worth changing to 4/10 gears?

[dward]

I have an 03 4x4 auto with the 3. 73 gearing. I have a large slide in camper (4500 lbs +) and regularly tow. GCW is around 18k lbs. I don't seem to drive alot empty and think the 4. 10s may be a better combo.

I usually drive around 60-65 and in OD, the rpms are around 1700-1800. I beleive the 4. 10s would bump up the rpm to around 2000, which would be a better rpm for moving this load.

I know I could add power mods, but my understanding is that auto trans don't like to operate at that low rpm receiving that much torque. The trans like high rpms, while the Cummins likes low rpm. I know what you 6 speedguys think, but it's too late, I already have the auto.

So, my question is would the gear swap be a viable solution? If not, what are some options. Also, I assume I would need to swap out front and rear, and any idea what the cost would be?

Thanks.

 

[VTomasso]

Have you considered...

Hi dward,



Just a thought for you. Check out a Gear Vendors underdrive unit. They're not cheap (about 3g's) but you would have 8 forward gears. Perhaps this might be easier than replacing both gearsets. I'm anticipating that getting the ECM to be happy with the new ratios might be tough either way, but I'm not an expert on this.



Just my . 02,

-Vic

 

[BigGunZ]

I have an 03 4x4 auto with the 3. 73 gearing. I have a large slide in camper (4500 lbs +) and regularly tow. GCW is around 18k lbs. I don't seem to drive alot empty and think the 4. 10s may be a better combo.

If not for any other reason, your transmission will thank you.

 

[CumminsBu]

Maybe an upgrade to the valve body might be cheaper. My . 02

 

[klenger]

I think you would like the 4. 10's, but cost might be an issue. I had 4. 10's on my 01. 5 and kind of miss them when I am towing.

 

[steved]

I'm looking to do just the opposite... I don't tow and want to get rid of the 4. 10s for added mpg gains...



As these guys stated, your transmission will be much happier with 4. 10s.



steved

 

[Grizzly]

Towing a cab-over camper is not that much weight, even a large camper. If you are towing mostly around the east coast, you don't have mountains to speak of. You don't need a 410, you need a transmission upgrade.

 

[Sarge]

The 4. 10's are great if you tow a lot. My dually runs about 2100 RPM at 65mph. I pull 11 to 12k regularly, and the 4. 10's make it a breeze. If your an 85mph guy, then I would advise against it. Otherwise, you'll be happier in the long run. Sarge

 

[betterthanstock]

dward, just as people use larger tires to get lower rpm, you could look at some lower profile tires. I don't know if they are even available in an E load, or if your truck would be dragging on the ground, as you would lose some ground clearance, but it's affordable for sure, and it would improve stability with the camper.

 

[dward]

Thanks for all the info. I got a rough estimate from 4 Wheel Parts for around $1300, but they said they would have to see the truck first to know what to install. I don't think I would have them do it, not really sure of their expertise, just wanted a ballpark price to see if it is worth it.

Does the limited slip diff. , affect anything. Different gears etc, and would it cost any more.

Also, I forgot which axel the 03s have, can anyone provide that info?

 

[steved]

AAM axles.



9. 25AAM front, either a 10. 5AAM (SO CTD/gasser) or 11. 5AAM (HO CTD) rear.



I was told that changing from 3. 73s to 4. 10s does not require a carrier change, so your LSD would be reused. Basically you are paying for gears and the setup labor.



steved

 

[dward]

Thanks fo the info

 

[steved]

I just reread the first post... your truck being an auto in 03 should mean a 9. 25 and 10. 5 since they didn't offer the HO with the auto in 03 IIRC.



steved

 

[JRhinehart]

Mu 04 had 4. 10 gears and I don't especially like them. I tow a 11. 5K enclosed tag, and wish I had more top-end. Plus the mileage goes down quick over 2000 RPM, DAMHIK!

 

[dward]

Actually, I do have the H. O in my 03. Had to buy it in Arizona to get the H. O.

 

[tkerrigan]

Could you lock out overdrive and run in direct? Save lots of money if that would work. What is the RPM'S in third at your towing speed? The transmission will also be much more efficient and stronger in third gear I believe.

 

[dward]

I believe I'm running around 2300-2400 at 65 mph, a little high for extended running. It will pull o/d most of the time, even on many smaller hills, but I believe the advantage with the lower gearing is that it places less stress on the trans.

 

[steved]

I believe I'm running around 2300-2400 at 65 mph, a little high for extended running. It will pull o/d most of the time, even on many smaller hills, but I believe the advantage with the lower gearing is that it places less stress on the trans.

I assume you are talking 2300-2400 in drive right??



What rear do you have?? I didn't think they offered the HO with an auto until 04?? If so, you have the 9. 25 front and the 11. 50 rear... that is standard HO axles.



Too bad you weren't closer... I'd swap gears with you. I do mostly highway and these 4. 10s are a little steep for me.



steved

 

[dward]

Steved,

Yes, I am talking about running in drive for those rpms, the 03 H. O did come with an auto. I have the 3:73 rearend.

 

[Cummins Cowboy]

since you have a 4x4, why not just sell it and get a different truck?? it will be more work than its worth with the 4x4, get a 3:73 w/6speed and shift into 5th on the hills or auto with 4:10, to me 6 speed makes more sense than anything else for you