[tabrinn]

I have a 67 Country Sedan with a bone stock 289 2V and 3.00 gears. I want to install an overdrive tranny but I'm concerned it might bog down the 289. Has anyone experienced this?

I have 2 AOD's that will probably need gone through but I'm also considering a low mile 4R70W out of a 4.2L F150. The 4R70W has a better 1st gear ratio but I'd need an electronic controller.

 

[wingnut_rb]

I had the same gearing and motor in my 66 custom 500. I put in the AOD and swapped gears to 3.50. I'm going to switch to 4.10. That way 0-60 is funner but also, once you hit OD, you're turning RPM's like you're running 2.75 gearing.
I think with the 3.00 gearing with an AOD, it's not going to stay in OD very long. It'll be like running 2.01 gears depending on which AOD you have.
In short, whether you are going AOD or 4R70W, you're going to want to swap gears.

 

[Mroldfart2U]

What wingnut says... 3.00 gear with the O/D is a poor combo. As he stated I wouldnt think the O/D would really be effective unless you are running way over the speed limit. The 4R does offer a little better ratio in the lower gears, but it will be the same in O/D as the AOD for the most part. M2C.....

At the minimum I wouldn't over drive with any thing less than a 3.70's range rear gear. MO..




MRO.....

 

[PSIG]

You won't lug it with an OD. I ran a 2.75 rear with OD for a few weeks, and it was very happy, though it was a stock 351W 2-V. But, based on the power for cruising, I don't think the 289 will mind at all, and the 351 could have used a second OD gear at times. Seriously. My point is, you can start with the 3.00s and take it from there without worrying about over-gearing just to drive it. To get perfect gearing for efficiency on the highway, you would likely need to move to 3.25 or 3.50 gears to use the torque peak of the stock engine if your tires are 26" or more. If it were modified in any way, or performance was a large concern, then I'd agree to move to deeper gears.

BTW - the wide-ratio of the 4R will lower your first gear to make the equivalent of a 3.30 rear gear. That alone makes the 4R more fun. The lockup will make it more fuel efficient as well, offsetting some of your investment over time. If you have the cash and desire - do it.
My 2¢.
David

 

[JEM]

I do think you're going to find a 3.00 rearend very tall with the OD.

Let's do the numbers.

With a 27in OD tire your rear tires are turning 770 RPM at 60mph.

Multiply that by 3.00 and you've got 2310 driveshaft RPM.

Now multiply that by 0.7 and you've got 1617 engine RPM at 60mph, and 2156RPM at 80mph.

That would be pretty tall gearing even by modern standards, and most modern vehicles are going to have a substantially better power to weight ratio than your 2bbl 289.

The 4R70W is a good idea, but I think you're eventually going to want at least 3.50 gears.

 

[PSIG]

Actually not - by modern standards. What did you get with a 1980s and up Mustang (stock with OD)? 2.73, 3.08 and usually 3.27 in the GT/HP versions. Even my truck has 3.08 gears and auto OD with 28" tires. The big ol' Crown Victoria (Panther chassis) is standard with 2.73 and the 4R70W, with later years 3.08 or 3.27 for Police Interceptor versions.

Anyway, I could go on, but the point is that the 1967 289 2V had a camshaft that had a torque peak of only 2200 RPM. That would indicate an efficient cruise range of 1800 to perhaps 2500 RPM at highway speeds, and even lower RPMs in-town at lighter loads. Many of us have driven stock Fox Mustangs with 2.73 or 3.08 gears, a 302 with a 2400 torque peak and OD. How many issues?

I'm not trying to argue here, but the numbers really do add-up - even with my adding tire diameter and suggesting slightly deeper gears in my previous post. Don't forget - the OD does not engage unless the speed and RPM dictate, and will only use it when advantageous. In this last sense, it really isn't an issue of lugging the engine - it won't engage under those circumstances.

David