HOW TO REMOVE SPRAG CLUTCH
Posted: Fri Oct 10, 2014 4:01 pm
Following a suspected Sprag clutch failure on 2003 500 Classic I tried to discover an idiots "How to do it" guide and couldn't so after a few helpful clues from others decided that anyone capable of taken a wheel out should be able to tackle the Sprag Clutch as it is really just a matter of spannering - so with a mate we set about getting to the cause of the problem - if it helps others this is what we discovered was needed to access and remove the Sprag Clutch.
Remove main fuse and then starter motor bolts (2) after disconnecting power feed and place safely to one side.
Remove nearside footrest and disconnect rear brake rod allowing access to outer case.
Trace back the alternator leads and disconnect at four way bullet connection noting that two wires are in fact the same colour, whilst I imagine it makes no difference which is which I simply tape one set of wires with a strip of insulating tape.
Place container under case and drain case of oil and remove exposing the clutch basket, alternator and duplex chain
Dismantle clutch spring plate undoing each of four bolts evenly and remove clutch plates in order and the correct way round thread a piece of string through centre so as to keep then all together in correct sequence (Clutch dished plates are often put in back to front and you then burn your clutch out)
Take small piece of wood wrapped in rag between duplex chain and clutch basket cog and undo alternator centre nut.
Remove three nuts retaining the alternator plate and remove alternator and stator
Set about removing Clutch basket clutch drive sprockets and duplex chain in one operation - You may need to use pullers these are simple to make up using scraps of metal and correct size bolts......REMEMBER OF COURSE to fit the clutch basket retaining nut on thread to prevent damage to centre.
Remove the duplex slipper stud (not the vertical adjuster) by locking the two nuts together and removing the stud with nuts complete....the stud also secure the outer and inner casings.
Fit socket set alan key head spanner to the each of the three recessed screws behind alternator and remove - if you use normal alan keys you are likely to slip and burr the heads....if you really must gently use an impact driver.
You can now remove the inner casing and place safely on clean surface.
Remove the five bolts securing the Sprag clutch drive cover casing (where starter motor fits) and gently start to separate the casings - this is a case of gentle and methodical leverage after firstly slipping a thin bade round the gasket to free the cement seal...........thereafter gentle persuasion as remember the there are two shaft's slotted into the case.
You now have access to the Sprag gear assembly and can check everything for wear or as in my case discover after I prised the the two clutch gears a completely disintegrated sprag clutch.
Check the inner surfaces of the two gears and now place your order for replacement parts REMEMBER if there are indentation on the surface of either gear fitting a new sprag alone is unlikely to be a success so go for the full kit i.e. new gears, sprag and circlip.
Finally I now understand the main reason for sprag clutch failure is more to do with starter kick back than anything else so use the de-compressor in conjunction with the starter to start the engine and the de-compressor to shut the engine down - NOT THE KEY OR THE KILL SWITCH and of course once engine stops remember to switch the ignition off.
Removal including having to make up tools and difficulty experienced in removing duplex took about two hours.
Matt
Remove main fuse and then starter motor bolts (2) after disconnecting power feed and place safely to one side.
Remove nearside footrest and disconnect rear brake rod allowing access to outer case.
Trace back the alternator leads and disconnect at four way bullet connection noting that two wires are in fact the same colour, whilst I imagine it makes no difference which is which I simply tape one set of wires with a strip of insulating tape.
Place container under case and drain case of oil and remove exposing the clutch basket, alternator and duplex chain
Dismantle clutch spring plate undoing each of four bolts evenly and remove clutch plates in order and the correct way round thread a piece of string through centre so as to keep then all together in correct sequence (Clutch dished plates are often put in back to front and you then burn your clutch out)
Take small piece of wood wrapped in rag between duplex chain and clutch basket cog and undo alternator centre nut.
Remove three nuts retaining the alternator plate and remove alternator and stator
Set about removing Clutch basket clutch drive sprockets and duplex chain in one operation - You may need to use pullers these are simple to make up using scraps of metal and correct size bolts......REMEMBER OF COURSE to fit the clutch basket retaining nut on thread to prevent damage to centre.
Remove the duplex slipper stud (not the vertical adjuster) by locking the two nuts together and removing the stud with nuts complete....the stud also secure the outer and inner casings.
Fit socket set alan key head spanner to the each of the three recessed screws behind alternator and remove - if you use normal alan keys you are likely to slip and burr the heads....if you really must gently use an impact driver.
You can now remove the inner casing and place safely on clean surface.
Remove the five bolts securing the Sprag clutch drive cover casing (where starter motor fits) and gently start to separate the casings - this is a case of gentle and methodical leverage after firstly slipping a thin bade round the gasket to free the cement seal...........thereafter gentle persuasion as remember the there are two shaft's slotted into the case.
You now have access to the Sprag gear assembly and can check everything for wear or as in my case discover after I prised the the two clutch gears a completely disintegrated sprag clutch.
Check the inner surfaces of the two gears and now place your order for replacement parts REMEMBER if there are indentation on the surface of either gear fitting a new sprag alone is unlikely to be a success so go for the full kit i.e. new gears, sprag and circlip.
Finally I now understand the main reason for sprag clutch failure is more to do with starter kick back than anything else so use the de-compressor in conjunction with the starter to start the engine and the de-compressor to shut the engine down - NOT THE KEY OR THE KILL SWITCH and of course once engine stops remember to switch the ignition off.
Removal including having to make up tools and difficulty experienced in removing duplex took about two hours.
Matt