What ratio would my '74 Dart Custom 4 door 225 slant, auto, made in Jersey have come with? What other ratios are (were) available to swap in?

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Grandpa's 1974 Dart Custom 4 door 225 auto, Aluminum Radiator, 1920 Holley.

Late model with Auto Tranny is most certainly a 2.76 factory rear...

You can find/get new gears for any ratio, but 'streetable' ratios would be 2.94/2.93 and 3.23

-D.Idiot

I checked it with Dan's turn the wheel method and it is the 2.76 ratio. What kind of rpms would I see at highway speeds, about 65mph, with the 2.93 or 3.23 ratios? Can these be found out of junk cars or trucks?

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Grandpa's 1974 Dart Custom 4 door 225 auto, Aluminum Radiator, 1920 Holley.

Depends on your tire size. Go here and have fun

www.csgnetwork.com/gearratcalc.html

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'63 Valiant V200 Convertible
225 Aluminum Block

Would anybody know the ratio that would come on a '71 demon w/a 3speed on the column? The tag is missing. I figured it would be a little lower than 2.76..

The final gear ratios in the transmissions are the same 1:1, whether it is auto or manual. I would guess that it is either a 2.76, or a 2.94/2.93.


I have a 71 dart with 3speed auto... and mine has a 2.76.


~THOR~

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1984 D100 Shorty Custom
Certified Auto Appraiser - RevItUp Classic Appraisals
President - Cherry City Bombers CC
Part of Tyrde-Browne Racing

'IF' the rear is 'stock'... then it could be a 3.23.... but someone could've blown it up and replaced with anything... the best hope is that it has 2.94's...

-D.Idiot

What would the best rear ratio be for good MPG? Would it be the 2.76 or dose the engine do better at a few more rpm's? Is there a good swap for the original tranny (automatic 1974) that would have 4 gears with overdrive?

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Grandpa's 1974 Dart Custom 4 door 225 auto, Aluminum Radiator, 1920 Holley.

If we say 4 gears WITH overdrive, meaning basically a 5 speed? Not sure we have anything to make that work without large mods, at least in the automatic realm. (Dan take it from there )


Now if what you mean is a 4 speed TOTAL transmission, the 4th gear being OD, I dont know off the top of my head if there is an auto trans that will work with our cars (Dan would probably know) but I do know that an A833OD manual transmission will give the same results (you just get the fun of shifting) in which case you would proabably want to opt for the 3.23... otherwise (i.e. 2.76) you may not be turning enough RPM @ speed limit to make it up a hill, and depending on where you live/how you drive, you may also find yourself in the power valve alot.

A 3.23 or maybe even a 3.55 would be spectacular for the overdrive trans, whether it be auto or manual...

Here is something that Ceej, Fopar and I are working on...

An external solenoid operated overdrive unit, that will bolt to the tailshaft. We were informed that there is a company who sells basically a universal overdrive unit (Ceej can fill in on the company name if he sees this), which is identical inside and out to a late 70s early to mid 80s Volvo overdrive unit.

Wishing Id known this earlier.... having had 3 cars with these overdrive units... I could have pulled them and saved myself the effort I have to put out now to find some. Just something else we are working on.

From what I've learned so far, (correct me if I am wrong) with a stock trans and engine, a 2.94/2.93 is awesome. I have the 2.76 myself, but it hurts intown getting the car to "jump" out of the way sometimes.


~THOR~

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1984 D100 Shorty Custom
Certified Auto Appraiser - RevItUp Classic Appraisals
President - Cherry City Bombers CC
Part of Tyrde-Browne Racing