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Re: Speedo. adjustment on TR6

To: Dean_Zywicki%NIHDCRT.BITNET@cu.nih.gov, british-cars@encore.com
Subject: Re: Speedo. adjustment on TR6
From: lupienj@hpwarq.wal.hp.com (John Lupien)
Date: Thu, 22 Aug 91 15:07:09 EDT
> Gabor asks about adjust the speedometer (or speedomometer from the
> guy I bought my car from):
> The front face twists off with a
> little WD-40 applied around the frozen together metal face and
> housing.  From there the needle can be taken off and repositioned
> wherever you want it.  The problem is that there is a wound up
> coil attached to the pin which the needle goes on, and I think it is
> supposed to have some tension on it while the needle rests at 0.  

This certainly sounds like a good way to screw it up more. The problem with
moving the needle around on the pin is that it does not adjust for the new
linear relationship between speed and wheel rpm. You can use this technique 
so that the speedo will be "right" at some critical speed (such as the 
nefarious 55mph), but it will still be wrong at all other speeds. What
would be better is a means of adjusting the linear relationship between 
indicated speed and wheel rpm. Then you can move the needle to "set 0",
and you're all set. By the way, the way to fix your "0 set" is to move the
needle up off the stop, then grip the pin (with very small pliers or something)
then remove the needle and put it back on in a new position (in your case,
probably a bit closer to the stop). Then release the pin, and check the 
calibration. I do not know how to actually calibrate the speedo relative to
the tire diameter - on many speedos, you have to get a different gear set
for the speedo cable.


-- 
---
John R. Lupien
lupienj@hpwarq.hp.com



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