Speedometer calibration

Riocobravert · 07-08-2008

Can you calibrate the speedo in a 97 Cobra without a speedometer gear change or a speedcal? The reason I ask is I have replaced the 4:10 gears that were in the car when I got it with 3:31's (back to stock basically). The speedo is off by very close to 25%. It has the pink 19 tooth speedo gear, and no speedcal. Were the 4:10's stock? I don't think so, 3:27's should have been. Can you program a chip? There's obviously something I'm missing. Any help would be appreciated.

charliesolhan · 07-08-2008

no you do not have an electronic speedo...yours is gear driven...the only way to correct is w/ a speedo gear!

Riocobravert · 07-08-2008

Can you explain how the speedometer was correct with 4:10 gears a pink 19 tooth speedo gear and no speedcal?

charliesolhan · 07-09-2008

becuase who ever owned it before most have changed the speedo gear for the 4:10 gears...now that you have changed them to 3:31...you will have to find a speedo to match...now if i remember correctly ford did not change to the electronic style till 98.

Riocobravert · 07-09-2008

The car has the speedometer gear for 3:27's in it (19 tooth). It should be close to dead on with 3:31's, but it is off by 25%. I expected just what you suggest, so I ordered the speedo gear for the 3:27's. When I went to put it in I found that was already what was in there. I know what common wisdom says, but it just doesn't seem to add up in this case. Any other Ideas?

Riocobravert · 07-09-2008

Do these 97's usually have a ridgid speedo cable?, because where the speedo gears is this one just has wires coming out.

RandyStinchcomb · 07-10-2008

Quote:

Originally Posted by Riocobravert

Do these 97's usually have a ridgid speedo cable?, because where the speedo gears is this one just has wires coming out.

A 1997 Is All electronic, so there is no cable going to the VSS, just 2 wires...now you have a 19th tooth speedo gear, just get a 21 tooth gear from a Ford dealer, part # C4OZ-17271-A which should adjust you @18mph

Riocobravert · 07-10-2008

Unfortunatly a 21 tooth would make it slower by another 18%.

Riocobravert · 07-10-2008

I'm sorry that would be 10%.

Riocobravert · 07-11-2008

So I went and bought a 16 tooth today, as small as they make according to the Ford parts guy. That got it closer, it's only off by about 6% now, speedo says 56 mph at 60 mph. Any ideas how this was changed for the 4:10 ratio. I'd really like to figure it out so that I can put it back the same way it was changed.

Riocobravert · 07-13-2008

Looks like the drive speedo gear must have been changed to a 6 tooth. Calculates out right anyhow. Anyone know what it takes to change the drive speedo gear in a t45? Here's a link that helped me Calculators