Olds 47

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December 2008

Hereís some info for those Buick guys who want to keep their straight 8 and torque tube rear.

My 48 Special have a very low 4.45:1 gear ratio from the factory and I was lucky to find an axle from a 1950 Super with Dynaflow. The gear ratios on the Dynaflow equipped cars are often 3.60:1 and I think this one will be perfect in my 48. The Buick differential carriers are interchangeable from at least 1940 up to 1955. 1956 they got more numbers of splines and are another story. This ratio will lower my rpm from nearly 3100 to 2400 rpm in 60mph. Here are some pics from the transplantation


This is the rear axle from a 1950 with the right gear ratio inside. The old one is out for now.


They have the ratio marked by numbers on the ring gear. To the left is my 48 witch has the number 49-11 and that is 4,45:. To the right is the -50. In this case 47-13 is 47 divided by 13 = 3.60


First remove the lock screw.                                                                 Take out the shaft.


The pinion spacer is located between the inner ends of the shafts and controls end play of axle shafts and have to be removed. Then push in the axle shafts to get access to the c-clips.


Remove the c-clips by knock them in and let them fall out in the housing. I have to make this simple tool to knock them out. Take the axle shafts all the way out.


C-clips that holds the axle shafts. The propeller shaft is connected to the pinion through a splined joint and a pin. Knock the pin out and remove the propeller shaft.


The 3.60:1 in place and just waiting for new gaskets. In the mean time I start cleaning up the housing.


The 3.60 carrier in place with new gaskets. And finally sliding the torque tube back and connect the control arms to the axle again. Connect the brake lines and thatís it.

It feels like Christmas come early this year so I wish you all a very merry Christmas.


Part 6