Question Hello Dick, My car has the 4:09 rear which I would really like to up to a later Packard carrier. Some sketchy info. I got recently suggested that the 53-55 cars with ultramatic.s used 3:07 or 3:54 rears.
I'm trying to find a way to change the carrier but not the whole axle. So, the real question is, is there anyway that those later carriers could be adapted to the 40 housing and axles? Thanks in advance for your time.......... Fred
AnswerYou are correctly informed, the Ultramatic equipped cars usually had 3.54 rear axle ratio differentials. The other ratios were available on special order, but having driven a 55 with 3.07 gears, I don't advise it! It was very slow off the line, and very difficult to get rolling without stalling the engine; also, clutch life would be very short.
I do not know for sure if it would be possible to put a later gearset into your 120 rear end, but I very much doubt it. If you have the parts book for both the donor car and your car, you could compare individual part numbers between the two units to see what if anything will interchange.
Your 4.09 ratio means the car was delivered with an overdrive transmission - which gives you an effective ratio of about 3.10 in overdrive, which is about all that engine can pull - I strongly advise you to leave it alone, and if you can get your overdrive working - you'll find the car will go along at modern speeds very easily, and get decent gas mileage doing it. I have a 4.09 in my 47 Custom Super limousine, with overdrive, and I get a consistent 17-18 on the road (this is with a MUCH heavier vehicle), and that is driving it on California freeways at 65-75 MPH.
Good luck with your car - that was the first Packard I drove (a 1940 120), in 1944 (I was 11 years old) and it turned me into a Packard fanatic for life!
Dick
