My friend just bought a new 06 2500 with the CTD. He is going to be putting on 35" toyo MT tires, and either the kore leveling kit or chase series. I told him he should re-gear to 4.56s with the bigger tires, and from my research on this forum, it sounds like a very beneficial mod. Who makes the best set of 4.56s for the Ram CTDs? After the gears and tires, will the speedometer need to be recalibrated?

 

yes it will and good luck at geting it back to reading the right speed

 

4.56's will be WAY to high, 4.10's would bring him back to stock settings. That truck will still haul with the stock 3.73's he would just need to have the computer re-programmed

 

fast read that post named "mileage"

 

Ok so 4.56s will end up gearing it lower then stock, which I think is actually ideal. I definitley do not think that he should not run the 3.73s on those 35s. Even with the hella torquey CTD, I would bet that he would see a noticeable acceleration decrease, which inturn decreases the overall driving enjoyment. So if he is going to bother regearing why not go for the 4.56s and get performance improvements rather then just getting it back to stock level. Coming from the Jeep world, and reading the discussions on 3rd gen forum, going to 4.56s on stock tires leads to significant performance increases, and even some people claim that they even saw mileage increases with 4.56s and stock tires. Even if there is a mpg decrease, there can't be that much of a difference between 4.10s and 4.56s right? So does all my logic apply for the CTD, or am I going about this all wrong?

RustProof - I read your thread, and I'm sorry about the problems your having. Sounds like a real headache. If I got the jist of the thread correct, The problem you are having is that the largest the computer can be recalibrated for is 33s and u have 35s, correct? Are you running stock gears. If you are, there would be a problem. But if you are running 4.56s for example, the computer would actually need to be calibrated for smaller tires then stock. 35s and 4.56s will actually cause the drivetrain to be turing at a higher RPM then a completly stock truck. So without doing the actual math, that combination is probably equivilant to running 29s or 30s, so the computer would need to be calibrated to that respective tire size.

So who makes the best gears?

Thanks for your help,

Tom

 

Tom. . . it just has to be asked. . .how much experience do you have with diesels?

gassers dont realy make peak torque untill they go above 4K rpm, this is one the reasons for re-gearing to get more power to the ground. the Cummins makes 610 ft-lb at only 1600rpm and keeps it to 2900rpm where it starts to drop off due to stock computer limitations. I know guys running 37's with 3.73's and are able to light them up at the drop of a hat. When one moves to 44's that would be when 4.10's would be needed.

if you looking at trying to keep stock form but larger tires then 4.10's would be good for 35's if you dont have someone that can re-program the computer.

acceleration decrease, not much when the turbo lights if he wants performance, a downloader or performance box is going to be better and cheaper than re-gearing.

 

having 3.73 gears and 34.5's i have no troubles with my acceleration way more in my stock (everything but tires wheels and leveling kit) than in anything else i have ever owned...

 

Honestly, I have very little experience with diesels, and some experience with gas engines. I have a 5.9L grand cherokee.... But what I am failing to realize is that if the time and money is spent to re-gear why not get some performance increase out of it, rather then just returning back to stock charateristics? I would think that the mountains of torque from the CTD going through low gears will make amazing performace accelerating aroung town. Or am I using false logic and running 4.56s with the diesel give me no noticeable performace gains, and just senselessy burn up more fuel? There can't be that much RPM difference at 75 mph with 4.10s to 4.56s right? Im sure this truck is going to see all of the basic bolt on mods for more performance in the near future anyway.

 

between 4.10's and 3.73's there is well over a 300rpm difference. going to 4.65's is overkill on a diesel unless your pulling MASSIVE loads. putting around town 3.73's or 4.10's will be enough and any more will burn way to much fuel in order to keep speed.

the Cummins will run all day at 2500rpm without a problem, but if your only doing 70 at that RPM your fuel mileage will be in the toilet. with the way this engine runs, as long as you keep the rpms above 1600 at highway speeds it will scoot.

I would go ahead and put the tires on and the kore suspension. if the performance takes too much of a hit go with 4.10's and no higher.

Ive been working on and around diesels for 11 years and I'm still just getting the hang of how they run. I used to be a gasser guy, untill I rode in a buddies 97 4x4 with a turned up cummins. . .I was hooked from then on.