Transmissions swap

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Mason Moran

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Hey all,

I am wanting to do a transmission swap on my 74 duster 225 auto. I tracked down a 74 valiant with a 3 speed and a 225. Would the 3 speed fit in my duster with little to no complications, provided I grab all the necessary parts?

PS the auto trans in my duster is failing and i love manuals so a swap is needed/desired
 
Don't forget the nutral safety switch and all the wiring and switches etc.
 
@Dana67Dart Wait sorry, what switches in particular? Where are those located? Would they be connected to the transmission or shifter and I can trace them back to unplug?
 
@Dana67Dart Wait sorry, what switches in particular? Where are those located? Would they be connected to the transmission or shifter and I can trace them back to unplug?
Yes....

I don't know all the details.

But there might be neutral safety and backup light switches that are different on a manual than on an automatic.

May or may not be attached to the trans.
 
You'll need the pedals, clutch linkage, pivots, NSS, bellhousing, flywheel, trans, driveshaft, shift linkage to start with; plus transmission tunnel hump & boot and carpet if floor shift, steering column if column shift. If floor shift, and if you have a bench seat, you may have to switch to buckets or modify the shift handle. If the parts car is 111" wheelbase, you'll need to locate a different manual trans driveshaft to fit your 108" Duster.
Don't forget that your crankshaft may or may not be drilled for a pilot bearing.
Hell, just grab the whole car.
 
Mason; I think you will be unhappy with the results. You will loose some take-off power, unless you slip the clutch to get the Rs up.
There are two A903s with ratios as follows;
.......2.95-1.86-1.00 and
.......3.22-1.84-1.00, compared to your A904
.......2.45-1.45-1.00 But at WOT,that changes to about 4.41/3.18-1.74-1.10 after including the Torque-Multiplication going on inside the TC.

With the manuals, direct and second are pretty far apart at ~54% so yur gonna have to rev second out if you need any pulling power in third, cuz the Rs are gonna drop nearly in half..

If you just wanna have fun shifting, that will depend on what rear gear is in it. With 2.76s, and 24.5 tires,2nd is;
2000 at 29mph /3000 is ~44/ 4000 is 59.
So most of the time, you will be in second gear. Not a whole lotta shifting going on.
There is no synchro on first in those boxes, so backshifting into first is gonna be a huge downer, until you learn to double-clutch and rpm/speed match. You can never do it with any kind of accuracy or consistency.

So IMO, I wouldn't do it; the slanty needs a Commando box;
3.09-1.92-1.40-1.00 and 3.73s will get you 60 at 4300 in third so, that's two shifts at WOT, 3 if granny shifting;
But in second 2000=20/ 3000=30/4000=40; so same old/same old.
However, with the tighter gear-splits, you can now granny shift. The splits are about 72%, except the 1-2 is 62%
So if you rev to 3600, the drops will be to about 2600, so then 2600 will be 53 in 4th, which being all three shifts. See; now yur having fun. Allbeit short shifting, so not going anywhere fast.
 
I have both.
A 64 Dart with a 225 and an auto 904, and a 66 Valiant with a 225 and a manual 903. Both are stock set ups. Both have 7 1/4 rears with 2:76 maybe? whatever highway gear came standard.

Personally I'd drive the Valiant all day over the Dart. It's much quicker off the line than the Dart with the automatic. Yes you get to 3rd gear by about 30 mph but she still pulls hard all the way to 70.
 
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