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Discussion Starter · #1 ·
Ok i have searched everywhere and im having a hard time finding an answer that satisfies my concerns. Alright so i have a 71 nova with a 383 and im doing a transmission swap. Originally a th350 move to a th400. so this is what i aready know. I know that the th400 i have is from a 82 gmc 3/4 ton pick up meaning i have a bolt in style yoke. I also know that the th400 has an electronic kickdown that need to be installed to make 3 to 1 downshifts. I also know that the crossmember needs to be changed and that there is and offset when using an sbc with a th400. my question is if i get a th400 crossmember from classic industries that says it fits 68-74 nova does it still need to be modified for my app. Also i am concerned with my yoke and driveshaft options. Do i get a custom driveshaft to fit the yoke style of the trans or do i change the tailshaft so i can use a slip yoke design?

Im young and this is my first build so im learning as i go. Any help would be greatly appreciated. Thanks in advance. :)
 

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Welcome to team nova!! Yes the crossmember and the trans mount will be different!!.the tailshaft can be changed so you can run slip in driveshaft and the crossmember that you will order will be ok for your application!
 

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The bolt in tail shaft (with the slip yoke in the drive shaft instead of the more common tail shaft) is actually stronger (not that you are likely to break either). If you do not want to go to the hassle of changing the tail shaft over you could get a custom drive shaft built (compare price differential).

As to modifying a store bought TH400 cross member I would say no once you explained to them that what your application will be (SBC with TH400 centered in chassis) as they can build it to fit your car.

Big Dave
 

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Discussion Starter · #4 ·
Thanks a lot guys are awesome quick helpful responses. As for the kickdown, is it really needed? From what i understand it just does a 3 to 1 down shift. Can i run the tranny without it as i am most likely going to us a hurst shift kit and do manual shifts anyway.

Thanx
 

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you can leave it off, as i did the same thing. but i think it works better if ya do put it on, your not going to wana shift manually all the time, i have the switch just one of those things you put off till later.
 

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It doesn't down shift from third to first but from what ever gear it is in to the next lower gear based upon throttle position (switch location), and vacuum reading (engine load), and RPM (determined by weights and springs in the governor). It means when you stomp on the gas to pass someone the tranny down shifts and the your factory equipped QuadraBog makes a bawaaa noise as it sucks in low flying birds to warn smaller cars to get out of the way of American Muscle on the move.

Big Dave
 

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Discussion Starter · #7 ·
I see so without it if i floor at cruising speed it won't downshift. Is it difficult to install on a non factory equiped th400 car? And does it matter that i have a 725 road demon to install the throttle mounted kickdown?
 

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You can install a switch under the gas pedal inside the cabin or on the gas linkage at the car either way works, and the factory did both.

Big Dave
 

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I used a factory crossmember and expanded the holes with a die grinder, then used big washers on the mount bolts. You could also cut the tab with the holes off and re-weld it a little to the left, which seems like a better idea to me.
 

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Is the lokar th400 kickdown kit also a good choice to avoid having ugly switches around my carb?
I'm not familar with the Lokar kick-down kit. I am trying to remember an application for a kick down switch at the gas pedal. First one I can think of is for a 1968 Impala, but odds of the dealer having that in stock is slim. Check some of the Impala resources (Impala Bob's, Year One, etc.) to see if they offer a throttle cable kick down for the gas pedal.

Big Dave
 
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