th400 Interchange question, quadratrac interchange question. HELP!

DylanWoods · 03-29-2009, 01:07 PM

ok im needing some help... ive got a 78 CJ7 that i just toasted the tranny, i also would like to goto a 2 speed quadratrac instead of the single speed.

so heres my question, ive found a TH400 and quadratrac with low range out of a 73 (wagoneer i assume, the guy did not specify) he mentioned somthing about a cast iron adapter ring? not sure what that is, just making sure this will work in my application before i go shell out some duckets for it.

thanks in advance.

**PavementPounder** · 03-29-2009, 01:27 PM

It would work if the donor had an AMC V8, but it won't bolt back together exactly the same as stock. I wouldn't go backwards to the Nailhead setup, personally. AMC-patterned QT are not hard to find. People on IFSJA will have them, but did you try posting a Wanted thread here in JF's own Classifieds? Also, if you find a good Chevy 4wd TH400 you can swap the guts into yours and then also have the tailhousing assembly to keep that would allow a Dana 300 if you ever decide to switch things up in the future.

BTW, if you elect to fix your trans, the low-range unit can just be added to your existing QT case.

DylanWoods · 03-29-2009, 01:41 PM

i do plan to make some major changes over next winter. going to goto an injected chevy engine with th400 and probably a dana 300.

this is a very cheap combo and im broke. LoL so im just looking for somthing to get me back on the road for a bit.
he said it had an AMC 360... is this ring im hearing of inbetwene the tranny and engine or tranny and tcase? thanks for your help again!

John N · 03-29-2009, 07:36 PM

The "ring" is between the engine and tranny. It was AMC's way of doing an adapter befroe they committed to actually having AMC T400 trans built. It won't work well in a CJ, because it''ll add length to the trans and your driveshafts will be the wrong lengths. AMC T400s aren't hard to find, if you do a little looking. As said above, the low range unit will bolt right on to your existing Q'trac.

DylanWoods · 03-29-2009, 11:17 PM

well thats a drag seeing as i just bought it. LoL

i was told that the length would still be the same because the BOP was shorter then the AMC to begin with. i guess ill measure tomarow morning and see... if it is indeed too long then i guess i will swap the guts out of the old school one to my burnt up tranny...

**PavementPounder** · 03-30-2009, 10:28 AM

Quote:

Originally Posted by DylanWoods

well thats a drag seeing as i just bought it. LoL

i was told that the length would still be the same because the BOP was shorter then the AMC to begin with. i guess ill measure tomarow morning and see... if it is indeed too long then i guess i will swap the guts out of the old school one to my burnt up tranny...

Just an FYI - that TH400 is not a "BOPC" like modern GM BOPC's. That trans was for use with Buick Nailhead motors (without the ring). Post up the length difference after you measure them.

**jfwireless** · 03-30-2009, 12:48 PM

You can just add the low range unit to your existing QT, it just bolts up.

Jim

DylanWoods · 04-05-2009, 03:57 PM

i understand i can add the low range unit to my T-case, but that wont make my tranny any less burnt up. LoL ill check the measurment in an hour or two when i get home and post it up.

03-29-2009, 01:27 PM	#2
PavementPounder Cool as Ice... Join Date: Dec 2006 Location: Sterling Heights, Michigan Posts: 2,727 Profile Gallery Classifieds My Jeeps	It would work if the donor had an AMC V8, but it won't bolt back together exactly the same as stock. I wouldn't go backwards to the Nailhead setup, personally. AMC-patterned QT are not hard to find. People on IFSJA will have them, but did you try posting a Wanted thread here in JF's own Classifieds? Also, if you find a good Chevy 4wd TH400 you can swap the guts into yours and then also have the tailhousing assembly to keep that would allow a Dana 300 if you ever decide to switch things up in the future. BTW, if you elect to fix your trans, the low-range unit can just be added to your existing QT case. __________________ This is how NAXJA Midwest Chapter elected officials like to treat their resident users and former multi-year supporters. <--- Click "Classifieds" under my avatar to see all my parts (mostly CJ & XJ) currently for sale on JeepForum!