Transmission / Overdrive: Best Rear Axle Ratio To Use With 700R Or 200R Transmission

[JoeHall]

I am guessing "best" is gonna be subjective, but what is the general census of those folks who have installed them, as to best ratio to run with a 289 motor in front?

Thanks,
Joe

[tempestan]

It's my opinion via experience that a rear axle ratio in the range of 3.50 is almost ideal for most applications for passenger vehicles. tempestan

[sweetolbob]

The 700R4 was installed in large vehicles with 2.89 to 3.07 rear ends so for a cruiser Stude that would weigh less I'd use a 3.07 or so. 3.31 to 3.55 with the 2004R.

Bob

[RadioRoy]

When Studebaker put overdrive stick transmissions behind 289 V-8 cars, they generally used 3.73. A stick overdrive is a 30% step up so that makes the final ratio in overdrive about 2.61.

Do you know the step up ratio for the 2004R? Also, does the 2004R have a locking torque converter, or does it have some slip at speed?

[M. Miller]

Depending on how much pick up you want and your tire size my guess would be around 3.50.

[rodnutrandy]

I am running a 3:73 with a 700r4. Very happy, peppy at take off ,cruises easily down the road.

[41 Frank]

A 3.73 works well, on my R-2 295 Cube Stude engine I personally use a 4.09 ratio behind my 200 4R and even it only shows 2350 RPM at 65 MPH with 225 75 15 tires. Used a 3.73 for a while but wanted more get up and go. With the 4.09 rear gear my final ratio is something like 2.87 to 1 in OD lockup. My 52 V-8 232 overdrive equipped Commander came with a 4.55 rear gear as did many cars with similar equipment in their day, 4.10 gears were common too. Granted those vehicles were down on displacement and horsepower but my 52 has no problem running down the highway at 65-70 mph without sounding like it will fly apart.

[PackardV8]

Best Rear Axle Ratio To Use With 700R Or 200R Transmission - I am guessing "best" is gonna be subjective, but what is the general census of those folks who have installed them, as to best ratio to run with a 289 motor in front?

Joe, you're usually more interested in fuel economy and quiet cruising than drag strip performance. If that's what you want, go down to 3.54 or 3.31. With the converter locking option, the 700R4 is effectively a 5-speed, and with the low first gear it can pull strongly with the taller gears.

The 200-4R has closer ratios and thus is more a performance transmission, so it won't pull the taller gears as well off the line.

jack vines

[wittsend]

As was already mentioned tire size factors in. For good or bad the first gear in the 700R4 is a rather low 3.06. So the car should still move off decently regardless of the rear ratio. I believe the B/W Studebaker trans had 2.40 first gear. Use a calculator and see what numbers you get. But, again, remember that tire size is also a factor - significant at times.

The most likely concerns would be the shift into the taller 2nd gear as there is quite a gap between 1st and second. The other would be the effects at cruising speed. My 700R4 swapped car is not on the road yet so I can't relay my experience. I have taller 225-60-16 tires and 3.07 final drive. A calculator had the engine turn about 1,650 RPM at 65 MPH. Only time will tell how it works out.

Tom

[plwindish]

I've been happy with the 3:31 rear end behind the 200 R4 in my 76 Avanti. 70 mph is 2000 rpm's versus 3000 rpm's with the THM 400 it replaced.

[Mike Van Veghten]

3.73
This is according to "many" sellers of these transmissions. Not just a single persons thoughts. It gives the best final ratios in both 1st gear and 4th gear.
I've spoken to a hand full of 200-4R remanufacturers over the last coupla years, and they all seem to agree, 3.50 is the minimum, 3.73 is the best overall ratio. This (3.73) is with a 25"/26" tall tire. Smaller thAn a 25" tire, 3.50 might be better.
I'd bet...no one would be happy with less thAn a 3.50:1 ratio. WAY to low an rpm on the highway/freeway.

My three 200-4R cars, one at 3.73, one at 4.11, one at (currently), 4.11, but it's a 15 minute job to change gear ratios..! All street driven cars.

Mike

Hmm..I see the answer just before me likes 2000rpm on the freeway. That's not even anywere near a good part of the torque curve. That's still the acceleration area..!
2700/3000 at 70/75 is a good spot for these engines.

[PackardV8]

[quote02700/3000 at 70/75 is a good spot for these engines. [/quote]

Mike, there are shades of difference on this one. Yes, the stock 225hp 289" V8 makes maximum torque at 2800 RPMs. If instant throttle response is the goal, then yes, go with the 3.73.

However, for maximum economy today's 6, 7, and 8-speed auto transmissions/axles are geared to run around 35+ MPH per 1,000 RPMs. That would be 2,000 RPMs at 70 MPH. The Stude V8 will pull that on the flat or gently rolling highway. In the hills, let the torque converter unlock and the transmission shift for itself.

Because I know Joe is more interested in fuel economy and longer engine life than max performance, that's why I suggested he might go with a 3.54 or 3.31. Those would give 2.48 and 2.32 respectively in overdrive fourth gear. Joe has run similar gears in his '56J, so he understands the tradeoffs.

jack vines

[plwindish]

I probably don't notice being in the low end (2000 rpm's) versus 2700-3000 rpm's because of the 400 motor in the car, which has plenty of torque.

[wittsend]

I'm not advocating this, but in my searching the Camaro came with the 305 engine, 700R4, 16" tires and 3.07 gears. In fact they were even available with a 2.something ratio also. Since I have a late Studebaker with the Chevy engine (and now upgrade from a 283 to a higher torque 350) I assume the 3.07 (installed) will be acceptable. Can't wait to drive it (someday) to know for sure.

BTW, Mike Van Veghten, how do you change a (presumed) Dana 44 gears in 15 minutes? What's the secret?

Tom

[JoeHall]

Thanks for all the input folks. Y'all are a wealth of experience to draw from. I have experience mostly with T85s, and converted one 56J Ultramatic over to a TH400. But the AOD seems like a different animal. I also wasn't sure about parasitic loss of HP with these trannys.

I am thinking 3.54 may be best, and 3.31 next best for a 700R; a 3.73 best, and 3.54 next best for a 200R. Other than the 3.07 under the car now, I only have a 3.31 on hand, so that is probably gonna be first pick.

I plan to wire the TC to where direct drive kicks in/out off vacuum, with an electrical over-ride option, per TCI's kit.

I plan to use a 700R due to OEM strength, availability and price. Looking at CL, if I shop locally, a recent, low mile rebuild from a wrecked car or truck should be no more than around $450. I figure another $1000-1500 for the rest of the miscellaneous.

That's the basic plan, but will see how it goes. I don't plan to start the mod for another month or so, but am chomping at the bit to get started. Just need to gain a little more confidence in the car first (wife's 63 GT).

Thanks Again,
Joe