The Columbia 2-Speed rear axle was developed in 1934 for Ford products, and with improvements, it was eventually made available as an option on Mercury and Lincoln Zephyrs (see S1A #21, p. 46). It was also standard equipment on Lincoln Continentals . . . and remained a Ford/mercury option right up through 1948. The Columbia 2-speed axle offers approximately a 30% overdrive effect . . . which means you can combine a typical Ford 4:44 or 4:11 standard rear end ratio with an economical 3:18 or 2:94 alternative for high speed cruising.
If your shifter happy, the 2-speed rear actually works in any gear, giving you six forward speeds to play with. Mostly though you'll use it only in third, approximating the feel of a wide ratio 4 speed. In the early fifties, before specialised gears became widely available, the columbia was popular with hot rodders, for it gave them a super-tall digger gear for darg racing., but a reasonable ratio in fourth for highway cruising. Though you probably wont be doing much racing with it, the same dual ratio feature improves the driveability of any early V-8 Ford.
The principle behind the Columbia 2-speed is simplicity itself. A mechanically-operated, clutch actuated vacuum line connects to a plate beneath the carburetor. It runs back to a vacuum canister attached to a set of planetary gears. These live in a modified banjo housing added to the Fords right hand axle. When driving, presumably in third gear, you merely step on the clutch, pull the dash mounted "overdrive" knob and pause a second for the vacuum unit to shift gears . . . with a klunk. Release the clutch, and youre in "fourth".
As a Ford option, the Columbia sold for a reasonable $100 throughout the Fourties, though it cost a bit more if you wanted to install it yourself. But installing a Columbia overdrive axle while requiring more mechanical skill than changing a windscreen wiper is definitely not a hassle if youve got the proper equipment. And its useful, economical option. If you own one of the cars the Columbia fits, you should seriously consider it. There cant be amore desirable, authentic Ford accessory.
To install a Columbia axle, the stock rear end must be removed from the car and completely disassembled which really isnt so drastic as it sounds. Just drain the rear axle, unbolt the springs castellated nuts from the rear crossmember and disconnect the brake rods (or hydraulic lines). Then disconnect the speedometer cable and carefully free the front of the torque tube.
After removing the rear wheels, slide the stock rear end and torque tube out from under the car with a floor jack. Its important to jack the car high enough so that the splines on the back of the transmission are free to let the torque tube slide off. And that means high. Removing the wheels and setting the axle down on the jack facilitates its release, though, once you get the car up in the air.
When you have it removed, lay the rear axle assembly on the floor . . . or put it on a large work bench. The transverse spring requires a spring spreader or Porto-Power to get it loose. Youll also need a special tool to remove the shackle plates. Happily its easily available from Dons Antique Auto Parts, 37337 Niles Boulevard, Fremont, California 94536 . . . for a mere $15.95, post paid. Be sure to specify the make and year of your car.
To split the banjo housing, remove the cotter keys, pull the axle nuts off, and using an hub puller get the hubs out. Disassemble both the left and right axle housings, and then disassemble the ring gear from its stock carrier and remove it. When we did it, we took off the torque tube and changed the ring and pinion as well. This is necessary only if you plan to change the rear axle ratio at the same time.
Assemble the 2-speed rear axle assembly to the right of the stock Ford banjo. Clean and oil all the components well before you try to assemble them. Then carefully insert the Ford axle shaft through the 2-speed unit. Reassemble the Ford differential pinions to the Columbia spider using the four special thrust washers. Make sure theyre well lubricated. Now assemble the spider and differential pinions (with washers already in place) in the Columbia section. Make sure the pinions mesh properly into the side gear.
Next install the Ford axle shaft through the original Ford ring gear and bearing assembly. Bolt this assembly to the Columbia differential. Be careful to use the proper thrust washers . . . and be sure to safety wire all drilled bolts after tightening them. Replacement of the axle seals is next. Then carefully tighten both the left and right axle housings. Be sure everything is free and nothing binds.
Carefully install the vacuum canister on the Columbia housing. Check to make sure that the shifter arm from the 2-spee unit meshes properly in the canister plunger. Install a hose clip on the right hand side radius rod for the vacuum line, and youre ready to install the axle. At this point, slide the rear axle under the car, connect the spring to the crossmember and hook up the torque tube, shocks and brakes.
The vacuum control unit can be mounted on the steering column or on the cylinder head studs. Usually, youll have to make up a custom bracket in order to fit it on. Once the control unit is snugly in, hook up the clutch rod. Then install the vacuum plate under the carburetor . . . you may need longer bolts in order to do this.
Run 3/8" copper tubing carefully along the left side of the chassis to the shifting canister on the Columbia housing (youll need about 16 feet of copper tubing and five feet of rubber hose). Be sure all connections are tight . . . and that the tubing is securely bracketed in a number of places. Check to see that it isnt kinked anywhere. Finally, install the control switch under the dash board. Its cable serves both the vacuum control unit and the dual-ratio speedometer cable adaptor at the same time.
Although its a perfectly straight forward installation, there are a few important things to note: the clutch pedal valve must not open until the engine clutch is completely disengaged; there should be ½" minimum pedal travel from the disengagement of the clutch to the opening of the valve; and dont forget, the larger Columbia assembly requires 4 ½ Pints of lubricant, as apposed to the stock rear ends much smaller2 ½ Pint capacity.
Classic Motorbooks, 3106/R21 West Lake Street, Minneapolis, Minnesota 55416, sells an excellent reprint of the original Columbia installation manual for only a dollar. And the early Ford V-8 Club of America reprinted the same Columbia manual in its July/August and September/October 1969 issues. If you think you need a more detailed set of instructions, its a wise investment. Write the club directly at Box 2122, San Leandro, California 94577. Unfortunately, many NOS parts for Columbia axles are no longer available, However, dash controls and rebuilding kits for the vacuum chambers are available from adveriswers in Hemmings Motor News, and Wayne Kopinski, 2998 Lyde Street, Scotch Plains, New Jersey, has a stockpile of some parts. Used Columbias often appear in HMN, as well . . . and also at flea markets.
Today the price of a good-condition, complete assembly ranges from $150 to $275, But if youd like to get top efficiency from your early Ford V-8 . . . not to mention less engine wear, lower operating temperatures and quieter highway cruising . . . the Columbia 2-speed is the best answer. Its a distinctive, practical, original accessory thatll add value to your car . . . not to mention the subtle prestige of an "overdrive" button on the dash.
1. First drain differential, then
remove four castellated nuts holding rear spring to crossmember.
Also remove brake rods (or hydraulic lines) and shock arms. (Ray
Figone, our mechanic is in foreground. John Cavagnaro, the car
owner is behind him.)
2. Remove speedometer cable and free front of torque tube.
3. After taking off wheels, slide
stock rear axle out from under car on floor jack.
4. Spread transverse spring with spreader or Porto-Power and remove spring.
5. Crack wishbones up front and
remove both axle housings. Youll need a wheel puller to
6. Unbolt ring gear from carrier and remove. Now take off right axle hosing and remove axle. We took off the torque tube to make a ring and pinion change, but removing the torque tube isnt absolutely necessary.
7. Install Ford banjo housing
on Columbia (new right hand) axle housing.
9. Replace axle seals, re-install
left axle housing, bolt on right backing plate, then key and bolt
10. Re-install spring, replacing any worn or threaded shackle bolts. Youll need special tools top get shackle bushings in and out.
11. Install vacuum canister on
Columbia housing. Be sure shifter arm from 2-speed unit meshes
in canister plunger.
12. Button up rear axle and slide back under car re-install.
13. Vacuum control unit fits on
steering column or head studs, and often the mechanic will have
to make up his own bracket.
14. Hook up clutch rod to vacuum control unit.
15. Copper tubing carries vacuum
from plate under carburetor (to be installed) to shifting canister
on Columbia housing.
16. Tubing must be fastened carefully along frame rail. Avoid kinks.
17. Install control switch on
dashboard, with cable serving both vacuum control unit and dual-ratio
speedometer cable adaptor.
18. Finally, heres a detail of the firewall installation showing alternate speedo cable, vacuum line and mounting bracket.
(Our thanks to John Cavagnaro, Stockton, California; Joe and Don Peirano and ray Figone of peiranos Garge in Stockton; and Okie Joe, also of Stockton. Thanks as well to Vince Mungillo, Kaplans Auto Parts, Cleveland, Ohio.)