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yet another transmission ID post


carterb

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Just got these two long tail transmissions in a lot.

The only thing the seller "knew" was that one is a close ratio, and one is a wide ratio.  I assume (fingers crossed) 5spds.

One has "75" written on it but that may be coincidence, not necessarily the year. 

They both appear to have the same bell housing/shifter clocking and the "lean" is minimal so L-series?

There were L-series and Z-series blocks in the lot so it's not a given.

 

 

08062021 datsun parts (1).JPG

08062021 datsun parts (2).JPG

08062021 datsun parts (3).JPG

08062021 datsun parts (4).JPG

08062021 datsun parts (6).JPG

08062021 datsun parts (5).JPG

Edited by carterb
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Carter, the CR or close ratio is definitely not a 75, as that is too early for that trans.  That one does appear to have most of the characteristics of the 81-83 280ZX box (single exhaust bracket, tall shifter ear height, tailshaft housing type, but can't see the speedo gear housing orientation in the photos).  The other does look like an earlier S30/S130 5 speed, but don't have those ID details handy at the moment.  Found a great site with pictures a while back.  If I can find it again, I will post a link.

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5 hours ago, iceman510 said:

Carter, the CR or close ratio is definitely not a 75, as that is too early for that trans.  That one does appear to have most of the characteristics of the 81-83 280ZX box (single exhaust bracket, tall shifter ear height, tailshaft housing type, but can't see the speedo gear housing orientation in the photos).  The other does look like an earlier S30/S130 5 speed, but don't have those ID details handy at the moment.  Found a great site with pictures a while back.  If I can find it again, I will post a link.

 

Bottom is a 71B 4 speed. F4W71B.

 

Speedometer pinion is visible in this picture

 

08062021 datsun parts (2).JPG

 

 

Top is a 71B 5 speed, FS5W71B and was made after '79. The '75 is meaningless as the first 71B was an option in the 280z and 620 truck for the '77 model year. Also used in the '79 810.  Perhaps it was pulled from a '75 vehicle but was swapped in. Taller ears on the shifter is not definitive for 280zx but not used before '80

 

 

 The only L series five speeds after '79 were in the 1980 720 truck, The 810/Maxima and the 280zx NON TURBO. The 5 speed in the picture lacks the emissions switches of a carbureted truck, so 280zx non turbo or 810/Maxima with EFI. As the 810/Maxima used a mid ratio gear set and the 280zx non turbo was a close ratio gear set, mark the input and output splines at 12 o'clock, place in first gear, get someone to count the output turns while you turn the input 20 times.

 

Wide ratio...... 5.5 output turns. Not used on cars.

Mid ratio........ 6.0 Used on 620 and 810/Maxima

Close ratio.... 6.5 Exclusive to '80-'83 280zx non turbo. The '80 has a slightly higher (shorter) 5th overdrive than the '81-'83 but otherwise is exactly the same.

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The closer first is to 4th, the closer 2, 3, and 4th gears are spaced with less RPM drop on shifts. A wide is 3.592, mid is 3.321 and a close is 3.062 first gear.

 

 

 

For the most part it's the ratio between the input gear and the counter gear below it that it drives. Fourth is always one to one but first second and third are multiplied by the input gears. (so is fifth)

 

Mid ratio box.

Mainshaft input gear 22

Counter gear............. 31 or 31/22 =  1.409

 

First gear

main......... 33

counter.... 14 or 33/14 for a 2.357*. First gear is 1.409 X 2.357* = 3.32

 

 

To make a wide ratio box you only have to change the two input gears make the smaller one smaller and the larger one larger by one tooth.

Mainshaft input gear... 21

Counter gear............... 32 or 32/21 = 1.523. First gear remains the same so 1.523 X 2.357* = 3.592 and with no other changes you have a truck wide ratio transmission.

 

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  • 3 weeks later...
On 8/10/2021 at 9:41 AM, iceman510 said:

Carter, the CR or close ratio is definitely not a 75, as that is too early for that trans.  That one does appear to have most of the characteristics of the 81-83 280ZX box (single exhaust bracket, tall shifter ear height, tailshaft housing type, but can't see the speedo gear housing orientation in the photos).  The other does look like an earlier S30/S130 5 speed, but don't have those ID details handy at the moment.  Found a great site with pictures a while back.  If I can find it again, I will post a link.

 

 

The top trans is a Z 4speed, easily identified by the 6 bolt plate on top of the tail housing, in front of the shifter.  None of the 5speeds had that plate.

 

The other trans looks like a second or third generation 280ZX 5speed, identified by the SINGLE forked ear, but we can not identify the speedo pinion housing bolt location (12 or 6 o'clock?), as iceman pointed out.  I think this one is the third generation late 280ZX 5speed, cuz I think I see it has the small 2 bolt plate on the drivers side of the tail housing.........??  That 2 bolt plate was an access hole to get to the then new reverse lock out.

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TJ you are probably right but that 71B 4 speed was also used in the '74 620 truck through '79. It doesn't have a reverse check sleeve so not an '80 720 4 speed. I can't see if there are any emissions switches besides the reverse switch so probably a Z car or 810. Both were EFI and did not need any switches. The last 71B 4 speed was in the '82 720 truck. There was a 71C 4 speed briefly in the '88-92 D21 Hardbody. Who uses 4 speed?

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