The RT Differntial Mount

The RT Differential Mount is a great upgrade for all Z-cars, but if you own a '70 or early '71 240z, it needs to be modified.

RT Differential Mount

For the differential, Datsun used a rubber mount underneath and a flexible strap across the top. The strap was supposed to limit any upward movement without transmitting vibration or noise to the interior. It was cheap and worked OK, but Ron Tyler came up with a better version.

Commonly known as the RT Mount, it bolts into the same holes as the strap (which gets thrown away) and has a polyurethane "bumper" to limit differential movement. It's very well made, but I found out the hard way that it doesn't fit the early cars.

RT Differential Mount

The differentials on a '70 and '71 240z were mounted slightly further back than with subsequent years. As a result, the polyurethane bumper makes contact with the flange that connects to the driveshaft. Above the bracket, the nut holding the bumper makes contact with the parking brake mechanism. Not good.

Unless I was willing to go back to the strap, I'd have to modify the RT mount or build a new one from scratch. I decided to modify the mount.

RT Differential Mount

I took off the polyurethane bumper, and with some corrugated cardboard and hot glue I made a mockup for a bracket that would move it rearward to clear the parking brake mechanism. It took a couple of tries, but cardboard and glue are pretty cheap.

RT Differential Mount

Not the prettiest thing I've fabbed, but it's rugged (12ga steel) and that's what counts.

RT Differential Mount

Here's the finished product. Sure, the yellow paint is goofy but it made me laugh.

Now the bumper is centered perfectly over the differential case. I trimmed it back to leave a gap of about 1/16". The nut holding the bumper no longer interferes with the parking brake cables.

It took longer to make than I'd hoped, but that happens all-too-frequently.

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