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My '41 Packard club coupe seems to be geared low as the top speed is 45-50 mph.

Thus, it is not safe for interstate travel.

Rather than finding an R-9 of R-11 overdrive unit, is it possible to put in a different gear ratio that will give my car another 15 mph?

I am not a mechanic so I do not not if the higher speed rear end is out there.

Suggestions are welcome, Thanks

Is your car a 115 six, a 120 eight, or one of the "senior" cars?

What size tires are you using?

Being the thread is headed up for a '41 110 Coupe, it's a 6.

And Frank D Roman,
to PackardInfo. I invite you to include your '41 110 Club Coupe in PackardInfo's Packard Vehicle Registry.

The standard axle ratio for the 1941 110 is 4.3 to 1. Optional ratio is 4.55 to 1, and overdrive equipped cars came with the 4.55 to 1 axle.

The 1941 120 series cars had a 4.09 to 1 axle as standard equipment.

A 120 series axle would probably fit under your car.

The 110 cars came with 6.50 X 16 tires, while the 120 cars came with 7.00 X 16 tires. The 7.00 X 16 tires are larger in diameter and will reduce engine speed at any given road speed somewhat. Some 7.00 X 16 tires are 31" in diameter, while some 6.50 tires may be closer to 28" in diameter.

The ideal setup for your car would be to install the overdrive transmission with the appropriate axle ratio. Changing tire sizes or axle ratios will affect speedometer accuracy.

The first thing you need to do is to determine exactly which axle ratio your car presently has.

The 120 axle is a different animal.

Best you join The Church of the Holy Overdrive. You will think an early taste of Heaven.

You can't beat an overdrive. With OD, you get better low speed performance plus a high speed cruising gear. You also get an on-demand "passing gear" which allows for quick pickup at speeds under 60 MPH or so.

With overdrive and the correct overdrive rear axle ratio, the car will be easier to drive in traffic and have better pickup at speeds from 5 MPH to about 35-45 MPH. Out on the highway, the engine will run about 25% slower in OD than it would with a standard transmission and axle, and much slower than a car with the optional low geared axle and no overdrive.

The car should be able to cruise at 65 to 70 MPH in OD under most conditions, assuming it is in good mechanical condition.

You get a quieter ride, longer engine life, and better open road fuel economy.

Any leads on acquiring an overdrive unit for my 1941 club coupe , 6 cylinder is appreciated. The tire size is 205/75/R15.

Thanks, Frank

Bill Aske, Parkton, MD.

I vaguely recall seeing an o/d unit for a 110 for sale somewhere recently - as in, in the last several weeks. Now if I could only remember where.


I'll agree that an o/d unit will help save on engine wear, but Packards guzzle fuel. It was one of the customer bitches for years.

"The tire size is 205/75/R15."

This may be part of your problem.

A smaller diameter tire will cause the car to move slower at any given engine speed in high gear.

A typical 205 75 R 15 passenger car tire will have a nominal diameter of 27".

A tire similar to what came on your car would be a 6.50 X 16 bias ply with a diameter of around 29.5".

A 7.00 X 16 tire of similar construction would have a diameter of about 31".


The larger diameter tire will roll farther with each turn of the rear wheels, allowing the car to go faster at any given engine speed.

I'm pretty sure your car came with 16" wheels. If it did originally have 15" wheels, the same math applies.

A 7.10 X 15 tire of the correct type for a 1941 Packard would have a diameter around 30".

I suggest finding out exactly what wheel size your car originally was equipped with, and what tire sizes were standard.

Detailed information relating to original equipment is available on this website in the Literature Archive.

Your car will ride and handle very well with original-type and size tires, and if your car has the standard axle ratio, you may find that you don't need to make any changes other than installing correct-size wheels and tires.

That said, the overdrive is a wonderful adjunct to any car, and is especially nice to have on pre-WWII cars.

If I owned your car, I'd want the correct wheels, tires AND the overdrive.