Transmission question

[tonyfromjersey]

I am having some issues with the transmission in my 77 Spider. I can get a rebuilt from an 81 for not too much money, definitely a lot less than having mine rebuilt. The question is, does the transmission from an 81 fit into my 77? If not, what is a reasonable sum of money to expect to pay to rebuild my transmission? The issue is that it "pops" out of 3rd gear sometimes, and occasionally gives me a little grinding going into 3rd.

Finally, option 3 is I can get a pretty much free transmission from an 81, and bench rebuild it myself over the winter, while the car is in the body shop. The condition of this transmission is pretty much unknown, so I'd basically be using it as a core.

I'd like to go with option 1, I think that's the easiest way to go.

[lanciahf]

Tony,

Yes the 81 Tranny will fit in your 77. Only problem I can see is that the 77 has emission switches on the passenger side of the tranny that control relays in the engine bay?? Anyway if you are smog free, meaning no more smog equipment then the 81 tranny conversion will be hassle free. If your car still has all of the emission controls intact then you will have to bypass these switches some how. Clear as mud?

Ralph

[tonyfromjersey]

Clear as mud, thanks. I don't think much of my emissions stuff is still hooked up, I'm running QQ plates so I don't have to worry about inspection. Of course, I seem to be headed to a "parade, car show, or special event" quite frequently.

I'm hoping to get the 81 tranny for a song, then rebuild it either myself or with help. It is of unknown condition, but I can continue to drive mine sans 3rd gear until I get it rebuilt and installed.

[baltobernie]

Going rate in the Balto/Wash area is $400 for a "known good" used box; $1100 for a typical rebuild by a Fiat expert.

I'd suggest reusing your existing speedo gear in the next transmission, if your gauge is now reading accurately. You don't know what combination the last tranny was used in.

[Ernie]

Tony and Bernie,

One thing to care about when using an '81 transmission in a "77 Spider -- Bernie suggests using the existing speedo gear in the new transmission.

To clarify/expand on that, you should know that the speedometer drive assembly and the gear inside the transmission are matched sets.

As posted by Jim Fierst on http://www.mirafiori.com:

• Model Ratio Dr Part # Teeth Color Dot Trans Gear# Teeth
  2000 3.9 4199595 15 Blue 4199596 7
  1800 4.3 4338462 14 Red 4233398 6
  1400 4.1 4163959 9 Grn 4130149 4

I'm sure some folks have just changed the speedo drive and are living with the resulting mph/kph difference. The right way to do it is to replace the set. And, it's a bit of a pain.

You'll need snap ring pliers and probably an impact wrench to bust the big nut of the tail shaft loose. Then you'll possibly mangle the rear seal getting it out. Then getting the gear swapped and putting it back together is the easy part.

Ernie

[joelbert2k]

Isn't it that the speedo gear is actually matched to the read end ratio rather than the trans?

[baltobernie]

Tony, you're absolutely right; I oversimplified the response, and also presumed that he or a mechanic were rebuilding the box, enabling a swap of the gear pair.

Joel, you're correct as well; I'm assuming the model year of the transmission is identical to the correct engine and diff of the vehicle model year in question. Probably not a good assumption, as many cars have a variety of powertrain component vintages.