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Gear Reduction High-Torque Starters: Inertia or Pre-engaged?


Jedi Knight
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I have had gear reduction starters on my 60 BT7 and 59 Bugeye (now my son’s) for well over ten years. I installed the gear-reduction units for their extra cranking power and smaller size/weight. In both cars I installed the starters as inertia starters rather than Pre-engaged. I must confess that I made the wiring decision based on maintaining the “original look” of the Lucas starter solenoid rather than considering any mechanical advantages or disadvantages. Why I was concerned about maintaining an original solenoid when I was installing a modern-day starter is hard for me to explain.

The starters have performed well; however, on the Bugeye we have always experienced what sounded like some ring gear mashing when the starter button was pushed. It has always started just fine, just noisy.

The other day I watched this video from Resto-Nation about the restoration of an AH 100. The segment is about the gear reduction-high torque starter. After watching the video I then took a look at the WOSP starter website. The Resto-Nation restorer refers to the inertia set up as “smash and grab” versus Pre-engagement where the pinion is inserted into the ring gear BEFORE it whips around. The WOSP website has a very well written description of each approach.

After watching the video and reading the article I have to wonder why anyone would prefer the inertia configuration over the pre-engage method. It appears to me that the pre-engagement approach might improve the operation in the Bugeye.

knowing that there is always “another side to the story” I thought I would make this post and solicit opinions.

Thanks for your thoughts.




Jedi Trainee
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You may have misunderstood what he was showing on his white board.

The original Lucas starters are "inertia" starters.

The gear-reduction units are "pre-engaged".

While there are at least two different ways to wire the gear-reduction units, it does not change the units function as a pre-engaged starter. For the sake of simplicity I have mine wired through the original solenoid with just a short jumper on the solenoid. Looks more "original" (for what that's worth), but also does not require modification of original wiring( lengthening the "trigger wire" so it will extend from the original solenoid down to the starter mounted solenoid).


Luke Skywalker
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Craig is correct. They are two different things regardless of whether you keep the starter solenoid or not. The original inertia starter is primitive compared to the modern gear reduction, pre engaged options now available.
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I think the consensus is correct, that how you get power to the starter does not affect its function.
I chose to do away with the "original" solenoid as an opportunity to eliminate another link in the chain which might cause trouble.
As to the source of the noisy engagement you might need to modify just a bit the starter's mounting holes, etc. to make sure it is aligned properly and is neither too far from nor too close to the ring gear.


Jedi Knight
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Okay, thanks guys. Thanks for clearing up my misunderstanding. What I take away is that the wiring method does not effect the operation.
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