David K Posted December 19, 2002 Share Posted December 19, 2002 Im beating my head on this one. A friend got me all confused on what differential i have in my Z. Its a 79 280zx, never changed the diff. I know its an r200, but what is the ratio? At 80mph, the rpm's are at/VERY near to 3k. Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted December 20, 2002 Share Posted December 20, 2002 Of the cars with the R200, deluxe models came with a 3.36 and GL models had 3.7 in 1979. Do you have an automatic or 5 speed? Quote Link to comment Share on other sites More sharing options...
Guest 240hybrid Posted December 20, 2002 Share Posted December 20, 2002 I dont know off the top of my head, some other guys might though. I do know that if you remove the rear cover plate and find the numbers on the gear to calculate your ratio all you have to do is some simple division. Example 3.7x11 gets you a 3.36 gear after dividing. Easy enough and exact. Quote Link to comment Share on other sites More sharing options...
David K Posted December 20, 2002 Author Share Posted December 20, 2002 I have a 5-speed. I also do not want to take the cover off. It is going to rain soon, so car will be unattended to until it stops. Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted December 20, 2002 Share Posted December 20, 2002 Working out the MPH at 3000 RPM using a 215/60-15 tire and .864 OD, a 3.36 gear would give you 77.34 MPH and a 3.7 gives you 70.24 MPH. You have a 3.36 in your car. Quote Link to comment Share on other sites More sharing options...
David K Posted December 20, 2002 Author Share Posted December 20, 2002 Yay! I will go high HP now thank you very much Quote Link to comment Share on other sites More sharing options...
Synlubes Posted December 20, 2002 Share Posted December 20, 2002 David, My R200 came out of a 79 and it is a 3.70! I didn`t think 3.36 even came in a R200??? (don`t know 4 sure) Try to get someone with a 79 Nissan service manual to look at specs! I also got the 5 speed out of same car and it has an odd gear ratio, different from other 5 speeds! Ck the specs in the Nissan manual 4 79 and like early 80`s, it shows the differences! Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted December 20, 2002 Share Posted December 20, 2002 Dave, Explain how you think it is an R200, because my book says it should be an R180 with a 3.36. Quote Link to comment Share on other sites More sharing options...
Mudge Posted December 20, 2002 Share Posted December 20, 2002 280ZX 79 MT 4 Spd, (3.364) (R180) 79 MT 5 Spd, (3.364) (R180) 79 AT (3.545) (R180) 280ZX 2+2 79 MT 4 Spd, (3.364) (R200) 79 MT 5 Spd, (3.7) (R200) According to: http://www.geocities.com/MotorCity/Garage/6212/diffswap/diffswap.htm Quote Link to comment Share on other sites More sharing options...
David K Posted December 20, 2002 Author Share Posted December 20, 2002 Originally posted by Greimann:Dave, Explain how you think it is an R200, because my book says it should be an R180 with a 3.36. I took it out of a 77 that was a race car. Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted December 20, 2002 Share Posted December 20, 2002 Originally posted by David Karey:.... Its a 79 280zx, never changed the diff.... This was what I was basing my research on. The ratio of 3.36 still works out, unless you have changed the transmission too? Quote Link to comment Share on other sites More sharing options...
David K Posted December 20, 2002 Author Share Posted December 20, 2002 Oh, well i thought the diff i was putting in was the same one. I looked around online and found out the 77 was a different diff. What i mean to say is that i never changed it to another ratio. I was under the assumption the 77 and 79 shared the same diff. This is too confusing. Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted December 20, 2002 Share Posted December 20, 2002 Ok. The best way determine your ratio without opening the case is this: Roll the car so the tires make exactly one revolution. At the same time look at the driveshaft and accurately count how many revolutions it makes. 3.36 driveshaft revs is a 3.36 ratio and so on. Don't run over yourself doing this and if you put it up on jack stands, turn BOTH tires the same direction. Also, if the diff side half shaft yoke has a single bolt in the middle holding it in, then it is an R180. If the diff side yolk has 4 small bolts in the flange, then it is an R200. Quote Link to comment Share on other sites More sharing options...
Mudge Posted December 20, 2002 Share Posted December 20, 2002 Originally posted by David Karey: quote: Originally posted by Greimann: Dave, Explain how you think it is an R200, because my book says it should be an R180 with a 3.36. I took it out of a 77 that was a race car. 77-78 MT (3.545) (R200) 77-78 AT (3.545) (R180) Quote Link to comment Share on other sites More sharing options...
Guest 240hybrid Posted December 21, 2002 Share Posted December 21, 2002 Its a good idea to mark the points you pick on your tire and driveshaft with a piece of chalk or something, so as to make sure you get an accurate number as far as revolutions of the tire and shaft. Simple tip that helps to keep you from having to start all over or get wrong ratios. I dont know about you, but I like to spend as little time laying under my car as possible. good luck on finding out your ratio. Also a R-200 uses 12mm bolts to hold the cover plate on and a R180 has 14mm bolts on the cover plate if your still in debate on that. Good luck Quote Link to comment Share on other sites More sharing options...
D83ZXT Posted December 21, 2002 Share Posted December 21, 2002 Here you go David... Maybe this will be less confusing for you. If you want to use this as a reference guide in the future http://www.geocities.com/z_design_studio/ Donna Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted December 21, 2002 Share Posted December 21, 2002 Thanks Donna, I've been looking for that link. Quote Link to comment Share on other sites More sharing options...
David K Posted December 21, 2002 Author Share Posted December 21, 2002 Dang! that is a cool tool! With that, we can put together a combo that rocks! Quote Link to comment Share on other sites More sharing options...
D83ZXT Posted December 22, 2002 Share Posted December 22, 2002 You're Welcome LOL... Perhaps, I could have gave this link faster if this post was posted in the correct topic location. Donna Quote Link to comment Share on other sites More sharing options...
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