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BS5 starter issues


mike@oldnut.co.uk
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Hi All, I am attempting to reach out in all directions to try and sort this 10 or maybe 16 year old problem! My boat has a 1942 2L2 which was restored, marinised and fitted into the Narrowboat during the build in 2003, having only owned it for some 6 weeks, it is apparent that for at least the last ten years(as far as the records I hold go back) it has had a problem with chewing up the 13 tooth bronze starter pinion, having been replaced several times, with the starter being 'supposedly' refurbished at least once, it has a problem meshing on operation, although it meshes fine when pushed in manually unless the teeth butt, the previous owners had given up trying to fix it and just pushed it into mesh with a screwdriver and held it there with a dowel on a bit of string, this does of course work, but is a pain in the butt, and it also means you do not stop the engine as often as you should but leave it ticking over, this is not acceptable to an old Engineer! I serviced the engine and gearbox last week, in the process I had the flywheel cover off, as well as the starter end cover, the pinion slides easily enough into mesh when pushed by hand provided the teeth mesh, otherwise you need to turn it a bit, the trip between 1st and 2nd contacts appears to work fine, not tripping until 1" into mesh, the pinion teeth were a bit galled so I tidied them up with a Dremel, put a small chamfer on them, moved the starter even closer(+/-0.060") then operated the starter with the stop lever down and the compression levers up whilst we got oil pressure up following the oil change, so kept operating the starter in short busts, going in and out of mesh lovely about 8 or 9 times, 10th time tooth to tooth I presume. kerrang, it just spins up milling the end of the pinion, so 10 years it has been doing this, the starter bracket whilst not original, is a quite a substantial welded construction, probably hand start originally, but seems more than adequate, it has had some copper shims placed to space it away from the CL a bit, it has plenty of rotational clearance when in mesh, it has had various people look at it, including the main tech guy from the Gardner forum, no joy. I am at home just now, when I go back I intend to clean up the pinion end again, put a better chamfer on the pinion, move it up to the recommended minimum of 0.031" flywheel clearance, put a bit of cardboard under the 2nd stage contact and see if it still 'spins up' It has a 13 tooth pinion as it always had, someone on a forum has questioned that, should it be 12, I can find thus far no way of telling which pinion it should have, I intend to measure the diameter of the flywheel when I go back, currently the ring gear teeth are as machined, dead sq, the CAV manual I have just acquired a copy of, talks about a cast one being sq and a steel one being chamfered, do you have any ideas.?

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I have encountered this very problem in the past and despite many hours head scratching and looking up flywheel/starter ratios, tooth lead-in etc it was ultimately solved by increasing the distance (fore and aft) between the flywheel and the starter. A heavy washer of around 5/16" between the starter and the mounting bracket on each bolt still allowed the register to locate but gave the motor, or more pertinently the bendix, a greater travel to build up rotation. 

Might be worth a try? 

 

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General comments on Bendix starters.

 

All I have ever had a lot to do with have  chamfered teeth on the Bendix, usually symmetrical on leading and trailing side of the tooth.

Now the ring gear will have a one sided chamfer, on the trailing side of the teeth.

Could you have the ring gear from a left hand starter engine? If it is square toothed I would try chamfering the teeth.

!2 or 13 teeth will make no odds providing the tooth forms fit one another. In the automotive world, automatic gearbox cars often had a different bendix to manuals but the same ring gear.

 

Hope that may help.

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1st James, thank for you response, there is no bendix, it is what is known as an 'axial' starter where the whole armature and the pinion moves forward slowly rotating a little, once fully engaged a 2nd contact comes in to give it the 'full monty' with this type 'closer is better' CAV recommended clearance pinion to ring gear is <0.125" to >0.031"  it is currently set at about 0.060". Now, as the Venerable Sir Nibble asks, this 2nd stage is held 'out' by a trigger, which is released by a 'cam'' for want of a better word as the armature moves forward about 1"in answer to his question, no it is not bent and the notch look in perfect condition, now the question might be 'when the pinion teeth butt is this enough to prematurely trigger the release of the 2nd stage, you would need a high speed camera to see this in action, now I found a video this morning of someone starting a 2L2 and when he pressed the button, well he actually turned a key, the first time it just went donk, obviously hit tooth to tooth and stopped, whereas mine spins up at this point, so you would think it must be tripping the 2nd stage contact somehow, so, I have a plan, not particurlary cunning, but a plan nonetheless, when I next go back to the boat, whip off the flywheel cover, dremel the pinion teeth back sg but with a chamfer, set the gap to 0.31" put a bit of cardboard under the 2nd contact to prevent it making, then see what happens, it should just slide all the way in if it meshes, or just stop if it hits. Elesewhere yesterday some one else said they filed the trigger <90 deg and that worked fine, it may be that the trigger spring is also a bit weak! I have tried today to buy a new solenoid as the contacts are regressed a bit. But there is no stck atm.

BS5 Starter 1.jpg

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Hi Tracy, see last response, there is no bendix, the whole armature and pinion move out together slowly, only 'spinning up' after the teeth are engaged, my problem is it spins up when the teeth butt, if they don't butt it works ? The CAV manual says 'if you have a cast ring gear, teeth are sq with chamfer on the pinion, if you have a steel ring gear then you have chamfer on both, but a new pinion has only a very small chamfer, see pic of a new one.

Best rgds

Mike

BS5 Starter 7.jpg

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Never heard of an 11 tooth, only 12 and 13, thats a new one on me, Melvyn from MPS reckons very little difference between them in diameter 0.1mm, mine meshes fine, when held in there is rotational clearance, my gut feeling is that stage 2 is coming in when the teeth butt, we shall see when I go back, i shall add you observation to the others and work my way through them.

rgds

Mike

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1 hour ago, steamraiser2 said:

Actually it is entirely possible that your starter motor should have an eleven tooth pinion on it. It is a common problem which we have seen quite often on Gardners. Like as recently as couple of hours ago as it happens?

Indeed, and ten tooth. I would suggest measuring the tooth pitch as 12 and 13 tooth are quite different. However, weren't ford transit starters retro fitted to these? That's a 13 tooth.

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Hi All, I have only ever seen 12 and 13 teeth bronze pinions for the CAV BS5 12V starter, not saying there is not 10 and 11, but I have never seen one, there was a comment above about left or right hand ring gear, this I would understand if there was a chamfer but there is non, and nobody has yet added a reasoned response to the CAV manual statement that 'a cast iron ring gear' has no chamfer, whilst a 'steel one would' I understand that a chamfer on a cast iron one would create a weak point, but a chamfer is either needed or not, now I suppose you might imagine that a cast one is 'more slippy' than a steel one when the teeth butt, however from what I saw on youtube this morning showing a starter 'butting' first try and it just 'stopped' I imagine with the teeth 'butted' releasing the key probably then allowed the pinion to rotate a bit more when the key was turned again allowing it to mesh and then start. My gut feeling is the 2nd stage latch dropping when the teeth butt, we shall see and I will report back! I would drop the pdf manual but it is too large, others have proffered links. I only wish that I could get a new solenoid which comes complete with contacts, latch etc.

Regards

 

Mike

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3 hours ago, mike@oldnut.co.uk said:

Hi All, I have only ever seen 12 and 13 teeth bronze pinions for the CAV BS5 12V starter, not saying there is not 10 and 11, but I have never seen one, there was a comment above about left or right hand ring gear, this I would understand if there was a chamfer but there is non, and nobody has yet added a reasoned response to the CAV manual statement that 'a cast iron ring gear' has no chamfer, whilst a 'steel one would' I understand that a chamfer on a cast iron one would create a weak point, but a chamfer is either needed or not, now I suppose you might imagine that a cast one is 'more slippy' than a steel one when the teeth butt, however from what I saw on youtube this morning showing a starter 'butting' first try and it just 'stopped' I imagine with the teeth 'butted' releasing the key probably then allowed the pinion to rotate a bit more when the key was turned again allowing it to mesh and then start. My gut feeling is the 2nd stage latch dropping when the teeth butt, we shall see and I will report back! I would drop the pdf manual but it is too large, others have proffered links. I only wish that I could get a new solenoid which comes complete with contacts, latch etc.

Regards

 

Mike

There's two possible solenoids, which is it? 

woodauto-lucas-cav-type-starter-solenoid-sl5-sp5-bs6-u6-serie-24v-138390-snd1430-1546037488712.jpgThis one?

 

131780l.jpgor, more likely, this one.

Edited by Sir Nibble
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I have no direct knowledge of these starters or engines but I did spend a working life in the engineering game so I may have some valid observations.


The first thing is that to use bronze for the smaller gear is odd, it is more common to use the harder, even hardened material on the smaller gear to minimise wear. I will admit however that starter gears are a bit of a special case


On the subject of chamfers I would have expected the chamfer to follow the contour of the involute rather than radially as seen in post No.6 if it is to work at all.

I would wish to see such chamfers cover more than 50% of both the pinion and ring gear faces.

I would also expect the chamfers to be on the trailing faces of the gears to give the pinion its best chance of finding engagement.


Is it known if the ring gear is original?

Is the Dimetral Pitch (DP) of the ring gear and pinion known? (It is likely to be DP given the engine's origin but CP or module is not beyond imagination or Sodd's law.) As there is some speculation about pinion tooth numbers it would be worth knowing everything is as it is supposed to be.

 

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Good morning, I follow what you are saying, however in marine applications on these Axial starters the pinion is generally Bronze, presumably because it is relatively easy to change the pinion not the ring gear. the picture i posted is a nos pinion and yes the chamfer does look a bit odd, the CAV manuals dictate no ring gear chamfer on an Axial starter, but yes on a 'bendix' type. from what I saw yesterday it would appear that if an axial starter comes out and the teeth butt(they come out quite gently)you just release the key and try again, as it slides out it is also slowly rotating so hit first time it should engage 2nd time. The starter I am trying to sort comes out but if it butts it then spins up, if it engages it works fine, there are two contacts, the first starte the axial and slow rotation, the second brings in the full power after about 1" of travel when the tetth are engaged, all this happens pdq so very difficult to see the sequence but it seems like my 2nd stage contact is coming on too early, yet all looks as it should and when pushed manually the 2nd stage trips when it should, so we have a few possibilities to check, bear in mind this starter has been doing this for at least 10 years, hence why the owners gave up and resorted to engaging it manually and chocking it engaged with a bit of dowel, this works 100% but is a pain and you don't stop the engine when you ought to. So there is nothing obviously wrong with it!

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hi, You are thinking the same as me, what happens when the teeth butt, I like you thought it needed enough torque so turn into engagement, that is not apparently what should happen, go to youtube and search 2L2 starting, there are a couple of vids there, what you hear is a bit of a clunk if the teeth butt, you then release the key or in our case button, then press again, as the pinion comes out it turns slowly, so if it hits first time you press, second time it will go into engagement and off you go.

My problem is when it butts I then have too much torque (has the second stage engaged too early?, we dont yet know as it all happens too quickly) and it just spins up.

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Presumably if the teeth butt, the second stage of the solenoid should not come in.

This would logically dictate that the pinion is allowed to travel too far when the teeth butt hence the second stage comes in.

Is the pinon too far back or the starter too far away from the ring gear, or is the pinion shorter than it should be with having been dressed with a Dremel?

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My six penouth. Personally I dislike axial and coaxial starters so have had little to do with them but as an apprentice I remember the electrician spending ages adjusting the second stage of power up on an axial starter so if yours is engaging second stage before full pinion engagement I think you need to look closely at the fault @Sir Nibble pointed out earlier and that is the second stage trip lever. I have no idea if yours is adjusted but that is worth looking at as well.

5 minutes ago, Tracy D'arth said:

Presumably if the teeth butt, the second stage of the solenoid should not come in.

This would logically dictate that the pinion is allowed to travel too far when the teeth butt hence the second stage comes in.

Is the pinon too far back or the starter too far away from the ring gear, or is the pinion shorter than it should be with having been dressed with a Dremel?

 

good point, the mounting clamp system seems to allow a degree of fore and aft movement. I am not sure if there are any locating dowls/pegs.

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Hi all, i read the cav manual incorrectly, the clearance between the ring gear and pinion at rest should be 0.125" +/- 0.031" I read that as max 0.125" and min 0.031" however the problem does appear to be the 2nd stage triggering way too early, when pushing the armature in by hand the 2nd stage does not trigger until the teeth are fully engaged, it all happens too quickly to see what is happening, the latch looks to be in perfect condition so I need to understand why it is 'tripping' when the teeth butt, when I next go back I will have more time and information on what to check, I am trying to purchase a whole new 12v BBNG solenoid assembly but they are 'hens teeth' atm, when I strted trying to fix the 10 year old problem the gap was +/- 0.125" I did mistakenly move it closer, see above. So my plan is:- remove flywheel cover, check out the flywhhel diameter and no of teeth for the records, probably remove the shims behind to see if it still meshes ok or not(what should the backlash be? I dont yet know) dress up the pinion, reset the gap to 0.125" put cardboard under the second stage and press the button, it should then do one of two things, either butt the teeth, in which case it should just stop with a small donk, release the starter button, press again, during which time as it travels forward and slowly rotates it should slide into mesh, or, it would have gone into mesh first time, if you think about it there are 50% flat teeth on the ring gear and 50% gaps, so you nearly have a 50/50 chance of donk or mesh first time, if not then second time ?

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