theprisioner
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| posted on 12/6/14 at 04:56 PM |
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More BEC prop shaft adapter woes!
My prop shaft adapter came loose at Croft recently.
http://westfieldbusa.blogspot.co.uk/2014/06/engine-prop-shaft-adapter.html
Comments welcome?
http://sylvabuild.blogspot.com/
http://austin7special.blogspot.co.uk/
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Guinness
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| posted on 12/6/14 at 05:26 PM |
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The ZZR has a large toothed washer that fits over the prop adaptor, and locks into the splines on the drive shaft. Once you have tightened the main
nut up to the torque, you then lever the washer into a hexagon using a screwdriver, locking the nut in place. I did 7,000 miles without issue with
this method.
Do you use a splinded / toothed washer to lock it in place?
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GreigM
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| posted on 12/6/14 at 06:04 PM |
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The westfield adaptor is a piece of crap. Mine came loose and effectively "spun" on the splines, welding itself on - which required
splitting the engine to remove and a new output shaft was needed. I have a new adaptor which looks similar to yours and had no problems for 18months+
now.
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daviep
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| posted on 12/6/14 at 06:54 PM |
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Am I reading it correctly? Is the new prop adaptor not clamped up to the shaft tightly, more just floating on the splines??
If so then it would seem counter intuitive to me, I'm imaging the new hardened prop adaptor is going to chatter on the output shaft and eat the
shaft, I can however understand how this setup would prevent the nut slackening. If it is as I understand then it wouldn't be my first choice,
however AB has a very good rep so I'm sure this is a proven fix. Out of curiosity what is the nut tightened against?
I also like the ZZR setup where the adaptor is clamped tight and the splined washer ensures that any slight movement of the adaptor is not transmitted
to the nut.
Cheers
Davie
“A truly great library contains something in it to offend everyone.”
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twybrow
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| posted on 12/6/14 at 07:55 PM |
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I had the same happen to me on the straight at Castle Combe. I had not used a locking tab washer as there was no room on my install. Just like you I
just used threadlock, and on track, it came loose, and made a bit of a mess of my engine cover and tunnel. I fitted a tab washer on two different
engines, and they have both been fine. Get a locking washer on there!
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CosKev3
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| posted on 12/6/14 at 08:27 PM |
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I liked the idea someone put on here regarding these recently,a hole drilled and tapped in from the side with a grub screw screwed in once the nut is
tightened pushing onto the nut 
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daviep
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| posted on 12/6/14 at 09:43 PM |
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quote:
Originally posted by CosKev3
I liked the idea someone put on here regarding these recently,a hole drilled and tapped in from the side with a grub screw screwed in once the nut is
tightened pushing onto the nut
I believe that the root cause is not the lack of retention on the nut, it is that some installations allow any movement in the adaptor to be
transmitted to the nut which causes it to loosen.
Just my opinion.
Cheers
Davie
“A truly great library contains something in it to offend everyone.”
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Andy B
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| posted on 12/6/14 at 10:29 PM |
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To throw a bit more light on the subject the purpose of the bolt or nut is to retain the sprocket or sprocket adaptor on the shaft and the purpose of
the splines is to transmit the drive. It is quite normal on a super bike to have quite a lot of end float in the sprocket, sometimes seemingly
alarming amounts. If the sprocket or adaptor is machined correctly, made of the right material and hardened adequately it will not wear the drive
spline surfaces.
Quite often people, seeing the end float, turn down spacers or fit washers to shim it out this then tightens the bolt or nut against the sprocket or
adaptor and causes any slight rotational loads on backlash and thrust to be transmitted to them, serving to slowly undo them. In nearly every case of
adapters coming loose or undone that I have witnessed this has been the case. If you allow the bolt or nut to tighten against the output shaft to
serve purely as an end stop and allow a small amount of float, providing you do the nut/ bolt up sufficiently it will not come undone. Employing this
technique I have never had a single one come loose over numerous builds spanning 12 plus years.
Hope that helps
Best regards to all
Andy
P.S as Previously stated - the stock westfield one does seem to have been machined from chocolate
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jwhatley
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| posted on 16/6/14 at 04:41 PM |
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I have installed a second Bolt and washer in to the end of my output shaft to stop the nut migrating off the shaft should it come loose. Im not sure
if you have the ability to do that? I have a 30mm HD output shaft.
I use a plain type nut torqued to 90LBFt with high temperature (green) loctite applied to the threads, A bolt then goes in to the end of the output
shaft with a washer attached that allows about 1mm gap to the main nut itself. This is to catch the adaptor if the nut was to come loose.
Ive not yet had it come loose yet.... touch wood. Although it is a point i do check regularly.
[Edited on 16/6/14 by jwhatley]
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40inches
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| posted on 16/6/14 at 06:50 PM |
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quote:
Originally posted by jwhatley
I have installed a second Bolt and washer in to the end of my output shaft to stop the nut migrating off the shaft should it come loose. Im not sure
if you have the ability to do that? I have a 30mm HD output shaft.
I use a plain type nut torqued to 90LBFt with high temperature (green) loctite applied to the threads, A bolt then goes in to the end of the output
shaft with a washer attached that allows about 1mm gap to the main nut itself. This is to catch the adaptor if the nut was to come loose.
Ive not yet had it come loose yet.... touch wood. Although it is a point i do check regularly.
[Edited on 16/6/14 by jwhatley]
If you bend over the tab washer behind the nut, in a couple of places, that should be enough.
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jwhatley
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| posted on 16/6/14 at 07:13 PM |
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Good point, didnt think of that. Every Little Helps!
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