I'm starting to understand that the 71C:swap is not an option for me because my 71A-trannies are too old. I'm not 100% sure that neither of them is a 71B. How can you tell?

I'm a little confused with these. Why didn't they just print the tranny type to the cover ?!

One more pic.

I think that those are 71B transmissions.  Your Europe market cars had 5 speed options throughout the years, we didn't here in the States.  Looks like one has a steel front cover (older) and the other has aluminum, from the casting shapes.

So you have several ways to get a 5 speed back together, but the wider/stronger gears only came in the later year 71C 5 speeds, somewhere around 1994 I think.

Are there teeth actually stripped off 3rd gear from too much torque, or are they just damaged from grinding up bits of metal?  The transmissions can fail in many different ways, one common way is for the adapter plate bearings to fail, letting the shafts move around.  What else as on the drain plug magnet?  Maybe you just have a worn out 5 speed, not an over-powered 5 speed.  You might not need stronger gears.

I think they're fs5c71b boxes. I'll dig out a pic of a fs5c71a shift linkage. It's quite different but anyway, the huge giveaway is that the case is in 3 pieces and the B boxes are in 2 pieces like the C boxes.

 

Edit: looked again and they've got brass synchros so they're fs5w71b

 

 

 

I bought the car 8 years ago, and the earlier owner had given the car punishment... Back then it had three dellorto carbs, 3,1 liters stroked and bored  L26. Little boost only. He told me not to add boost, because of the old gearbox. Well I didn't. But still it was fast. He had had a little more boost, when he drove 12sec-200kmh.

Then I did the stupidest thing: swapped this carbureted turboengine to an imported L28ET, And some money.  Now that I'm a little older, I understand I should have kept the three carburetors. But I try to forget that blackout moment.

The funny thing is: When I swapped to this L28ET, the old gearbox remained. Only last winter I drained it because of starter gear problems. And now I recall: there was nothing in the plug magnet! (I haven't had gearbox issues ever in my life before) Oil wasn't very black, and the plug was not covered with anything. The previous owner hadn't changed the oil before selling it to me. But he drove it hard. The box worked these years with me fine, only when shifting from 5 to 4 I had to be careful.

When the third gear teeth got loose, I was driving easy. No pulling. And when I opened the plug, there was some metal powder in yhe magnet ,no chips or anything. Well, those loose teeth of course.

So what made the teeth fly?

Fs5c71a

 

 

Looks like you have many options.  You could use a 4 speed while you search for a "wide gear" 71C 5 speed.  Use your spare to do the bellhousing swap while the car has the 4 speed in it.

If you got 8 years out of the old 71B, it might just be metal fatigue that broke 3rd gear.

Forgot to say, consider gear ratios when you're looking for a solution.  There is a wide range, some very low 1st gears and some not so low.  Match what you have or plan a diff swap also.

Edited September 16, 20195 yr by Zed Head

My Datsun diff is a 3.9, so I need an overdrive gear. I hope I don't have to consider a diff swap.

We have a cold and wet winter time ahead, so all interesting vehicles disappear for about six months. Plenty of time to solve problems. 

 

1st gear is what you want to consider.  A 3.9 with a super low 1st gear can make 1st gear almost useless.  Plus the turbo engines tend to run "taller" gearing since they have more low end torque.  Just be aware of the differences when you're looking.

"Plus the turbo engines tend to run "taller" gearing..."

Sorry can you translate this?

You should be alright with that diff. It was originally for the 280ZX Non turbo 2 coupe. 81 - 83.

The 280Z 5 speed had a 3.321:1 1st ratio with a 3.545 diff.

The 280ZX turbo had a BW T5 with 3.50:1 ratio with a 3.545 diff

You had a 280Z 5 speed ( well, I think it is) with a 3.321:1 1st ratio and a 3.9 diff.

If you go to the 300ZX 71C transmission you will have a 3.321:1 1st gear with a 3.9diff. Same as what you have now.

If you liked it with the 71B. The 300ZX 71C will be fine but with a better shifter.

The photo is two 5 speeds, but are they both widd ratio 280Z or close ratio 280ZX? See "How to" doc on how to tell the difference.

 

 

How to - F5W71B Wide and Close ratio transmission.pdfFetching info...