The 510 Realm

Can anyone fill in the blanks on this 5 spd transmission? From what I can find on the web it seems like its a FS5W71B which could have been from a variety of vehicles (Incl 280ZX?) and years. Any info appreciated.

that looks like a wisp of non-factory sealant

Blue is the spoor of a previous owner that drove a Chevy. They love using that shit. Put it on by the hand full.


Definitely an L series FS5W71B 5 speed

Made before 1980 because there is no reverse check sleeve.

Not from a 620 truck as it doesn't have any emission switches on it.

This would narrow it down to the '77-'78 280z or '78-'79 810 both, optional 5 speeds. Technically the first year '79 280sx would fall into this category, but I have one, and all the 5 speeds I have ever seen have the reverse lamp switch about a inch forward of this one on the round boss in the bottom picture. (this is the first picture of a 5 speed with this I have ever seen) The 280z car did have an F4W71B 4 speed with the reverse switch in this location. So, I'm going to say the '77 and up 280z or maybe the early 810. The internal mid ratio gearing was the same on both cars, so they are basically identical.

If you mark the input spline (or slip an old clutch disc on it) Place in first gear. Mark the output spline.

Turn the input exactly 20 times while counting the output turns.

A wide ratio transmission will turn 5.5 times.
A mid ratio transmission will turn 6 times. Probably this one * I like this ratio for cars.
A close ratio transmission will turn 6.5 times. Probably not. Only found on the '80-'83 280zx.

Look on the top front where it is against the head. If any cereal numbers post them. Maybe we'll get lucky.

Great info, thanks Mike.

I found it all here... http://www.jdmjunkies.ch/wordpress/wp-c ... cation.pdf .... I only wish I knew this much about transmissions.

5.5 turns...it's the wide ratio.

Well my information says only the '79 620 truck used a wide ratio 5 speed option.

Are there any numbers/letters stamped along the top leading edge??? Looks like it in this picture...

It looks like 7/13687

That would be about half way through the first year the 71B 5 speed was offered as an option in the 280z and 620. Assuming the standard transmission build dates are ID'd the same as the automatics. Are you sure about the number of turns?.... it should be a mid range gear set.

IDing a transmission is not an exact science. It's usually easier to know what transmission it isn't. They get swapped into different vehicles and years and judging from the sealant, it's been apart and the front and rear cases can be swapped. The rear rubber mount is from a truck not a 280z or zx but the shifter is too short for a truck.

Checked again, it turns 5.5 times.

OK (bear with me) one last thing. Place in 5th gear and confirm that the out put turns fewer times than the input. If 20 input gives about 17-18 output then I guess it's a '79 620 5 speed.

1st... 3.592
2nd... 2.246
3rd... 1.415
4th... 1.000
5th... 0.812

1st through 4th agree with your ratios. 5th seems like it is 0.93 (20 input turns = 21.4 output turns)

That would be an odd gear set. I had a 78 KC PU with the factory 5 spd, and admittedly the 4-5th shift dropped only a few hundred RPM's at 80 KM/H, but a 1:1 to .93:1 would feel like you didn't even change gears!

The comp gear boxes had a 1:1 5th gear with a tall 1st gear and the ratios in between closer together. If I weer to drive your box I'd have through that's what you had. But you've confirmed 4th as 1:1, so it's not a comp close ration box.

That's an interesting gear set for sure, I've not seen this one before.

Byron

It does seem like an odd ratio, not much different from 4th. On the plus side, I guess it might still pull in 5th.

As 510rob pointed out, it looks like someone has been tinkering with it.

Only the '79 620 got this 'wide ratio' gear set. The '77-'78 got the 'mid ratio'. The reason was the '79 standards dropped from 4.357 down to 4.11 differential. This would be somewhat difficult to pull away from a stop fully loaded so a lower first gear was needed. Out on the highway the 4.11s would give slightly better mileage.

Mid ratio...

1st... 3.321
2nd.. 2.077
3rd... 1.308
4th... 1.000
5th... 0.864