New Speedo, Old Tranny and it's slow

[ORCoaster]

I purchased a used Speedometer from out of a 1981 VW Pickup because mine was way off calibration.  Showed me doing 45 when I was really doing 65 mph, on the GPS.  Now when I am doing 65 the speedo shows 58 and when the GPS shows I have gone 100 miles the odometer only shows 94.

So I am low and slow.  What color gear would I have to have to go into the FF Tranny with the new Speedometer/odometer combo?  I think it has the 1570 numbers under the MPH symbol on the gauge.

Seems I need to spin it faster to make it all even now.

Searched around and couldn't see anywhere that gave a ranking of the gears by color.  White faster than red? 

What do you guys know on this?

DAS

[mystery3]

What size are your tires? Could be between a slightly misreadinug speedo gear and tires which are giving you a false reading could add up to a big difference. When I switched to 185/60r14 my speedo started reading dead on.

[theman53]

White/Gray gear is what you should need.

[ORCoaster]

Running standard 155-13 tires.  When I was running the Winter Snow tires 165-14s the mileage was a tad off, maybe only 2 miles in 100, on the GPS.  No Idea on speed as it was broken.

Is the white/gray color like striped TheMan53?  or are you saying either will work?   

[theman53]

no the entire gear is white or whitish gray. it is the 155/80r13 right? the 80 makes a difference.

just reread the problem and I think the new speedo is to blame. It should never be off like that. If it was the gear it would change more linear. There is something on the back of them that sometimes needs redone.

[ORCoaster]

Got the 155 80Rs on it for sure.  I have heard placing a magnet to the back where it says sender when twirling with a drill at 30 mph makes changes.  Not sure if that is true and how do you know North or south pole of the magnet?  I guess if it goes up you flip the magnet the other way.  Now that i have a known bad spare I should try to test this fix method.  But alas it is 225 miles away on a rainy weekend.  Perfect time to play and no toys. 

[Smokey Eddy]

my speedo has become out of calibration over time. Reads about 10-15km/hr faster than what im actually travelling. And that's with normal tires. It also is not linear. The faster I go the bigger the gap.

[R.O.R-2.0]

all my VW speedos are off.. by atleast 2-7 mph.

some read high, some read low..

from my experiences, the older the cluster, the lower it reads.

my 90k jetta cluster, reads 4 high.

my 180k GTI cluster, it reads 3 low

375k GTI cluster read 5-6 low

400+k Rabbit cluster read like 7 low.

ive NEVER had one read dead on, and match up with GPS indicated speed..

[745 turbogreasel]

A speedo is never off by xMPH, it's off by xMPH@ySpeed, or more simply z%.
If you must specify it as a speed, 60 or 100 MPH actual are the logical ones to  use.

My truck is way off after a gear change and a tire change, but it didn't take long to figure out I need 45 indicated in a 40 zone, and >75 indicated on the freeway.

[R.O.R-2.0]

A speedo is never off by xMPH, it's off by xMPH@ySpeed, or more simply z%.
If you must specify it as a speed, 60 or 100 MPH actual are the logical ones to  use.

My truck is way off after a gear change and a tire change, but it didn't take long to figure out I need 45 indicated in a 40 zone, and >75 indicated on the freeway.

ok, well all my numbers should be read as X mph off @ 60mph

[Estacaco]

My speedo is over 500k and it reads close to 10 under when I'm at 100km/h and about 5 under at 50-60km/h

[ORCoaster]

Ok, I need to be at 56 on the speedo to be doing 65 on the highway.  Those are the two correlations I have in my mind so if I am without the GPS I can still safely avoid a ticket.  Unless I am in a 40 MPH zone.  Then I just try to do the 7% thing in head.  7X40 knock it back by about 3.  Or just about 37.  If I think the coppers are about make it 35 on the speedo and have them chase me down for impeading the flow of traffic.  LOL