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(Maximum) Overdrive

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mtrosclair View Drop Down
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    Posted: Mar/20/2023 at 8:27pm
As I have been putting miles on my car the need for higher gearing is apparent, it sounds like its spinning over pretty quick at 60 mph.  I have the 3-speed manual which I think is a T-96, but I believe that there was an overdrive version, which from pictures appears to have been in the tail housing between the gearbox and torque tube.  MY thought is how hard would this be to source and add to my car, or would it be worth it?

Thanks 
1963 Rambler Classic 550
Originally a 196, this one has a 199 from a 69 American.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mtrosclair Quote  Post ReplyReply Direct Link To This Post Posted: Mar/21/2023 at 8:03pm
So it looks like I would need a R10 or R11 over drive unit, can anyone confirm that I would just replace the tail housing with the overdrive and add the appropriate electrical gear? If that's the case then I'd just need to locate one of those thats close. 

Edited by mtrosclair - Mar/21/2023 at 8:06pm
1963 Rambler Classic 550
Originally a 196, this one has a 199 from a 69 American.
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Ken_Parkman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken_Parkman Quote  Post ReplyReply Direct Link To This Post Posted: Mar/21/2023 at 8:13pm
I dunno a lot about the Rambler R10, but I'm just finishing up my Willys R10. So a can't comment on what the torque tube does but can some on the R10.

You need an overdrive version of the T96, and those came with the R10 which is pretty strong; much stronger than the T96. There are a lot of changes they made, the case, output shaft, and the reverse shifter rail. I think you'd pretty need a proper donor.

To me it's worth it. Those OD's are great and drive nice.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mtrosclair Quote  Post ReplyReply Direct Link To This Post Posted: Mar/21/2023 at 8:23pm
So I'd need one of these basically? Or similar, I wonder if I can find someone to trade me that nice automatic trans in my garage for an overdrive trans...Wacko

https://www.ebay.com/itm/144837188800?epid=15047087754&hash=item21b8f81cc0:g:mNUAAOSwdZVjiiIF&amdata=enc%3AAQAHAAAA4Hckp5qbTZ91wghSyJXSuyYww7GXqBzzBbuoCW0m9HPWuWGQH1sZn30crnw10Ev%2FD6wNEFOTy%2BSleb215hPYZKwEEJ2RheTEJynmYa4rTFae%2BEKBDJkHpm3gty%2FfiOn3cVZ7RE6JNiu3owwf80GoJWsdEDP%2Bn%2Bc5dZ0K4UE%2Be2NCUSOSSCTTyfxnOkvhZZggsJlmnWpmFoq9s1Tvkc4EPEU6oRY4VMdVXVeQ8mzWdz%2FLnxgilZwAD1gFzExDPIBuTD3Q%2FiKpd4d%2B%2BAhHDn5NNFsFvaPb3ufKa3AeUK7qNWeO%7Ctkp%3ABk9SR8Tv3_HgYQ
1963 Rambler Classic 550
Originally a 196, this one has a 199 from a 69 American.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken_Parkman Quote  Post ReplyReply Direct Link To This Post Posted: Mar/21/2023 at 8:39pm
Basically yes, but I don't know if that is compatible with the torque tube. Someone here must have one.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Mar/22/2023 at 2:13am
Nash used a different torque tube design up until merger with Hudson and AMC in 56/57. Had a different front front yoke assembly. Jeep/Willies did not use a torque tube to my knowledge.
The add you reference is confusing as that unit may bolt to a Nash or AMC I6 but unknown is the model vehicle and driveshaft assembly. And what Jeep???
Don't believe the seller knows exactly what they are selling or what model vehicles it would fit. If they did, likely worth more money.
There were many changes once Nash/Hudson/AMC merged 56 through 61/62 until the dust settled in 63. Those few merger years had some unique parts to specific models. Even the shared engines had different motor mounting. A 57 - 63 327 had 3 different cast in motor mounts that I'm aware of. 
Your better off looking for a donor vehicle or something a lot narrower to the era of your vehicle, which will be harder to find. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Mar/24/2023 at 9:49am
That trans has the older torque tube mount used through 61. So it won't work with yours.

You need a T-96 trans with OD from a 63-64 Classic. A 64-69 American with six trans w/OD will bolt in, but you still need the torque tube adapter from a 63-64 Classic. You can't just bolt the OD unit to your trans -- there is a different output shaft and a reverse lock-out on the OD version of the T-96.

Another thing -- you would need a lower geared rear axle to run an OD trans. Most people just think OD gives you a higher cruising gear. It does, but you still need to be turning at least 1800 rpm when cruising on the highway for the engine to be in it's torque band. If you intend to cruise at 70 most of the time you want to be turning about 2000 rpm at 70 mph in OD. Then you will still be turning 1700-1800 at 55-60, and not much over 2200 at 80. The Borg Warner OD units are all 30% overdrive (0.70:1). That's too much with the stock 2.86 or 3.08 gearing typical with an auto in the early 60s. OD cars usually came with 3.78 or even 4.11 rear axle gears. So what you're doing with OD is getting a lower first gear and a bit higher fourth gear -- mainly a better spread of gears than the standard three speed.

63 Classic Six rear gears:
Manual trans standard: 3.31; Optional 3.78
Manual OD standard: 3.78; Optional 4.10

Auto trans standard: 3.31; Optional 3.78

What gears do you have?  This also begs this question: what highway speeds are you running?
The 195.6 isn't a high revving engine. You might want to get a cheap tach and install it. The sound might be deceiving! I ran mine with 3.31 gears and auto trans in a 63 American and would cruise at 65-70 at times. It's turning a good bit then -- 2800-3000 rpm. It really cruises better at 55-60 (2400-2600). Overdrive with 3.78 gears would bring rpm down to 2300 @ 65, 2400 @ 70.  With that heavier (than my American) car you really need the 3.78 gears. Even with 4.10 gears and OD 70 mph would only be about 2600 rpm. Oh, the rpm figures here are assuming 15" tires -- 195/70R15 to be exact (26" diameter). A larger diameter tire has the same effect as a bit higher axle ratio.



Edited by farna - Mar/24/2023 at 9:51am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mtrosclair Quote  Post ReplyReply Direct Link To This Post Posted: Mar/24/2023 at 7:48pm
Originally posted by farna farna wrote:

That trans has the older torque tube mount used through 61. So it won't work with yours.

You need a T-96 trans with OD from a 63-64 Classic. A 64-69 American with six trans w/OD will bolt in, but you still need the torque tube adapter from a 63-64 Classic. You can't just bolt the OD unit to your trans -- there is a different output shaft and a reverse lock-out on the OD version of the T-96.

Another thing -- you would need a lower geared rear axle to run an OD trans. Most people just think OD gives you a higher cruising gear. It does, but you still need to be turning at least 1800 rpm when cruising on the highway for the engine to be in it's torque band. If you intend to cruise at 70 most of the time you want to be turning about 2000 rpm at 70 mph in OD. Then you will still be turning 1700-1800 at 55-60, and not much over 2200 at 80. The Borg Warner OD units are all 30% overdrive (0.70:1). That's too much with the stock 2.86 or 3.08 gearing typical with an auto in the early 60s. OD cars usually came with 3.78 or even 4.11 rear axle gears. So what you're doing with OD is getting a lower first gear and a bit higher fourth gear -- mainly a better spread of gears than the standard three speed.

63 Classic Six rear gears:
Manual trans standard: 3.31; Optional 3.78
Manual OD standard: 3.78; Optional 4.10

Auto trans standard: 3.31; Optional 3.78

What gears do you have?  This also begs this question: what highway speeds are you running?
The 195.6 isn't a high revving engine. You might want to get a cheap tach and install it. The sound might be deceiving! I ran mine with 3.31 gears and auto trans in a 63 American and would cruise at 65-70 at times. It's turning a good bit then -- 2800-3000 rpm. It really cruises better at 55-60 (2400-2600). Overdrive with 3.78 gears would bring rpm down to 2300 @ 65, 2400 @ 70.  With that heavier (than my American) car you really need the 3.78 gears. Even with 4.10 gears and OD 70 mph would only be about 2600 rpm. Oh, the rpm figures here are assuming 15" tires -- 195/70R15 to be exact (26" diameter). A larger diameter tire has the same effect as a bit higher axle ratio.


That does seem a bit more complicated than I thought it would be, I wonder if the juice would even be worth the squeeze?
1963 Rambler Classic 550
Originally a 196, this one has a 199 from a 69 American.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FSJunkie Quote  Post ReplyReply Direct Link To This Post Posted: Mar/25/2023 at 3:04am
Tire size can make a big difference. The original bias ply tires were really tall, which brought down the engine RPM. Radials (even 75-series) are shorter and wider. The only way to match the height of the original tires with a radialis to go extremely wide with radials, and that has its own problems. 

You are in the dark without actually putting a tachometer on it or finding out what axle ratio it has. Sometimes things sound like they are really winding up when they aren't. Anything under 3500 RPM sustained should not be a problem but staying under 3000 is nice. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Mar/25/2023 at 8:09am
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...
Frank Swygert
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