Engine/Transmission (1998.5 - 2002) 4.10 swap for 3.54 and speedo change

[GeneA]

I just swapped a damaged 3. 54 for a 4. 10 as I am doing some heavey towing. My question is what does this do to reading for mph and how to change the speedo to make it accurate.

 

[59Turbo]

You don't have to change anything. The computer gets the mph reading off the rear abs tone wheel on the ring gear in the differential.

 

[Valv]

You are going to regret it many times. Mine with a 4:10 does 15mpg empty and 12mpg loaded with a 12K gooseneck.



I am trying to find somebody that wants to swap my 4:10 for a 3:55 or ideally a 3:73

 

[SnoKing]

You are going to regret it many times. Mine with a 4:10 does 15mpg empty and 12mpg loaded with a 12K gooseneck.



I am trying to find somebody that wants to swap my 4:10 for a 3:55 or ideally a 3:73

U. S. Gear over/direct

 

[Nate]

That's not much less than my truck gets with 3. 55s.

You are going to regret it many times. Mine with a 4:10 does 15mpg empty and 12mpg loaded with a 12K gooseneck.



I am trying to find somebody that wants to swap my 4:10 for a 3:55 or ideally a 3:73

 

[GeneA]

Found out yesterday that Inland Truck Service doing the swap for me got a used '99 4. 10 and the abs is not compatible with my 98. 5. Also to change the speedo requires a reflash which can only be done by Dodge as it is proprietary. I am not too concerned about saving one ortwo mpg as I am finding reliability doing heavy (max and greater GCWR) short haul ltl and urban delivery with my reefer gooseneck. I found out that the 3. 54 will not take the exteme use. The common wisdom says that the 4. 10 is heavier duty. I may find out that what I really need is a medium duty truck. I di 150k delivering RV's to all points of the compass and the 3. 54 was perfect for the deadhead 80mph sprints in double overdrive. It all depends on what use you put your truck to as to how it is equipped.

 

[steved]

You don't have to change anything. The computer gets the mph reading off the rear abs tone wheel on the ring gear in the differential.

Actually, his might take the low speeds from the tone ring, but the high speeds come from a sensor in the transmission tailhousing... ask me how I found this out!



steved

 

[59Turbo]

Actually, his might take the low speeds from the tone ring, but the high speeds come from a sensor in the transmission tailhousing... ask me how I found this out!



steved

ok ok... I'll bite, how did you find out?

 

[steved]

ok ok... I'll bite, how did you find out?

My speedo would work from 30mph up, but not 30mph down... I too assumed it was just the tone ring wizbang since my ABS and brake lights were on too... and everyone on another site said there was only one sensor... we assumed it was the computer showing speed based on engine RPM and gear...



I took my VIN in to dodge and they listed two speed sensors for the truck... one does low speeds (the ABS sensor) the other did the high speeds (the one in the tcase adapter)... I "think" the change to two sensors was in 97, but I'm not 100% sure on that.



steved