Racin_Jason Posted February 28, 2001 Share Posted February 28, 2001 Im getting ready to go have a look at a car and the owner claims it has a 300Z or ZX (unclear which) rearend in it. Im totally new to this stuff and would appreciate a way (pictures maybe?) to determine exactly which is actually in the car by looking at it. Thanks alot! Jason Quote Link to comment Share on other sites More sharing options...
jeromio Posted February 28, 2001 Share Posted February 28, 2001 You can tell alot by the rear cover. The R180 has a small, rectangular cover. R200s have a larger, stop sign shape. The typical 300zx (Z31) rear swap is the clutch LSD (3.7 ratio). This ordinarily has a lare, finned rear cover. But it won't fit without a custom rear transverse link. So usually people just swap that cover for a regular R200 cover. My 85 turbo 200SX (4.11) R200 has an aluminum (but normal, non-finned) rear cover. I also have a 280Z (3.54) R200 which has a plain rear cover. You can't tell much else visually though. For ratios, put the car in neutral, jack up one rear wheel. Make a mark on the jacked up half shaft and one on the driveshaft. Turn the driveshaft 10 time, and count how many times that halfshaft mark spins around. Multiply that number by 2, and that's your ratio. If it really is an LSD, then turning the driveshaft while only one wheel is jacked will be really, really hard to do (unless it's a VLSD, but it's not, unless you are buying this car from James Thaggard). If you jack up the whole rear (but not by the diff pumpkin as it's hard on the front mount), then spin one wheel, if the opposite wheel turns in the same direction, then it's a LSD. ------------------ 240Z.jeromio.com Quote Link to comment Share on other sites More sharing options...
Racin_Jason Posted March 1, 2001 Author Share Posted March 1, 2001 Thanks alot Jeromio. That seems to be pretty straight forward. He already said it has a "3.55 gear and its a 300 rearend". I didnt ask if it was LSD (doh!). Is 3.55 available in the "300 rearend" and were most of them posi or LSD? Thanks again Jason Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted March 1, 2001 Share Posted March 1, 2001 If it's 3.55 chances are VERY good that it's NOT an LSD! The only 300 other than the very latest ones to have an LSD were ALL 3.7. Ask him the year it was pulled out of - the LSD 300s were all 87.5 through 89 and were ALL turbos. Unless you're lucky an LSD will usually run you about $500 and will be used. To go new costs even more. I'd ask him if it's LSD, he may think it is. If he says yes jack the rear up and turn one wheel - if it's posi I believe the other wheel will turn in the opposite direction. Someone PLEASE correct me ASAP if I've gotten this wrong (50-50 chance right?). Another way is to jack up just one wheel and try to turn it - should be difficult to turn, if it turns pretty freely it's NOT an LSD. Viscous LSD will turn freely with one wheel jacked up but only one special edition version of the older 300ZX had those - damned impossible to adapt - and the very latest 300ZXs had them too. There ARE a few Zs withthe very latest pumpkins in them but they're rare and the swap over is yet to be documented (dammit - and those things are all over the place cheap too!). You might be able to use this cars lack of an LSD as a bargaining point - especially if the seller thinks he got an LSD by using a 300Z diff Good Luck! Quote Link to comment Share on other sites More sharing options...
jeromio Posted March 1, 2001 Share Posted March 1, 2001 BLKMGK, as I stated in my reply above, clutch LSDs will rotate both wheels in the same direction (when one wheel is turned). Only the fluid LSDs behave like open diffs (wheels turn in opposite direction) when turned by hand. This is because the VLSD only works when it's spinning alot (much more vigorously than you can do by hand) which heats up the fluid, causing it too thicken, thus locking the diff. ------------------ 240Z.jeromio.com Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted March 3, 2001 Share Posted March 3, 2001 Thanks, I skipped over that. I know how the viscous stuff works but wasn't quite sure on the clutch ones and didn't look closely enough at your response. Heh, should've gone out and spun the one on my garage floor Quote Link to comment Share on other sites More sharing options...
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