Date:         Sat, 29 Jun 2002 14:27:03 -0700
Reply-To:     mike ingle <mikei@ANCORE.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         mike ingle <mikei@ANCORE.COM>
Subject:      Re: Speedo Calibration
Content-Type: text/plain; charset="iso-8859-1"

I don't know the answer,  BUT, I suggest you locate the ratios on your
transaxle, and convert.

Converion:
engine rev/min * 60 min/hr * transaxle ratio =  wheel rev/hour
now,
measure your tires from side to side (to eliminate the little flat spot you
rest on) in inches.

wheel width in inches * 1 ft/12in * 1mi/5280ft = miles / wheel revolution

now,
multiply wheel rev/hr * miles/wheel rev to get miles/hr

simplified :   engine rev (rpm) * transaxle ratio *  wheel dia (inches)  *
946.9697 * 10^-6  = miles per hour.

This will work for any gear or wheel diameter, just plug in.

test:   3200 rpm * 1.0 ratio * 28" * 946.9697e-6 = 85 mph

Mike


---- Original Message -----
From: "Dennis Haynes" <dhaynes@OPTONLINE.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, June 28, 2002 4:24 PM
Subject: Re: Speedo Calibration


> 3800 rpm = 68 mph
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
> Of Jay L Snyder
> Sent: Friday, June 28, 2002 3:35 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Speedo Calibration
>
> I repaired an odometer for a friend by installing a new gear from Palo
> Alto
> Speedo.  The odometer works great, but the speedometer is now pretty far
> off.    It is reading much faster than actual speed as checked by the
> interstate mileage markers at 60mph.  When replacing the speedo needle,
> there evidently needs to be some pre-load of the dial clockspring.  I
> guess
> this must be done by trial and error?  I re-installed it with no
> pre-load.
> Anyway, what is the consensus for a tach reading at 60 mph on a  4-speed
> '87 GL.  3200rpm? 3400rpm?  He has stock size tires.    This will make
> calibration easier than getting on the freeway.
>
>
> Jay
>