65 GS TKO 600 5-speed Conversion

[Rollaround]

Great info and well presented.  It will be a completely different ride.

[wildcat65]

Greetings Marty
How is this going?  I'm curious about how the 4.11 gear is working.  I'm torn between the 3.42 and a 3.91 for my Tremec conversion on a 65 Wildcat.
3.42 is in the car and I'm about to try it out finally - started this in like 2003.

[moteaux]

My selection of gear ratios--transmission and rear end--were based on the 401 torque curve. I love the low RPM high torque of a 401. Said differently, I love the drivability of a muscle car with max torque at a low RPM. And the combination of a TKO 600 with a 0.64 OD gear and 4.11 rear end gears is nothing but pure fun around town. It is also a ratio combination that makes interstate driving reasonable and practical. In hindsight, I would not change anything. Therefore, I recommend you go with 3.91 gears.

You will hit the max torque of a 401 at ~2,800 RPM. Your tire height matters. I used my tire height (255/45 R17 = 26.04in) and the rear end gear ratios your considering for the calculations below. I used the Tremec Toolbox App to do this.
Pic 1: Tremec Tool Box App
Pic 2: 3.42 rear end gear with a TKO 600 (0.64 OD Gear)
Pic 3: 3.91 rear end gear with a TKO 600 (0.64 OD Gear)

I would get the Tremec App or find a calculator to play around with gear ratios to fit the kind of driving you would like to do with the car, keeping in mind the 401 torque performance curve.

[WkillGS]

Greetings Marty
How is this going?  I'm curious about how the 4.11 gear is working.  I'm torn between the 3.42 and a 3.91 for my Tremec conversion on a 65 Wildcat.
3.42 is in the car and I'm about to try it out finally - started this in like 2003.

The difference in first gear will be noticeable.
Your 'First gear starting ratio' is 1st gear multiplied by the rear ratio:
2.87 first x 3.42 rear = 9.8
2.87 x 3.91 = 11.22
General recommendation is around 10:1 for a street car.

A 9.8 ratio is ok, might have to slip the clutch a bit to get the car moving.
A 11.22 ratio would get the car moving from a stop easier but it will be a short first gear.... you'll have to shift into second at a slower speed.
You're likely running tall tires which will affect the above a little.

At the other end, compare your highway speed/rpm to see which works better for you.
You have some other stick cars, so do that 1st gear calculation on those for comparison.