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Re: [Spridgets] Rotor quality problems

To: <spridgets@autox.team.net>
Subject: Re: [Spridgets] Rotor quality problems
From: "Guy R Day" <grday@btinternet.com>
Date: Thu, 27 Sep 2007 12:21:08 +0100
Try - and only try - finding fault with the dizzy cap.  The central contact 
may have a worn carbon brush causing arcing between cap and rotor instead of 
a proper contact.  The spring may be worn.  It might just need a clean and 
when replacing the rotor you give enough of a clean to solve the problem.
Have a look at the metal contacts on the inside of the dizzy cap, is there a 
grey coloured surface on the metal?  If so, get a small screwdriver / blade 
and scrape the contacts clean.  The amount of build up there can be amazing 
at times.
I am in full agreement with Tim as to his reasoning.  They should / do not 
go wrong.  I clean the edge of the rotor against a tyre sidewall (say once 
every 5-6 years!), rarely does the middle need cleaning and a single twist 
of wire wool does that.  If it is an old one they can wear a hole through 
the metal to the plastic underneath.
Yes there can be problems with rotors, cracks allowing an electrical short 
to the drive spindle, arcing across the plastic etc but it is not a common 
failure.  To have more than a couple of failures in a lifetime does seem 
Is there wear in the central drive spindle bearings?  Is that moving about 
and creating problems?

One of the more amusing but helpful things to do is the run the engine in 
complete (and I stress complete) darkness.  You'll soon see where your 
electrical problems stem from.  It might be instructive to do that first!!


----- Original Message ----- 
From: "Timothy H. Collins" <thcollin@mtu.edu>
To: <spridgets@autox.team.net>
Sent: Wednesday, September 26, 2007 12:00 PM
Subject: [Spridgets] Rotor quality problems

>I don't understand why you guys experience "out-of-the-box" rotor
> failures. Just how do they fail? A rotor is a small lump of plastic
> with a bit of metal. I understand a part built incorrectly, or wear
> after some number of thousands of miles, but how do they fail OOTBox?
> The electricity "should" follow the path of least resistance which
> should be through the metal parts rather than through the plastic.
> Are you really saying that they are built with poor tolerances? That
> seems odd too as if one is out of tolerance then every one of them
> should be OOTolerance. It's such a simple part. What's the failure 
> mechanism?
> Tim Collins
> 1966 AH Sprite

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