"83 280ZX close ratio box and 3:90 differential

Engine, Transmission and related drivetrain.
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Re: "83 280ZX close ratio box and 3:90 differential

Post by bertvorgon » 09 Sep 2018 09:44

If it was me, my last word...15" tires are kinda tall from what our 510's came with, they are going to be 23.5" or so tall.

If you have a line on a 4:11, you will really benefit from that, Guaranteed. Unless you spend all day, 5 days a week, at 70 MPH on the freeway, you will enjoy the slightly shorter gearing in the real world of stoplights and general day to day driving. Having a 'snappy" car is what makes our 510's fun and 3:9's will just be a bit lame IMHO. I drive with a group that runs from 4:11, 4:3, and of course my 4:6's and they are all pretty zippy cars.
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Keith Law
1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

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Re: "83 280ZX close ratio box and 3:90 differential

Post by funwithmonkeys » 09 Sep 2018 10:13

I agree with Keith. Don't think twice about it. Go with the 4.11's. I have 4.44's and a second diff with 4.6's that is going in next month. With the .74 OD it makes the short gears totally bearable for hwy driving. It is also the cheapest HP you can buy.
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Re: "83 280ZX close ratio box and 3:90 differential

Post by datzenmike » 12 Sep 2018 21:15

Not everyone who has a Datsun has a 'true' close ratio box, would even know about them, where to find one, could afford one, and if they did they probably wouldn't like them anyway for their predominantly street driven cars. The 'close ratio' box is simply too esoteric for a street car. So that leaves the 71B 5 speeds that actually came in the cars sold and can be found relatively easy in the three ratios mentioned. For want of a better way to identify them they are (relative to each other) wide, mid and close. That there are even closer ratios is splitting hairs. No one is going to find one in a wrecking yard and outside of a NISMO parts catalogue they almost don't exist.
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Re: "83 280ZX close ratio box and 3:90 differential

Post by Gereed75 » 17 Oct 2018 17:40

Realize that this thread is a bit old and most know this, but the 84-85 200SX non turbo 5 speed is very close to the NISMO N3130 ratio's at 3.321/1.9/1.308/1/.833. These things are readily available in junk yards for cheap. They do require a fairly simple adaptation of an L series bell housing. It is a 71B tranny some times called a "near C". IMHO, a much better choice than the ZX tranny.

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