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MG MGB Technical - Which gear-reduction starter fits an earlyI MGB?

I am looking for a gear-reduction (or pre-engaged) starter to fit an MGB 3-main engine.

I see a number of them advertised, most specifying that they fit MGBs from 1968-1980. There are also some advertised to fit earlier MGBs. The 1968-1980 starters are less expensive than the earlier ones.

My question is whether I can use one of the 1968-80 pre-engaged starters for 5-main engines on my 1964 3-main engine.

Thanks for your advice! Mike
M.E. Whalen

The mounting holes are in different locations for the pre-engaged starters that fit '68 and later Bs. The '64 3 main engine also has a different diameter flywheel, so you'll need a starter specifically designed for the pre '68 transmission and flywheel combination. RAY
rjm RAY

One used on an MGA should fit.
David Werblow

Earlier inertia starters have 9 teeth on the pinion, later pre-engaged on the 4-cylinder cars have 10, so you have to get the correct pinion. Whilst inertia starters have a pinion that is pulled into engagement with the flywheel, pre-engaged including geared starters push it, but that doesn't cause a problem when replacing an inertia with a geared.
Paul Hunt

I use a late model MGB inertial starter on an 18GB block and trans. Even though it pulls the 'wrong' way, it meshes just fine with the 5 main flywheel.

The 3 main flywheel is the same diameter as the 18GB flywheel, so I don't see why it wouldn't also work on the 3 main.

If you are doing this on an MGB, just offer up the later MGB starter. If you are using it in an MGA, the MGB starter solenoid will foul the frame, but you can avoid that by using the version made for a Marina.

See attached picture and ignore the top of the engine (it is a Twin Cam raced engine, but the block is as I said, a 5 main MGB unit)

Bill Spohn

The same type of inertia starter was used on both 18G and 18GA 3-bearing, and 18GB 5-bearing engines, and all inertia starters pull the pinion into engagement with the flywheel. There is no 'later' type of inertia starter as such, much less an inertia geared starter

The flywheel changed for the 18GD and later engines, which had the pre-engaged starter, which pushes the pinion into engagement with the flywheel. I doubt you could directly fit a later MGB pre-engaged starter - geared or not - to an 18G, GA or GB engine, as the number of teeth on the pinion are different. As I say you can get geared starters with the correct 9-tooth pinions, and even though they push the pinion into engagement with the flywheel instead of pulling, that doesn't cause a problem. I'm not surprised the correct ones are more expensive, there would be less call for that size pinion hence smaller production runs hence higher cost per unit.
Paul Hunt

" I doubt you could directly fit a later MGB pre-engaged starter - geared or not - to an 18G, GA or GB engine, as the number of teeth on the pinion are different."

Incorrect, Paul.

See my post above yours - that is a later pre-engaged starter (that one is out of a Marina, but same as an MGB except for solenoid location) and works perfectly despite tooth bevel direction and number of teeth.
Bill Spohn

I have a '66 B-GT with a later engine w2ith a an 11 1/4" flywheel. I needed to change the backing plate and fit a 10 1/2" flywheel to fit the '66 trany. The ring-gear for this flywheel and the MGA flywheel are the same. I have been using an MGA starter for a bit now.
David Werblow

Beware if the ring gear fitted looks like this - these are commonly supplied these days.

Chris at Octarine Services

because this can happen with pre engaged starters of any type

Chris at Octarine Services

Why bother with preengaged starter anyway? the inertia types work perfectly well - if you insist on fitting the preengaged type then pull the engine and have a new ring gear fitted the right way round to accept it.
Chris at Octarine Services

I fitted a gear reduction starter from www.britishstarters.com.
They are relatively cheap, lightweight, small and much more powerful than the original starter.

It fit with no mods to the electrics and is very reliable, the engine starts much better because it turns the engine over so much faster.
Joern-M

Cheap? Where did you get yours from? The ones I've seen are about double the price - albeit outright purchase vs exchange.

I agree about it being pretty pointless to deliberately swap an inertia for an original style pre-engaged. The gear-reduction starters do have benefits, although none of them are essential, the lower drain on the battery is about the only significant one.
Paul Hunt

The current NEW starters supplied by the MGOC are gear reduction ones and half the size of the original - they cost a mere £75...
Chris at Octarine Services

This thread was discussed between 16/10/2013 and 02/11/2013

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