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MG MGB Technical - Late starter in early B- wiring?
|I have a late gearbox in my '67 GT now and am ready to install the new type starter. |
I know I will still use my fender well mounted starter solenoid, but from there I am lost. I've read some archives but can't understand exactly how to connect the wiring and battery cables.
My new starter has 3 terminals on it (see photo).
Any help would be greatly appreciated.
|David. Why will you use your fender mounted solenoid? If I remember correctly, the early model starters had a starter motor with the solenoid mounted on the fender. Later model starters have an internal solenoid. Thus, it seems to me that you are trying to run two solenoids, the fender mounted one and the one of the later model starter motor. Does not seem to make sense to me as the solenoid on the new starter motor has to be a part of the system.|
As to the three terminals, the early model starters, for the four syncro gearbox, had the main terminal to which the cable from the battery and the brown wires from the alternator (and to the fuse box) were connected. Later model starters had an additional terminal that, when the solenoid was powered, provided full 12V input to the coil for enhanced starting. When the ignition switch was released, the starter solenoid was no longer energized and the white wire circuit provided a lower voltage to the coil. The recent four syncro transmission starters all seem to have this second terminal which, if not used, should be insulated with a piece of shrink wrap insulation to prevent any possibility of a short should something hit it while the starter solenoid is energized. At any other time, it is a dead terminal.
Have you converted your car to negative earth (ground)? You may have to?
The main connections will be to move the heavy cable from the existing solenoid to the old starter to the side of the solenoid that comes from the battery- (both heavy cables on the same terminal) the other end will be connected to the terminal on the new starter that would normally be straight from the battery (your #1). Then run a wire (maybe 12 gauge) from the side of the existing solenoid (where you removed the cable and moved it to the other side) to the terminal on the new starter (your #2 on my car) that would come from either the starter switch or relay, (White with a red trace). You need to use a relay or the original solenoid to trigger the new starter or you will eventually burn out the contacts on your starter switch. (The new starter has an attached relay that draws a lot of power). The other wiring stays as is. I hope this helps.
|M. H. Dabney|
|My car is negative ground. I had read (or so I thought)in archives about the original fender mounted solenoid being used in doing this. |
So would I just by pass that piece entirely and extend my wires to reach the new starter?
It do like features of the original solenoid, like bumping the engine with the button and having a power source for my timing light.
|David, I've used this system for over 20 years with no problems whatsoever. Keep the fender mounted solenoid and run the main cable, from the fender mounted solenoid, to the larger lug on the new starter motor. Now, make up a small jumper lead with a large ring terminal on one end and a female spade terminal on the other end. Connect the large ring terminal to the starter motor lug and the female spade terminal to the lower terminal on the solenoid. Now, when power is supplied to the fender mounted solenoid, it will be sent to the starter motor and the starter motor's solenoid at the same time. I set mine up like this almost 25 years ago and am still using the '68 starter motor that I got for free from a friend. It also allows you to crank over the engine from under the hood when setting the valve clearance by pressing the rubber button on the fender mounted solenoid. RAY|
|Thanks everyone! |
Ray, by "main cable" I assume you mean the battery cable from solenoid, not the large wire.
|By main cable, I was referring to the original cable that went from the solenoid to the inertia style starter, used from '62 to '67. The original cable may be a few inches too short for the new application and a slightly longer one, of the same gauge, will be needed. I used one that was 3 feet long. RAY|
This thread was discussed between 02/09/2011 and 11/09/2011
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