank Swygert

JakeSchultz Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Apprentice Joined: Aug/22/2019 Location: Georgia Status: Offline Points: 30	Post Options Post Reply Quote JakeSchultz Report Post Thanks(0) Quote Reply Posted: Aug/28/2019 at 10:09am
	Well thank you to everyone for all the info and such, but I don't think I'm gonna pull the trigger on a trans swap. I don't really need performance, and the car will be driven short distances. Also I can do a trans swap further down the road. What I've decided to do is either put a flat flange crankshaft in the 360, or is it possible since the motor is at the machine shop that they could machine the crank to be a flat flange, and not stepped. I know y'all are gonna frown and using the BW trans, but I just wanna get the car back on the road ha. Thanks y'all

brownspirit Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Mar/07/2009 Location: Georgetown, MA Status: Offline Points: 1021	Post Options Post Reply Quote brownspirit Report Post Thanks(0) Quote Reply Posted: Aug/28/2019 at 10:16am
	I responded to your other thread before seeing this, TH400s are great transmissions, but 904s and 727s came factory installed in these cars and is a much simpler swap, you can probably find a 2wd 727 or 904 (v8 version) fairly easily. (no machining for speedos) and you will probably be able to find a used driveshaft for sale if you post a wanted ad. Andy
	69' BBB AMX 390/4-speed 69' s/crambler project 69’ International F210d Cummins/5+4

farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19686	Post Options Post Reply Quote farna Report Post Thanks(0) Quote Reply Posted: Aug/29/2019 at 6:59am
	You should be fine as long as the trans is in good shape and you're just cruising around and not dogging it and showing off a lot. Not much you can do to beef up that trans without a full rebuild, and even then you're limited in increasing power handling capability. You should be bale to have the crank machined flat. Remove the pilot bushing if there is one too. You might need to install a pilot bushing the right size for the BW torque converter. I'd take the converter to the machine shop and let them check that as well. If you decide to get a 904/998/727 later (the 2WD models aren't so easy to find since it must come from an AMC car, production ended in 1983!) there is a bolt-on crank adapter available. A Jeep 4.0L 2WD trans will also work -- the AW4 -- from a 2WD CXJ Cherokee. Not to hard to adapt, there is a good AW4 swap page in the trans section (sticky). Jeep used a 999 (slightly upgraded 998) through 2006 in the Wrangler, but it would have to be converted from 4x4.
	Frank Swygert