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#862364 11/04/21 3:46 am
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The clutch on my 69 Lightning started slipping really badly so I inspected everything and replaced some clutch parts. I replaced the clutch springs and the cork driving plates because the plain steel plates appeared okay. The springs and the clutch rod were adjusted according to the manual and the correct amount of oil was added. It worked okay for about one mile and then it started to slip again. Should the steel plates have been replaced? Incorrect adjustment? Any ideas as to what could be wrong?


Thank you in advance.

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I would try scuffing the steel plates first before replacing them. Maybe use emory paper or a scotch brite pad.

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Does the centre rock about on the hub?
To test you will need to remove the plates.
If it does the spider is knackered.

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MrCarb, I learned a trick years ago that served me well over the years. If the tabs on the driven plates are in serviceable condition, they usually can be reused, and even enhanced by scuffing them on a flat sidewalk in a figure-8 pattern, both sides. The resulting scratches offer more grip to the driving (friction) plates. This allows a lighter pre-load on the clutch springs, a lighter clutch action at the lever, and a lower chance of clutch slippage under load. Of course, a properly adjusted clutch rod is essential, and I found that fitting the clutch plates dry helped with engagement. I understand they won't stay dry forever, but limiting your oil level in the primary chaincase to 140cc will help keep the primary chain lubricated without saturating the friction plates.
-Dave


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Originally Posted by The Bonneville Shop
MrCarb, I learned a trick years ago that served me well over the years. If the tabs on the driven plates are in serviceable condition, they usually can be reused, and even enhanced by scuffing them on a flat sidewalk in a figure-8 pattern, both sides. The resulting scratches offer more grip to the driving (friction) plates.


If your fortunate enough to have a blasting cabinet (or a friend with one) blasting them with a media (like sand or similar) will do a really good job. it'll remove all the oil residue but also leave a dimpled finish. good for a clutch.


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I like the sidewalk idea. That’s a true British repair and should be in the workshop manual.. No sarc intended by the way.

Last edited by Roadwarrior; 11/10/21 9:09 pm.

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There is a gap at the back of the clutch basket that the last disc falls into when disassembling and a magnet or two is needed to maneuver the disc into the slots to get it out. Is this slot size normal?

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Quote
the correct amount of oil was added.

What kind of oil are you using? It has to be either a motorcycle 4T oil with the JASO-MA spec for wet clutches or a classic car oil with an API grade no higher than SF or SG, ATF can also be used if it's type F.

Other oils will have friction modifiers that are not compatible with wet clutches. and will cause slippage. If you've used one of these oils then wash the plates in solvent and remove any oil. Hopefully, they should be reusable after cleaning.

Fill up with oil as specified above and you should be ok.

Last edited by gunner; 11/18/21 9:54 am.

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Your clutch hub centre is knackered., the internal spider is badly worn, a new unit costs about 100 quid in the UK, I firmly believe these are service items which should be replaced at least once every 50 years.


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Six steel and six friction, the friction goes in first. A friction is held by the tabs in the chainwheel so it cannot drop behind the hub. If the chainwheel wobbles a lot with the plates out the thrust washer behind it could be worn, but they do wobble a bit.

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Good one Gavin


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Originally Posted by mrcarb
There is a gap at the back of the clutch basket that the last disc falls into when disassembling and a magnet or two is needed to maneuver the disc into the slots to get it out. Is this slot size normal?

The last disc out should be a friction disc, and the clutch basket should hold it centered so it can't slide behind the clutch center.

Or what you may be experiencing is that the slots in the clutch basket are notched, and the tabs on the disc are catching in those notches, so you have to rotate the disc to center the tabs in the slots to clear the notch.

The tabs on the discs wear down on the edges and sometimes even get dog-eared. Then they bang back and forth in the slots and form notches. It's a vicious cycle; as the clearance increases, the rate of wear increases, and so on. This also inhibits the discs from sliding in and out freely when you disengage the clutch. If the notching isn't too severe, sometimes you can fix it by filing the slots; however, if the notching is severe, the only solution is to replace the clutch basket.


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