Hello to all.. I have put about 5K miles on a new 3500 ctd 6spd. I have found i seem to want to shift "one more time". I am considering re-ratio-ing the diff along with a limited slip upgrade. which my truck did not come with. the ? is, will the computer realize the new ratio correctly?..( in other words does the sensor read the axle speed)..or will i have to make other changes?...I have drivin it..and many other diesels enuf to believe that while not pulling i can get better mpg..with a taller gear. I understand that all aam offers is 3.54 i think but i'm open to taller gears....ideas?

 

as far as i know the speed sensor is out of the transmition so u will have to either learn how much off it is or buy a programer that can adjust for new gears. but remember if it is a 4 wheel drive u have to do both the front and back

 

thanx 4 yur reply. I have found a simple spreadsheet solution to the problem. It seems that if i use the revs per mile of these stock michelin's the 3.54's may not even be able to get me to the 1450-1550 rpms i want to cruise at.....if i come up with other solutions I'll re-post. I realize that fuel mileage may not be a very exciting topic but it is one of the reasons i bought this diesel equipped behemoth. I have driven truck for many years and have found i don't need that "smell"..except for "performance"..and fuel economy....and of course, re-buildability.

regards:

 

Today, gas mileage is an exciting topic. I know two guys ata work who drive the exact same car, down to the trim level and color, and they compete to see who gets better mileage.

 

If you make the change, your local dealer can recalibrate your speedo for you for about $40.

 

i hav a 98 12 valve ctd 2500 that is equipped with 3.54's and was also thinkin about a different gear but i was wanting maybe a 4.10 or so. I hav an automatic and at 60 u step on it and it won't do much of anything. You can feel it gaining but slowly and when you hook a trailer on 60 is ALL the faster your going to go. I was wondering how big of a task this would be or if it is even possible. I know the speed sensor is on the rear pumpkin of the axle so i shouldn't hav to hav that changed right?

 

You shouldn't need to do anything if your changing gears...you only do the programming if you change tire size...the speed is taken off the tone ring in the rear.

You should be warned, if you have a new dodge CTD 6spd, then you are sorta screwed...the 05+ trucks now have a G56 tranny, not the NV5600 tranny...the G56 has a lower OD ratio...they only had one choice in gearing, 3.73. At this point, there is only rumored to be higher gearing (3.42 or 3.55) that is available...I have looked into it and haven't found any yet. I don't know if the new higher ratio OD G56 has been intro yet or not...it might only be for the 4500/5500 trucks.



steved

 

I have the same problem and I find myself popping out of 6th to find 7th some times[:@]

I have 4.10's and the NV5600. so at 2000rpm I'm only doing 62mph. but I love the 4.10's, it realy gives my truck major low end grunt. the only thing I have found so far that will let you keep the low end grunt and lower the engine RPM's would be either a U.S. Gear or gear vendors overdrive.

 

Glad I'm not alone...

 

it wasnt as bad when I drove the companys freightliner at the last job I was at. I had 13 gears at my disposal and in 11th you could hit well over 100