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1939 Buick rear axle removal/gear change=help needed

Discussion in 'The Hokey Ass Message Board' started by bobwop, Sep 15, 2009.

  1. bobwop
    Joined: Jan 13, 2008
    Posts: 6,098

    bobwop
    ALLIANCE MEMBER

    does anybody have experience removing the rear end from a 1939 Buick Special 40? We are going to change the gearing to something more highway friendly. So far, we are unable to pull the axles. Something tells me it can't be all that hard, but it may take somebody with more smarts/experience than I to make it seem simple. Please advise!!! Incidently, we have the entire torque tube from a 1953 Buick Special and hope to be able to use the gears or entire diff. from that to give this old girl some legs. Thanks in advance for your assistance.
     
  2. 39cent
    Joined: Apr 4, 2006
    Posts: 1,569

    39cent
    Member
    from socal

    I have seen an article where a 1940\ 53 differential gear housing [pig ?] will bolt to a 39 axle housing but will need mods to have the differential housing flange face milled approx .125, [check it out] The 39 axles are deeper in the 39 housing so the later axles will line up. The 53 to 39 driveshaft coupling will need to be adapted as will the torq tube. [see BOB WOP's ed. below]. Another way is to go is go open driveline, which could be done adapting a open drive transmission using the 39,s wishbones as torq arms. Another way I was told just using the complete later straight 8 rear ends, supposedly the same length but will need some frame mods.
     
    Last edited: Jul 12, 2015
  3. Dale Fairfax
    Joined: Jan 10, 2006
    Posts: 2,585

    Dale Fairfax
    Member Emeritus

    You need to contact Joe Taubitz in Swartz Creek, MI. He's converted his '40 convertible to a hiway friendly gear using the sam approach you're pusuing. My memory says he didn't have to cut, weld, or machine anything. I know he is out of town for a while on vacation but i"m sure he can give you the straight goods when he returns. He's at: buickjoet@comcast.net. Or, find his phone in the white pages.
     
  4. 39cent
    Joined: Apr 4, 2006
    Posts: 1,569

    39cent
    Member
    from socal


    The 'straight goods' you are mentioning are correct if BOBWOP had a Roadmaster or Limited series car. But I,m sure Joe would tell you that a 39 Special and Century altho it is a closed driveline is a completely different driveline than the 1940 models. 39 Special/Century series chassis were one of a kind with a short torq tube and the u joint in the middle of the x member, [as most 39 owners quickly learn]. And the later differentials need to be milled off the diff, bolting face [need to check] so the axles/spiders will line up. See bobwop, posts on the HAMB.
     
    Last edited: Jun 16, 2015

  5. bobwop
    Joined: Jan 13, 2008
    Posts: 6,098

    bobwop
    ALLIANCE MEMBER

    thank you for the input. Any clues on how to remove the axles from the 39 diff.?
     
  6. Buford
    Joined: Aug 30, 2001
    Posts: 314

    Buford
    Member

    You have to remove the cover on the center section. You will see a big pin in the center that goes through a block. Remove the bolt that holds the pin, then the pin, then the block. This will allow you to push both axles IN, when you'll see the C clip retainers on the axles. Remove these retainers and pull the axles. Done! Frank
     
    LONG and 302GMC like this.
  7. bobwop
    Joined: Jan 13, 2008
    Posts: 6,098

    bobwop
    ALLIANCE MEMBER

    thanks for the help fellas. We had to remove .250 from the mounting surface of the 53 center section for alignment. Now we are working on splicing the driveshaft/torque tube together. I hope to add more later.
     
  8. 39cent
    Joined: Apr 4, 2006
    Posts: 1,569

    39cent
    Member
    from socal

    bob, thanx for the update, let us know how it comes out, and if you can get some pix of your installation please post them we need the info. I mostly got my info from some oldtimers, especially for 39,s but its also good for 37, and 38, torq tube Buicks, we don,t have any actual pix and step by step first hand info,so it would be most appreciated.
     
    Last edited: Oct 16, 2009
  9. bobwop
    Joined: Jan 13, 2008
    Posts: 6,098

    bobwop
    ALLIANCE MEMBER

    I likely won't be able to get photos posted. We are gaining, as the 53 pig has been milled to provide axle/spider alignment. We re-installed the gears and set all tolerances. Put in the new gasket and put in new seals. It holds grease!

    tomorrow we will begin mating up the 53 pig to the torque shaft/tube. This will take some doing as the configurations are different. Measure twice/cut once.

    next up, tube shock installation and exhaust manifold replacement.
     
  10. 39cent
    Joined: Apr 4, 2006
    Posts: 1,569

    39cent
    Member
    from socal

    ok if you cant get pix just give us the facts man! yeh I had heard the driveshaft torq tube thing was a little tricky.
     
  11. bobwop
    Joined: Jan 13, 2008
    Posts: 6,098

    bobwop
    ALLIANCE MEMBER

    what an improvement!!!! Drove the car tonight and just loved it. The four tube type shocks certainly improved both ride and handling. You can likely figure out how to fab up mounts and order up the correct shocks, but Steve did a great job. The rears are mounted forward of the coil springs and at a bit of an angle, the fronts mount to the sway bar mount and then to custom top mounts.

    The rear gear change, 441 to 350, made a huge improvement. Before, 50 mph was about it, now 70 is easy.

    The diff had to be shaved .25 inch. Steve drilled a brake drum to the flange on the housing and then turned it down on the brake lathe. No area machine shops could help us. Took a couple hours, but it worked and the cost was great. The torque tube took some effort. He did plenty of measuring and some ingenious fitment. He actually reversed the pinion shaft from the 53 diff and mated that to the shaft from the 39. The 53 tube was cut very close to the diff. flange and then the 39 tube was mated to it. The 39 tube had to be kept due to the ujoint configuration at mid-ship.

    It looks very stock, with the tube shock nicely tucked away. What a great improvement.

    I am pretty much convinced to bringing the car to the Pileup
     
  12. 39cent
    Joined: Apr 4, 2006
    Posts: 1,569

    39cent
    Member
    from socal

    Thats great, and great info for adapting, taller gears for the '39 specials and centurys. I am contemplating doing that to my 39 century. Glad its working so well, the older cars were mostly geared too low for todays traffic, however some were equipped with overdrives [i.e. packards, chryslers,]. they were comparable to Buicks in power, sadly, GM didn't use OD,s much, so there was always something lacking in highway cruising. This adapting to higher gears works really well in older cars, making them much better for everyday use. Your info here is realtime and I am copying, saving it to my bookmarks. thanx 39cent

    the 37 and 38 Specials and Centurys will need to mill the diff. housings the same way. I don,t know about the torq tube but it may also need the same mods. Also reportedly the later open drive differentials [61 and 62?] are bolt in the early housings. As far as transmissions go there are plenty of standard an overdrives to pick from. my info isnt first hand so chekitout, old Buick gear changes are getting harder to find.
     
    Last edited: Dec 9, 2014
  13. ii623
    Joined: Apr 27, 2014
    Posts: 1

    ii623
    Member

    Great info...I have a '39 special and would love to drive it a bit faster...

    Sales literature from '39 says std gears are 4.441:1, but 3.9:1 was available option. Anyone know of a source for the 3.9 gears? Manual says that would drop the engine speed by 800 rpm or so at 60mph...a big deal when high speed means 3800 or so rpm...
     
  14. 39cent
    Joined: Apr 4, 2006
    Posts: 1,569

    39cent
    Member
    from socal

    Well, if you can find 39 Century 3:90 gears or complete rear end, grab it. also there was a 3:61 gear option for 39 Centuries, but those gears are rare. The saving grace is that the 1940 to 1955 gears are about the only ones that can still be found as many guys are replacing torq tubes with open drive shafts. Ratios, from 4:41, 3:90,3:61, and 3:43, are what are out there. I have obtained this info from old timer Buick guys etc. The 39 differential casing needs to be faced off to line up with the axles, as you will be able see. The drive shaft couplingwill need to be adapted also.
     
    Last edited: Mar 18, 2015
  15. 39cent
    Joined: Apr 4, 2006
    Posts: 1,569

    39cent
    Member
    from socal

    Bobwops post-----
    what an improvement!!!! Drove the car tonight and just loved it. The four tube type shocks certainly improved both ride and handling. You can likely figure out how to fab up mounts and order up the correct shocks, but Steve did a great job. The rears are mounted forward of the coil springs and at a bit of an angle, the fronts mount to the sway bar mount and then to custom top mounts.

    The rear gear change, 441 to 350, made a huge improvement. Before, 50 mph was about it, now 70 is easy.

    The diff had to be shaved .25 inch. Steve drilled a brake drum to the flange on the housing and then turned it down on the brake lathe. No area machine shops could help us. Took a couple hours, but it worked and the cost was great. The torque tube took some effort. He did plenty of measuring and some ingenious fitment. He actually reversed the pinion shaft from the 53 diff and mated that to the shaft from the 39. The 53 tube was cut very close to the diff. flange and then the 39 tube was mated to it. The 39 tube had to be kept due to the ujoint configuration at mid-ship.

    It looks very stock, with the tube shock nicely tucked away. What a great improvement.
     

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