Has anyone ever seen an overdrive adapted to a 1937-48 Cadillac or LaSalle transmission? I have a '37 LaSalle and would like to put an overdrive in it.
There's been a couple conversions built. Ak Miller's Iron Horse Mexican Road Race T had one, and there's one here in town in a '40 75 series formal car. Maybe search the details of the horse
I'd sure be interested in learning about one in the '40 75series car...but I am not hip enough to know what "search the details of the horse" means, so if you could inform me I'd appreciate it. And/or if you know the name of the person who owns the 1940 car I may be able to contact them. Thanks.
Carl, 302 meant to search for details of the Caballo de hierro model t bodied road racer that Ak Miller built. I've read probably all the articles on it in the old magazines and very little detail was given on the overdrive other than it being from a 35 Nash chosen because it had more planetaries making it stronger.
The '40 owner & I aren't close … Iron Horse .. Everything I've read so far was from magazine articles - same info as Joe posted. One of the hardback history books surely has more detail. I'm certain one of our older mentor-type members knows who most likely did it. It's not in any of the Don Montgomery books, though he may help us out, I hope … Over the time period starting '53 until into the 60s, quite a few HRM & Car Craft articles covered adapting various tail ends to the Cad box, such as both Chev & Ford torque tube, & '50 Olds short tailshaft. The basic operation to add OD would be comparable - determine if the front of the OD & rear of the Cad come anywhere near matching. Then comes the drilling, tapping, plugging, welding, shortening, re-splining ...
I would think it was probably a matter of shortening and resplining the output shaft to match the overdrive and some sort of plate adapter or possibly redrilling the case similar to adapting the cad/lasalle to a Ford torque tube.
Almost all, if not all, American automobiles used Borg Warner overdrive units, most being either the 3 planetary 'standard' R10 or the stronger 4 planetary R11 model. The latter can be found (not necessarily easily) on late '40s through early '50s Lincolns, 'mid '50s Mercury and Ford T-Bird, typically when equipped with 312 engines. There are subtle transmission main case differences between with and without OD that would have to be taken into consideration in an adaption. There is another route to explore that may be 'easier' in some respects. The Gear Vendors over/under drive unit is comparatively easy to adapt to a variety of transmissions. It is a self contained OD that bolts to the back of (more commonly) automatic transmissions in place of the tail housing. It is 'shifted' via an electric switch. I can imagine that being a feasible adaption to your Cad/LaSalle gearbox. It would almost assuredly require some machine work, at a minimum, and possibly fabrication of an adapter plate. But if you want an overdrive unit, imo it would be worth investigating. Ray
I've got a Borg Warner R10 behind a 1937 LaSalle trans. The adapter was built by my father, but I do not know a lot about any machining of the internals that might have been required. If I am feeling adventurous, and decide to disassemble it, I will post pictures. It definitely can be done.
Thanks so much. I found several photos of the adapters, some home made and some were commercial. I am installing a Tremec 5 speed so have scrapped the LaSalle transmission idea. My engine is a 500" Cad with too much torque for the LaSalle trans, but I sure do like its looks and stick..will have to settle for the Tremec which was pricey.
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