F4W71A trans. - fix it or ditch it?

[astrohog]

My car is a numbers matching, very original 1971 (12/70 build) series 1 240Z.  I'm getting ready to pull motor and trans before sending it to the body shop for some work and new paint.  Motor was running fine, but I am going to strip it and have it rebuilt before re-installing it.  Transmission was okay, but it was grinding going in AND out of 2nd gear.  I had not changed the trans oil in years, and it was a bit funky when I drained it in prep of removal.  

I'm just now finding that the F4W71A is not supported anymore and was not the best gearbox to begin with.  I've read where good quality gear oil has "fixed" some grinding problems, and I also found where 2nd gear synchro's may be available for my box.  I've read everything I can find on this subject and I am still stuck on what to do.

Bite the bullet and buy a rebuilt close-ratio 5 speed from California Datsun for $2,500.00?  Source a F4W71B?  Try to cobble together bearings, gaskets and synchro and attempt to rebuild mine?

I've always thought I wanted the 5 speed, but they were much easier to find and a whole lot cheaper a decade ago!

Any sage advice from all of you guru's?

[Zed Head]

22 minutes ago, astrohog said:

Bite the bullet and buy a rebuilt close-ratio 5 speed from California Datsun for $2,500.00?

 

Post #33

 

[astrohog]

Okay, Zed Head, point well taken!

But that only changes my options to sourcing a "B" box, trying to cobble together a rebuild kit for my "A" box, or sourcing a 5 speed and re-building it.

Any sage advice NOW? 😆

[Patcon]

Don't buy from California datsun! I would prefer the 5 speed if it were mine. I believe you could go the 240SX route, too?

[Zed Head]

I wouldn't assume that whatever you might find needs a rebuild.  Look around for a complete junked 280ZX or 280Z.  Buy the whole car and scrap the rest for $50.

As far as the 71A the car will probably be worth more with it installed.  Not clear what your long-term plans are.  Your problem description makes it not clear what exactly is wrong with it.  Might be a simple fix, who knows.

Don't overlook just buying a cheap 71B 4 speed while you look for a long term solution.  Sometimes people give them away.  @Racer X has what you need, probably of all three varieties, but it might take some work to get to.  He's right down the road...

1 hour ago, astrohog said:

Transmission was okay, but it was grinding going in AND out of 2nd gear. 

 

[Terrapin Z]

You may have determined this already but keep in mind any B/C trans will need the shifter hole enlarged some to accommodate the more rearward position of the shifter. Not by much but still an alteration. As Zed says worth more in the long run, unmodified.

The 5 sp is nice for the highway speed runs. 4th is 1:1 on both the 4 and 5 speed. Makes the twisty back roads about the same. 1st-4th.

I too have some 4Sp 71B transmissions and even a couple of 71A models. You can still find 5sp ZX cars but they are getting harder and harder to find, with the price going up some too. I bought one from Everett for $300 and have parted out most of it. (I am keeping the transmission.)

 

Edit: this is in your neighborhood. looks like he just dropped the price. 83ZX 2+2 $100.00

https://offerup.com/item/detail/9f4db155-79df-305b-8fba-72401858e4ad?q=datsun&cid=5.1

Edited October 11, 2022 by Terrapin Z
Found a link.

[Mark Maras]

Years ago I disassembled my late 70 4 speed because it had the same problem going into second gear. When I got it apart I found pristeen synchros. I replaced them ,the bearings and seals because I had the new parts. I later reused the pristeen used synchros in a friends gearbox. The used synchros worked just fine. The experience left me thinking the original problem with my trans could have been fixed with different gear oil.

[Racer X]

13 hours ago, astrohog said:

Okay, Zed Head, point well taken!

But that only changes my options to sourcing a "B" box, trying to cobble together a rebuild kit for my "A" box, or sourcing a 5 speed and re-building it.

Any sage advice NOW? 😆

I've never seen a "kit" for manual transmission rebuilds. Usually the gearbox is disassembled, cleaned and inspected. Out of spec and worn or damaged parts are replaced, and reassembly is done. 

You mention a grinding going into 2nd gear. That is indicative of a worn or damaged syncronizer. It should be obvious on inspection during the cleaning and inspection.

If new components such as seals, syncros, gears or bearings are needed, some can be sourced as NOS, bearings and seals can be sourced at any bearing supply house (they don't have to be genuine Nissan, as Nissan usually buys from the same sources), and gaskets can be made easily by hand (or a thin film of RTV silicone used).

As a last resort, sourcing used gears and syncros is a n alternative, or, have a machine shop make a replacement.

 

[EuroDat]

Hi,

You have not mentioned what your plans are for your series I. If you want originality then you will want to keep this 71A transmission. You can very likely fix your problem by using a good oil suitable for brass synchros.

Try oil from AC Delco or GM. Yes, it does wonders on these old trannis. The part numbers are AC DELCO USA part number is: 88900399. GM USA part number is: 12377916. I can not order the GM or AC delco oil here in Europe. I'm using Redline MT 75W-90 and find it very good. Here is a thread on the oil subject for these transmissions.

 

 

Another option could be to dismantle the transmission and replace the bearings. If you can not find new synchros, you could swap it with 3rd gear. 

You might want to read through this thread as well. He had issues with 3rd gear, but his journey to fixing it is informative.

 

 

Just for the info. People mention the 280ZX close ratio, but the 2+2 has the same wide ratios as the earier 280Z. The 2+2 also uses the 240mm clutch/flywheel. $100 would be an absolute bargin over here.....

6 hours ago, Terrapin Z said:

Edit: this is in your neighborhood. looks like he just dropped the price. 83ZX 2+2 $100.00

 

[Terrapin Z]

4 hours ago, EuroDat said:

Just for the info. People mention the 280ZX close ratio, but the 2+2 has the same wide ratios as the earier 280Z. The 2+2 also uses the 240mm clutch/flywheel. $100 would be an absolute bargin over here.....

I have seen you mention this before. I can not find any data to support this info. Even Carl Becks site does not list this difference. My parts manuals don't show it either. 

Do you have some reference material you can point me to for the late 2+2ZX having the same as the late 280Z ratio's. 

I did find the early ZX had that same ratio and a short lived 80ZX had a similar "close" ratio to the the commonly sought after 81-83 (2+0 and 2+2) 

[Patcon]

@EuroDat

You can't buy this but if you ever want some. I will gladly ship you some...

C

4 hours ago, EuroDat said:

I can not order the GM or AC delco oil here in Europe.

 

[madkaw]

I worked on an early 71 that had the original 4 speed - A . The shifter was terrible and that’s what I learned what monkey motion meant - lol. 
Anyhow - I don’t even remember how I made the connection with Lou Mondello in Australia that had a make potion for the A trans shifter . I ended up sending the tail section down under to get reworked . It took time and money - but boy was it worth it . The owner texted me - OMG- YES !

It transformed that A trans . The shifter was great and made for fun shifting regardless that it was just a 4 speed .