What is this thing under my bonnet?

[CBinAus]

Just purchased a lovely early 84 V8 RR and have been giving it a full service and tidy up under the bonnet, but i'm confused to what this "after market" looking item is.
It has wiring going to it and then a cable (looks like throttle type) going under neath the carbs to a lever.
It doesn't seem to do anything when reving the car the cable just bends back
Any ideas, and if it does bugger all can i just remove it?

[Graeme]

It looks like a vacuum-assisted cruise control device.

[101RRS]

Yes is a cruise control unit.

[p38arover]

Yep. There should be a control in the cabin.

[JDNSW]

Looks very like the one I fitted to my 110 about thirty years ago, still going strong albeit with a few minor repairs.

[p38arover]

Looks very like the one I fitted to my 110 about thirty years ago, still going strong albeit with a few minor repairs.

Ditto for the one I fitted to my '86 RRC.

[Richard Kaye]

Yes, cruise control. I fitted one to a HD Holden when I crossed the Nullarbor from Melbourne to Perth and back.

[CBinAus]

cheers guys, yea there is a control in the cabin but it's not working :-)
Any ideas what goes wrong with them?

[101RRS]

Disconnected, no vacuum from the engine, blown fuses, perforated vacuum actuator, no speed sender.

[JDNSW]

Poor connections, broken wires........

I suppose the control unit or the vacuum gadget could be faulty, but both have been faultless in mine. My most common issue has been broken wires, followed by the accelerator cable breaking, and a bad connection at a plug.

The sensor is a pickup coil on a bracket close to several magnets wired to the propeller shaft, in my case the front prop shaft, just in front of the transfer case. This is a relatively vulnerable spot, but seemed simpler than accessing the rear shaft behind the handbrake drum, which would have needed a long bracket. Another possibility is a blocked or missing vacuum line (teed into the line to the brake booster).

[p38arover]

I'd forgotten the magnet on the propshaft. :(

[101RRS]

If it is a petrol engine and you only want cruise on top gear - then take ignition pulses from the coil. If you are good at changing down gears and keeping revs constant then can also be used in lower gears but requires resetting each time.

[Mercguy]

Looks like the same vdo unit that was fitted to my 91RRC. I removed it. Aftermarket stalk, electronic control unit under dash, actuator in engine bay and VR sensor next to propshaft which had a magnet zip-tied to it.

[bigrolf][bighmmm]