Transmission swap

[Reptoid Overlords]

I have an 82'ZX NA parts car with a Nissan transmission that I am considering putting in my '80 ZX NA car. The transmission in the '80 shifts fine, but will need a clutch soon. I'm pulling the engine/trans out of the parts car anyway. My questions are:

 

Should the '82 trans mount directly into the '80 car without modifications?

 

Is there a different gear ratio between '80 and '82?

 

I remember when the parts car was running its transmission shifted tighter and smoother than the one I have in the running car. I haven't checked, but unless the PO put a T5 in it, its a Nissan transmission.

 

 

[EuroDat]

2 hours ago, Reptoid Overlords said:

 

I have an 82'ZX NA parts car with a Nissan transmission that I am considering putting in my '80 ZX NA car. The transmission in the '80 shifts fine, but will need a clutch soon. I'm pulling the engine/trans out of the parts car anyway. My questions are:

 

Should the '82 trans mount directly into the '80 car without modifications?

Yes

 

Is there a different gear ratio between '80 and '82?

That depends on the production date on the 80 ZX. After 6/80 they are the same transmission. Pre 6/80 the fifth is a little different.

Pre 6/80 is 0.773

After 6/80 is 0.745

Both models are essentually the "close ratio" FS5W71B.

 

I remember when the parts car was running its transmission shifted tighter and smoother than the one I have in the running car. I haven't checked, but unless the PO put a T5 in it, its a Nissan transmission.

 

 

 

 

Edited October 9, 2017 by EuroDat

[Reptoid Overlords]

Wonderful. Thank you. The build date on the '80 is 11/79. I appreciate the reply.

[7tooZ]

The build date would suggest that you have what is called an open ratio. You can check by looking at the speedometer mount screw location. It’s probably a 12:00 o’clock. This a still a good 5 speed.
Are you using a stock 180 rear end?


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[Reptoid Overlords]

I am running the stock R180 differential. If I swap transmissions, and discover that the donor has an R200 would you suggest using it in place of the 180? The '80 it would be going in has a bone stock engine. This is all just preliminary planning. I might just pull all of it out, and store it until something actually wears out to the point of needing to be replaced. Thanks for the input.

[Reptoid Overlords]

I guess it should be noted that the reason I'm considering fixing something that isn't broke is that I was planning to pull the engine/trans out of the running '80 ZX just to clean up the engine bay, replace mounts, and paint. Before I got it, the PO ran it with a leaky oil pan gasket/valve cover gasket and a leaky power steering pump.

[Zed Head]

It should be a straight across super-easy swap.  The only difference you would see is in 5th gear, if the 80 has the .773 ratio.  5th gear would be farther from 4th, which makes it a bit less usable, but will drop a few RPM on the highway, for a smoother engine and better mileage.

But you should verify that it hasn't been swapped in the past, using the signs 7too mentioned.  The speedo gear lock-down screw, and the exhaust hangers.  If the 80 car actually has the older 5 speed then you will notice the difference.

[Reptoid Overlords]

Excellent, thanks. I will verify the speedo screw as 7too said, and let the chips fall where they may. I appreciate all of the good input.

[7tooZ]

Plus the is no need for a R200 unless you have high horsepower or abusing it in some other way.


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[EuroDat]

Btw, you can tell the "wide ratio" and "close ratio" FS5W71B transmission apart by several external differences. Speedo adaptor retaining bolt, the exhaust hanger support, commonly known as ears and reverse lock-out mechanism.

The "close ratio" came in two versions. 1st to 4th are the same, but 5th is slightly different.

If the boxes ars still original, you should have two of the later version of the "close ratio". The general consensus is they changed around 6/1980 give or take a couple of weeks.

 

How to identify - F5W71B Wide and Close ratio transmission (1).pdf