510 5 speed question

[Topher88]

I am picking up a 3.70 Clutch LSD today and from what i have read a 280zx 5 speed wont work very well with that numerically low rear dif. Im running and L20 so should i pick up an early or later 280zx tran? from what i have read a later one will have better trakbility where an earlier will be better for the streets. I simply want a fun fast car and dont care to much about practicality.

[Topher88]

basically all im asking is whats the best 5 speed with 3.70 rear end for racing. lol

[jefe de jefes]

You can change the ring gear in the rear end for that.

[Topher88]

You can change the ring gear in the rear end for that.

 

i did not think of that. so just find a 4.11 ring gear or something like that for a r160? am i understanding that correctly?

[jefe de jefes]

i did not think of that. so just find a 4.11 ring gear or something like that for a r160? am i understanding that correctly?

The hard part about finding these LSD units is that almost any Subaru could be ordered with one, yet very few actually were. I'd guess that less than 5% of the cars came with LSD units, judging by what I've seen in yards. Perhaps those of you in mountainous/snowy climes might see more LSDs than those of us in flat/hot areas. What this means that there is no "one" Subaru that for sure has an LSD unit of a given ratio. Most likely LSD candidates are the 4WD turbo cars, often with the 4AT (4 spd Auto) tranny. High-buck XT-6s, XT Turbos, and RX hatchback turbos also have them, and possibly even Brats. Anyway, the LSDs you'll find will be 3.70 ratio. This is fine for a street 510, and will actually make freeway driving less buzzy, as your engine revs will be lower at any given speed (compared to the stock 510 3.90 ratio), but it may hurt your 0-60 acceleration times. For an auto-x or road-racing car, you'd probably be happier with a 3.90 or 4.11. I've heard rumors of 3.90 and 4.11 Subaru LSDs, but never actually found one myself, nor seen one. As an aside, most Legacys have 4.11 R-160s that are non-LSD, giving you a 4.11 ring & pinion you can drop the 3.70 LSD clutch unit into (using the special LSD bolt set described below). I did just this by purchasing a used Subaru 3.70 LSD unit and a used legacy 4.11 open R-160 differential and creating a 4.11 LSD unit from the parts. I paid a rear-end shop $120 to drill the six 10mm holes out to 11mm so the LSD unit's bolts could be used, and to set up the newly assembled unit with the correct tolerances. Gary Savage did put a Subaru LSD carrier from a 3.70 ratio differential into his 510 using the 510 differential case, the NISMO LSD bolt set and the Nissan 4.11 ring & pinion to get the 4.11 LSD he wanted.

 

http://www.legacycentral.org/library/literature/differential.htm#What%20is%20a%20Limited-Slip%20Differential,%20and%20what%20are

[jefe de jefes]

Where'd you get your LSD? Jy or fleabay/c-list?

[Topher88]

im getting it from a member here tonight. so do you think with that ratio both 280zx 5 speeds will feel like a turtle? but will they at least be an improvement to my stock 4 speed?

[jefe de jefes]

im getting it from a member here tonight. so do you think with that ratio both 280zx 5 speeds will feel like a turtle? but will they at least be an improvement to my stock 4 speed?

Idk man. Maybe someone here can chime in? My car is all stock with a 4 speed and I have never driven a car with the LSD and 5 speed swap. I'll be doing the rearend swap sometime in the near future but I'm after low freeway rpm's and better fuel economy. I'm not really into the racing part of it. Especially with the L16 sitting under the hood :)

This is what I'm working with.

[datzenmike]

Very simply put the early 280z and first year zx 5 speeds were a wider ratio gear set with a lower starting 3.321 1st gear compared to the later '80-'83 non turbo 5speeds 3.062 first gear that placed the gears much closer together. A wide ratio transmission has a larger RPM drop between gear changes. A closer ratio gear set looses some mechanical advantage on take offs from a start but once moving the gears are 'closer' will less RPM drop on shifts. Something that has little effect around town is the overdrive 5th gear. The early tranny has an 18% overdrive compared to the later with just over 25%. The later would be good if running a 4.11 or 4.375 ratio differential for bringing up highway mileage