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Lately I've had the bike jump when starting out as though I just dumped the clutch instead of steadily releasing it. Now I find myself very slowly releasing it from stand-still. I did fully lubricate the cable not too long ago but I've never had to baby a clutch like this in my life (11 bikes). This is a set of clutches from MAP with ~1000 miles on them. Clutch components appeared excellent at the time. Haven't changed oil type (20/50 Valvoline Motorcycle oil) Primary shares oil with engine. Is it time to inspect or just learn to use it very slowly and carefully? Is there a known cause for this and is it damaging if left un-handled. Thanks! Brian


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I had a similar situation recently. I changed the shock hub rubbers and it's gone now.


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Originally Posted by DavidP
I had a similar situation recently. I changed the shock hub rubbers and it's gone now.

Thanks DavidP. I did fail to inspect these when I was in there and I'm sure they are original. Somehow it doesn't make sense that this would cause rapid engagement but I may have a look-see and change these out in the process. -Brian

edit; How difficult was it to change them out? Where did you buy yours?

Last edited by BAinLA; 08/12/21 6:11 am.

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The importan question is what are the slots in the chainwheel like & which plates are you using ?


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SENSODYNE tooth paste also cures "sensitivity."

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Originally Posted by BSA_WM20
The importan question is what are the slots in the chainwheel like & which plates are you using ?

Slots were pristine, M.A.P. set of steels and frictions.


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Originally Posted by BAinLA
Originally Posted by DavidP
I had a similar situation recently. I changed the shock hub rubbers and it's gone now.

Thanks DavidP. I did fail to inspect these when I was in there and I'm sure they are original. Somehow it doesn't make sense that this would cause rapid engagement but I may have a look-see and change these out in the process. -Brian

edit; How difficult was it to change them out? Where did you buy yours?
+1
bad rubbers can cause the cush drive to skew as it compresses .
Rather than just compressing and rebounding , the hub in action , adds a bid of "wonk"
in an area without much room to spare to begin with .
( once the rubbers are taken out )
a really bad cush drive will show gouging on the backing plates
where the spider arms rubs troughs .( hardened metal sliding against hardened metal )
At some point replacing the rubbers isn't good enough .

Last edited by quinten; 08/12/21 11:59 pm.
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Thanks DavidP and quinten, I appreciate the tip and the explanation. I guess I need to get in there and have a looksee. Leaks a little oil anyway from the primary. Low miles bike (21K miles) just old. If I remember from the last ice age, It is sometimes a bit of a bear getting those new suckers in there. -Brian


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You can make a tool with an old steel plate and a a bar.
Grip the hub in a vice and use the plate/bar to twist the centre. Not too bad a job.

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To rebuild: There are a number of videos and how to's out there on the internet showing you in varying degrees of detail how to rebuild the clutch center. For example, Lunmad has a real helpful video with practical tips on how to do this,
and the Lowbrow site covers it, but far less completely. https://www.lowbrowcustoms.com/blogs/motorcycle-how-to-guides/triumph-650-clutch-inspection-service and there is a Lowbrow movie part 12 at about 5 minutes on Youtube
, but neither Lowbrow video or guide really sheds the practical light on the process that Lunmad does.

Or, if you have the budget, and the rebuild job is not for you, you can just buy a new complete hub. There are lots of places with these for sale, such as in LA near you https://www.classicbritishspares.com/products/triumph-bsa-complete-clutch-hub-assembly

Take a look at all the wear parts and surfaces. Although you said the slots were pristine, you may need a new assembly anyway, once you get in there, depending on how much wear there is on the front and back plates from the spider; after 21,000 miles it all could be worn out. It is worth fixing that wear too, and practically speaking, by the time you buy the plates, maybe the spider, and the rubbers, you may just find buying new is a better alternative, but YRMV.

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BA, are your new discs cork or Surflex? The Surflex discs can be exceptionally grabby. I put a set on a T140, and they were so grabby the owner had me switch it back to cork discs, which performed "as normal".

(Note, I'm not saying you DON'T have a problem with your clutch rubbers. Inspection will tell the tale there; if the rubbers are hard and shrunken, they should be replaced.)


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They were put in new about 1000 miles ago, bought from M.A.P. as a set of steels and frictions. If I had to guess I would definitely say Surflex but I don't really know what material is used. Good to know about your experience.If it gets any worse at all I will have to do something. -Brian


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I've heard nothing but praise for the MAP clutch discs.


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I love my MAP clutch. It never sticks but it is very "grabby" when cold.

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Originally Posted by chew652
I love my MAP clutch. It never sticks but it is very "grabby" when cold.

Hmmm. Good to know, thanks. -BA


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