what does it sound like when the sprag bearing goes?

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terry66
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what does it sound like when the sprag bearing goes?

Post by terry66 » Wed Nov 06, 2013 5:12 pm

Hi all, went to start the S2 the other day and it turned over for about 2 seconds before it just started whirring and it sounded as if the battery was a bit flat? is it the battery or is the sprag bearing gone? Im going to charge the battery tonight and see if that helps. The battery is a motobatt 9. cheers

terry66
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Re: what does it sound like when the sprag bearing goes?

Post by terry66 » Wed Nov 06, 2013 11:32 pm

ok so im a newb :doh: , charged the battery for 1 hour threw it in and it was whirring and then kinda catching and then burst into life :rad: let it run for a while, turned it off and it started up straight away, tried this several times and all good. So looks like just a flat battery so took it out again to charge overnight. Thank god as im not quite ready to do any work on it yet!!

terry66
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Re: what does it sound like when the sprag bearing goes?

Post by terry66 » Thu Nov 07, 2013 9:02 pm

>:|!!! Nix that, today fully charged battery and nothing but spinning, took cover off and can see it spinning but not engaging!! So where can I get instructions on how to change it? cheers

Zanetti
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Re: what does it sound like when the sprag bearing goes?

Post by Zanetti » Thu Nov 14, 2013 8:20 pm

You need several special tools and a good hydraulic puller, it's not that hard with medium level mechanical experience
See http://www.ducatimeccanica.com/t2image.jpg
Need to remove inner cover #8 which means pulling the clutch assy off first
Part numbers 42, 43, 45 come off as an assembly this is where you need the puller, there was a factory tool but they would be like hens teeth now

Inspect the surfaces the sprag runs on, the inner bit of the fly wheel #42 and the journal of the starter gear #38 if they are shagged you will need them hard chromed and ground to the correct sizes (not cheap)

If your lucky the spring in the sprag has broken and/or the drive faces on the sprag teeth are worn or glazed and you are fine to go with just a new sprag bearing
Only get the bearing from bevel heaven or Damien at http://bevelrubber.com.au there are similar size ones from other bearing places but they don't have the correct angle on the sprag teeth and crap springs
Another thing which was recommended to me was drilling a few holes in the sheet metal cover #39 the theory being oil sludge builds up in the sprag bearing limiting the sprag teeth movement

While you're in there rewire the pick ups with good silicone insulated wire and consider getting an uprated starter motor from road and race
You need to replace the tab washers behind the primary drive nut and the clutch basket (also need a special socket to torque up the 'K' ring that holds the clutch basket on) might as well do the big oil seal #14 too

Good luck

terry66
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Re: what does it sound like when the sprag bearing goes?

Post by terry66 » Sun Dec 01, 2013 11:49 pm

well got the sprag from Steve, it got put in today with new oil and it fired up straight away sweet as!! The bikes a bit modified but I think it looks great.

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Re: what does it sound like when the sprag bearing goes?

Post by BevHevSteve » Mon Dec 02, 2013 3:26 pm

Steve who ? :))
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Jonas F
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Re: what does it sound like when the sprag bearing goes?

Post by Jonas F » Mon Nov 24, 2014 11:18 am

Hi,
I have a similar problem with my Mille. But instead my starter motor will not disengage after the engine fires. So the starter motor spins up at a very high speed. Obviously I immediately shut off the engine. I have a few times before noticed that there was a short time after start when the starter motor spun with the engine but only to disengage after, say, 1 second or so. But now it won't disengage at all. Putting the engine in gear and spinning the rear wheel (forward) by hand with the plugs out you can hear the starter motor turn as well. I took of the clutch casing and when I turn the starter motor chain gears anti-clockwise (opposite of its normal working direction) by hand I feel that it turns with a resistance greater than what I would have expected. So this resistance, I take it, is what makes the starter motor turn when it really shouldn't.

So, has anyone had any experience of this? Is it the sprag gear that is worn in a way that it cannot disengage fully? I haven't taken anything more apart yet since it seems to be a great deal of work, but feel that there is likely to be very little chance of resolving this without doing so. But first of all I thought I'd ask for some advice.

Thanks,
Jonas

jockduck
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Re: what does it sound like when the sprag bearing goes?

Post by jockduck » Tue Jan 06, 2015 2:05 pm

Hi, I believe that Millies have a different starter motor to the earlier bevel twins, on their minareli motors at the non drive end is what I can only describe as a small brake, this causes a drag on the motor shaft when the motor is not energised causing a torque reversal which helps to disengage the sprag or the pre-engaged bendix in 860 motors, There must be something similar on the Mille motors.
Jock

wdietz186
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Re: what does it sound like when the sprag bearing goes?

Post by wdietz186 » Thu Jan 08, 2015 7:24 pm

Yes, the sprag can hang up and not disengage if the rollers and race are worn. Time to take it apart.

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