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Starter motor teeth, how many?


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I have a 1500 engine (think it was from a  Dolly). The starter motor I am using with it had 10 teeth. I am not sure if this came with the engine or was the original one when I had the 1300 engine in the car. All the sites I have looked at suggest that the pinion should be 9 teeth and most replacement motors seem to be 9 teeth.

So can you use a 9 or 10 tooth starter motor or does the fly wheel have to be changed to suit the starter motor teeth?



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If you have a 1500 Dolomite engine this was fitted with a pre-engage starter motor. The 1300 Dolomite and Spitfire starter motor will not work on this engine due to a different starter ring on the flywheel. You have to fit a 1500 Spit flywheel or get the correct starter motor which are difficult to find.


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I've read recently that 10-tooth Bendix gears will work on a Spitfire flywheel, even if they're not strictly right. However, they definitely don't work on a Dolomite 1500 ring gear, which has much finer teeth for a pre-engaged starter, as Dave said. If this is your existing engine, presumably you swapped the flywheel over? Are you on a Herald gearbox still? What clutch do you have?

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the std does seem to be 9t

my lucas product manual shows 10t but only n pre engaged 24v units 

Daves right the lead chamfer on the flywheel  teeth is reversed as the pinion on pre engaged throws in from the front  where as a bendix throws in from the back

pre engaged being a much better supported drive than bendix  and  a pre engage solenoid indexes the pinion 1/2  tooth on each operation  to aid engagement   


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ok just checked the engine number (FP) which I think makes it originally from a MG 1500 Midget!
I think this used a standard Lucas Bendix type started motor

The tapper on the teeth is away from the engine so I think is correct for a Bendix type starter motor rather than a pre engaged starter.

So assuming that its from a MG 1500 then MG sites seem to show both 9 and 10 teeth for the  MG 1500 starter motor....
So still don't understand why the starter has 10 teeth and where its come from.... I have just carefully taken the 10 tooth bendix of the original starter motor and fitted it to a spare GT6 starter motor (which had a 9 tooth pinion on it).

I beginning to think that I should be using a 9 tooth pinion on it.


The gearbox is ex spitfire 3 rail OD with 10 spline shaft, the clutch plate is GCP103 and the pressure plate is GCK160.

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just switched the pinion on my starter motor from 10 to 9 and its seems to work fine, in fact sounds better so I think it should have always had a 9 tooth pinion...

Just need a some cold weather to see if it will start when very cold...
Previously it was pulling the battery down to 10V (new fully charged battery) when trying to start it and it was turning the engine very slowly. This has caused problems with the timing pickup (its on a Megasquirt fuel and ignition) making it very difficult to start.

Have checked the volt drop between the battery and starter motor (when 10 tooth) it is was ~0.7V which doesn't seem too bad considering the current being drawn. No voltage difference between the engine block and negative terminal on the battery so the earths connections seems good. The starter is almost new with very good brushes.

BTW The original reason for asking was that I was/am thinking about buying a Hi Torque starter which all seem to be 9 tooth.


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