Question about 5-speed FS5W71B

[Gmac708]

I am looking at a couple FS5W71B "close ratio" transmissions. One has an aluminum adapter plate installed between the front and rear case. The other has a steel adapter. I have read about the steel adapter but have never heard mention about the aluminum one. Aluminum in back VVV steel in front.



Close-up of stamping on aluminum adapter.



A few more pictures of both to compare.











All things being equal...which one would you buy???
Anybody heard of the aluminum plated ones?

Gord

[datzenmike]

Fascinating. First aluminum one I have ever seen or heard of.

Both 5 speeds are '80 or newer and have reverse check sleeves.

There were only three L series FS5W71Bs in 1980 and two after. Neither of those appears to be from a 720 truck so 810/Maxima or 280zx are left. Of those, only the '78-'80 California emissions 810 had both a reverse lamp and a neutral switch like the one on the left. The 280zx FS5W71B only had reverse lamp switches like the one on the right. Though not definitive, I find that the zx 5 speeds tend to have the oil drain on the passenger sides. (like the one on the right also)

One other thing different about these two transmissions is the striking rod guides. The thing the bottom of the shift lever attaches to. The one on the left supports a short throw shifter while the right one is a normally long throw. Did the zx, at least some of them, not have a short throw shifter?

I see the aluminum adapter plate is well stamped (340) and in such a way that front and rear case can't be swapped out without notice. Maybe re-built?

[datzenmike]

Thought of something last night so I checked my Datsun Competition Parts Catalog this AM. But turns out the FS5C71B uses the same adapter plate part number as many 620 and Z car transmissions also. So dead end.

Something that may help is to ID the internal ratios. There are three Nissan ratios that I call wide, medium and close. The wide ratio is usually used in later trucks and some cars with 2 liter engines and high differential ratios. (lower numerically) The medium is on earlier trucks and most 280Z cars and 810/Maximas, and the close only on the later 280zx

First gears

3.592....... wide
3.321....... medium
3.062....... close

Place your transmission in first gear.
Mark the input spline or better place an old clutch disc on it and mark it at 12 o'clock.
Mark the output spline of the mainshaft or place the spline from a driveshaft in the end so you can see it
Rotate the input 20 times while counting to output turns.

5.5 output turns....... wide ratio
6.0 output turns....... medium ratio
6.5 output turns....... close ratio.... this would be an '80 or an '81-'83 280zx with 0.773 or 0.745 overdrive fifth.

I hope this helps you to select a close ratio. I'm also sure there are people driving around with mid instead of close ratio '280zx 5 speeds' so now everyone can check before buying. Only the '79 280zx had the mid ratio FS5W71B and it was an option that year. Four speeds were dropped the next year.

On the odd chance this is a non factory competition box...

FS5C71B (with overdrive 5th)
2.906 first gear..... 6.9 output turns

F5C71B (with direct drive fifth gear, and I think flange output so these probably don't apply)
2.818 ....... 7.0 output turns
2.348 ....... 8.5
2.192 ....... 9.12