Can someone tell me what I need to do to match the speedo to the 3.07 gearing I plan to install?
Herb
Can someone tell me what I need to do to match the speedo to the 3.07 gearing I plan to install?
Herb
You need to get it re calibrated…contact a speedo repair company…they will give you details of the info they require…basically a distance measured by wheel rotations for a given distance…Steve
Purchase a new speedometer that is set up for that gearing.
Have your existing speedometer rebuilt to match the new differential gears.
Install a speedometer gear ratio adaptor installed in the speedometer cable between the transmission and speedometer.
I chose #3 when I changed the gearing in my differential. Simple to do; can be installed in a few hours.
Price is reasonable and it simple to reverse should you ever decide to go back to the original gearing. And you don’t have to ship your speedometer off somewhere and wonder if and when you’ll ever see it again.
Gearing only tells you something if you are running a particular tire. If you let me know what tires you plan to run, I can tell you what the TPM of the speedometer should be, which is information you would have to provide to the instrument rebuilder.
If purchasing a new speedo do not purchase latest available from smiths in Uk…… it will not match the look of your other instruments.
Either buy a nos or secondhand or better still use your as mike suggests
Hello John,
A GPS device is also available that drives a small Servo Motor that drives the Speedo. I’ve not used one, but reports back from colleagues say that they are very good.
Regards,
Bill
Oooo!
I gotta look into that, for the Rover!
Just my opinion, but that seems less than 100% reliable.
Changed the rear end to 3.07 last year and ordered speedo adapter from
Speedometer Cables USA , Denver
1-888-907-65-06
$97 for adapter + $50 if you need a new cable.
Quick turn around and accurate, verified by GPS.
I did the very same thing last year…I sourced Speedometer Cables in Denver to install an in-cable ratio adaptor to a cable that I provided. My original 3.57 speedo reads spot on per GPS with the 3.07 final drive installed.
BTW…I’m very pleased with the 3.07 gear change…So much less hurried on the freeway, pulls better in the mid-range and I don’t feel like I surrender much off the line.