Starter clutch slipping

Maestro, SEI-V
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Starter clutch slipping

Post by penman »

Has anyone experienced a problem with the starter clutch slipping? Mine has started doing this in the last few days. When I first re-commissioned the bike I had to overhaul the starter motor, replace the (broken) chain and get the clutch shoes re-lined. It's always worked well until this slipping started a few days ago. I don't find it the easiest bike to kick-start, what with the kick-start being on the "wrong" side and it seems to need a good fast kick to get it going - but I have had to resort to that a couple of times.

I haven't stripped it yet, hopefully I'll get a chance today and maybe the cause will be obvious. Any comments gratefully received though!

Regards,

Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
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72degrees
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Joined: 31 Aug 2007 21:24
Location: West Midlands

Re: Starter clutch slipping

Post by 72degrees »

They were often less than perfect once they had been used a few times. Lots of dodges have been tried over the year to increase the friction. Some very inadvisable ones have seemingly led to damage to the 'drum'. I'll confess to centre punching the drum surface a bit and very slightly slotting the shoe linings on my 79 350 Sport (it certainly worked on the start line for a 'production race' at Snetterton), but this is very frowned upon.

Just cleaning out any lining dust may help, but others will probably be along soon with their solutions.
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 took it apart this afternoon and this is what I found:

Image

The starter clutch assembly looks OK, everything in place, plenty of lining material and all the pivots nice and free. So far so good.

Image

The "drum" (for want of a better word) looks sound, but in places it's polished to a mirror finish and in others it's dull. There is evidence of some previous owner having scored a zigzag line into the surface, so this is not a new problem

Image

The shoes are polished in limited areas, while other areas haven't been making contact.

I decided to roughen up the shoe linings with 300 grit emery paper, concentrating on the shiny areas. I also did the same to the very polished areas of the drum. I tried it several times and it's still slipping, though it does start the engine more reliably. When it slips it makes an awful noise, much worse than before.

I'll have to think about what to do next, but if anyone has any suggestions....? My left foot kick-start technique is improving though!

Regards,

Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
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72degrees
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Location: West Midlands

Re: Starter clutch slipping

Post by 72degrees »

Evguru would point to the fit of the shoes in the 'drum', and as Harrymuffin advises, that really needs the shoes re-lining with thicker material then reducing so that they only just fit inside.
penman
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Location: Milton Keynes, UK
Location: Milton Keynes

Re: Starter clutch slipping

Post by penman »

When I had the shoes re-lined, they were too thick to enter the drum, at least on the leading end of the shoe. I spent some time with a file and emery paper trying to profile the shoes to fit as well as I could. Of course when the drum is in place, you can't see or feel the linings (or the shoes, come to that!) so this is hardly an exact science. Even if you remove the sprocket from the starter cover you can't see much, but I did end up with it looking as if the linings were touching along their full length if you pulled them out against the drum.

I'm not particularly surprised to see that the wear (polishing) is limited to certain areas, it will only need a couple of very slight high spots to create that effect and I'm not really sure that it matters. Also, this has worked fine for about 18 months, it's only in the last week or so that I've had a problem. I was really expecting to find some very obvious failure when I took it apart.

I believe the design of the shoes was changed on later bikes, does anyone know if this was to stop them "chattering" against the drum? I think (not sure) that is what is happening.

Joe
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
MickeyMoto
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Joined: 22 Nov 2008 17:41
Location: Even further oop North

Re: Starter clutch slipping

Post by MickeyMoto »

My 500 had the same problem. Graunching on starting. Refurbished everything, no joy.

Changed the battery and starter restored to rude health! It needs a fair whack to engage and turn the flywheel on the slippery ring supplied... :)
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Starter clutch slipping

Post by penman »

MickeyMoto wrote:My 500 had the same problem. Graunching on starting. Refurbished everything, no joy.

Changed the battery and starter restored to rude health! It needs a fair whack to engage and turn the flywheel on the slippery ring supplied... :)
Thank you for that, I'll check the battery and charging. That could potentially explain everything.

Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
harrymuffin
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Joined: 07 Apr 2014 16:06
Location: west midlands

Re: Starter clutch slipping

Post by harrymuffin »

I had two sets relined last year with much thicker linings than what you seem to have on yours. I chamfered the leading edges which i think are opposite to the way you have done them,(without taking the cover off I cannot be sure) so that when thrown out the whole liner is in contact with the drum. I have no problem with them turning the engine of the hybrid and the compression will try to stop the starter from rotating. When hot it starts very freely. Some time ago I had a set relined by SafteK in Telford who had the shoe holder complete and they skimmed the shoes in a lathe with the shoes wedged in the open position as the shoes on drum brakes used to be done in racing applications, they worked with no problems. As already mentioned, making sure the battery is fully charged and delivering the full current enables the motor to turn more quickly and hence greater centrifugal fore. I replace the starter solenoids in preference to originality with solenoids from a Kawasaki or some other crap bike which can handle the current better than the it alien rubbish where I have had the contacts weld themselves together with the starter continuing to run with the engine also running.
penman
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Location: Milton Keynes, UK
Location: Milton Keynes

Re: Starter clutch slipping

Post by penman »

harrymuffin - thanks for your reply. These linings were a good deal thicker to begin with, but I had to reduce them significantly for them to fit into the drum. As I said above, I did my best to profile them to fit with full contact and to be fair, they worked perfectly for a good 18 months before this problem arose.

I checked the battery and it is fine. It still had 13.4v after standing for more than 24 hours and on charge it was around 14.6v with all the lights on, a bit on the high side actually. I've checked all the connections, cable terminals and so on, everything tight and in good condition. The starter relay is original and hasn't given any trouble up to now, but maybe it's a bit high resistance. I think I could convince myself that it's not spinning all that fast these days. Maybe I'll substitute the starter relay from the Trident for a test.

Joe
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 »

Have checked the shoes on a couple of spare starters and you have chamfered the right way. The lining material on all the spare shoes is at least 3/16" thick at the forward end though - used, and I think I had the two sets done last year to about a 1/4" so I could fit them exactly with just enough clearance when at rest and the engine running. If the starter is not spinning fast enough check the brushes, you can get them for pennies from Lucas electrical factors.
penman
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Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Starter clutch slipping

Post by penman »

harrymuffin - thanks for checking your spare starters, much appreciated.

As you know, checking the fit of the shoes in the drum is a bit of a palaver by the time you remove the sprocket and shoes, remove the back plate from under the shoes, remove the flywheel and try the fit on the bench. I will have another look, but when I fitted the new linings 18 months ago, I did go through all that and I tried to keep the linings as thick as possible without the drum scraping them with the engine running. There is a strip of soft material inside the elbow of the shoes, presumably an anti-rattle measure, and I had to thin that quite a lot to allow the shoes to retract fully. By the way, the new linings were fitted by a guy who NLM use. It wasn't cheap!

When I first got the bike, the starter didn't work because the chain had broken and was wrapped round the sprocket, which had a broken tooth and the result had cracked the outer casing. A bit of a mess! I got a new (old) casing and sprocket from Paul Compton and a bit of chain off ebay. The motor needed a full overhaul and I fitted new bearings, new brushes and tidied up the commutator. Considering how little actual use the starter gets - a couple of seconds once or twice on every ride - I didn't expect it to give me any more trouble. Wrong again!
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
carlosfandango
Posts: 2
Joined: 14 Oct 2018 20:21
Location: Northampton

Re: Starter clutch slipping

Post by carlosfandango »

Really useful info guys, stripped mine today.

Anyone know where I can get get the starter clutch relined now that NLM is no longer around? plus i need a new starter relay, anyone sourced a reliable alternative

Thanks

Carlos
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Ming
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Joined: 01 Aug 2014 16:32
Location: France
Location: Central France

Re: Starter clutch slipping

Post by Ming »

I don't know about the relining, maybe Villiers Services (https://villiersservices.co.uk/index.ph ... v887o85jh2)? I think this was also discussed earlier this year. For the starter relay, any of the Japanese bike's relays should be just as good and probably cheaper.
Greybeard
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Joined: 27 Oct 2018 18:47
Location: Cottingham
Location: East Yorkshire

Re: Starter clutch slipping

Post by Greybeard »

Hello, Carlos.NLM supplied me with a new set of shoes a couple of weeks ago - 80 quid plus vat mind :shock:
For relining you could try safetek engineering. They have a good reputation and im going to be sending them a couple of sets of shoes from one of my Matchless' and an AJS before long. I would imagine theyd need the full assembly including the stator drum to set it up to machine the tapers.
My starter elay is also playing up but Im going to try stripping it to check the contacts before replacing it as it is clicking when the button's pressed.

Steve
harrymuffin
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Joined: 07 Apr 2014 16:06
Location: west midlands

Re: Starter clutch slipping

Post by harrymuffin »

I have Saftek do starter linings for me sometime ago. They will turn the linings to the diameter of the forum like fitting shoes on racing bikes in the old days. They will need the dial,ever of the drum and I think I let them have the shoe career so that the shoes cane shimmed out. They used to be in telford.
The sets of shoes I recently had relined were done by Villiers near to the Brierley Hill, and I had a 1/4" lining material fitted so that I could fit them in the engaged position. I think they send them to a place in Station Road, Blackheath and then put their 10% on.
I would certainly ditch the starter solenoid and fit one from a Jap Crap bike, mine are ones fitted to some 1ltr Kawasaki thing. I have had standard ones fuse the contacts together so that the engine was turning the starter motor over until the chain snapped.
I had such reliability from my Morinis that I removed the kick start levers, the 507 hybrid starts first touch of the button cold or hot.
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