Mechanical cruise control to suit early 240

If you do get a lead, make sure you get everything. With the early cruise control, the gauge cluster is different as it has an electronic speed output.

81-85 mechanical speedos had an inductor which fits in the back of the speedo.

Pic stolen from Dave Barton shows where it fits; there's usually a plastic cover there.

Pre-81 (square speedo with small centre tacho) , they put a speed measurement box between the gearbox and the speedometer and had speedo cables going to each. (aka ALT 1)

For some bizarre reason I was thinking early as 81 to 85 or there abouts whenever the speedos went full electronic.

Of course James would be after one for the early gauge cluster like you have shown @Major Ledfoot

I have never seen one of those before. Can only imagine it was a very expensive and hence rare option.

From the driver's perspective, the 85+ electronic speedos all look the same as the 81-85 mechanical speedos. Cruise control was offered as an option in OZ as far back as 1982 - I had a dealer sales brochure for it once but lost it sometime last century - and this was back when OZ cars were either K-Jet or carb, all with mechanical speedos.

I stumbled onto this when I was looking at how they did cruise control on pre-81 cars (with the early cluster) because I wanted to know how they did the VSS, which I needed for the LH2.4 swap into the GT.

I guess the easiest modern way to do cruise control with a pre-81 speedo is by using a Brantz BR4 sensor connected between the gearbox and cable to the speedo to supply a vehicle speed signal, together with a later style electronic Cruise Control Unit, and adding some pulse conditioning hardware between it and the BR4.

The BR4 supplies 4 pulses per revolution at the speedo end. It's not rocket science to knock up a pulse conditioner / pulse multiplier circuit using some 74xx series TTL chips to give an output signal that matches the requirements of whichever CCU one decides to use.

The tricky parts to get will be some mechanical items, like the throttle spool.

I've sent you a PM