Challenger Posted September 19, 2006 Share Posted September 19, 2006 Hi everybody, Ive got a rebuilt 82 5 speed (got for 100 bucks:burnout: )and a 78 4 speed. I like the fact the 4 spd has better acceleration, but the 5 speed would help mileage. I've looked at the 280z 5 speeds and a very reliable mechanic friend of mine said he didnt like how they were built. I was wondering If theyre was a trans. with a good first few gears for acceleration (like 3.3:1 1st) but still a tall overdrive like the 82. I've read about toyota or nissan truck trans on Z's in the past but couldnt find it or any info on a transmission like this on hybridz. Any info is appreciated. Thanks Also is it possible to use the 4 gears from the 4 spd in the 5 speed or is it totally different? Probably wouldnt work but I thought I'd ask. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted September 19, 2006 Share Posted September 19, 2006 Forget about the 4 speed and get a lower diff ratio. That will give you the better acceleration and still have top end cruise gears. Your 3.54 that your 78 diff should have will make the ZX transmission ratios seem really tall. The ZX's that came with that trans came with 3.90s in the back for a reason! From personal experience I can tell you that on the track with similarly matched NA cars, my close gear ratio allowed me to pass a friend with a wide ratio trans when he switched from 2nd to 3rd, due to the large gap in the ratios there. The truck trans is worse yet with the gaps in the ratios and I would avoid that one in particular. The 280Z and ZX NA transmissions are pretty damn similar, so if your friend didn't like the 280Z transmission he's not likely to think much of the ZX tranny either. Quote Link to comment Share on other sites More sharing options...
Doug71zt Posted September 19, 2006 Share Posted September 19, 2006 For the weight of the Nissan 5spd, I don't think that you'll find a better transmission out there. I am running in the high 11's with a dead stock ZX 5spd, with new bearings. If you don't shock load them, they are really reliable up to around 300 hp on the street. One good thing to do is to replace the shift fork to shift rod roll pins with solid steel rivets, that way they won't shear. Doug Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted September 19, 2006 Share Posted September 19, 2006 Datsun put 4 speeds in the early Z cars shipped to America but 5 speeds for the rest of the world. Every magazine I have ever read listed the 5 speed variants as having better acceleration numbers and top speeds. The 4 speed transmission were simply a bad marketing ploy for the American market. My guess is they wanted the "four on the floor" moniker for there cars. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted September 19, 2006 Share Posted September 19, 2006 For the weight of the Nissan 5spd, I don't think that you'll find a better transmission out there. I am running in the high 11's with a dead stock ZX 5spd, with new bearings. If you don't shock load them, they are really reliable up to around 300 hp on the street. One good thing to do is to replace the shift fork to shift rod roll pins with solid steel rivets, that way they won't shear. I have heard another method on this that I was going to try. Apparently the issue isn't with the roll pins shearing off, it actually has more to do with them sliding out under heavy vibration. So the trick is to safety wire the pins in. That's what I'm going to do on mine when I get around to rebuilding it. Quote Link to comment Share on other sites More sharing options...
veritech-z Posted September 19, 2006 Share Posted September 19, 2006 Jon, what tranny are you using? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted September 19, 2006 Share Posted September 19, 2006 80ZX. Also thinking about going to truck 5th gear cluster for .86 5th gear. Rebuilding it is on my list of things to do... Quote Link to comment Share on other sites More sharing options...
Challenger Posted September 19, 2006 Author Share Posted September 19, 2006 Thanks. If I was to put in a 3.90 wouldnt it just make the 5 speed have almost the same ratio for the last gear. Instead of having 4 gears to get to around 1:1 you have 5? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted September 19, 2006 Share Posted September 19, 2006 No, it wouldn't be the same. You can compare the difference in each gear here: http://www.geocities.com/z_design_studio/ Enter in your tire size and your rear gear ratio and you'll see how fast you can go in each gear, and how far the red lines are spread apart. The closer the lines are the less rpm drop between shifts, which should give faster acceleration on a NA car. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted September 19, 2006 Share Posted September 19, 2006 To Jon's point, I think you'd find the 82 5 speed coupled with either a 3.7 or 3.9 diffy to be pretty close to what you say you want. And you lose that big chasm when you shift from 2nd to 3rd. I went with a 4.11 and the 82 5 speed because mine is not a daily driver. Quote Link to comment Share on other sites More sharing options...
Challenger Posted September 20, 2006 Author Share Posted September 20, 2006 No, it wouldn't be the same. You can compare the difference in each gear here: http://www.geocities.com/z_design_studio/ Thanks for the post, Im not sure of what to do at this point but thanks for all the info. Quote Link to comment Share on other sites More sharing options...
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