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[Mg-t] TF "Generator" Light

To: mg-t@autox.team.net
Subject: [Mg-t] TF "Generator" Light
From: "gunnellj tds.net" <gunnellj@tds.net>
Date: Thu, 21 Jul 2011 21:22:25 -0500
Listers

   Since installing a rebuilt generator (uh, dynamo) on my MG TF 1250
recently, the red light on the dashboard has been staying on longer than
usual.

   First I will give a brief but complete story of the car's electrics and
then describe what's happening recently. Maybe someone has an idea or
suggestion.

   Car was purhased in 2003 and when received I found the battery to be
installed backwards. I reversed it and never really had an issue in
thousands of miles of driving over 8-9 years. The gauge always read
discharging (to the right on a TF for some reason), but the battery never,
ever went dead. I never worried about it and assumed that someday I would
get ambitious and just reverse the leads. Last September, after a trip to
the vintage races in Elkhart Lake the generator started making noises, but
it was still doing its job.

   Not liking noises, I took the generator apart along with the generator
from a TD "barn fresh" $500 parts car. I thought perhaps I could swap things
and do a cheap fix, but the generator on the TF turned out to be toast.
Kaput. Even though it had been generating, the armature was damaged and
burned. The TD armature was actually better, but the whole works was overall
pretty sad and no good for parts use.

   I had both generators rebuilt by Fondy Auto Electric, a company that has
three shops in Wisconsin and seems to know its stuff. They told me that both
armatures really needed to be "sent out and rewound" by another shop. I told
them to do both for around $200 each. The TD generator is of the same
family, but with a different suffix and has some kind of shield on the end
that looks funky, but makes it not right for a TF.

   I put the TF generator on and all seemed fine. i even noticed that the
generator bracket spacing needed to be tightened up. That may be why the old
one was making noise as the loose spacing may have damaged the bearings a
bit. I went on the Internet to figure out how to "polarize" the new
generator. From the moment I did that, the car seemed to run better.

   For the last week or so, when I start the car, the red generator light
has been staying lit for a time. The gauge needle also reads slight
discharge. the car idles at about 9000-10,000 rpm and the fan belt is per
the manual. The generator light will stay on (and the needle will go to
discharge) for the first mile to mile and a half of driving. After that, the
light will go out and rarely come on, even at a stop sign, unless tickover
(I love that term) drops very low. The light being on has not caused any
problem other than the light being on.

   This morning, the light did not go on when I started the car. this
afternoon, when I came home, it did go on.

   Tonight I moved the car into my building and let it idle for a length of
time that would be equal to driving it a mile and a half. The light came on
and did not go out. I then revved the engine to higher rpms. Once I got up
to 2500 rpm or so, the light immediately went out. I re-started and the same
thing happened -- the light lit until I hit 2500 rpm.

   I would like to think this is not a generator problem. Fondy will
probably redo the generator if it is, but I just hate taking it all off
again if I don't have to.


"Gunner"

John Gunnell
PO Box 87
Iola, WI 54945
Ph: 715 445 4262
Cell: 715 281 5925

Please visit Gunner's Great Garage
Restoration Shop - Automotive Book Shop - and Art Gallery
at the corner of Highway 110 and E6110 Fuhs Road in Manawa, WI
Shop: 920-596-2273
www.gunnersgreatgarage.com



Check my blog Gunner's Garage at www.oldcarsweekly.com
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