When changing rear gears to a 3.73 rear axle ratio does the speedo go off a small amo

[JBsZ06]

When changing rear gears from 3.42 to a 3.73 rear axle ratio does the speedo go off a small amount and can the pcm be altered to compensate or is it not worth the trouble..?

Thanks in advance.

JB

[Zed]

Originally Posted by JBsZ06

When changing rear gears from 3.42 to a 3.73 rear axle ratio does the speedo go off a small amount and can the pcm be altered to compensate or is it not worth the trouble..?

Thanks in advance.

JB

The speedo works fine. I think it uses the ABS sensor (or another sensor) to tell how fast it's going unlike older cars (or mustangs).

Zed

[Kens06]

JB, I've seen this in another thread here or on a different forum that says the pickup is tied into the output shaft some way?
You can change gears without reprograming but if you change tire height/circumference you have to let the pcm know for accurate speed readings!
I may be spreading gossip, but these people seemed knowledgable??

Ken

[c4c5specialist]

HI there,
1.4 mph change is between the 3.42 and 3.73.
Verify by the ABS wheel speed sensors and the live plot feature on a Tech 2.
You cannot even worry about it.
Allthebest, c4c5