2nd Gen Non-Engine/Transmission Question for anyone whose gone from 3.55s to 4.10s

[Dave Ratcliffe]

Did you have to change the ratio in your PCM to get your speedometer to read correctly? I know tire size can be adjusted via the PCM, I just wasn't sure about gearing.



Dave

 

[rweis]

I did, I do not think so. BECAUSE



The ring that is attached to the ring gear that provides the rear axle speed to the PCM still provides accurate wheel revs as long as you have not changed tire size.



Bob Weis

 

[Silver_Ram]

The only thing I had to have adjusted was the tire size (35") with a DRB.

 

[GeneA]

I did. Had to take my truck in to Dodge to recalibrate as changing the ecm is proprietary.

 

[Dave Ratcliffe]

Thanks for the replies. Hmm, that's two votes for no change to the electronics and one for. Clear as mud! As rweis stated, I've also heard there is a tone ring transmits the axle speed, I just wasn't sure what years it applied to.



GeneA, not sure I understand your "ECM is propietary" statement as it relates to this. Did you change tire size at the same time of the swap?

 

[GeneA]

Dave, I'm not sure what I mean either. To explain: Inland Truck Repair ( a local independent) changedout my oem 3. 54 which was trashed for aused 4. 10. The speedometer was off by about 10% and Inland told me they could not recalibrate it as that was proprietary to Dodge. So I took the truck in to Dodge and they adjusted it. Now wheter it was the pcm or ecm that I am not sure of. I know it cost me an additional 50 bucks or so.