Sprag Clutch

Forzavale · Mar 28, 2009

Hi guys,

Been reading a lot of the threads and there is a wealth of information out there! Been having issues starting my 2001 Mille. All the electrics seem to be fine (new battery) and the starter motor itself turns no problem, fuel pump is working but when I try to start the bike get a horrible graunching sound, so loud that I can't tell if it's actually turning the engine over. Stopped trying straight away because it doesn't sound nice! I'm thinking it's the sprag clutch that's gone :-( which would fit in with the noises that everyone else has mentioned.

I've followed the (excellent) how tos, taken alternator housing off and tried the operation of the sprag gear and intermediate gears and they seem fine, quiet. The sprag gear will only turn one way (by hand) and there didn't seem to be a lot of metal swarf lying around. Still want to check out the sprag clutch itself.

Questions were:

If the sprag clutch has gone should the gear sound rough when turning by hand?
Should it be possible to turn sprag gear wrong way by hand if it has gone?

Any input much appreciated!

Thanks

Chris

lees rsv · Mar 28, 2009

Hi mate it will seem fine when you turn it by hand but when its trying to start the bike it sounds like a bag of bolts your sprag has had it maybe not all of it when mine went it was just the spring i took it out and cut about 10 mil out of it and its fine now so take it out and just check it dont spend all your cash on parts that you dont need it non that hard to do :thumbup

Forzavale · Mar 28, 2009

Hi,

Thanks for the advice. Could you tell me what it is that you did to the spring please? Where did you cut? Just want to be sure before I start cutting stuff!

Thanks again,

Chris

lees rsv · Mar 28, 2009

The spring twists together find the ends and undo them and cut the biger end when you put it back together when you try to start the bike the spring hold the sprag inso its tight around the other part that drives the crank the spring gets weak and stops holding cut 5 to 10 mil out and try it when you put the spring back together put some lock tight on the small end so it go's inside the biger end i done mine and saved some cash if it dont work you lost nothing good luck mate

amb67 · Mar 28, 2009

Seeing as you have it all apart, check it for damage.

No point in shortening your spring if the sprag itself and the housing are all chewed up.

TTrouble · Mar 29, 2009

Don't forget to search for the threads on fitting a BMW sprag and save yourself some proper dosh.

Sprocker · Mar 29, 2009

This post maybe of some use.. SPRAG

sauber · Oct 23, 2009

how long did u heat the fly wheel 4 im struggling t get mine off

Kiwi_rsvr · Oct 23, 2009

depends what you are using to heat the flywheel with ?, but you need to heat it until the loctite starts sizzling and melts then using a decent flywheel puller it should "pop" off. put something soft on the ground as it will come off with a bit of momentum !!.

Forzavale · Oct 24, 2009

sauber said:
how long did u heat the fly wheel 4 im struggling t get mine off

I used a heat gun for a couple of minutes then as I didn't have flywheel puller I used a compressed air impact wrench and it popped right off. Been a long time since I did it though!

A303 · Oct 24, 2009

10 mins with a blow torch on the centre boss - until you hear that Loctite spit and sizzle, like Kiwi says. Then an impact driver or a big old breaker bar should crack it off.
BTW. If you use the BMW sprag then NO NOT use the circlip with it - in fact take that circlip over to the bin and drop it in, go on, do it now. Well done, you've just avoided finding shards of ground-up circlip in your oil because it the BM sprag doesn't have proper locating slots for it. Don't ask me how I know.

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Sprag Clutch

Forzavale

lees rsv

Forzavale

lees rsv

amb67

TTrouble

Sprocker

sauber

Kiwi_rsvr

Forzavale

A303

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