Packard Forum Index » Post-War (1946-54)

Hello,

I would like to add overdrive to my car. What is needed? Thanks.

John

For the easiest and quickest install a complete transmission with R11 overdrive from a 48-50 junior model. The overdrive is integral with the transmission and can't just be bolted on to your existing trans so you need the complete assy. Junior models (288/327 engine) are needed because 47 and earlier 356 engine trans/ODs have some different heavier parts that would need to change to fit the smaller engines and I believe the same was true for the first of the 48 356s and maybe all of them. You want the R11 OD which was introduced in mid 48 instead of the earlier R9 because it is a much simpler unit both mechanically and electrically and parts are easier to find.

A parts car would be nice because you could see how everything mounts and there are some small pieces you could grab but most of those can be worked around. Once you have the transmission/OD, for a complete factory type install you will need the lockout cable assy and all the electrical components. If you cannot find a parts car or a complete removed system most electrical for the R11 except the governor and lockout cable and switch is in repro although some of the pieces are a bit expensive. Modern components will also work for some of the original electrical items. Some changes to the driveshaft and speedo drive cable will be needed and some of the rear mount or stabilizer pieces are different.

Typically the overdrive cars also had a different rear axel ratio which provides faster starts from a full stop and more power at lower speeds. The non-OD ratio was something of a compromise so best to change the rear end too.

Respectfully, absolutely do n o t change your differential. It is a blessing in disguise if you're installing overdrive. Many install the slightly taller, more long-legged ring and pinions from cars leaving the factory without overdrive in overdrive cars for still more relaxed cruising on today's highways. There were Hudson dealers out West whose service departments often did this after the war for those driving long trips on increasingly faster roads, and imagine this done at Packard service departments, too. It is hard to over-gear a Packard, unless you live in the mountains and travel with a pair of Sumo wrestlers. You can always downshift, but it's a real drag to "run out of gears."

As late as 1950, most manual shift automobiles retained trucky rear axle ratios because not having to downshift, doing most driving in third gear, was a mark of refinement to people born or who came of age when horse-drawn delivery wagons still shared the roads. When your Packard was built, we still had speed limits as low as 35, and 60 was really moving. To many people, a little snappier acceleration was more important than reducing sustained piston speed.

This is not encouraging you to cruise at 80 mph, because brakes that were good for 1950, even by early '60s standards, are no match for today's ABS four-wheel discs and more crowded roads full of cellphone nattering, texting, tweeting folks eating, drinking, putting on make up. Well adjusted drum brakes can stop you as fast as discs, but can fade if repeated fast stops on mountain roads.

The other advice above is what you need. Jeff Adkins, Moose Motors, Penngrove (Petaluma, CA in the North Bay) has everything you need. (707) 792-9985, packardguy54@sbcglobal.net
Please tell him a '47 Super Clipper in Walnut Creek referred you.