720_potter Posted March 13, 2022 Report Share Posted March 13, 2022 Okay quick question, doing a ka24e swap in my 84 720 rwd. Want to do a manual swap on it since it's auto as of rn. Can I use a 240sx trans in my 720 or is it diff from the 720 manual? Thank you for any info! Quote Link to comment
datzenmike Posted March 13, 2022 Report Share Posted March 13, 2022 The '84 720 had two different lengths of 75B 5 speeds. 26" and 31.5" The 71C in the S12/13 is around 35" long. Either way the drive shaft will need to be shortened. The first 4 gears are, I believe, the same as the 720 but the 71C has a monster 0.745 or 25.5% over drive* whereas the 71B in the 720 is 0.883 or 16.7% OD. *This is the same as the 280zx non turbo transmission. Quote Link to comment
720_potter Posted March 13, 2022 Author Report Share Posted March 13, 2022 1 hour ago, datzenmike said: The '84 720 had two different lengths of 75B 5 speeds. 26" and 31.5" The 71C in the S12/13 is around 35" long. Either way the drive shaft will need to be shortened. The first 4 gears are, I believe, the same as the 720 but the 71C has a monster 0.745 or 25.5% over drive* whereas the 71B in the 720 is 0.883 or 16.7% OD. *This is the same as the 280zx non turbo transmission. Alright, so just find a manual transmission for the 72p that came out of one basically Quote Link to comment
datzenmike Posted March 13, 2022 Report Share Posted March 13, 2022 Measure yours so you know what length to look for. Quote Link to comment
bottomwatcher Posted March 14, 2022 Report Share Posted March 14, 2022 Don't use the B they are weak. Use a hardbody 2wd. You will still need the driveshaft shortened but the trans is so much stronger and plentiful in scrapyard. I have one happily living behind my ka swap for a long time. 1 Quote Link to comment
Crytek89 Posted March 14, 2022 Report Share Posted March 14, 2022 2 hours ago, bottomwatcher said: I have one happily living behind my ka swap for a long time. Hey BW, aside from the driveshaft, what other modifications, if any, did you have to do for the swap? Quote Link to comment
datzenmike Posted March 14, 2022 Report Share Posted March 14, 2022 The 71B is 'weaker' that the 71C but strong enough for the 280zx non turbo six cylinder. That's about twice the HP of the Z24. If a 71B is available it's a better fit. If the 71C is cheaper and more available then the driveshaft shortening is not so bad. Not sure if the transmission mount may need relocating. Don't forget the 71C has a terribly high over drive 5th and won't be much use unless on the highway. 1 Quote Link to comment
bottomwatcher Posted March 16, 2022 Report Share Posted March 16, 2022 On 3/14/2022 at 12:54 AM, Crytek89 said: Hey BW, aside from the driveshaft, what other modifications, if any, did you have to do for the swap? The only other mod was a small adapter plate to mount the trans mount. The holes don't line up and trimming trans tunnel. Shifter is more towards the front of trans. 1 Quote Link to comment
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