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Re: Speedometer error......

To: mgs@autox.team.net
Subject: Re: Speedometer error......
From: DAVID SIMS 1 713 275 7792 <SIMS@SUGAR-LAND.SL.SLB.COM>
Date: Mon, 20 Nov 1995 21:54:03 -0600 (CST)
Hi again folks,

  I think that I may have answered my own question (with a few clues from
net :-) .....  So I thought that I probably should report on what I figured
out..... (Anybody thought of making an FAQ?)..... I hope it isn't impolite
to answer your own question on this group :-)  .....

  It seems that the speedo gearing on a 1974 four speed (the ratio of the
gear on the tailshaft of the tranny to the gear on the speedo pinion) is
10:26 (giving a ratio of 0.3846153846)[I discovered this little known fact
in the MG workshop manual under 'general data']..... If you divide the
little number on the face of the speedometer (1280) by this number, you'll
get 3328..... Remember that!

  I also discovered that the Victoria British catalog lists the 75-80 speedo
tailshaft gear (with O/D) as having 6 teeth and the speedo pinion as having
21 teeth for gearing of 6:21 (giving a ratio of .3)..... now, if you
multiply the number that you're remembering from before (3328) by .3 you'll
get 998.4 (or about 1000)..... 

  If anyone has a 75-80 B with an overdrive and wouldn't mind looking, I'll
bet the little number on your speedometer is 1000!  (1280 _is_ such an odd
number..... how typically British).....

Please let me know..... anyone......

Thanks,

Dave Sims

PS. And now what do I need to do the get the @#&%* O/D to engage?? Any other
suggestions in regard to that?? I really don't want to pull the engine again.


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