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Author: Subject: Old Inertial type starter running slow - Any suggestions
John P

posted on 29/5/20 at 02:34 PM Reply With Quote
Old Inertial type starter running slow - Any suggestions

Hi,

Nothing to do with a kit car but I also have an old 1929 Austin 7 which has a CAV starter motor with just two brushes.

When I operate it the motor turns reasonably quickly but the initial acceleration isn't enough to cause the Bendix to move into gear. The Bendix has been cleaned and runs freely so I'm almost certain the issue is with the speed of pick up of the motor.

The motor was an e-bay purchase so I've no real idea of it's history but it looks OK and I've just fitted some replacement brushes to try to solve this problem

The battery and leads are all new and I have virtually full battery voltage at the starter motor connections.

Whilst I don't really know what I'm doing electrically there is continuity between the field winding connections and they are not down to earth. The commutator is also not down to earth and with my rather basic Multi-meter there appears to be continuity between all the commutator segments which strikes me as odd but may well be correct.

I don't really want to go to a specialist if I can help it since as the motor does run I feel the problem can't be that major.

Any suggestions,
John.

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britishtrident

posted on 29/5/20 at 02:56 PM Reply With Quote
I would start with voltage drop tests measure any voltage drop in the cable between the battttery terminal and stater and then measure between starter casing and the battery ground. As it will be a a positive earth system measure from Battery Negative to starter terminnal then measure battery positive to engine block.
On a 12v system it should normally be less than 0.2 v drop on a 6v you want it as low as possible.

You also want to measure the voltage accross the battery when operating the starter as a bad cell in the battery will give the same symptoms.

[Edited on 29/5/20 by britishtrident]





[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]

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westf27

posted on 29/5/20 at 03:00 PM Reply With Quote
my Austin 7 is 1933 and has 6v electrics and battery,so I assume yours is unless everything has been up rated to 12v
It doesn't really matter the problem would have the same diagnosis /repair.
Your battery fully charged should read just over the 6 or 12 volt.A multimeter probably shows the starter cabling ok but due to poor connections and higher resistance
Won't pass the starter cranking current.If you have a set of jump leads jump from battery straight to starter .If it still cranks slow then it's either the battery or the starter.
If it is lively then the cabling is at fault,check chassis to engine block earth strap.Faulty connections after starter cranking can get very hot but will locate fault.
Checking a 6v battery on a tester at tyre centre etc may prove difficult as they mainly do 12v.Blag a 6v from a mate if you can,some old mg b's had two 6v batteries.
Let us know what you find.
Steve





Roof and doors pah ! who needs 'em.......well not March/April or parts of October

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rusty nuts

posted on 29/5/20 at 03:00 PM Reply With Quote
It’s not a 12v starter by any chance?
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steve m

posted on 29/5/20 at 03:04 PM Reply With Quote
Starterman on here would be your best place to go,

and as said, it could be a 12v starter, and I believe running 6 volts it would turn, but slowley





Thats was probably spelt wrong, or had some grammer, that the "grammer police have to have a moan at




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starterman

posted on 29/5/20 at 06:25 PM Reply With Quote
Does the starter have a part number on it?

I see that you are only in Paington so you could always take the starter off and come down to Callington and I'd be more than happy to have a look at it for you.

Cheers
Mike

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Dingz

posted on 29/5/20 at 08:57 PM Reply With Quote
Is it one of those that you pull a cable to operate the starter switch/actuator? if so it may be the contacts in the switch assy are shot.

[Edited on 29/5/20 by Dingz]





Phoned the local ramblers club today, but the bloke who answered just
went on and on.

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fazerruss

posted on 29/5/20 at 09:00 PM Reply With Quote
I wish my parents were still with us as they had a successful business refurbishing these and alternators. My dad could rebuild any starter to as new condition.
From memory a sluggish starter could be a combination of things like failing insulation on the field coils, worn bushes not holding the armature centre, dead or shorting winding in the armature, worn comutator. My old man bless him used to overhaul all these parts in his workshop. Wished I were not so young and I could have learnt more from him.

Starterman do you remember the Growlers?





"if assholes could fly this place would be an airport"

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rusty nuts

posted on 30/5/20 at 07:44 AM Reply With Quote
I vaguely remember using a growler at college about 50 years ago
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westf27

posted on 30/5/20 at 12:12 PM Reply With Quote
Most of my old teenage women thinking back were a bit growlery.
But a proper growler was a meat pie we used to buy on Chelsea bridge whilst at the cruise.
Sunday was the day you could fill a blimp with gas.





Roof and doors pah ! who needs 'em.......well not March/April or parts of October

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rusty nuts

posted on 30/5/20 at 02:12 PM Reply With Quote
I don’t know any “old teenagers” all of them are way younger than me!
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starterman

posted on 30/5/20 at 05:51 PM Reply With Quote
I'm nearly as old as god so yep I can remember them and using them. I do an awful lot of vintage rebuilds. Very frustrating and rewarding.

quote:
Originally posted by fazerruss
I wish my parents were still with us as they had a successful business refurbishing these and alternators. My dad could rebuild any starter to as new condition.
From memory a sluggish starter could be a combination of things like failing insulation on the field coils, worn bushes not holding the armature centre, dead or shorting winding in the armature, worn comutator. My old man bless him used to overhaul all these parts in his workshop. Wished I were not so young and I could have learnt more from him.

Starterman do you remember the Growlers?

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britishtrident

posted on 31/5/20 at 09:19 AM Reply With Quote
quote:
Originally posted by Dingz
Is it one of those that you pull a cable to operate the starter switch/actuator? if so it may be the contacts in the switch assy are shot.

[Edited on 29/5/20 by Dingz]


Those starter pull switches were pretty reliable --- if bad would show up doing a voltage drop test between battery and starter termminal.





[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]

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britishtrident

posted on 31/5/20 at 10:05 AM Reply With Quote
With a decent charge a 6 volt battery should show at least 6.25v -- fully charged in summer weather 6.4 volts ---- measure after the battery has been off the charger for at lest 2 hours --- 12 or 24 hours is better.

Operating the starter motor expect the battery to show at least 5 volts.
Old style battery load testers that will test both 6v and 12v batteries are in the £13 to £20 range on eBay but take extra care using this type of tester.





[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]

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JeffHs

posted on 31/5/20 at 05:23 PM Reply With Quote
I remember an inertia stater on one of my old bangers with just the same symptoms. Turned out to be not an electrical problem but a knackered bearing at the Bendix end. Once engaged it wouldn't turn.
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