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(Maximum) Overdrive
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mtrosclair View Drop Down
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Points: 486 		Post Options Post Options   Thanks (0) Thanks(0)   Quote mtrosclair Quote  Post ReplyReply Direct Link To This Post Posted: Mar/25/2023 at 8:38am
Originally posted by farna farna wrote:

We're talking about a 196, so no more 3000 rpm sustained would be best.

As far as cost to change out to OD -- well, it depends on what you find an OD trans for. But most likely not...

I have the 199, so hopefully that will be a little more accommodating for higher speeds.  

I didn’t know that about the tires, that might explain the speedometer reading higher than actual speed. 
1963 Rambler Classic 550
Originally a 196, this one has a 199 from a 69 American.
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Points: 6881 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Mar/25/2023 at 9:11am
You may find this helpful in figuring out what you may want to change and expected results:
Usually just calculate 1st and final gear ratios and then play with tire size and rear end gearing to get an idea of were things would line up to best suit the driving requirements.
Typically for a street car you want approximately 9:1 overall gear ratio for 1st. If you lived in the mountains or took the car to the strip occasionally, 11:1 to 12:1 1st is likely better.
You may have to sacrifice 1st to get a better final gear/engine RPM or vice versa.
It's always some give and take. 
It's particularly helpful when changing transmissions/tires to figure out the speedometer gear to use.
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Points: 19676 		Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Mar/26/2023 at 12:51pm
The link Trader posted will be helpful. You can get the approximate tire diameter from the size by using the calculators at www.4lo.com. Ignore the "LT" in the metric tire size calculator -- it means "light truck", which is the same as passenger cars. If you use their gear ratio calculator for rpm/speed/ratio, use "1" for transfer case ratio. I say approximate tire height (diameter) because there is some minor variation between manufacturers. Won't be enough to throw it off much though.

Frank Swygert
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Points: 486 		Post Options Post Options   Thanks (0) Thanks(0)   Quote mtrosclair Quote  Post ReplyReply Direct Link To This Post Posted: Apr/28/2023 at 11:30pm
So I've been driving it a bit (1200) miles so far on the engine, and now that I have a tach I can keep an eye on things.  At 70 indicated which is about 68 mph I'm turning about 3200, 65 indicated, 63 actual is about 2800 RPM.  I think this is certainly within a range that the 199 can handle so I don't think it would be worth it to pursue the OD trans, unless it was free and then maybe... 
1963 Rambler Classic 550
Originally a 196, this one has a 199 from a 69 American.
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Points: 2725 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Buzzman72 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/29/2023 at 9:22am
Using your 3200 rpm @ 68 mph figure, you're running somewhere around 21 +/- mph per 1000 rpm.

To put that into some perspective my PT Cruiser [don't judge me!] is at 3000 rpm @ 78 mph. Or 26 mph per 1000 rpm. That's with an overdrive automatic.
 
The 199 should produce better torque numbers than that naturally aspirated Mopar 4-banger. I calculate that a 0.8:1 ratio overdrive would lower your 68 mph rpm to 2560 rpm. That would put you in the 26.5 mph per 1000 rpm range, comparable to what my Chizzler product does. 

While my car is more aerodynamic than yours, I believe you'd be in great shape using the OD...and you wouldn't lose your low-speed takeoff ability either.


Edited by Buzzman72 - Apr/29/2023 at 9:26am
Buzzman72...void where prohibited, your mileage may vary, objects in mirror may be closer than they appear, and alcohol may intensify any side effects.
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Points: 16611 		Post Options Post Options   Thanks (0) Thanks(0)   Quote purple72Gremlin Quote  Post ReplyReply Direct Link To This Post Posted: Apr/29/2023 at 9:43am
Basically if you want OD, You will be much better off to buy a complete 1963-64 car to have everything to swap everything.  But is it cheap?  All depends on the parts and the car.
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Points: 3313 		Post Options Post Options   Thanks (0) Thanks(0)   Quote sweatlock Quote  Post ReplyReply Direct Link To This Post Posted: Apr/29/2023 at 9:52am
Obviously, the power band of an engine (torque, horsepower) at a certain RPM has to be taken into account. Some may think that 3K RPM for that Mopar 4-banger is too high at ~70MPH, but it would probably be undrivable at highway speeds turning at 1.7K RPM’s and constantly downshifting or lugging. There is such a thing as too low of RMP’s for the engine…the OEM’s knew what they are doing. 

And too low RPM’s at highway speeds is a concern with carbureted cars and overdrive with regards to vacuum signals. 

All this needs to be taken into account before slapping on an overdrive.  
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Points: 3313 		Post Options Post Options   Thanks (0) Thanks(0)   Quote sweatlock Quote  Post ReplyReply Direct Link To This Post Posted: Apr/29/2023 at 9:56am
Originally posted by purple72Gremlin purple72Gremlin wrote:

Basically if you want OD, You will be much better off to buy a complete 1963-64 car to have everything to swap everything.  But is it cheap?  All depends on the parts and the car.

It would depend on how much would it lower the RPM’s vs. how difficult to find, how expensive to buy when found, and how difficult to changeover. And I doubt that the setup from a ‘63-‘64 wouldn’t need any work and would perform flawlessly without $$$ put into it. 
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Points: 16611 		Post Options Post Options   Thanks (0) Thanks(0)   Quote purple72Gremlin Quote  Post ReplyReply Direct Link To This Post Posted: Apr/29/2023 at 5:06pm
Originally posted by sweatlock sweatlock wrote:

Originally posted by purple72Gremlin purple72Gremlin wrote:

Basically if you want OD, You will be much better off to buy a complete 1963-64 car to have everything to swap everything.  But is it cheap?  All depends on the parts and the car.

It would depend on how much would it lower the RPM’s vs. how difficult to find, how expensive to buy when found, and how difficult to changeover. And I doubt that the setup from a ‘63-‘64 wouldn’t need any work and would perform flawlessly without $$$ put into it. 
   Thats why I said "Depends"
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Points: 3313 		Post Options Post Options   Thanks (0) Thanks(0)   Quote sweatlock Quote  Post ReplyReply Direct Link To This Post Posted: Apr/29/2023 at 5:09pm
Originally posted by purple72Gremlin purple72Gremlin wrote:

Originally posted by sweatlock sweatlock wrote:

Originally posted by purple72Gremlin purple72Gremlin wrote:

Basically if you want OD, You will be much better off to buy a complete 1963-64 car to have everything to swap everything.  But is it cheap?  All depends on the parts and the car.

It would depend on how much would it lower the RPM’s vs. how difficult to find, how expensive to buy when found, and how difficult to changeover. And I doubt that the setup from a ‘63-‘64 wouldn’t need any work and would perform flawlessly without $$$ put into it. 
   Thats why I said "Depends"

Yes sir, I just filled-in the ‘Depends’ 
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