Z20 5 speed. Does L series 4 speed have a interchangeable front housing to swap?

[Datsunscott]

I have been looking around to see if a z20 5 speed will fit a l series application.

If I have a stock L series 4 speed is there a front housing that could be swapped between the two?

Ending up with a Z20 4 speed and a L 5 speed?

[datzenmike]

 Yes, this will swap if you check first the placement of the reverse light switch on the four speed you have.

 

 

 

In some rare earlier 4 speeds the reverse switch is located just to the left of the one pictured. You can see there is a cast in boss (not used) If your reverse switch is like the picture you are good to go.

 

 

 

Under the snap ring (shown above) is a select fit shim. I would keep the 5 speed shim with the 5 speed.

 

I highly recommend you replace the 56mm counter bearing while the front case is off. (it's the smaler diameter one) It's a high wear item that takes a lot of abuse and also a known failure point and hard to replace once the transmission is in and it growls. Nachi bearing of Japan are good. Mine was $12 Canadian.

 

https://www.nachiamerica.com/4-21/Bearings/Catalogs/General/

 

The OD is 56mm I don't have the thickness or ID but you can measure your 4  speed one.

 

 

 

[Datsunscott]

Awesome info! Thanks very much.

[Stoffregen Motorsports]

And remember to use sealant on the threads of the bolts going into the open holes of the front cover.

[Datsunscott]

More info?

Turns out I was not able to get the Z20 trans. Thanks for the good info.

Does the info apply to a F5w71a/b/c transmission also? or is the early bell housing not compatible? something too different?

[datzenmike]

The F4W71A was used on the '70 240z and is basically a Roadster 4 speed with an L series bell  on it. It has the A type shifter similar to the 510.

 

The F4W71B followed in '71 and is a totally different transmission with a B type shifter. In '74 the F4W71B was used in the 620 truck.

 

The FS5W71B was available for '77 as an option in the 280z, 810 and 820 truck and shares some parts with the F4W71B.

 

The F4W71C and FS5W71C and similar to the 71B but have a C type shifter. 71B 4 or 5 speed front cases can be swapped onto the 71C if the counter bearing hole is increased to 62mm or an older 56mm bearing put on the 71C, the 1st/2nd shift rod hole is increased to 16mm and the thickness of the front case shaved down to 0.48" out to 3.5" around the counter bearing for gear clearance.

 

Some early Z car F4W71B front cases had the reverse switch mounted slightly to the rear of where all other F4W71B and FS5W71Bs mounted their reverse light switch. Rare but check your donor 4 speed.

 

Below is where almost all F4W71B and FS5W71B reverse switches are located. You can see that there is a boss just to the rear of the reverse switch is. If your 4 speed has this the front case can't be used to convert another 5 speed to L series. You can drill it and tap it moving the switch forward and plug the rear hole.