1940 Buick rear end

coolcar348

New member
I recently purchased a 40 Buick Super that needs a rear end from lack of fluid. I hear that 40-54 ring and pinion are the same but I don't know how to set up the gears properly. I would like to find a complete rear end but if I cant I was wondering about just changing the center chuck and I don't know if the inner driveshaft is part of the pinion gear or does it separate? Would I have to include the driveshaft with it? Also what year and series would interchange?
 

firstofeight

Active member
I recently purchased a 40 Buick Super that needs a rear end from lack of fluid. I hear that 40-54 ring and pinion are the same but I don't know how to set up the gears properly. I would like to find a complete rear end but if I cant I was wondering about just changing the center chuck and I don't know if the inner driveshaft is part of the pinion gear or does it separate? Would I have to include the driveshaft with it? Also what year and series would interchange?
1940 through 1955 interchange. Yes, just change the entire center "center chunk" or "pumpkin" . In other words, the whole gear set. I did this on my 1950 with one from a 1955. The inner drive shaft does seperate, but would not need to if the length is the same.

Ben
 

coolcar348

New member
Is there a u joint or is it a spline type between the inner shaft and the pumpkin? Would I be able to separate it by jacking the housing back a little or would I have to remove the whole rear end? Better yet, would you know what years have the same length driveshaft?
Bill
 

firstofeight

Active member
Bill, they are splined and pinned. Can be difficult. I did it , so you can I am sure. Rear end has to be removed. I do not know the answer to the last question.

Ben
 
A little bit of trivia, I have built the running gear for a '52 RM convertible. I could see the install and removal of the drive shaft was going to be a challenge. I had a 4 dr. trashed parts car in my inventory. For what ever reason, I opened up the drive shaft tube and found that shortly before its demise, someone had replaced the drive shaft with an aftermarket one that did not require special tools to install! I thought I would have to shorten the shaft for the convertible from the 4 door, but it was even the correct length! You just never know where you will find what you need:)
 

firstofeight

Active member
A little bit of trivia, I have built the running gear for a '52 RM convertible. I could see the install and removal of the drive shaft was going to be a challenge. I had a 4 dr. trashed parts car in my inventory. For what ever reason, I opened up the drive shaft tube and found that shortly before its demise, someone had replaced the drive shaft with an aftermarket one that did not require special tools to install! I thought I would have to shorten the shaft for the convertible from the 4 door, but it was even the correct length! You just never know where you will find what you need:)
Installed how, Bob?

Ben
 
Installed how, Bob?

Ben
It was probably close to 25 years ago I did this, so my memory won't be perfect, but I think the slider that went over the pinion was simply a lighter slip fit than the OE Buick, so installed without special tools by any service provider. I remember at the time researching to proper tooling to do the install, and before the internet, these things were more difficult!
 

tjbian

Member
I recently purchased a 40 Buick Super that needs a rear end from lack of fluid. I hear that 40-54 ring and pinion are the same but I don't know how to set up the gears properly. I would like to find a complete rear end but if I cant I was wondering about just changing the center chuck and I don't know if the inner driveshaft is part of the pinion gear or does it separate? Would I have to include the driveshaft with it? Also what year and series would interchange?
I have owned a 1940 Super for over 50 years. About 20-25 years ago I bought a Century 3.90:1 center section. The unit I removed has been in my
shed ever since. It never gave me any trouble and I recall having it adjusted by a friend of my dad's when I put in a clutch. The car probably had between 50-60K when I pulled the rear. You can have it for the cost of freight, I have kept it all these years because I didn't want to junk it and
would like to see it in a new home. I agree the shaft is hard to remove but I was able to do it.
 

coolcar348

New member
I have owned a 1940 Super for over 50 years. About 20-25 years ago I bought a Century 3.90:1 center section. The unit I removed has been in my
shed ever since. It never gave me any trouble and I recall having it adjusted by a friend of my dad's when I put in a clutch. The car probably had between 50-60K when I pulled the rear. You can have it for the cost of freight, I have kept it all these years because I didn't want to junk it and
would like to see it in a new home. I agree the shaft is hard to remove but I was able to do it.
 
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