MG Sports Cars

Anyone have advice about adapting VOD speedometer to Rover 5 speed. I have a rover sender for the fuel injection ECU but on English sites they advise not trying to split the electrical signal to go to both the ECU and a VDO.speedometer. Unfortunately I have not been able to find any discussion of what to do to get a signal to the speedometer. I did get a VDO GM sender but there is no way it will adapt to my ECU speed sender mechanicnally. I had thought to piggy back them to each other or use cable. The GM thread is much greater that that of the Rover thread and there is no way to screw the two together although the actual cable ends look the same. Any ideas? .

Richard,

We replaced the smiths speedmeter with a 100mm VDO in my sons '64 MGB (with a 5 main 4 cylinder and 3 syncro transmission). We had a local speedometer shop make a cable about 15 inches long from the original by replacing the speedometer end with a end for a GM cable. Then we hooked the GM sending unit to the cable, fastened it to the underside of the car , and ran the wires through a small hole in the tunnel. It works and was cheaper than fixing the old speedo and is also more accurate.

Al

Richard, I like the solution that Allen came up with . In doing some research to try to find a signal source for my EFI I came across this site which has several types of signal generators and adaptors for various transmissions. [www.partshp.com] Might help you or someone else with a conversion. I wanted to retain the stock speedometer, so the inline unit and a special cable would work great in that case.

I have come to the conclusion that I bought the wrong sender from VDO. I should have 340-011. Per Allen I can then have a speedometer shop replace one end of my Rover cable with a GM nut. Should then all work. Bill thanks for the info about gears. Will be great help to someone with T5 transmission. I wanted to keep my Smith Gauges but now that I have the VDOs I am convinced they are a good alternate. Look like they were made for the car. Thanks guys.

Hi Richard,

Most newer electronic speedos have a signal output on them.
You can run your speedo from the present sender on the rover trans and then run the fuel ecu from the speedo output.
The ecu just wants to see a pulse so that it knows whether it should be on its idle map or not. The frequency and amplitude don't matter. It only needs to know if the car is moving or stopped.
The earlier VDO speedos don't have this output so you might have to run the piggybacked senders or you could build a pretty simple buffer circuit to isolate the ecu signal.
The VDO speedos use a 5volt ref signal that the ecu doesn't like. So a couple of resistors and a small capacitor should calm it down enough for the ecu to accept it.

Hope thats helpfull
Cheers
Fred

Now there is an idea thanks Fred.I bet the UK rover sites were talking about the older VDOs.