Twistedlizard720 Posted December 21, 2013 Share Posted December 21, 2013 I was under the Z tonight chasing a clunk, which turned out to be the rear mount bolts starting to back off. While there, I figured I would try to figure out what it is and the gear ratio. I'm still very much a squid with the Z cars, but I have suspicion that it is an R200. The bottom bolt spacing seems to be greater than the 80 mm (3.15") and the drain and fill holes appear to be that of an R200 from pictures I found on the net. I could be very wrong though. Also, the gear ratio isn't too certain. One turn of the wheel yields a smudge over 2 turns of the driveshaft. Does this mean I have a 2.--:1 gear ratio in there? Some pictures. Quote Link to comment Share on other sites More sharing options...
seattlejester Posted December 21, 2013 Share Posted December 21, 2013 A shot of the whole back cover would be the easiest way for me to identify the diff. Based off of the shift or the offset, I'm pretty sure that is an R200. The offset of the R180 is pretty minimal. I would turn the driveshaft a good 40 times and count how many times the wheel turns turns, unless you have a welded or lsd rear end. The ratio should be 3-4.3 driveshaft turns to 1 wheel rotation. A 2 to 1 sounds a bit too far off, that would mean a theoretical top speed of like 250mph with a 4 speed. I remember someone saying the theorhetical is ludicrously around 200mph for US spec 240z at redline in top gear with stock tires, so 2:1 doesnt seem right Quote Link to comment Share on other sites More sharing options...
Meph Posted December 21, 2013 Share Posted December 21, 2013 r200, its probably a 3.545:1. Do you own a 280z? It was stock with the r200. Quote Link to comment Share on other sites More sharing options...
zgeezer Posted December 22, 2013 Share Posted December 22, 2013 A shot of the whole back cover would be the easiest way for me to identify the diff. Based off of the shift or the offset, I'm pretty sure that is an R200. The offset of the R180 is pretty minimal. I would turn the driveshaft a good 40 times and count how many times the wheel turns turns, unless you have a welded or lsd rear end. The ratio should be 3-4.3 driveshaft turns to 1 wheel rotation. A 2 to 1 sounds a bit too far off, that would mean a theoretical top speed of like 250mph with a 4 speed. I remember someone saying the theorhetical is ludicrously around 200mph for US spec 240z at redline in top gear with stock tires, so 2:1 doesnt seem right I agree, it is an R200. My junk yard experience is that if you lock down one wheel, rotate the other, and count pinion/drive shaft rotations and multiply that number by 2 will give you a ball park figure. Your's is probably a 3:9. The only real way to determine ratio is to pull the cover, rotate the crown gear until the numbers appear: the small # will be the number of teeth on the pinion; the larger # is the tooth count for the crown gear. Do the math. G Quote Link to comment Share on other sites More sharing options...
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