Hello dudes and dudettes. A question for the early GM ring and pinion experts... I recently got a 1947 Buick Super 4-door sedan. Original drivetrain...rebuilt 248 straight eight, 3-speed standard-shift trans, and torque-tube/original rear axle. Two issues that are prompting me to change the ring and pinion. 1. Whining. (Not me this time...lol...the gears.) 2. The gear-ratio is so high, that the engine runs at uncomfortably high rpms, (good thing the engine is rebuilt) and I don't wanna travel very much over 45/50 mph. And of course, the car is getting extremely crappy gas-mileage. So I'm on the hunt for replacement gears with a lower ratio. My old buddy and early GM expert confirmed my thinking that I probably want gears from a car with the Dynaflow auto trans. He also seems to remember that there was a change in '55 to a different style of differential, so apparently, '55 and later won't fit my car. Another friend has a 1960 Buick, (last year for the torque-tube) with parts for the taking, but I don't know if they'll fit my car. The question(s): Do any of you know for sure which years of differentials will fit my axle? And...I'm aware that the Century/Roadmaster used some heavier components than the Super/Special, such as engine, trans, brakes, etc...but I'm not sure about the differentials. Anybody know? One more...Pontiac/Buick/Cadillac/Olds used some common components. Will gears from one of those work? Thanks guys. And 'cause we all like pictures, here's a couple of the car. It's a decent, amateur restoration. A big ol' 4-door boat just for fun, that I don't worry about too much. Rebuilt engine, average body-work and paint, some gen-u-ine JC Whitney seat-covers and interior door-panels and a brand new set of Coker Classics.
Rears changed between 55 and 56. I'm not sure how far back from 55 will interchange but I think to the early 40's. An auto rear end from 47 should be more road worthy ratio.
Beautiful car! you sure thats a 47? looks like a 46 to me... to answer some of your questions, Do any of you know for sure which years of differentials will fit my axle? 38 - 56 use the same enclosed drive line. they used enclosed all the way up to 60 but the later ones are not compatible with the earlier ones. And...I'm aware that the Century/Roadmaster used some heavier components than the Super/Special, such as engine, trans, brakes, etc...but I'm not sure about the differentials. Anybody know? they are the same housing/size but the bigger cars used taller gear ratios One more...Pontiac/Buick/Cadillac/Olds used some common components. Will gears from one of those work? not at all, sadly its like apples and oranges. there are some suspension pieces that they share with cadillac and the big olds, but other than that, theres really nothing thats interchangeable. hope this helps. I just replaced the rear end in my 48 about 6 months ago, i found a Very tall rear end out of a 55 roadmaster. its a 3.36 and my engine is barely turning at 60. even with the sloppy old dynaflow. the real fun is when it comes time to install it... you have to drop the whole drive shaft... heres how fun it can be...
I did this swap on my 48 some years ago. Here you go http://www.jalopyjournal.com/forum/showthread.php?t=319814
Hey Orn - you were right, it wasnt all that bad... the results outweigh the discomfort of a dirty job.
Sorry I wasn't here when you guys answered. The wife wanted to head out in the Buick to A&W for chile cheese burgers and rootbeer. Wasn't gonna deny her...lol. I agree...the switch is absolutely worth the effort...not only in comfort and less wear on the engine, but as I mentioned...gas-mileage too. After installing friendlier gears, I'll very quickly make up the cost of parts in gas savings!...lol. Judd, Lobsterboy X, dutch deuce, orn...thanks so much! Excellent and thorough info...exactly what I needed. The H.A.M.B. is awesome, and it's members such as you guys, that make it so. Best wishes to all of you. Rick Edit: BTW...forgot to mention...Yes, Lobsterboy X, it's a '47, not a '46. Duh...lol. I've had a few cars over the recent years...'46 Ford, '48 Chevy, and still have my '47 Hudson. And now the '47...uh...'46 Buick. Get 'em mixed up sometimes. My poor old brain...lol.
Get on the phone and talk to Joe Taubitz over in Rankin (probably a Swartz Creek postal address). He's done this with his '40 convertible. He may even have the parts. 810-655-8988.
yea the rear ends are interchangeable 1940 to 55. Its the only way to do it with a reasonable cost, and not that hard to do. You can use your driveshaft. Going overdrive, open drive, etc, is a lot more complicated on Buicks. They are still out there just keep your eyes open. Makes stock Buicks a good driver on the freeways. Ratios usually 4:11 up to a 3:43, and you may find them mixed in all series. get one you will like it. info add. '36 to '39, Special, and Century, need to take off approx. 1/4 in. from differential mounting face, to make them fit. You can measure the distance from the axle centerline.
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