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Rear End Gear Swap

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Hi-

 

I have a mostly original '38 Special business coupe.  When I acquired the car a set of Century rear end gears were included in the deal.  When I looked in the service book to see what will be involved in the swap, I broke out in a cold sweat.  It looks like every phase of this project requires various special tools, gauges and brackets for indicators.

 

It seems from my search of this site that this swap is a fairly common occurrence.  At least it gets suggested a lot.  I consider myself a fairly competent mechanic but have not done a gear swap like this before.  I'd hate to have things spread out on the bench and then find out that I do need one of those weird gauges to do the job correctly.  

 

So does anyone here have first hand experience with this swap?  Did you find yourself needing one of those special tools? Do you think it was worth the effort? 

 

Thanks,

Tom

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 Tom;

   I'm in a similar quandray with a '41 Roadmaster. About the only thing that I have never done in 40 years or so of working on cars, is a rear gear swap out. I saw some info a few years ago about how to do this, but this summer I'm ready to get into I cannot find the info again. My stock gears are 3.9's and I have a good set of 3.42's, still in the housing that I'd like to put in for better highway cruising.

  There is a club for 37-38 Buicks, and they have a publication called the "Torque Tube", and I think some of it may be online. Give it a try.

  I'll be watching your thread too, so hopefully some one will come up with an answer.

  Keith

Edited by Buicknutty (see edit history)

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 Tom, as Keith said, check with the boys on '37-'38 group. I believe a little machine work is required.

 

  Keith, yours is simpler. You may be able to exchange the entire thing if the length is right. 

Willie  [old tank] has a good write up for this on his website. I did it on my '50. Happy as a lark.

 

  Ben

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Ben;

 I didn't know about Willie's website, I will check it out. I have been given to understand that it is fairly straightforward to do, but I don't really know the procedure.

 Thanks.

 Keith

Edited by Buicknutty (see edit history)

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If the century gears are from a 1938 then its a straight swap.

If not from a '38 a lot more work. At worst may not be able to fitted. Buick changed the differential  parts (numbers) frequently from year to year.

 

Look at the bottom of post 5 here http://forums.aaca.org/topic/207201-39-buick-team-membership/. Has links to posts about high speed diff's

The 37 38 Buick club is now defunct, but the web site is maintained http://www.1937and1938buicks.com/The-Torque-Tube/The-Torque-Tube.htm

There is a pre war division of the BCA http://www.buickclub.org/regionschapters-divisions/and BCA 1936-37-38 club http://3638buickclub.org/

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 1939_Buick is correct. The old 1937-1938 Buick Club is defunct and has been for many years. The newer 1936-1937-1938 Club which now accepts all straight 8's is a newer organization.

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I was told by a Buick expert that the rear ends from 1940 to 1955 are all the same except for possibly the series 90 cars. I had the pumpkin changed on a 1948 Special and went from 4.45 to 1 to 3.36 or 3.41 to 1. There are mechanics who specialize in differential work and they are very good at setting up the clearances and specifications.

I have read in the past that Buicks prior to 1940 are more complicated to fit higher gears in, although everyone seems to like the Century gears for the late 1930's.

Joe

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 1939_Buick is correct. The old 1937-1938 Buick Club is defunct and has been for many years. The newer 1936-1937-1938 Club which now accepts all straight 8's is a newer organization.

 

YOU ARE RIGHT

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