If you have 3" body lift, 5" suspension lift, Cummins 24v, Auto, and 38" tires......

[RamThis]

Would you use 4.10's or 4.56's? I had a guy come in today that wanted to lift his ram and I told him to do a 3" body, 5" suspension, and some 38"s. He has a 99 2500 HD 4x4. I think 4.56's would work best because someone else mentioned before that over a 33" tire, the 4.10's lose their effectiveness. He might sign up as a member, but Id like to give him good advice on his gear ratio. Am I right here about the 4.56's 4x4 guys??

[RufusTheRam]

i think being a diesel i'd stick with 4.56's, diesels are rpm challenged engines in the first place, and no lack of grunt to turn big meats. i think 4.88's might actually be too steep if he does any amount of highway driving. if it was gas, i'd say 4.88's all the way! btw, if he really wanted 40's would fit under that lift on a 2500, maybe slight fender trimming if any.

[prostock]

Keep in mind that diesel's don't need to turn high RPM's to make power.

Mine has 3.54's with a LT235/85/16 tire, and is right in the "sweet spot" (1,800) rpm's at 65mph in overdrive.

[Dom]

I agree with Rufus and prostock. Choosing the proper gearing for any vehicle should take into account the height of the tires as well as the powerbands (hp and tq) of the engine. Since the curves of a gas and a diesel engine differ so much, what works for a gasser is not always the best combo for a diesel-equipped rig.

Remember that diesels are low-revving engines and produce ALOT of torque down low. Torque is what gets you moving. Getting moving is the reason for re-gearing. Since there is so much torque on tap with a diesel, it doesn't take much gearing to get the truck moving.

I'm no expert, but just wanted to give my opinion...

Thanks,

Dom

[RamThis]

Yeah I told him I would lean toward 4.56's with the diesel and I didnt even personally consider 4.88's, that would definitely put him into too high of rpm's on the highway. The diesel dont need as much help as the gas engines

[ralston]

Any idea where he got a body lift? I wasn't aware that anyone had one for a 2500 with a cummins.

[RamThis]

he hasnt purchased it yet, just in the planning stages Im sure you could use one for any 2500 ??? Isnt it just the spacers for the cab and bed and core support and something doing with the steering shaft? Should all be the same, as far as I can tell

[RamThis]

Ahh yes the intercooler, didnt think of that. Could require a little creative plumbing, but Im sure its nothing too terrible. Any heliarc shop should be able to make a pipe to match up from aluminum.

[ralston]

I've heard of a few that did have custom body lifts, but... I've never actually run into anyone with it done. So... I was just thinking this might be a first for me.

[RufusTheRam]

from what i'm told, the gas 2500 performance accessories body lift will work withe a few minor mods.

[KatDiesel]

Keep in mind the 24v redlines 3200rpm. Kinda depends on how he is going to use the truck.

[HighBlackRam]

Considering my RPM's with 4.56's and 35's, he would be fine with 4.56's. With 38's and 4.88's, he'd be about where I am now, and the Cummins doesn't need to spin that fast to make power. He won't be over revving though, so 4.88's would be good if there is any chance he'll go bigger later, or he just wants the max grunt. Take alook at this, it's prettty accurate:http://www.ring-pinion.com/calculators/rpm_1.html

[ralston]

I actually found a guy this afternoon that has a body lift on his diesel truck. He said that his only concern was the fan. He runs hotter now because things don't line up as normal. So... he's going to install an electric fan to help keep the temp down. The concern about the temp is when he is pulling his trailer. ~8000lbs

I also talked to him and a Dodge diesel mechanic concerning gears. I've got a 2500 with 37's and was looking at regearing. I've got 3.55's and wanted to move to 4.10's. Both said stay with the 3.55's and find other performance enhancements for additional power. The diesel mechanic has a diesel with 4.10's and said with his 285/85/16 or 35" tires he can just get to 80mph with about 2500rpm. The guy with the body lift has diesel with 3.55's and power upgrades from TST. He can go over 100mph and burn rubber in the parking lot at take off.

Needless to say... after today... I'm rethinking about regearing my truck.