The V8 Owners Forum -

Hi All,

I’ve just bought a genuine SD1 clutch slave cylinder off the Bay of E.

The port for the flexi pipe appears to be about 1/2 inch diameter but isn’t unf so assuming it’s metric fine?

Can anyone confirm the thread size please?

Thanks for the help.

Pretty sure it's 7/16" UNF

richyb66 wrote: ↑Mon Dec 10, 2018 9:11 am Pretty sure it's 7/16" UNF

It's not UNF, because I used an SD1 slave cylinder on a P6B 3500S LT77 conversion and I had to fit the SD1 fitting on to the end of the clutch hose.
I'd say it's a fine Metric.

I'm fairly sure all the SD1 brake etc fittings are metric. But there is a UNF size very easily confused with it, and even has the same TPI, so sort of fits.

richyb66 wrote: ↑Mon Dec 10, 2018 9:11 am Pretty sure it's 7/16" UNF

7/16" unf is the size of the thread on the very similar cylinder used on Defenders etc.
Genuine SD1 cylinders have an M12 thread.

I'm amazed anyone at rover in the 70's knew what a metric thread was.

When I fitted my helix clutch last winter I had to swap the SD1 Master Cylinder for a bigger bore Defender V8 one because you couldn't physically press the clutch pedal. The inlet sizes were different so I ended up getting a new hose made - they don't make these things simple do they?

The SD1 is of course BL rather than Rover, and was designed when metric was coming in. Pretty well all of it is metric, except the RV8.