The Columbia with the 3:54 will only add to the possible top speed. I can imagine doing 75MPH+ in a '40 Ford. I can't imagine. stopping and / or steering well in case of an emergency.
Personally I like a 3:78 with a Columbia. Allows the car to cruise well at 60MPH and still can move away from corners nicely.
I switched it over to 4:11's when I started driving it.
After I "hopped it up with a Mercury "stroker" engine, I jumped up to 3.78's. I don't know what the "terrain" is like where you live, but If you "elect" to go with your Columbia, I'd just make sure you have a low enough ring and pinion ratio to accommodate the terrain.
If you live in the "flatlands" like I do presently, I'd "skip" the Skyway Drive, and keep it simple with the 3.54's.
and 2) With whatever gear you choose will the OD reduction still keep the vehicle in the optimum torque range for your targeted driving conditions? If not you will find yourself excessively shifting into and out of OD.
3.78 is my choice as well - have to agree with Mike. Without an OD plenty of torque and pep around town/off the line and as well comfortable cruising at 60 mph actual/2,500 rpm on flats or in the foothills and mountains. Plenty of flexibility when taking long tours such as driving several hundred miles one way to a national meet. If I had a 30% reduction Columbia, which I do not, but if the '47 did, the car would realize 1,750 rpm at 60 mph (very low in the optimum torque range for a 59AB) and shifting into and out of OD frequently would be realized, particularly here in central and western NC. With a 3.54 around here - and getting anywhere out of the state - this problem would be worsened more, and worsened even further with additional passengers and/or luggage/loading.
To Mike's other point - once, and only once, I pushed the car on a rare, local 4 mile straight to see what it would do after making it (suspension/front end/shocks/tires/brakes, etc.) mechanically and functionally safe to drive/as new. Never floated the valves and backed off (well) north of 4,000 rpm (leave it to your imagination on actual GPS speed - I'm a bit embarrassed to admit I did this). The moral of the story here is this was way, way WAY more than enough to convince me 60 mph is the MAX from handling and safety perspectives, hence no need for an OD. Scary to think what might happen in the event an emergency move might be required above 60 with these 3,200# boats - on bias plys or otherwise.
Just helped purchase a '40 Deluxe recently (with kubes40 help and advice) with a Columbia and 3.78 gears. The owner, a colleague of mine, has driven it 1,800 miles so far and other than shifting the Columbia to confirm functionality he has yet to find the need to use it in practice. He too limits his top speed to 60 mph and likes the torque he has at this speed.
Just further food for thought. Cheers -
Steve
That is the combination using 6.00/16 tires along with a stock motor that I run in my '39 coupe.
When running in normal third gear without the Columbia engaged, the RPM's are around 2600 at 55 mph. Engaging the Columbia the rpm's drop to
around 1880 rpms. That, in my opinion, is the beauty of the Columbia. Less wear and tear on the motor and the corresponding noise reduction is perfect. Also, it seems that 1850/1900 rpm's is right around the bottom of the power/torque curve which allows nice acceleration in a passing situation if needed.
Ken
Not being experienced with the Columbia as Ken/others, are they available with differing reductions (say 33%) and if not what is the 'standard'?
Steve
In "the day", (early 60's) I regularly drove my 38 Station Wagon at 70 mph on our newly-constructed Southern California Freeways.
To do "otherwise" would have gotten me rear-ended. The "beauty" of the Columbia was that the motor just "loafed-along" at those speeds even with my 3.78:1 gearset.
When I had the 4.11's installed, I mostly ran the car in overdrive unless I was challenged to accelerate.
Today, we'd call the motor I had a "full-race" engine, and (because of the lack of low-end due to camshaft timing);
I NEEDED that "low range" to get off the line quickly.
A word of caution though. Unless you have one of the "modified" Columbia's with the strap around the planetary gear set case; DO NOT attempt to "take-off in a hurry" from a standing stop in Low-Over.
I once split the differential gear case on my Columbia doing that. EV8CA member John Connoly http://www.columbiatwospeedparts.com/ makes a strap-reinforced planetary to "solve" this issue.
Regarding the overdrive "ratio" Steve, Columbias are ALL 30% overdrives.
This message was edited by Stroker on 4-28-17 @ 9:35 AM
With the dash mounted control pushed in (for direct drive), the sliding clutch in the rear axle locks the sun gear and the differential case (in which planetary pinions are mounted) so that the entire planetary gear system (sun gear, pinions, and outer internal gear) rotate as a unit and the ring gear drives the rear wheels directly.
When the clutch is released and the control pulled out to the overdrive position, the vacuum cylinder pulls the sliding clutch out so that the differential case is free and engages the stationary clutch plate so that the sun gear is prevented from rotating.
The ring gear then drives the differential case and pinions, and the rotation of the pinions (on the stationary sun gear) causes the internal gear and the axle shafts to revolve at a faster ‘overdrive’ speed.
Steve
I believe that given your plethora of gear-sets, I would put the 3.54's in and join the "modern world". Given the fact that most of what we drive upon is occupied by cars running 70+ mph, it will help you survive.
The only caveat would be if you are confronted with lot's of hills, or high altitudes in your home neighborhood. If you are, I'd stay with 3.78's.
Like you, I have a choice of available gear-sets; 4.56,4.44, 411, and 3.78's. I do not have a set of 3.56's however, but if I did, I'd install them.