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MG MGB Technical - Which Starter Do I Need?

Dumb question for those who are familiar the back end of early and late B engines. I'm considering a gear reduction starter for my MGB, but I'm having difficulty determining which one will fit. The car is a '67, but the engine is from a '73. According to the book, a different starter is required for a '67 as opposed to a '73. My car does have the earlier 3-synchro transmission and Bendix-style starter. I think this means I need the replacement for the '67 starter, right? Or is it possible that the flywheel and ring gear from the later engine were retained? If so, would I be better off with the replacement for the later starter? Thanks. -G.
Glenn G

Glenn. Take a look at your starter and see what it looks like. The early model starters had a cylindrical body. The later model starters had a cylindrical body with a solenoid grafted onto the cylinder. The two are visually distinctive and you should order the new starter to replace the existing type.

But, why do you want a gear reduction starter? The standard ones have done fine for me from harsh winters in Germany to hot summers in Arizona. Thus, I would like to understand what, if any, advantage these newer types of starters are supposed to offer.

Les Bengtson

The difference is night & day...I was a hold out but put one in this fall because I got tired of the slow cranking in the cold weather...even with a new battery...I am AMAZED by how strong the car now cranks...and it's smaller and 1/2 the weight...
Bob Dougherty

Glen - Your 73 engine could (and probably does) have an early flywheel with the ring gear to match the inertial starter, especially since it has an early 3 syncro transmission (that is what I did when I put a 18V engine in our 66 MGB and kept the 3 syncro transmission). The later pre-engage starter should not be used with that combination. If you want to go to a gear reduction starter, you will need to get on that matches the ring gear on your car. Cheers - Dave
David DuBois

@Bob - are you sure it wasn't just a tired old starter motor which needed decent rebuilding (admittedly that can be hit and miss)?

...or the ancillary connections and cables you might have also replaced and cleaned up? The stock starter in good nick has more than enough juice to get the car started in an English winter, presuming all is properly maintained.

Another factor some don't like about the high torque motors is the non-original sound of the starting crank - sounds more like a modern car than a 'Gee.

That said, glad you're enjoying yours! :)
Curtis Walker

You need to look at the pinion on the existing starter. Original inertia starters have 9 teeth, pre-engaged have 10 teeth (but Note V8s have 9 teeth!). You MUST get the starter with the correct number of teeth on the pinion. I'll say again, pre-engaged geared starters that push the pinion into engagement with the flywheel are sold to replace inertia starters that pull the pinion into engagement, although I've never fitted one.

The difference with geared is amazing. I fitted one to my V8 a few years ago and first time I turned the key my heart sank as there was just a whirring noise as if the motor was spinning without turning the engine, I was amazed when it fired up. As well as being quieter they are lighter, take less current out of the battery extending it's life, which also drops the cranking voltage by less giving a better spark for cranking. The down side is that they cost quite a bit more. Having said that with everything in reasonable condition the standard starter should be fine, after all they started these cars for 30 years or more. I did replace the one on the V8 with a conventional unit as the geared starter was attached to the adapter plate with just a couple of self-tappers and super-glue, which parted company after just a couple of days.
PaulH Solihull

Thanks for the comments, guys. It seems likely that my '73 engine has an earlier flywheel and ring gear since it does use the older inertial starter. I will try the replacement for the early starter.

To answer Les's question, the standard starter is not doing fine for me. It gets jammed in the flywheel. This is rare, but still a concern since the car is my daily driver. I would prefer to keep the standard arrangement, but previous comments in this forum point to replacing the ring gear as part of the solution. I can't afford the time to do that now, but I can spare a couple of hours to change out the starter.
Glenn G

This thread was discussed on 20/12/2010

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