As the name implies, an inertia starter uses the inertia of the motor to engage the pinion. This means that the pinion is spinning as it engages the ring gear on the flywheel, and causes damage every time you start the engine. Eventually, the ring gear and the pinion wear to the point that it won't engage reliably. The solution used to be to replace the ring gear, but that is both difficult and expensive.
A modern starter uses the pre-engaged system, which means the pinion is engaged with the ring gear by the solenoid before the motor begins to turn the flywheel. As such, they come with a built in solenoid, making the old one on the flywheel housing or the end of the block redundant. Pre engaged starters also use the opposite side of the ring gear, so even if yours is worn beyond working with the original starter, it will have a new lease on life with a new starter. They also have a much higher cranking speed and are more powerful - perfect for that high compression big-bore engine!
What To Use
The best starter to use is from a 1975 - 1984 rear wheel drive petrol motor Holden Gemini ( TX, TC, TD, TE, TF, TG). Common part numbers are RUTS007 and HUS007S. New motors are probably no longer available, but factory reconditioned ones are just as good, and about the same price as an original Lucas starter.
A Gemini starter has the same mounting diameter as a Moke at 3 1/2", but the centre to centre of the mounting bolts is 5", instead of the Mokes 4 1/2". All that is needed is to file the mounting holes 1/4" inwards, and it will bolt straight in. This picture shows a standard starter and one that has been modified to fit a Moke.
Starters are also available that have already been modified to suit a Mini/Moke, and are a good way to go if you are not confident to do the job yourself.
There are also a few changes needed to the wiring, but they are quite simple to do without any alteration to the harness.
First job is to disconnect the battery, remove the grill (if you can) and then remove the old starter motor - just one wire and two bolts. Keep the bolts, you can use them with the new starter.
You may find lots of metal filings inside the flywheel housing - it's quite normal, but this is what the old starter has torn off the ring gear. Also check for any fresh oil, which may mean you need to replace the primary gear oil seal. Any grey dust is from the clutch plate.
Now is a good time to do a trial fit of the new starter. Line the bolt holes up as best you can, and check that you have some clearance with the distributor cap. Normally you will have 1/2" - 3/8". Any less and you may have to file the holes at an angle. I have never had a problem, but most starters you will buy now are reconditioned and may vary in their dimensions.
If the clips that hold the distributor cap on are in the way, you may have to turn the distributor to get clearance. The easiest way is to rotate it exactly 90 degrees and then move each plug lead back to it's original postion. You will need to check the timing afterwards, but there is no need to remove the distributor or the drive shaft.
You will also notice how far out the mounting holes are - time for some filing!
Before starting, it is a good idea to wrap the pinion with tape to stop any metal filings getting into the pinion or motor.
Mount the motor securely in a vise, supporting the back of the motor as well if possible. You can see the need for the tape.
The alloy is pretty soft, and shouldn't take more than a couple of minutes for each hole. Stop and check your progress occasionally. The holes don't have to be exact - the mounting locates the motor, the bolts just hold it in and stop it turning. Better to be a bit loose than too tight.
You should end up with something like this-
When doing a trial fit, you should be able to screw the bolts in with your fingers. Any binding usually means more filing is needed. And because there is now a large slotted hole, it is a good idea to use a flat washer as well as the spring washer if you can, or at least a new large spring washer.
Looks like it was made for a Moke!
There are a number of ways to wire the new starter, depending on how neat/easy you want it to be. But basically the solenoid on the Gemini starter should be wired exactly the same as the original Lucas solenoid.
Unfortunately the original battery cable is too short to reach the new starter, but there are a couple of ways around this.
The easiest way is to leave the original solenoid in place and just move the thick cable that went to the old starter across to the battery cable post. Then move the start wire (white with red trace) to the new starter, leaving all the other wires intact. (Boots removed for clarity)
Using this method, there are just two wires to the starter. You may have to enlarge the hole in the old cable from the solenoid to fit the larger terminal bolt on the new starter.
A neater way is to remove the old solenoid (it's not needed anymore), and join the two battery cables with a small bolt.
This joint will need to be very well insulated with either the old terminal boots or better still, a piece of heater hose and some tape. The other wires will need to be joined to the new starter like so.
These wires should be long enough, but you may need to unwrap part of the harness to get to them. Just make sure they don't stick out too far and rub on the grill when it is replaced.
To join them to the starter terminal, you will need the correct terminals. They can be scavenged from the old solenoid, or I make my own from stainless locking strap.
Another alternative is to fit an isolation switch in place of the old solenoid, using the original battery cables.
Again, you may have to enlarge the holes in the cables to fit the isolator terminals. All other wires need to be fitted to the starter as before. And remember, don't turn the switch off with the motor running, as you may damage the alternator. Note the original boots as insulators, and the coil terminals have been shifted to clear the cables.
The neatest solution of all is to make some longer battery cables, and remove the old solenoid and bracket completely. 2.55m is a good length for the positive cable, and 32mm2 is about as thick as you will get to fit in the cable cover on the side pannier. Again, make sure it is very well insulated, with grommets in the side boxes and firewall. A cable of this size will set fire to your Moke in seconds.
If done correctly, it will look like Mokes actually came factory equipped with a modern pre-engaged starter. They will start better, be more reliable and look neater. All you have to do now is get used to the different sound it makes when you start it!