baslow
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| posted on 21/5/15 at 08:16 PM |
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Gauges Bouncing
Hi all,
I have a westfeild megablade with vdo gauges. I've been having an issue with the gauges where they are bouncing randomly. examples are:
1. driving along and the speedo will show 0 although doing 40mph. it will then bounce to 60mph and then to the correct speed that i'm going at
no pattern to this;
2. driving along at around 6k revs and will drop off to 0. few minutes later it come back. if i drop a gear then still remains at 0 so not like its
getting stuck again no pattern;
volt, oil, temp and fuel all fine and don't bounce. I noticed whilst out tonight when i had my lights on that voltmeter dropped below 10 when
usually just over 12. When i put the indicators on it dropped to around 8 and i noticed that both the speedo and rev gauges started bouncing all over
the place.
the battery is new.
Any ideas what this might be? i'm stumped.
cheers
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theprisioner
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| posted on 21/5/15 at 08:36 PM |
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Is your alternator charging anything below 12.4V is not!
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baslow
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| posted on 21/5/15 at 08:52 PM |
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Sorry pal. I don't quite get that. Are you saying the alternator is not charging? If you ignore the lights / indicators then it still does it at
random with no strain on battery. Cheers
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Xtreme Kermit
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| posted on 21/5/15 at 08:56 PM |
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Have a good clran up of the battery connections, both of them and the battery to earth connection.
Caused me a few issues.
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KitCatE1
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| posted on 21/5/15 at 09:29 PM |
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does sound like the alternator isn't charging, sounds like electrical surges
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bi22le
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| posted on 22/5/15 at 12:16 AM |
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It needs to be reading 13.8v to be chargin.
Also check your earth. Most gauges are resistor based and have a narrow band. If they don't get good supply they don't work. On the flip
sides your senders need good earth's so make sure you have earthing straps for anything rubber mounted.
Last of all it may be broke. I had an oil temp gauge that just read over by 15 deg. New one was spot on.
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
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Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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britishtrident
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| posted on 22/5/15 at 04:02 AM |
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Sounds very much like poor connection, first place to start looking is the connections at the alternator, these carry high current and are subject to
vibration, dirt and heat. If you have an alternator with the bold style Lucas 3 blade connector these are particularly prone to arcing.
Also check your battery connection and earth wires especially as you have had the connection off to change the battery.
Your battery voltage should be fairly steady between 13.4 and 14.9 volts at 2500 rpm, and remain in that range when you switch the head lights on and
then off again.
[Edited on 22/5/15 by britishtrident]
[I] What use our work, Bennet, if we cannot care for those we love? .
― From BBC TV/Amazon's Ripper Street.
[/I]
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baslow
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| posted on 8/6/15 at 09:11 PM |
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Thanks for info guys. Back from holiday so will look at this tomorrow and post back. cheers 
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DIY Si
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| posted on 9/6/15 at 09:28 PM |
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My Indy Bird would do this when the battery was low. It was the first sign of what turned out to be a failing regulator. As you have found out, low
voltage gives bouncy/not working gauges. Although in my case I had the stock Honda gauge pod, but I assume the basic reaction is the same.
Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.
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My new blog: http://spritecave.blogspot.co.uk/
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Lander
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| posted on 10/6/15 at 12:09 PM |
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Not sure it will help but I used to have a CBR600 which would periodically have a flat battery if I forgot to put it on the trickle charger. Once Jump
started for the first 10 minutes of riding or so the dials would be bouncing as though there was a loose connection. I would say your problem is
related to low power getting to the gauges.
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baslow
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| posted on 10/6/15 at 12:51 PM |
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Thanks for all you help on this guys. BT was right saying the battery should be steady between 13.4 and 14.9 volts at 2500 rpm. Mine was always at 12
volts. With everything switched on it went to 9 volts and engine started to splutter. Traced all the wires back and there were two wires touching
where the three wires from the alternator terminate (sorry i don't know the right terminology - i'm a newbee!) Once separated i fired her
up and straight to 14 volts. Turning lights on had no effect so working as should be!
Thinking this through, i'm surprised i didn't run out of battery when when out as i expect it wasn't charging or perhaps it was just
charging intermittently which may have explained the random dial bouncing if it was getting surges.
Just replaced friction plates, steels, oil and filter and it works like a charm. Finishing work early today!
Thanks again.
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