copacetickid Posted September 28, 2007 Report Share Posted September 28, 2007 I bought a 620 a few months ago and a 280zx 5-speed a week later and my next couple weeks were all laid out in front of me. I've never done any major work on any cars I've owned, but that's partly why I bought the truck :). I got lucky and was able to use my girlfriend's parent's garage (and her dad's tools). First I decided to open up the 5-speed and see how it looked (partly just because I wasn't straight on how everything worked). Getting it apart was an adventure in and of itself... bent a forged wrench getting the front cover off. First bad thing happens: the residual fluid had apparently dripped off the top of the driveshaft while it was stored and the whole top side rusted. The 1/2 gear selects and rings were badly pitted and all of the gears had at least some mild rusting but looked OK. Should have stopped there and demanded a refund... *sigh*. Putting it back together was fine, except I was too anxious and didn't order a new front cover gasket. I kept the old one and sealed it with a little Right Stuff so I don't know if the shim that was in there is big enough. Getting the 4-speed out was a piece of cake, I drained the fluid, sawzawled the tailpipe, removed the driveshaft, loosened all the bolts, no prob (I think DatDoug did all the hard work for me). I even wrestled it out without all that much of a problem, I don't know how. But getting the 5-speed in? Ouch. I only had a floor jack, and I must have spent an hour trying to fit it in between the torsion bars. Finally with my gf's dad's help, and only after putting it in almost upside-down, I got it into place. Then *WHAM*, my knee spasms and locks while I'm supporting the tranny entirely with one arm. Totally random, and it hasn't happened since I was 12, but it took the entire night to relax straighten out. Well, the rest went pretty well, except the muffler place didn't have any joints and so they just welded it back together and I'm going to have to cut it the next time I take it out. Test drive! eeeeeeEEEEEEEEE, eeeeeeeeeeEEEEEE, eeeeeeeEEEEEEE... FUCK! It whines like there's no tomorrow. I guess the gears with the rust were't fine after all. Now it's been a month and I can't stand it! A little bit more of my soul dies every time I accelerate... I bought some MoS2 and some new gear oil, but no change. The 2nd gear syncro is fucked too, I have to hold it just outside of 2nd for a second every time I shift into it. Even worse, it's got the shortest 5th gear ever, and combined with a truck's differential, I basically cruise at 45 mph down surface streets in 5th. And I bought it for road trips!!! ARGHHH! Oh yeah, and my gf's parents moved, so even if I had the money, and a new 5-speed, I wouldn't have a place to swap it out. *curls up in fetal position on floor* It was pretty fun though, all in all. :D Quote Link to comment
Bleach Posted September 28, 2007 Report Share Posted September 28, 2007 1) the first thing that goes out on a 280Z/280ZX transmission are the 2nd gear syncros. I drove mine like that from 132,000 miles to 232,000 miles until the rest of the tranny let go 2) Short 5th gear is the same as a Datsun truck's short 5th gear. You got a 1979 Z tranny or earlier. Should have tried for a 1980-83 which had a lower rear gear in the car so 5th gear in the tranny was taller. Sorry to hear that it whines. Use thicker oil! :D Quote Link to comment
datzenmike Posted September 28, 2007 Report Share Posted September 28, 2007 They won't rust just sitting. This one was outside and must have filled with rain water. If it was rusty at the top it was stored upside down. The bearings are probably rusty too and causing the whine. Any way to take it back and get another? Quote Link to comment
copacetickid Posted September 28, 2007 Author Report Share Posted September 28, 2007 I syncro isn't a big issue for me -- not yet, it's the whining I can't stand. I don't think it's the bearings that's making the whining sound, because only 1st, 2nd and 3rd gears whine. I think it was just stored for a really long time and the oil slowly dripped off of the top of the gears. That, and maybe the speedo pinion or switch was not sealing it from the outside. On a side note, I bought this from a kid in Renton and he said that it shifted fine, and was in good condition -- obviously not the case. How can I go about making sure it's decent next time? Quote Link to comment
DatDoug Posted September 29, 2007 Report Share Posted September 29, 2007 Dude Bring it over and lets put the 4speed back in. Or buy another 5-speed and i will help you out. Or get that one rebuilt so you know what ya got. Quote Link to comment
datzenmike Posted September 29, 2007 Report Share Posted September 29, 2007 On a side note, I bought this from a kid in Renton and he said that it shifted fine, and was in good condition -- obviously not the case. How can I go about making sure it's decent next time? Drain the tranny, if rusty water comes out start walking, if the oil looks like yogurt but is grey, start walking, unscrew the bottom 'bung'. It has a magnet that collects metallic powder and filings. All trannys will have some black metallic 'paste' but if it has gear chunks (even small ones)...... start walking. Quote Link to comment
Fineline Posted September 29, 2007 Report Share Posted September 29, 2007 Drain the tranny, if rusty water comes out start walking, if the oil looks like yogurt but is grey, start walking, unscrew the bottom 'bung'. It has a magnet that collects metallic powder and filings. All trannys will have some black metallic 'paste' but if it has gear chunks (even small ones)...... start walking. Hu hu.......you said BUNG! Quote Link to comment
copacetickid Posted September 29, 2007 Author Report Share Posted September 29, 2007 Funny thing about the 4-speed, I thought I could swap out all of the gears and the synchros into the 5-speed... I only realized after I pulled the countershaft bearing that it's all one piece and can't be used in a 5 speed. shit. Anyone looking for 4-speed parts? I really just want to get a new 5 speed. Does anyone have a post '81 280zx 5-speed they'd like to sell to me? :rolleyes: Quote Link to comment
DatDoug Posted September 29, 2007 Report Share Posted September 29, 2007 There is a guy on the Portland craidslist who has a bunch of Z trannys. Check it out Quote Link to comment
Icehouse Posted September 29, 2007 Report Share Posted September 29, 2007 Sounds like my tranny. It makes a whines in the same gears, its been doing it since in installed it.. I took the speedo gear out because I thought I had the right one... I didn't.... When I pulled the gear out a bunch of metal shavings fell out :eek: My fix is turning up the tunes :D My Ipod broke a few days ago :( so I may be installing a new tranny to :D Quote Link to comment
lynchfourtwenty Posted October 10, 2007 Report Share Posted October 10, 2007 im content with the 4 speed with the l20b.. ka on the other hand is a different story Quote Link to comment
bonvo Posted March 31, 2008 Report Share Posted March 31, 2008 5 speed is a mustv for freeway driving my 610 used to run at 4000 rpm on the freeway with my new 5 i dont think that will be an issue Quote Link to comment
Datsun4u Posted March 31, 2008 Report Share Posted March 31, 2008 I syncro isn't a big issue for me -- not yet, it's the whining I can't stand. Got some cheese with that whine?:rolleyes: Quote Link to comment
DISLEXICDIME Posted March 31, 2008 Report Share Posted March 31, 2008 i forked out the money for mtl when i putt thee truck 5 speed in my dime just in case it was a whiner after having a loud zx tranz i never want to deal with that again. plus i like the truck trans better in my 510 than my zx one Quote Link to comment
datzenmike Posted March 31, 2008 Report Share Posted March 31, 2008 The 620 trans has much lower first three gears than a Z car but a bigger drop into 4th. Quote Link to comment
DISLEXICDIME Posted April 1, 2008 Report Share Posted April 1, 2008 i like the close ratio better Quote Link to comment
djlotus Posted April 1, 2008 Report Share Posted April 1, 2008 When I read the thread title I did not immediately think transmission... Quote Link to comment
mnementh666 Posted April 10, 2008 Report Share Posted April 10, 2008 I threw a '81 ZX 5spd (the one with the numerically low OD) in my 521. LOVE the overdrive. Then I swapped to a 3.90 rear end from a 720. That may have been a bit too much. :blink: At 3k rpm, I'm doing about 72mph. She'll cruise real nice at that speed, too. But as soon as I hit a hill, it's either WOT or downshift. But 4th gear seems too high revving for me. Don't want 4k rpm at 55mph! And I'll probably be swapping trannys again this year. My input shaft bearing (I think) is bad, and is noisy as all hell. And the gears whine :D Anyway, my 2 pence. Quote Link to comment
datsunaholic Posted April 10, 2008 Report Share Posted April 10, 2008 Even with 4.88s and a 4-speed you aren't turning 4K at 55. Not even at 60, unless you're running clown car tires. My Mom's '73 620, all stock (4.88s and a 4-speed) just bumps 4K at 65MPH. Sounds like it's revving through the roof but that's pretty much in the L16's happy range (until the cam went flat, but that's another issue). I've had several tachs in the truck, I almost never saw 4000 on the freeway (at 70 the front tires wanted to float). But 3.90s and a ZX overdrive... be turning just over 2300 RPMs at 60. WAY off the power band. Downshifting to 4th only pops it up to 3100. I have the ZX trans in my '76 KC with an L18, but the stock 4.375 rear (same as a L-series 521). 35MPG highway, but it's gutless. Like merging on the freeway with a 4cyl Chevette (ok, not that bad. BTDT). Quote Link to comment
mnementh666 Posted April 10, 2008 Report Share Posted April 10, 2008 You're right. 3000 @ 55. Sorry :o And it IS way off the band. It'll pull hills at 75mph in 5th, but at 55mph it's chugging pretty bad. But cruising flat straights it's pretty happy at ~65mph. I'm trying to decide whether to just find a cam with better torque, or to find a 4.88 rear gear. Thankfully it's an L20, so it's got some midrange grunt. Call me strange, but I don't like pushing this motor to high rpm. Quote Link to comment
datsunaholic Posted April 10, 2008 Report Share Posted April 10, 2008 I run my 4X4 at over 3K all the way to Portland and back (that's WITH a 5-speed, but I'm running 75+). Stock those things made peak HP at 5600 RPM. I wouldn't run there all day, but under 4K is just fine. Quote Link to comment
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