How to mate a five-speed Datsun gearbox to an A-series engine

Trying to mate a Datsun five-speed transmission to an English A-series engine–like the one we have in our Bugeye Sprite project–sounds like it might be a real nightmare but, fortunately, Rivergate Restorations offers a swap kit.

We can attest that the kit is quite complete, and the instructions are good and provided the info we needed.

To make the swap, you will first need to find the correct transmission. That transmission is from a 1979-’81 Datsun B210. The same transmission as in the coupe, sedan and wagon. The input shafts should be 20mm diameter with 18 splines.

Rivergate Restoration tells us the transmission serial number (located on the top of the bellhousing) needs to start with an F. Transmissions with an FL, FA and FX number are all acceptable. The cars with these transmissions would have an FS5W60A on the serial number plate on the firewall of the car.

When you buy the transmission, you will need the shift lever, throw-out bearing carrier and the clutch release fork. There are a couple of other transmissions that will work. You can check Rivergate’s site for more details.

Our journey started with a supposedly rebuilt Datsun five-speed that we picked up at Carlisle’s import swap meet. With a price of about $300, we figured we could take a risk. These transmissions generally sell for two to four times that figure. As it turns out, ours functioned quietly enough but will need a new second-gear synchro.

The only other Datsun part you will need is the shift lever. New shifter bushings are readily available for just a few dollars, so the lever itself, and of course the transmission, are all you will need.

The first step is to remove the transmission mounting plate from the rear of your engine. You will not be using the plate, but you need to transfer the round cap that covers the cam to your new adapter plate that comes with the kit. The directions are quite specific as to how to seal this cap into the adapter plate so nothing leaks. A leak here could oil your clutch and flywheel in a very bad way.

While the transmission fits the adapter plate, you will need to grind down the transmission in a couple of places (especially around the starter mounting area) to make sure there are no clearance issues.

The kit is designed to use the original Sprite starter, but using that starter will require drilling out the back of the bellhousing to make it fit.

The hot setup is to use a gear-reduction starter from someone like Gustafson like we did. This gets you a lighter, smaller, stronger starter that does not require drilling the bellhousing to fit.

Next, bolt the adapter plate to the transmission and attach the crank seal on to the plate. From there, you can bolt the flywheel to the crank, install the clutch, and start working on the hydraulics. The kit includes a clutch disc that matches the splines on the Datsun transmission as well as an alignment tool.

Before you do that, the instructions recommend you install a new tail shaft seal, and Rivergate is kind enough to include one in the kit.

They also include a drive shaft yoke that matches the original Sprite drive shaft. No cutting and welding are needed on the drive shaft.

The slave cylinder bolts to the Datsun transmission, and the line included in the kit is sized and threaded to bolt right up to your Sprite master cylinder. A new throw-out bearing is also included.

With your transmission bolted to your engine, you can now install the assembly with the new transmission mount provided in the kit.

The instructions recommend that you cut the rib that runs along the top of the transmission for easier fit. Trust us, you need to do this. And we would have clearanced the heater box that is above where the bellhousing sits had we known how tight the fit is.

We were able to squeeze the transmission past this area and, voila, everything fits perfectly.

Rivergate Restorations did make a speedometer adapter kit that we luckily purchased. That kit is currently unavailable due to parts supply issues, but keep an eye on their site.