Paul G
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| posted on 19/11/05 at 10:37 AM |
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R1 Propshaft wobble
Morning all
Got a bit of a problem with this, cars basically finished now but I havent taken it for a drive yet. When I jack up the rear and run it in first gear
the prop can be seen wobbling by about a millimetre side to side right up by the engine adaptor flange. Anyone have any ideas what to do here - I
dont want the prop self destructing on me!
Cheers
Paul
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serendipity123
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| posted on 19/11/05 at 12:53 PM |
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jublie clip
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Peteff
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| posted on 19/11/05 at 05:29 PM |
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the prop can be seen wobbling by about a millimetre side to side
Borrow my eyes, you'll not see it then  . I'd get it checked for runout if it's worrying you. Put something a millimetre away from
it and fix it in place then see if it catches it in any position as it turns.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Paul G
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| posted on 19/11/05 at 06:46 PM |
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Oh I didnt realise that this was within the tolerances, I thought there should have been no visible movement in the prop - it just looks a bit
worryingm, especially when I know it'll be spinning at 12000 rpm right by my side! I've heard all this talk of putting spacers behind the
adaptor flange or altering the sliding joint on the prop but dunno how any of this would help the side to side movement. Didnt even know my prop had
a slider on it - its an mk one and there is a knurled bit right by the end, does it just screw up and down the prop to shorten or extend it? I cant
see how it is supposed to slide.
I.ve put an inch thick aluminium spacer where the prop fixes to the tunnel like on hellfires website, would a jubilee clip be all I need to balance it
out?
Excuse the stupid questions I've been in the pub all day!
Paul
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Hellfire
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| posted on 19/11/05 at 07:06 PM |
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I wouldn't be too worried about it just yet. Get it built and on the road and then see what, if any, effect it has. Are you sure it actually
wobbles and it isn't just a mark on the shaft/adapter which throws your eye when its spinning?
The sliding part on your propshaft isn't adjustable, it just slides freely. As long as both ends of the prop and the adapter flange are all
bolted up tight, I wouldn't be too concerned. 
If it does cause excessive vibration when its up and running, you can always take the propshaft out and get it dynamically balanced.
[Edited on 19-11-05 by Hellfire]
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Paul G
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| posted on 19/11/05 at 07:13 PM |
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Cheers Hellfire I'll get it finished and just keep an eye on it but it does move from driverside and then over to passenger side as it spins,
even if its only a very small amount its noticeable. Its all bolted up nice and tight though so I'll try the jubilee clip trick to see if that
balances it out any.
Cheers for the advice fellas
Paul
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Hellfire
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| posted on 19/11/05 at 07:43 PM |
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Personally, I wouldn't bother with the jubilee clip. If it causes you concern, take it out and get it balanced properly.
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ChrisGamlin
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| posted on 21/11/05 at 12:41 PM |
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Is the nut that holds the prop flange done up tight? Obviously not visible or easy to check when the prop is bolted on so its easy to overlook?
Could be that the flange itself isnt 100% true so try running it up without the prop attached and see if you still see the movement.
Chris
Chris
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andyharding
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| posted on 21/11/05 at 04:50 PM |
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When I fitted my prop I jacked the back up, stuck it in top gear and started it up. I slowly increased the RPM from the engine bay to see if there was
any vibration in the chassis. There wasn't. I suggest trying this and if you get any vibration from it at all have it balanced.
Are you a Mac user or a retard?
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Paul G
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| posted on 22/11/05 at 05:07 PM |
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the nut that holds the prop flange should be done up tight, I'll try jacking the rear and checking for vibration, if it still happens i'll
take the prop back off later this week
Cheers again
Paul
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02GF74
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| posted on 23/11/05 at 08:30 AM |
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Interesting. I would have expected the actual propshaft to run true, certainly true enough not to be obviously out when viewed by the huiman eye..
Is it the drive flange, prop. flange or prop. itself that is out? And what is it like at the other end?
Also if you hold the gearbox, diff or chasis, can you feel any vibration that is due to the prop?
I would be worried by this unless proven to be safe otherwise. The forces involved are related to the square of the speed (omega squared stuff from
school) and you are revving very much higher than a car engine - presumably this is a modified car prop?
Think about what could happen if the prop. should let go, you may cause much damage to your car, cause much damage to yourself and possibly to anyone
else travelling behind you should the prop. fly through their windscreen.
I would investigate further.
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stevebubs
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| posted on 23/11/05 at 09:27 AM |
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quote:
Originally posted by 02GF74
(snip)
I would be worried by this unless proven to be safe otherwise. The forces involved are related to the square of the speed (omega squared stuff from
school) and you are revving very much higher than a car engine - presumably this is a modified car prop?
Not true - the prop will rotate at the same speed for a CEC as to a BEC.
quote:
Think about what could happen if the prop. should let go, you may cause much damage to your car, cause much damage to yourself and possibly to anyone
else travelling behind you should the prop. fly through their windscreen.
I would investigate further.
Agreed - have seen the result of a prop letting loose. Could have serious consequences.
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Paul G
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| posted on 23/11/05 at 10:23 AM |
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I'll definitely get it seen to, its an MK modified item - would these not be balanced already?
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02GF74
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| posted on 23/11/05 at 01:36 PM |
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quote:
Originally posted by stevebubs
quote:
Originally posted by 02GF74
(snip)
I would be worried by this unless proven to be safe otherwise. The forces involved are related to the square of the speed (omega squared stuff from
school) and you are revving very much higher than a car engine - presumably this is a modified car prop?
Not true - the prop will rotate at the same speed for a CEC as to a BEC.
bangs head on table; I realised this whilst on my lunchtime run; yes, the gearbox will reduce the prop revs.
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