Lucas inertia starter motor misbehaving

[vitesseefi]

This is the starter from my Mk3 GT6, came with the heap of bits that was the car and seemed to work reasonably well, so I gave it a good clean (no "wet" lubricants) and kept it.

However, it's now occasionally misbehaving in that it refuses to engage and just spins uselessly, repeat attempts rarely work any better though there is the occasional fluke. It probably works as it should about 75% of the time, but when it misbehaves it prefers to do it when it's really inconvenient and/or embarrassing. I'm carry a chunk of wood around that can be used to give it a clout and the clout is 100% successful.... but obviously not ideal if you are trying to leave a car show, or the petrol station, or even the traffic lights after you've stalled it (the last hasn't happened...... yet).

When it does engage it whips the engine over just fine, so electrically I think it's just fine. Today I've hauled it out for a bollocking....

Problem seems to be that the gear doesn't fully return and hangs in the half-way position and consequently won't flick out properly next time.



I assumed it was dirt, though it wasn't horrible so took it apart for a good clean.



It's not really helping though and I've tried a fair bit of fettling, polishing and even (temporary) use of light lubricants, none of which is making very much difference.

Anyone know what the secret is?

Thanks in advance

Nick

[comfortablynumb]

Even though you say you don't think it's electrical Nick, I'd still have a look at the brushes and commutator just make sure it's not hanging because it's slowing down, or not actually spinning up fast enough occasionally to allow the drive dog to work.
Going on the 'if it's not what you think it is, it's something else' logic

[vitesseefi]

I take your point - but I can see it’s hanging? It hangs to the extent that I photographed it……

I’ll check the brushes as it’s out but it turns the engine really well when it can be bothered to engage….

Nick

[comfortablynumb]

IME with mk2cortina starters, they require a pretty good 'kick' to fire the drive dog out in the first place, which happens in the initial crank of the motor, and before it's even done one complete revolution.
If it's not engaging, it sounds to me like it's not getting it, hence the electrical theory.
What happens if you bench test it?

[vitesseefi]

Ok, will check tomorrow and report back.

Thanks

Nick

[jimi]

In the past I've had success in curing this kind of problem by washing the bendix gear out with petrol. Don't use any lubricant, it can attract dirt and make this worse. Let the petrol evaporate off before trying it.

[colnerov]

Hi, Yes the clue's in the name 'inertia' the motors shaft spins quicker than the dog and the difference in the inertia makes the dog travel down the bendix to engage with the flywheel. So make sure the brushes and commutator are clean to make a good connection. Plus make sure that both faces of the spiral of the bendix is clean with no 'scars' to make it hang. As you realise no lubricants that will soak up clutch dust and cause drag.

Colin

[comfortablynumb]

Makes sense, that's why the spring is there, to absorb the impact from the flying out dog

[jamesd1972]

On the LR the dog got a tiny bit rusty after being dipped in the local ford once too often so did the same thing -spinny spin spin no brrrruuuummmm.
Cleaned it up and put it back, success ! and then repeat every time you get it wet... Eventually got it behaving using some graphite (just used a marker pencil ) as a lubricant that just seams to free things up a bit.
James.

[vitesseefi]

Back in the day I used to use this stuff on them because we had loads of it where I worked.

www.rocol.com/products/dry-molybdenum-sulphide-aerosol-spray

Applied sparingly it worked really well. Just looked it up - wow - MoD tax or what….. Maybe there is a similar alternative?

Nick

[jimi]

Feb 12, 2022 21:20:57 GMT comfortablynumb said:

IME with mk2cortina starters, they require a pretty good 'kick' to fire the drive dog out in the first place, which happens in the initial crank of the motor, and before it's even done one complete revolution.
If it's not engaging, it sounds to me like it's not getting it, hence the electrical theory.
What happens if you bench test it?

Not sure if your meaning of out is confusing me but looking at the picture the dog comes in i.e. towards the starter body, not out i.e. away from it?
The dog normally sits on the far side the flywheel from the starter, rotating the starter pulls it in towards the flywheel ring gear.

vitesseefi
Have you checked the ring gear ? Many years ago I had a mini ( my first car) that developed a habit of the starter not engaging, eventually discovered the ring gear was badly worn at one point ( which the engine always seemed to stop at) new ring gear cured the problem.

[misterm]

I think I would be trying to ascertain what, exactly, the precision rectification tool (the lump of wood) was achieving. Usually I would suggest it is resetting a brush in it's holder, but in this case, it could be putting the dog back into it's correct starting position and it then gets a good run up the shaft (oo-er). I think, but I'm not certain, that I have seen inertia starters with a very light coil spring between dog and casing to help reset it.

[vitesseefi]

Thanks for replies.

The ring gear is fine. I had been assuming that the “adjustment tool” was resetting the travelling pinion as it wasn’t returning fully every time. However, I did take the point made above that sticking brushes was a possible issue (though the starter turns the engine very well when it does engage) and pulled the other end apart.

It wasn’t horrible (I think I cleaned it up about 3 years and 1000 miles ago), couple of the brushes were a little less free-moving than I would like, though not obviously hanging up. All cleaned up and free-moving now.

The pinion (which does have a light spring in it) is better but still hangs sometimes when all is completely static. Not a fair test maybe. The moly dry-lube hasn’t changed things much. Just awaiting some graphite powder. I’ll dose it with that and refit. If it still misbehaves I’ve found another that has been “in stores” for a while. It’s rather worse as it stands but looks to have had slightly easier life so may clean up better…..

Failing that, I’ll be adapting a more modern ND reduction unit (unless I can find an early Trooper one that bolts straight up).

Nick

[colnerov]

Hi,Be aware that inertia and pre-engaged starters come at the ring gear from different directions and so have the 'lead' on the teeth on different sides which can cause problems. You may have to change the ring gear as well.

Colin

[vitesseefi]

Thanks for the warning. However I’ve been using a modified pre-engaged ND starter (originally from a Toyota Carina II IIIRC) on my Vitesse for the last 18 years without problems and that still has the original flywheel and ring gear, which is exactly the same as the GT6. My experience is that the inertia starters do care about this, but the pre-engaged ones generally don’t.

Canley Classics used to sell a conversion kit at very reasonable cost but these days the only readily available routes are the likes of Wosp and Powerlite, at very unreasonable cost.

Nick

[doshy]

The old wives tail for this was to use a pencil to rub on the mating surfaces, I guess it means the graphite gets pushed down into the surface and almost burnished. Gotta be worth a punt? Failing that, I’ve got a dead starter for a herald you’re welcome to nick parts from..

[vitesseefi]

Bought some powdered graphite (sold as lock lube) and worked a little in to the spiral. Wow - instant cure. No hint of stickiness remaining, even returns directly upwards every time.

Refitted now and working perfectly. I’ll go through the extra one and put it by as a spare.

Thanks to all for suggestions

Nick

[jimi]

Good result, handy tip for future use