Starter clutch slipping

Maestro, SEI-V
EVguru
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Re: Starter clutch slipping

Post by EVguru »

Tungsten/Tungsten carbide is 2-2.5 times as dense as steel and makes a good weighting material.

Pure Tungsten rod can often be found cheaply in the form of TIG welding electrodes in diameters up to 1/4".

Broken Tungsten Carbide endmills would be another source of material.

As has been said before, the weight of the shoes is just one factor. Battery health (cranking amps), wiring and starter relay resistance, brush, commutator and output gearbox condition all play their part.
Paul Compton
http://www.morini-mania.co.uk
http://www.youtube.com/user/EVguru
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Starter clutch slipping

Post by penman »

EVguru wrote:The shoes are still in production by Surflex.
Hi Paul,
Do you know of a supplier? I've had a good search today without luck.

By the way, I take your point about the battery, cables, relay etc being in good health. I've ordered some new cable and eyelet connectors to replace the 40 year old ones. The battery is in very good shape. There was about 1v drop between the battery terminal and the starter, with about 0.1v of that being across the relay contacts. That sounds OK to me, but having said that, it is slipping pretty well continuously, so maybe the current isn't all that high. The battery is showing over 12v when cranking (i.e. slipping) which sounds too high. I'll have to have another look at the motor, but I did check the brushes and commutator visually and they look fine. I skimmed the commutator about 2 years ago and it is still clean and bright. The brushes are good length and free to slide.

This is my only set of starter shoes so I'm a bit reluctant to start drilling holes in them, especially as it was all working fine for a year or so after the rebuild. These shoes are the laminated type, made of steel, so I think I would have to insert a pretty big piece of a heavier material to make much difference. I didn't know they ever made them from Mazak, that's a lot lighter and I can see how that would benefit from a heavier steel plug.

Many thanks for the replies, much appreciated!

Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
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Re: Starter clutch slipping

Post by EVguru »

Surflex sugested Mdina...

They may not have any in stock, but presumably they have an account in order to order the clutch sets.
Paul Compton
http://www.morini-mania.co.uk
http://www.youtube.com/user/EVguru
harrymuffin
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Re: Starter clutch slipping

Post by harrymuffin »

The shoes when thrown out have a 'leading' effect or a mild wedgeing into the drum. Thinking logically, it could just be that the shoes are simply not spinning quickly enough to grip/wedge onto the drum and therefore simply go round wearing themselves out and glazing over. Have you checked the brushes and commutator and that there is no ingress of oil form the worm and wheel gear end, if there is any in the first place? Considering the age of the bike and from evidence I have seen -out of sight out of mind - they do not get much maintenance, this is one of the reasons people give up on the starter motor and ditch them. They take the easy route out, making excuses of weight saving when they could probably achieve more preferable power to weight ratios if they themselves lost 1/2 a stone. Whilst waiting for your electical goodies, I would be inclined to overhaul or at least inspect the motor, if you can switch on an idiot phone, which I cannot, then you should be able to use a screw driver to undo the long bolts, the brushes are accesible to push back when putting the end cover on without any special tools. After all they are assembled - quote "by peasents".
penman
Posts: 325
Joined: 08 Mar 2016 09:20
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Location: Milton Keynes

Re: Starter clutch slipping

Post by penman »

harrymuffin wrote:The shoes when thrown out have a 'leading' effect or a mild wedgeing into the drum. Thinking logically, it could just be that the shoes are simply not spinning quickly enough to grip/wedge onto the drum and therefore simply go round wearing themselves out and glazing over. Have you checked the brushes and commutator and that there is no ingress of oil form the worm and wheel gear end, if there is any in the first place? Considering the age of the bike and from evidence I have seen -out of sight out of mind - they do not get much maintenance, this is one of the reasons people give up on the starter motor and ditch them. They take the easy route out, making excuses of weight saving when they could probably achieve more preferable power to weight ratios if they themselves lost 1/2 a stone. Whilst waiting for your electical goodies, I would be inclined to overhaul or at least inspect the motor, if you can switch on an idiot phone, which I cannot, then you should be able to use a screw driver to undo the long bolts, the brushes are accesible to push back when putting the end cover on without any special tools. After all they are assembled - quote "by peasents".
Thank you for all that! I overhauled the motor a couple of years ago, I gave the commutator a very light skim and replaced the brushes, which were worn right down. The commutator segments were already quite deeply under-cut, so I just went round and cleaned out any brush debris, etc. I replaced the ball race from the end of the rotor shaft and gave everything a good clean. The gears were in very good shape, so I just filled the gearbox with fresh oil.

I see now that oil is weeping from the seal on the side of the gearbox, but it hadn't got inside the motor casing and I don't believe it is causing a problem - there was still plenty in the gearbox. If I power up the motor on the bench, it spins up strongly and you do need to pin it down with one hand to avoid it flying off the bench. As I mentioned above, the commutator is still clean and bright and the brushes are free to move and show practically no wear.

I've just reassembled it with all new cables and a new relay and it's made no difference at all. I do think it's possible that the motor isn't producing enough power, maybe a shorted turn in the field (for example) wouldn't be obvious when spinning with no load, but would be seriously down on torque under load. I'm clutching at straws here though!
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Starter clutch slipping

Post by penman »

EVguru wrote:Surflex sugested Mdina...

They may not have any in stock, but presumably they have an account in order to order the clutch sets.
Many thanks Paul, Mdina do have them and they are in stock now. Somewhat against my better judgement I've ordered a set (£106!!) so we'll see what happens.

I've given the starter motor a good visual inspection and I can't see any signs of damaged windings, etc and as I say, it spins up instantly. In the past someone has scored a zig-zag line on the inside of the starter clutch drum, so I guess this isn't a new problem. The drum is very polished, but I guess it's bound to be and I don't think it should matter. Anyway, I'll report back in a few days.

By the way, coincidentally the starter solenoid on my Guzzi went open circuit last week - do these things gang up on you??
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
harrymuffin
Posts: 292
Joined: 07 Apr 2014 16:06
Location: west midlands

Re: Starter clutch slipping

Post by harrymuffin »

Just a thought, check the voltage drop with the starter motor activated and attempting to start the engine; use the output from the starter solenoid, anything less than 11ish volts could be high resistance across the contacts or battery not holding up.
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Daddy Dom
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Re: Starter clutch slipping

Post by Daddy Dom »

I got my set of heavyweight shoes here:
https://www.ebay.it/itm/Dispositivo-avv ... %7Ciid%3A1
MRC 3082½
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Starter clutch slipping

Post by penman »

Well I fitted the new set of Surflex starter clutch shoes and it has completely cured the problem. The clutch bites immediately and cranks the engine strongly with no slipping. Phew! I hope that's now the end of this saga. The new shoes do feel significantly heavier than the old style ones and the lining material resembles those "sintered" brake pads. The linings come ready profiled and were an excellent fit, making it a dead easy job. At £106 they weren't cheap - but they do work, which is quite an advantage in my book!

Regards,

Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
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