[Vwdiesel] Speedometer issue

[Roger Brown]

Roger Brown wrote:
> Caleb Van Dyke wrote:
>> Does anyone know if there are different gears that drive the speedometer on a 1981 Rabbit diesel pick-up? I changed the transmission from a 4-speed to a 5-speed (code F0) and also upped the rim and tires from 13's to 14's keeping about the same height (as I had 185/75/13, now I have 185/70/14). Now my speedometer appears to be reading a bit low, but I have yet to figure out how much. I believe I can go out on the freeway and see if it matches mile markers, but if it's off how do I calculate the error? Also, if I need a different speedo drive gear, where might I purchase one?
>>
>> Caleb
> 
> Yes, there are three different ones:
> 	http://www.4crawler.com/Diesel/VW_020_transmission.shtml#Speedometer
> 

Oh, and to calculate the speedo and odo errors, find a good stretch of local highway with 
regular mmile "paddle" markers or a special speedometer check section.  What you want is 
5-10 miles of fairly level straight road to hold a constant speed on.  Then hit the 
beginning of the test section @ 60 MPH and time the transit over 5-10 miles.  If driving @ 
60 for 10 miles, you would have 10 minutes (or 600 seconds) transit time.  If time is less 
than that you are going faster than 60; if longer than that, you are going slower.  Same 
on the odo, record the starting mileage reading, estimate the fraction of the tenths digit 
then get the reading at the end of the test section.  If you rear 10.00 miles for 10 miles 
traveled, you are dead on, if you read 9.00 miles, you are reading 10% fast, etc.  Note 
your speedo and odo readings/errors may not be exactly the same.  Or the high tech version 
of the above is a GPS.

I picked up a red gear to replace my white one from someone on the VW Vortex manual 
transmission forum.  I regeared my FN transaxle w/ 3.67 gears.  I haven't put the red gear 
in yet, the white seems to be pretty close with my taller than stock tires.

-- 

   Roger