Guest Anonymous Posted October 31, 2001 Share Posted October 31, 2001 hey, the diff on my 280zx at the moment is rooted and i have a diff sitting in my shed but i know nothing about it. can someone please help me im not sure if it is the top or bottom but on one side it says: 757 82 3 KN 23 and on the other it says: S60 757 and has a big K on it also can someone tell me anything about this diff??? the year? the model? anything like that would be great? and how many teeth does it have on the crown of the diff gears? Quote Link to comment Share on other sites More sharing options...
auxilary Posted October 31, 2001 Share Posted October 31, 2001 here's some info I dug up, it was originally by Ross C. quote: Want to know what gear ratio that Z rear end is, before you remove it from the car or install it in your Z? Take a buddy, and just turn it to find out. My dad and I have turned at least a dozen. Fix one rear wheel so it can't turn (pry bar and foot of the driveshaft counter, or jam it otherwise). Mark the driveshaft w/ chalk or scratch w/ a nail. rotate the other rear wheel 10 times, other person counts the driveshaft rotations. Then multiply the driveshaft rot's number by 2(and divide by ten I spose) and whammo its your diff ratio. If 10 turns gives you (x driveshaft rotations) just shy of 17, then its a 3.365 17.5 then a 3.54 18.5 then a 3.7 19.5 then a 3.9 Each difference is at least a whole number (except 3.36->3.54, but still 16 or 17?) so this always works for us. Don't forget to grab the speedo gear out of the tranny (one 10mm bolt), even though you don't need it (w/ a 700R4 for a V8 conversion), if you ever sell it it'll help out a Datsun dude. Others reccomend removing the rear cover plate and readig the ring gear. The number of teeth on the ring and pinion are stamped on the ring gear - so just divide one number by the other. The units I look at most of the time are still in the cars, so this "counting the turns" method works for me. here's also a reference guide quote: Differentials.... When checking the stamp on the ring rear, if you don't have 20/20 vision. Bring a magnifying glass. It really isn't easy to read. Also have a flashlight and some steel wool... just in case ya need to do a bit of cleaning. A shop rag is required as well. R180's and R200's with 3.364:1 gearing came in... 240 - 260 Z's / 1970 to 1974 - R180 280ZX 6/78 - 9/79 - R200 280ZX Automatics and turbo's - R200 Maxima Sedans Automatics - R180 Ring gear is stamped with 37:11 Math tip... 37 divided by 11 is 3.3636 R180's and R200's with 3.545:1 gearing came in ... 240Z - 280ZX Automatics - R180 280Z Manual - R200 280ZX Turbo w/Automatics - R200 Maxima Sedan Manual - R180 Ring gear is stamped with 39:11 R180's and R200's with 3.70:1 gearing came in ... 810 Sedan - R180 280ZX Manual from 6/78 to 6/79 - R200 300ZX Non-Turbo and Turbo's - R200 Ring gear is stamped with 37:10 R200 3.70:1 LSD – Clutch Pack – Finned Alum. Cover 300ZX Turbo only 1987-1989 R200 3.70:1 LSD Viscus 300ZX Turbo Only 1988 Cars are all White. Diff is Labeled. I’ve only heard of One person that knows How to install this in a 1st Gen Z – 240Turbo on Zcar.com I have seen other comments on other mailing listed that indicated that the expense to do this conversion will out weigh the benefits of performing this swap. Unless you have access to machine tool equipment, I would advise ya to swap to an lsd with clutch pack. Custom Mounting brakets – Dave in Portland, OR. Eric on the East Coast R180's and R200's with 3.90:1 gearing came in ... 720 4X4 1/83 to 6/83 - R180 280ZX Non-Turbo 1980-1983 - R200 200SX Turbo 1984 - R200 200SX V6 - R200 Ring gear is stamped with 39:10 R180's and R200's with 4.11:1 gearing came in ... 720 4X4 6/83 to 12/85 - R180 200SX Turbo 1985 to 1986 - R200 200SX Non-Turbo's 1984 to 1988 - R180 Ring gear is stamped with 37:9 This is only a reference guide... of course... things do happen to cars and rear ends do get changed out. So always measure with rotation. I use chalk make a white mark on the driveshaft. Do the same on the tire if its on, or whatever can be rotated. Place the mark at a point of reference. Like straight up or down. Then turn the drive shaft and count the turns. Do this for one full turn of the wheel/hub/rear half shaft. This will give ya a good guess as to what gearing is in the rear end. When you find something close.... then pull the rear cover and start looking for the marking on the ring gear. I am sure someone else can provide much better info than I. Quote Link to comment Share on other sites More sharing options...
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