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Author Topic: That damn sprag clutch again!  (Read 1637 times)

DocVSK

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That damn sprag clutch again!
« on: November 26, 2012, 09:04:11 PM »
Hey guys, so this is a first time post from a long time reader of the forum.

I have an 2009 AVL Classic that recently had the sprag clutch go bad. Well at least its a reasonable assumption on my part. I went to start the bike after about a week of vacation and while trying to kick start it I heard a little "bang" followed by incredible resistance on the kick start. I attempted to use the electric start and it sounded like one of those windup flashlights. The kick start had a lot of resistance and had the same windup flashlight like sound.

I took the primary cover of and found a couple of small broken teeth at the bottom. I made the assumption that the sprag clutch was damaged and using the wisdom of other Bulleteers I decided to just pull the starter motor off. First kick and the bike started up beautifully. I plan on gutting the starter motor and then just reattaching it to the primary so there isn't a huge gaping  hole. I kick start the bike 99% of the time anyway, so losing the electric start is really no big deal.

Now to my question. With my limited time off and little time left in the riding season here in VA, I would love to ride the bike without going through the tedious job of removing the sprag clutch. I was wondering how bad would it be for the bike to just ride it as it stands, with a broken sprag clutch? What am I risking damaging by doing so?

Arizoni

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Re: That damn sprag clutch again!
« Reply #1 on: November 26, 2012, 10:33:02 PM »
Did the "broken teeth" look like gear teeth or were they weird shaped?
Also, did you notice any chipped or missing teeth on the gear drive train between the starter motor and the sprag clutch?  (I'm assuming the drive is somewhat like a UCE here).

If the pieces you found look like gear teeth with their charactistic curvature then IMO, removing the fragments and the damaged gear will leave the engine quite reliable.

If the pieces are somewhat "lumpy" in shape like the large ends of an hourglass with a rounded bottom they are sprag pieces.
If the sprag clutch is the culprit and it is now missing a few teeth, more teeth may fall out of it at any time.
If one of these pieces works its way between the crankshaft sprocket and the drive chain or between the starter drive gears it could cause some major breakage in there.
Jim
2011 G5 Deluxe
1999 Miata 10th Anniversary

DocVSK

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Re: That damn sprag clutch again!
« Reply #2 on: November 27, 2012, 12:32:03 AM »
The broken pieces looked like teeth from a gear, not the sprag clutch actually.

Do I need to remove the inner primary cover to get to the sprag clutch?
If so, is it difficult to remove the inner primary cover? I spoke to Tim over at CMW and he reiterated that not removing the broken parts may end up causing more damage in the future. Which makes sense, but I was just holding out hope that I wouldn't have to wait until my next day off before being able to ride it.

I'm not as mechanically inclined as many of you, so I just don't want to get in over my head with this.
« Last Edit: November 27, 2012, 12:57:15 AM by DocVSK »

Arizoni

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Re: That damn sprag clutch again!
« Reply #3 on: November 27, 2012, 03:42:03 AM »
I can't tell you how to get to the sprag clutch but if the problem was some broken gear teeth in the drive between the electric starter motor and the sprag clutch, removing the  gears with the broken teeth would get you safely up and running.

You may have to remove the inner primary case to get to the gears but removing them should be just a matter of pulling them off or, at most, removing a circlip that restrains them and then pulling them out.

As I say, if the sprag clutch is okay, there is no reason to remove it so you won't have to remove the drive sprocket, clutch, primary drive chain etc.


If you don't remove the gears with the broken teeth, they will eventually lock up
Jim
2011 G5 Deluxe
1999 Miata 10th Anniversary

DocVSK

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Re: That damn sprag clutch again!
« Reply #4 on: November 28, 2012, 04:26:08 AM »
I may be mistaken here, but don't I need to remove the primary drive chain and clutch to remove the inner primary case if I want to get to the gears?

I looked for a video or guide, but was unable to find one. My biggest concern is the primary drive chain.

LarsBloodbeard

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Re: That damn sprag clutch again!
« Reply #5 on: November 28, 2012, 08:29:23 PM »
You definitely don't want to keep running the bike with broken teeth, or even worse, chunks of metal floating around inside it.

I'm not real familiar with the AVL, but I think the primary is pretty similar (if not the same) as the older Bullet.  Removing the primary chain is not a big deal.  You will need a puller for the clutch though.  Auto parts stores will probably have a loaner that will work.  Don't use an arm puller, use the flywheel style.  The alternator *should* come off easily without a puller.

DocVSK

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Re: That damn sprag clutch again!
« Reply #6 on: November 30, 2012, 09:01:34 PM »
Thanks fellas. I am going to give it a shot this Sunday. I have a coworker who has a variety of pullers so hopefully one of those will work.

DocVSK

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Re: That damn sprag clutch again!
« Reply #7 on: January 16, 2013, 10:33:21 PM »
So after getting the magneto puller and clutch puller I went to work again on the bike. I was able, after a significant amount of elbow grease, to get as far as the sprockets that sit behind the magneto.

They are my last step before pulling the inner primary cover off, however, I cannot for the life of me get them off! I have removed the woodruff key and the nut that sits behind it. I expected the sprockets to slide off, but that was of course not the case.

How do I get them off? I even tried prying them off.

I would like to spend my next day off (which are very few and far between) actually riding my bike. Please help!

barenekd

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Re: That damn sprag clutch again!
« Reply #8 on: January 17, 2013, 12:00:39 AM »
I'm pretty sure the AVL inner primary case does not need to be removed.
Bare
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DocVSK

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Re: That damn sprag clutch again!
« Reply #9 on: January 17, 2013, 01:05:15 AM »
To get to the sprag clutch I don't need to remove in the inner primary, but to get to the gears that the electric start drives I do. Also its the sprockets in front of the sprag that I can't get off. I even called nfieldgear and they were unsure why they didn't just slide off.

Arizoni

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Re: That damn sprag clutch again!
« Reply #10 on: January 17, 2013, 03:57:02 AM »
The best I can suggest is for you to get a heat gun.  The kind that is made for removing paint, not your wife's hair dryer.

Heat the sprocket up at least to 180 degrees F, 200 degrees F is even better.
That will expand the bore a little over one thousandth of an inch which should be enough to allow it to break free.
To help with this, you might want to try to use the wheel or gear puller if it fits.
Jim
2011 G5 Deluxe
1999 Miata 10th Anniversary

DocVSK

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Re: That damn sprag clutch again!
« Reply #11 on: January 17, 2013, 04:18:04 AM »
Thanks for the tip Arizoni.
I'll give that a shot, I hope it works. I just want to make sure there isn't anything I'm missing here. I'm just concerned about damaging something.

DocVSK

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Re: That damn sprag clutch again!
« Reply #12 on: February 01, 2013, 12:16:29 AM »
FIXED!!

After 2 months (about 20-25 hrs of labor), $200 in tools, and a lot of patience I have finally removed the sprag clutch from my bike. It's running better than ever and with seemingly more power. That amount of happiness and elation that washed over me when the bike started will probably only be superseded by the birth of my first child.  ;D

I hit a number of roadblocks during disassembly, including a hex bolt that needed to be drilled out and a seized sprag clutch (making removal of it and the idler gear more than difficult). The special tools I required were a magneto puller, clutch center puller, impact driver, and heat gun. This was quite an achievement for me as I have never really done something this mechanical before.

For whomever decides to remove their sprag clutch, either prior to or after it has gone bad on you, feel free to msg me for help/questions.

I really appreciate the help of the members in this forum.


REpozer

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Re: That damn sprag clutch again!
« Reply #13 on: February 01, 2013, 03:27:53 AM »
Sweeeet Job!

I'm still running the sprag on mine,...I  guess is a matter of time.

Buy the way, are you using the green TCI box,and have a litre of motor oil in the primary?
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DocVSK

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Re: That damn sprag clutch again!
« Reply #14 on: February 01, 2013, 08:06:09 PM »
Sweeeet Job!

I'm still running the sprag on mine,...I  guess is a matter of time.

Buy the way, are you using the green TCI box,and have a litre of motor oil in the primary?

Thanks!

I'm not using the green TCI since I converted the bike to kick-start only and the green TCI would provide no benefit. I'm using ATF Type F in my primary.

KB8ANY

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Re: That damn sprag clutch again!
« Reply #15 on: February 04, 2013, 07:45:11 PM »
Neither the type of lubrication nor the ignition mapping have anything to do with the sprag clutch failing.  It fails because of the zillions of small "kickbacks" when it is in there, mostly because of the drag it imposes on the crankshaft.

It should take about 30 minutes to take it out, and then about 20 to put everything back together.  If you use an air or electric impact wrench, you don't have to immobilize the drive train.  (I got a cheap-o electric 1/2 drive one for $19.95.)

You will need the gaskets.  The first time you take these off you will probably have to replace them - from then on, if you just scrape the mating surfaces with a razor blade, you can keep using them over and over.

If you just take out the starter, the offending component is still in there, and in it's present condition (if indeed it is the problem) it will drag on the crankshaft, causing running problems like hard starting and stalling out.  I speak from experience.

You have told us that there were already loose pieces in the primary drive.  If you wait to see whether any more come loose you may regret it.

neil

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Re: That damn sprag clutch again!
« Reply #16 on: February 05, 2013, 03:20:42 AM »
Good job Doc. You are now a member of the "Ditch that damn Sprag" club. I removed mine from my iron barrell bullet 65. You are now enjoying a bike that has better balance and is lighter. If the bike is fairly well tuned, kicking it to start is pretty simple. I stop for gas and then it's the kick routine. You'd be surprised at how many onlookers check you out to see if you can do it. Some seem disappointed if it starts the first kick.

I give em a nothing to it look and ride off. Get lots of queries about - - - do they still make em like that? I assure them that they do.

Neil and Buzzy the Bullet.