Author Topic: Clutch Slipping when kicking Over  (Read 560 times)

Offline Slymo

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Re: Clutch Slipping when kicking Over
« Reply #15 on: 06.05. 2021 01:24 »
It should be fine with oil on the plates, most of it is centrifuged off when in use but it is a wet clutch by design. I use ATF but ordinary engine oil shouldn't make it slip unless you've got molybdenum disulfide or similar in it.  If its a 6 spring original check that the pressure plate fits on without interference to the basket as even a slightly restricted fit will mess with the operation. You may have to bend the tabs on the basket that penetrate the pressure plate so that it fits on nicely. then spend a lot of time adjusting it so that it lifts evenly. Someone said that they used a DTI but I've found that careful eyeing up will give a good result. The difference between a clutch that slips and one that doesn't is very subtle and overtightening makes for an unpleasant riding experience and puts a lot of strain on the 1/4" posts that will pull out after time if you are brutal. I remade all of mine and riveted them in when one popped out. A lot of shagging around but a completely usable and pleasant clutch to use I've found now its right. If you've got a four spring replacement just forget everything I've said :)   
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Online Billybream

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Re: Clutch Slipping when kicking Over
« Reply #16 on: 06.05. 2021 04:22 »
It's worth spending time getting the clutch pressure plate to lift evenly, setting with a dial indicator or some form of pointer is highly recommended, even lift within a few thousands  of an inch will vastly improve clutch operation.
The standard pressure plate can be changed for a machined alloy version with top hat type bearing, this modification is highly recommended.
Your 4 spring clutch is very good and once set up correctly should result in 2 finger operation and give reliable performance.
1960 Super Rocket, owned since 1966, back on the road 2012 after being laid up for 29yrs.

Online Swarfcut

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Re: Clutch Slipping when kicking Over
« Reply #17 on: 06.05. 2021 09:49 »
 Just read this thread from the beginning. I reckon Col's problem of deposits on the plain plates is more down to the poor quality of the friction material or bonding adhesive. For material to be leached off by lubricant in such a short time is not how these plates usually behave. A non bargain if ever there was one.

 For those folks having similar problems with the earlier S/A 6  Spring clutch and its penny pinching design, I've noticed this contraption also comes comes in various guises adapted to fit the models in the contemporary B, M  and early C range. For example there are varying depths of clutch basket, flat and dished pressure plates, corresponding different numbers and combinations of plates and clutch centres with different styles of driven tabs. Plain Clutch Plates also vary in thickness, some pattern types are extremely thin. Add to this the wear that takes place, notching components that should slide and there you have a recipe for a clutch that sticks or slips.

 If you have a problem with this clutch it is worth checking that the basic parts are correct and not an assortment of bits from different models. Lower powered models from the other ranges have less plates for starters. A previous owner may have fitted whatever was to hand, and if the bike came as a basket case, nothing can be considered to be the right parts, and yes, ebay sellers haven't a clue either so be careful. That Rocket Pressure Plate  could have started life on an M20 or C11....certainly not the right part.

 Set up correctly the 6 spring pressed steel centred clutch is fine, but why BSA moved from the superior Plunger type 6 spring robust centre design can only be down to the cost accountants. The later 4 spring design cribbed from Triumph addresses most of the failings, going back to a solid or cush type centre but as here can still be problematic for the simplest of reasons. Use the "oil flicking past the hole" fill method to run the primary chain in oil without overfill allowing a high level of oil to enter the clutch.

 Swarfy.

Offline Colsbeeza

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Re: Clutch Slipping when kicking Over
« Reply #18 on: 06.05. 2021 11:20 »
Thanks Swarfy,
I have cleaned the plates, (which came from D'Fly) and will use 190mls of ATF. If the problem persists, the plates will be turfed and new ones from SRM or whoever.
Col
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Online KiwiGF

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Re: Clutch Slipping when kicking Over
« Reply #19 on: 06.05. 2021 12:07 »
Thanks Swarfy,
I have cleaned the plates, (which came from D'Fly) and will use 190mls of ATF. If the problem persists, the plates will be turfed and new ones from SRM or whoever.
Col

The friction modifiers in car engine oil DO mess up set clutches and makes them slip (it even happened on my suzuki 1400 when I skimped and put car oil in it instead of motorbike oil) but in that instance just swapping the oil to the correct type made the slipping go away.

I agree with the earlier post that the 6 spring s/a clutch is pretty good if you have all the correct parts and set it up with a dial gauge.

I reckon having incorrect spec clutch parts from other models (pre unit singles etc) is partly responsible for the bad reputation of the 6 spring.

I fitted a Newby belt drive and clutch to my A10, and found the Newby clutch is only slightly better in operation than a 6 spring, but I fitted the Newby kit for others reasons.
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Online berger

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Re: Clutch Slipping when kicking Over
« Reply #20 on: 06.05. 2021 14:22 »
i must say a lot of 6 spring trouble comes with pattern part middles that flex, break or just disintegrate like mine did. when i found and fitted an original BSA one with the reinforced bits and made of toughened steel you can have a very good clutch but a lot of people prefer the 4 spring triumph one. i even swapped mine when i found a triumph one