Re: Overdrive R-9 from 6V to 12V

Posted by HH56 On 2014/8/28 13:34:08

I don't believe you will find any 12v components for an R9.

The R9 solenoid has a different length plunger than a commonly available 12v solenoid for the R11 to that wouldn't work and the wiring is different anyway. If you knew the individual solenoid coil current draw, it might be possible to calculate the proper resistor for each coil but being that one of the relay coils is in series with the solenoid hold coil, it might prove more trouble than it's worth.
As to using the R9 relay on 12v, since it cannot be easily isolated the effort and expense of finding another R9 relay if plans didn't happen to work as advertised makes that an experiment I wouldn't try.

Assume you would also be going to negative ground with the 12v conversion so if I were contemplating a change, since the OD has a one wire feed off the starter solenoid I would remove that wire and power the entire OD with 6v using a voltage reducer module such as this one. That way the entire OD is working at the proper voltage, no resistors to calculate and no need to change anything else.

The fellow making the units has a nice writeup at the end of his listing of some of the other advantages. While he doesn't specifically address positive ground cars, with the individual input leads to the module it should be possible to use it with positive ground but maybe worth an inquiry if you are going to keep that part stock.

An added benefit is if you get the 20 amp version of the module there is capacity available to work a couple of other hard to modify items. The Electromatic clutch (if you have one) comes to mind. Also, if you sell the car and the next owner wants to revert back to 6v, he doesn't have to worry about reversing a lot of changes.