What gear would you recommend on a 81 280zx and where can I find some ?

 

If it is a non-turbo then you should have a 3.9 rear gear. You can only go one step lower for more power. An R200 4.11 gear can only be found on the 1984 to early 85 200SX turbo.

If you have a turbo Z, then you have a 3.54 You should get a 3.7 LSD from a 1987-89 300ZX turbo

 

Okay, just to clarify, because I've had mixed responses on this - my Z is an '81 2+2, non-turbo 5-speed ... I've had a lot of people tell me it already has an R200 in it, and others tell me it's got the R180 in it ... what do I have? Either way, the diff is acting up, so it'll get replaced anyway. If I have the R180 diff, can I install an R200 from a turbo 280 or are the mounts not right? I'm open for any options, the help is appreciated.

 

All 2+2s have an R200.
Use a rear end from a 1981-83 non-turbo 280zx. 2-seater or 2+2 will be fine. That will keep your same 3.9 gear ratio.
If you use a turbo R200 then you'll increase your rear gear ratio to 3.54

If you want more speed with fewer rpms then you can up the gear ratio. (less torque though)

 

Thanks for clearing that up, bleach. The R200 is a limited slip from the factory, correct? At least that was my understanding. Anyway ...

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Project RallyBeater is in full swing - getting a rollcage, suspension lift, and high-performance cams!! Long live beaters! The Z is still on jackstands, and will be for a while, until I get all my parts straight ...

 

Oh no. R200 is just the width of the gearset. I think 200mm??? I dunno.
Anyway, R200 is just more heavy duty than R180. The gear ratios just depend on how it was manufactured. LSD is a totally different option. The R200 gearset only came from Nissan with the LSD option in the 1987-89 300ZX turbo and only in 3.7 gear ratio those years. All 280zx differentials are open diff. Even the turbo.

Now, to add to it, the 3.7 and 3.9 gearsets both share the same number of teeth on the ring gear. I think possibly you can take the LSD unit out of a 3.7 and put it into a 3.9 R200. (ONLY 3.9) and have a 3.9 LSD Somebody buy all the stuff and find out!

 

Hmmm ... sounds like a plan - I'll have to visit the local Z junkyard and pick apart a turbo 300 ... It might take awhile before I can get to it, but I'll try the hybrid R200 deal on Project Z and let you all know how it turns out. If anyone beats me to this, let me know how it goes! Thanks, the help is always appreciated.