allen dodson Posted June 13, 2008 Report Share Posted June 13, 2008 Is the 1970 4 speed out of my 521 geared as same as the 1978 620 4 speed? Quote Link to comment
datsunaholic Posted June 13, 2008 Report Share Posted June 13, 2008 No, though 4th is always the same (since it's 1:1). The older transmission has a somewhat wider spacing. Quote Link to comment
datzenmike Posted June 13, 2008 Report Share Posted June 13, 2008 Not exactly. This is the same tranny that came with the 510 and had two different sets of gears, one for the sedan and one for the wagon. Both were supposed to be available for the 521 but I doubt this. The lower 'wide ratio' is probably what went into them: '70 521 F4W63 4spd. WIDE 1st... 3.657 2nd... 2.117 3rd... 1.419 4th... 1.000 Used in the heavier 510 wagon. CLOSE 1st... 3.382 2nd... 2.013 3rd... 1.312 4th... 1.000 used in the 510 sedan. '78 620 FS4W71B WIDE 1st... 3.592 2nd... 2.246 3rd... 1.415 4th... 1.000 As you can see both wide ratio trannys are a pretty close match for ratios only. The trannys themselves aren't even close. The F4W63 is about 26.3" long, the '78 is 31.5" The F4W63 has a flange output the 78 has a spline. The F4W63 has the speedo on the driver's side, the '78 is on the opposite side. Allan, if you plan to put the '78 into the '70 use the '78 drive shaft as it's shorter to allow for the longer tail stock tranny and will eliminate the flange problem as well. Use the '78 speedo cable and the 521 release bearing collar and shift fork. You may also have to cut the shifter hole slightly. If you are going to all this trouble get an FS5W71B over drive 5spd. Same length 31.5" Quote Link to comment
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