Pontiac59 Posted October 3, 2005 Share Posted October 3, 2005 Anyone know how new a differential will swap to the 1940 Roadmaster? Wondering if I could round up a hydramatic car gear and lower the ratio a bit. Link to comment Share on other sites More sharing options...
The Old Guy Posted October 3, 2005 Share Posted October 3, 2005 Any diff from 1940-1955 Buick's will interchange. The V8 Dynaflow Buicks had 3,3-3,5 ratios which are much more suitable for cruising. Link to comment Share on other sites More sharing options...
jerry burger Posted January 11, 2006 Share Posted January 11, 2006 ive never seen 3,3-3,5 ratios for buicks.i have seen 3.4 3.6 and 3.9 or 4.44. Link to comment Share on other sites More sharing options...
The Old Guy Posted January 12, 2006 Share Posted January 12, 2006 The 1940 60 series had a 3.9 as standard and a 3.6 option. The 1940 40-50 series had 4.1-4.4 as standard ( depending on body style) and a 3.9 option. The V8 Dynaflow cars had 3.2 -3.42- 3.6 You are correct in that there were no 3.5 axles availableI have a 3.4 in my 1940 Super convertible, and it cruises effortlessly at 70+ on the interstates Link to comment Share on other sites More sharing options...
jerry burger Posted January 12, 2006 Share Posted January 12, 2006 wow!,the change in rpm`s would be fantastic.were you able to change out your speedometer gear also?i have a 3.6 from a 54 super,and the speedo gear and am considering the change to my 41 century.when i was a kid my friend had a 40 super convertible,a real snazzy car. Link to comment Share on other sites More sharing options...
The Old Guy Posted January 12, 2006 Share Posted January 12, 2006 There are units available for trucks that screw on the tranny and the cable fits onto them. They have all different ratios and I just figured out how slow my speedo was, and got the unit and "voila" my speedo is right ( actually it is still a little slow ,so the wife stays off my back about speeding) Link to comment Share on other sites More sharing options...
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