UK Monster Owners Club Forum » .: Technical :. » Engines, Clutch, Gears » sprag clutch replacement

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Old 06-04-2020, 11:38 AM   #1
alan s4
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sprag clutch replacement

Finally decided to sort out the iffy starting from cold with the S4. Over the years I've changed the following:

Starter and Earth Cables
Reg/Rect
Batteries x 3
New Starter Motor
New Solenoid

The sprag clutch is getting worse, especially when cold, so it's time to get it sorted. I've had the cases off before when changing the starter motor so I'm happy with that side of the job.

My only real concern is removing the Flywheel nut. I don't have an air gun/rattle gun or a flywheel holding tool. I've watched a couple of vids where they use a bolt to lock the flywheel, any other recommendations?

From the diagram, I'm going to order item 21 (one way clutch), 20 (the driven gear) and 17 (thrust washer). I've seen some replacing the flange (13) however not sure whether this is really required? Looking at circa £200 in parts

Any other hints and tips while I'm at it?

Cheers

Alan

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Old 06-04-2020, 11:52 AM   #2
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I can’t see the point in replacing the flange, it really is just a spacer.
I’d change the gear return spring (27) and the spring on the selector pawl (20) while I was in there, under a tenner for the pair, but a PITA to get to unless you’re already in there, and the return springs are prone to breaking at ~30k miles in my experience.



mark the position of the pawl (24) on the selector drum with paint pen/tippex before taking it out to ensure you still have proper selection when it goes back together.

Last edited by slob; 06-04-2020 at 12:01 PM.. Reason: added img
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Old 06-04-2020, 12:55 PM   #3
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Quote:
Originally Posted by slob View Post
I’d change the gear return spring (27) and the spring on the selector pawl (20) while I was in there, under a tenner for the pair, but a PITA to get to unless you’re already in there, and the return springs are prone to breaking at ~30k miles in my experience.
Sage words from slob there, (I got less than 10k from mine before it broke). Definitely change them now while you have the access. They're only a few pounds. http://www.ukmonster.co.uk/monster/s...ad.php?t=57677

When reassembling the flywheel assembly, be careful with the thin washer (17) that goes between the flywheel and the crankshaft bearing face. It has to be centred with the bush (18) as, if it slips before tightening down, it will get chewed up as the engine turns.

From the 1100 Evo workshop manual:

"Refitting the flywheel-alternator assembly
Fit the washer (17), duly lubricated, the needle roller bearing (19), and the inner ring (18) to the crankshaft. Make sure the inner ring is centred on the washer.



Fit the previously assembled flywheel-rotor-driven gear on the crankshaft, taking care not to alter the position of inner ring (18) with respect to the washer (17)."
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Old 06-04-2020, 01:05 PM   #4
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Quote:
Originally Posted by Luddite
...When reassembling the flywheel assembly, be careful with the thin washer (17) that goes between the flywheel and the crankshaft bearing face. It has to be centred with the bush (18) as, if it slips before tightening down, it will get chewed up as the engine turns...

...Fit the previously assembled flywheel-rotor-driven gear on the crankshaft, taking care not to alter the position of inner ring (18) with respect to the washer (17)...
Yes, turning the engine once assembled should allow you to see any misalignment in the rotor, before the cover goes back on. * If you do it by pressing the starter button oil will spurt out if the end of the crank!
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Old 06-04-2020, 01:17 PM   #5
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Cheers Rob, just the type of advice I was looking for, I'll get the springs changed at the same time.

I've got the thrust washer on the list as well Luddite.

Any thoughts on not using a proper flywheel locking tool?

Finally, moto rapido best for parts/they offer a 10% discount for the club don't they?

Thanks again, Alan

PS - I'll post pics of the job once I get underway.
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Old 06-04-2020, 01:59 PM   #6
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I've got one of these
https://www.ebay.co.uk/p/4026978555
not a perfect fit but it does the job ok

i believe the fitment is the same for MY02 S4 but MY01 parts book lists a completely different tool
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Old 06-04-2020, 02:24 PM   #7
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Or you could order one of these:

https://rover.ebay.com/rover/0/0/0?m...2F264630198001

I’ve not used the Flywheel tool but I have one of his Clutch holding tools which worked brilliantly as it locates against the ground allowing you to give maximum effort to undo the nut.

Using my ‘man maths’ I worked out that the combined cost of the holding tool plus mains powered impact gun was cheaper than a shop doing the job, equaling the satisfaction of doing it myself combined with getting more tools!

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Old 06-04-2020, 02:59 PM   #8
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If you buy the rattle gun (between 50 and 70 squids off e bay) you may not need the flywheel holding tool - except to do it up again.
I would go with Flip's solution - although you can easily make a clutch holding tool with some old plates if you have any and a length of steel flat or even angle
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Old 06-04-2020, 03:23 PM   #9
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I would advise you use a proper flywheel locking tool.

Whilst you might get away with a clutch tool or other means, I have heard of shafts being broken in doing so due to high torque required and that really would be a nightmare.
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Old 06-04-2020, 03:24 PM   #10
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I posted this up in another thread recently but this is very similar to the one I have:

https://rover.ebay.com/rover/0/0/0?m...2F161945783962

As I also said in the other thread, it’s not very subtle and I wouldn’t use it to do anything up but it did the trick undoing the clutch centre nut.
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Old 06-04-2020, 03:28 PM   #11
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Quote:
Originally Posted by Dukedesmo View Post
I would advise you use a proper flywheel locking tool.

Whilst you might get away with a clutch tool or other means, I have heard of shafts being broken in doing so due to high torque required and that really would be a nightmare.
I wasn’t suggesting (nor was 350TSS I believe) using a clutch tool for the flywheel- my link is to a flywheel holding tool.

I only posted up my clutch tool for a reference as it was made by the same chap and does it’s intended job perfectly.
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Old 06-04-2020, 04:08 PM   #12
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Quote:
Originally Posted by slob View Post
I've got one of these
https://www.ebay.co.uk/p/4026978555
not a perfect fit but it does the job ok

i believe the fitment is the same for MY02 S4 but MY01 parts book lists a completely different tool
That's odd because I wasn't aware that they had different flywheels. It should be the same as ST4 or 996 for the same model years I imagine.
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Old 06-04-2020, 04:14 PM   #13
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Quote:
Originally Posted by Flip View Post
I wasn’t suggesting (nor was 350TSS I believe) using a clutch tool for the flywheel- my link is to a flywheel holding tool.

I only posted up my clutch tool for a reference as it was made by the same chap and does it’s intended job perfectly.
OK, I didn't click on the link.

I, too would recommend the guy who makes/sells these - I've got one of his flywheel tools (for the older, single-phase engines) and it does the job perfectly.

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Old 06-04-2020, 04:18 PM   #14
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Maybe they are, I only have the 01 parts book and the link referred to 02 S4
My 03 DS manual shows a c-clamp type holder.
It could just be the recommended tool changed.
I was erring on the side of caution, since I wouldn’t want to advise spending fifty quid on the wrong tool.
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Old 06-04-2020, 04:19 PM   #15
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Maybe they are, I only have the 01 parts book and the link referred to 02 S4
My 03 DS manual shows a c-clamp type holder.
It could just be the recommended tool changed.
I was erring on the side of caution, since I wouldn’t want to advise spending fifty quid on the wrong tool.
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