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Author Topic: Sprag Clutch tips  (Read 634 times)

JVS

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Sprag Clutch tips
« on: January 10, 2013, 01:11:44 PM »
Happy New Year everyone, hope you all are doing well.  :D

Reading forum topics on failing sprag clutches over time, I just want to have some insight from fellow members on how to avoid a failed sprag clutch or at least maximise its life in today's UCE RE.

I have very little understanding of the purpose of the sprag clutch, besides that it aids the electric start motor whilst powering up and then disengaging when the engine fires up?

Since I purchased my B5 last year, I have used the kick-start almost 99% of the time. Does kick-starting ensure that the sprag clutch will not be under load and not wear out at the same rate of using E-start? Also, say, at a certain point in time the sprag clutch fails, what are the obvious signs/sounds that one can expect and is this from the LH side of the engine? Can these be replaced easily by an average rider who is not that afraid of getting their hands dirty once in a while?

Will appreciate all the input. Thanks  ;D

Sons continuing wars, our fathers were enemies


TWinOKC

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Re: Sprag Clutch tips
« Reply #1 on: January 10, 2013, 10:15:24 PM »
I have also been interested in sprag clutch info.  Seems a lot of people have had theirs replaced under warranty.  Some have done their own replacement using just part of the sprag - cost is approximately $80.  It is my understanding cost of the entire assembly $300 +.

My bike does not have a kicker, the starter does not always "hook up" sometimes requires patience to get it to finally crank and start.

Note:  I also have a Triumph Bonneville E start only- it does the same thing only not as bad.

I am not replacing anything until it breaks.
2010  C5  Teal
Triumph Bonneville T100

fritz1914

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Re: Sprag Clutch tips
« Reply #2 on: January 10, 2013, 11:03:21 PM »
i have replaced my sprag,and when i did the research it seems that the triumph and enfield were the same,the best way to keep the sprag happy is to allways start the bike with a full battery charge.

GlennF

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Re: Sprag Clutch tips
« Reply #3 on: January 10, 2013, 11:22:44 PM »
I would think the following will all help:
- kick (or bump if you live on a hill) start when ever possible
- make sure battery is fully charged
- to reduce load on the sprag use the kick starter to get to just past TDC before hitting start button

Ducati Scotty

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Re: Sprag Clutch tips
« Reply #4 on: January 10, 2013, 11:37:19 PM »
So here's what it is: http://en.wikipedia.org/wiki/Sprag_clutch

They are used in many motorcycles for the starter to turn the motor over.  +1, a full battery ensures strong engagement and no slipping.  Once they start slipping they can get damaged.  There have been a few failures but not really all that many considering how many people are on the forum.  The old iron barrel and AVL bikes were much worse.  They tended to kick back violently on failed starts and that's what caused the damage.

Scott

Royalista

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Re: Sprag Clutch tips
« Reply #5 on: January 11, 2013, 12:39:16 AM »
Since I purchased my B5 last year, I have used the kick-start almost 99% of the time. Does kick-starting ensure that the sprag clutch will not be under load and not wear out at the same rate of using E-start? Also, say, at a certain point in time the sprag clutch fails, what are the obvious signs/sounds that one can expect and is this from the LH side of the engine? Can these be replaced easily by an average rider who is not that afraid of getting their hands dirty once in a while?

Will appreciate all the input. Thanks  ;D
Here's from another ardent adept of the kickstart only bunch:

If you have access to a manual you will find a chart under 04-20 of the LH crank case. The sprag clutch is located on the front.

A failing sprag clutch makes lots of noice, from the front LH side. A sure way to find exact location.

I had to replace the sprag clutch once. Information that I got was that the ones used after october 2010 (mine was may 2010) are better, made by Tsubaki, Japan. There is another model on the market of high quality.

Kickstart can kill sprag clutch just as well as electric start. Any backlash stresses the element. With kickstart the priming is important to ensure a single kick. Priming consists of clearing the clutch, kicking oil through, switch on contact and a gentle kick (not forcibly but decisively). In extreme cold help of the bi-starter.

Lastly but not least a loaded battery prevents lots of mishap.
moriunt omnes pauci vivunt

TWinOKC

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Re: Sprag Clutch tips
« Reply #6 on: January 11, 2013, 12:45:19 AM »
FWIW   I have owned 3 sportsters all of them were no kick models, they all had the same starter issues (as the RE).  I owned each one for more than 2 years and never replaced a starter.   

I am unlucky enough to own one of the only RE models to NOT have a kicker. 
2010  C5  Teal
Triumph Bonneville T100

JVS

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Re: Sprag Clutch tips
« Reply #7 on: January 11, 2013, 06:34:46 AM »
Interesting.  :) Some very good points in here. I really appreciate it. Thanks for all the information, people! I will try to keep all this in mind from now on. Hopefully the sprag clutch will hold up for a long period of time.
Sons continuing wars, our fathers were enemies


Ducati Scotty

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Re: Sprag Clutch tips
« Reply #8 on: January 11, 2013, 05:25:32 PM »
One other point, if it's slipping at all and you're under warranty GET IT REPLACED WHILE IT'S STILL COVERED.  Of those I've heard of here that were replaced within the warranty period all were covered.  If you're out of warranty and want to nurse it and limp along, so be it.  But if you're in warranty use it.

Scott