Which rearend gear do you think???

blown65 said:

its about 26 inches.

Ford AOD 4-spd automatic

2.40, 1.47, 1.00, 0.67

.67 OD at 60mph with a 26" tire is right about 2500 rpm with 6% figured in for converter slip.

28" tall would be about 2300 with 6% slip figured in. Could have more slip but still its close for most purposes.

For comparison, my 65 when it had a 3500 stall converter at 60mph with 3.89's turned right about 3200rpm. Thats with 6% slip figured which is pretty much dead on to what I saw. With my 4.56 gears now though, I see 3800 at 60.

TCI - TECHNICAL INFORMATION: Racing Calculators

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If someone is using an AOD (or AODE/4R70W), most times they're using the lockup converter (I know I am), so there wouldn't be any slippage in OD.

In my 70, I'm using a 4R70W and with 3.00:1 gears and a 25.7" tire, I am turning 1920RPM at 70MPH in OD w/convert clutch engaged.

With 3.50 gears, that same combo would be turning 2240 RPM and with 3.70 gears it would be about 2370 or so.

Keep in mind--these are real world figures, and this is at 70, and I am using a tire that is slightly shorter than 26"

The 4R70W has slightly different gear ratios: 2.82 first, 1.55 second, 1.00 third and .70 OD, which means that with an AOD, you'd be turning a little bit less than what I am seeing, but really not worth mentioning.

ya, no lockup converting in ours, but its slip is pretty minor at cruise anyways.