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Discussion Starter #1
I want to assemble information on swapping my TH400 auto to an overdrive in my 72.

How difficult would it be to swap in a manual tranny? If I go manual I'd use the 6 speed with the .5/1 6th gear. Is engine torque a big factor pulling 6th?

If I went auto, it would probably be the 200R beauce it's lighter than the 700R and the 1st gear ratio is more street friendly.

My diff gear is a 3.08 and I'll leave that alone.

Help me with all the pro's and con's you can muster.
 

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DC PIT CREW BOSS
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For what it's worth. Us old hot rodders have been doing this swap for years. Actually going to a 4 speed would be the easiest as far a finding parts. The best way would be to find a donor Vette. To change out the petals to get the clutch involves removing the instrument cluster side of the dash but essentially it is a bolt in. Changing to an overdrive or a 5 or 6 speed would involve some fabrication. Not difficult just work. The clutch assembly would be the same as with the 4 speed. You will need to fabricate a crossmember for a 5/6-sp or 200/700 swap since the mounts are in a slightly different location. You will also need to make a drive shaft to get the correct length. If you or a buddy are a good welder then this should not be a problem. Good luck
 

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To throw in my 2 cent i wish you luck in whichever trans you decide to go with, I personally do not like to see mods done to the ole sharks other than beefing them up with what they came with. I rebuilt the 400 in my 74, did a little work on the valve body
and got rid of that softer shift. It now shifts alot firmer like the old 350's
 

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Discussion Starter #4
mytoy74, I have a shift kit in the TH400. That was a good mod:thumbsup:

I'll probably swap in an automatic, but I do miss the fun of manually banging gears.
 

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DC PIT CREW BOSS
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As a side note. The TH400 is a good strong tranny. If you decide against any swap you can build it for performance. I've got one behind a 500cid 345hp Cadillac in a Model A roadster and don't have any problems at all except for the leaks from the shifter bolt. It hits the gears hard and doesn't overheat.
 

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biltogo said:
I want to assemble information on swapping my TH400 auto to an overdrive in my 72.

How difficult would it be to swap in a manual tranny? If I go manual I'd use the 6 speed with the .5/1 6th gear. Is engine torque a big factor pulling 6th?

If I went auto, it would probably be the 200R beauce it's lighter than the 700R and the 1st gear ratio is more street friendly.

My diff gear is a 3.08 and I'll leave that alone.

Help me with all the pro's and con's you can muster.
I went from a 400 to a 700 and after blowing 3 700R's in one summer I went to a mustang T5 and yes with very little work a ford T5 will fit. I then bought a Tremec TKO for reliability.

I went with a hydraulic clutch and the clutch master out of a 85 one ton truck other then a slight linkage shortening bolts right in. Even the holes in the firewall are already there.
As for changing pedals, that was the hardest part. There are 10 bolts. It can be done with the instrument banel installed but the drivers seat should come out along with the steering column.

The removable crossmember needs a extension welded on the front to accomidate the trany mount regardless of what you swap and the driveshaft might need shortening depending on the transmission.
I prefer the tremec over the 6 speed with it's internal rail shifter and more compact size. I have .68 overdrive and that is good enough for me.

Good luck but the overdrive transmissions are worth it.
 

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Discussion Starter #7
good points so far guys, thanks:thumbsup:
 
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