2nd Gen Non-Engine/Transmission rear end 4:10 to 3:53 or 3:73

[RCrosby]

hey guy, looking for some information I'am still going to pull 9,000# camper at times only down south la. no more mountains. all within 3hrs. I do pull in o/d, rpm on eng at 65mph 2,000 rpm, high bridges run with o/d off. rpm's at 50mph is about 2,000 rpm's what rpm's you guys are seeing with the 3:53 or the 3:73 gear. and the rpm's when the o/d is off like 3rd. gear. I only pull camper maybe once a month. and i may have to get trans reset for the higher gears also. even if i have to pull with o/d off, all flat land, I only pull at 60 mph rcrosby

 

[MAllen1]

With 4. 10's I would feel comfortable towing in overdrive where you are going (flat land for the most part). I have 3. 55's and the infamous five speed. I haven't had a problem with the nut in over 225000 miles, but, I have 285's tires and anything over 5000 pounds and it's no more using overdrive time. Reason is that with oversized tires on the 3. 55's i'm running under 2k at 70 m. p. h, and 1500 rpm at 60 in overdrive. On that note, if you are trying to lower your rpm's, a cheaper option maybe oversized tires rather than changing the axle.

 

[RCrosby]

just had new set of tires put on, a little over a year ago. I have the 265 tire size that came with truck. rcrosby

 

[surfbeetle]

I went from 4:10s to 3:54s and I have an 11,000 fifth wheel that I pull into the mountains but I too have the manual 5 speed. I am also running 265's and have modded the injection pump for more power. I have no problems with pulling my trailer.

 

[RCrosby]

I see you got the standard, I have the auto trans. I would like to see if there are auto trans, pulling with 3:55 or 3:73 gears, like i said even if i have to pull camper with o/d off because it will be local camping. just looking to get better mpg when not pulling. thank

 

[Joe Mc]

Our trucks have either 3:54s or 4:10s no 3:73s till 3rd gen AM Axles - I guess you could have them installed $$$$ but like the other guy said a tire size change is cheaper but then you loose with rolling mass and drag issues and . . . .

 

[SHobbs]

Last time I checked with a local shop here in Ft Worth it would cost 750 to change my 3:55's to 3:73, another 250 if they removed the axle from the truck. They like to do the swap with the axle out from under the truck. I think it was 500 for the gear kit and 250 install. I can't get tires for that amount. I have thought about the swap but so far I have no issues towing my 5er and the mileage is real nice.

 

[surfbeetle]

A couple of years ago, mine was 1900. 00 to have it changed from 4:10s to 3:54 on my two wheel drive, but I also added Positraction. What a difference with the posi. I went to Pro Gear in San Diego.

 

[Grizzly]

My first Dodge/Cummins, 95, had a 4:10. My 05 has a 3:73, which I like much better for hauling the 12K 5er in the Rocky Mountains.

 

[McCRam]

If you want my two cents, I would keep the 4. 10. With you are going to have to apply more torque through the automatic to keep the same speed. And at the speeds your talking about, 65mph, your motor is going to be running less than 2000 rpms, which is less than optimal in my book. However 9000 lbs is not pushing the limits of your truck in any way, so you could get by with either gear.
One thing to consider is if you switch to 3. 54, you will have to change the carrier in the rear axle. You can get a 3. 73 to fit your current carrier.
I am going through my axles this year and will be switching from 3. 54 to 3. 73. I believe that it will be a good compromise. It will give me a hundred more rpms at 65 - 70 mph and not kill me when I am traveling empty at 75 on the interstate.

Randys ring an pinion website has calculators that will help you figure out what rpms you will run at different gear ratios.

 

[pcarlson]

hey guy, looking for some information I'am still going to pull 9,000# camper at times only down south la. no more mountains. all within 3hrs. I do pull in o/d, rpm on eng at 65mph 2,000 rpm, high bridges run with o/d off. rpm's at 50mph is about 2,000 rpm's what rpm's you guys are seeing with the 3:53 or the 3:73 gear. and the rpm's when the o/d is off like 3rd. gear. I only pull camper maybe once a month. and i may have to get trans reset for the higher gears also. even if i have to pull with o/d off, all flat land, I only pull at 60 mph rcrosby

I had 3. 55 and now have 3. 73's for about 4 years now and was the best move for my truck. I get better mileage (hand calculated) and pulled my 14,000 lb 5er with absolutely no problem. Going 3. 73's you should see approximately a 200 rpm drop and 300 rpm going to 3. 55's. It isn't a cheap change unless you have the tools to do it yourself. Taller tires is an easier and cheaper fix and the trade-off with rolling resistance is marginal I think.

 

[sweeda]

O. K. I'll chime in with my dime. I've owned a 2nd gen with 3. 55's that I changed to 4. 10's and my current 04. 5 came stock with 3. 73's I also changed to 4. 10's. BOTH were auto trans trucks with mods to the trans. (converter and valve body). BOTH got better mileage after the gear changes, due to the type driving. More rural roads and city driving than freeway. The stop and go KILLS your mileage and the brakes. Total truck wieght is very close to 8000 lbs. NO towing. The 3. 73's with 265 tires at 2000 rpm was 72 mph. This is 17 mph over the rural speed limit. After 15 your in a higher penalty fee. With the 4. 10's 2000 rpm and 285 tires I'm at 67 mph. The real differance is the throttal input to get there and the less brake it will take to slow it down. The auto with the 4. 10's I think is the best combo. A manual trans can go with either gear because you have more control over the trans gear and rpm than you could get away with in the auto. I would stay where your at and use the money to spoil your Valentine. If you do the change be sure that you take it to the dealer to change the computer to the new gear or you will get no benifit at all. GOOD LUCK.

 

[RJWEST]

3. 53 to high for your load at 60 and below.
I run a truck camper, and 3. 53 just a tad to low,( std shift )
I need to push 70 to stay in the power band, kills fuel mileage. .

 

[KevinSmith]

Ive got an 01 with auto and 3:54s. I have no trouble towing 10K in Nv even with a few long steep pulls. I do have a few upgrades on the engine and I would hook a transmission temp guage up just to monitor things over time. Im in south La right now and I haven't seen any bridges that would give me any concern. A few nutty drivers, but no bridges.

 

[EKlem]

I think that you really need to figure out your priorities here. Is fuel economy or towing ability more important? If fuel economy is the driving factor, the thing that is hurting you the most is not the engine rpm but the wind resistance. The only way to deal with this without major body modifications is to slow down. Changing gears will help your mileage when you are not towing but it isn't addressing the biggest problem.

For towing, you will get better performance and mileage with your current gears. However, running empty you will get better mileage with a numerically lower rear end. It will mean that you spend a lot of time out of o/d with the trailer which will be annoying. You will definitely be able to pull the load but just in a lower gear.

Regarding the comments to change the tire size, I believe that this would be counterproductive if I understand the goals properly. Yes, the engine rpm would be lowered but larger tires give worse mileage due to wind resistance increases and rotational inertial increases.

 

[jkidd]

3. 53 to high for your load at 60 and below.

I run a truck camper, and 3. 53 just a tad to low,( std shift )

I need to push 70 to stay in the power band, kills fuel mileage. .

I agree. If you drive at 60MPH loaded and 65MPH unloaded you have the perfect gears. unloaded with 3. 55 gears you would pick up 1 mpg, but it would be not as much fun towing.



I have towed with 4. 10 automatic and my 6spd with both 4. 10 and 3. 55. When I tow I wish I had my 4. 10's again.

 

[RCrosby]

thanks for the info, looks like i will stay with the 4:10 gears thanks.

rcrosby

 

[rluft]

I have the 3. 54's and tow 12,000lbs in overdrive all the time. It seems that the truck pulls the load better at 75 - 80 mph which gets the rpm above 2000. I don't like pulling that fast and would like to have a different ratio maybe 3. 73's.



I think a better question would be how much better fuel mileage would you get with 3. 54's in your normal driving compared to the 4. 10's you now have. I would suggest that if most of your miles are empty, stop-and-go miles the 4. 10's are a good choice. If you mostly run empty hiway miles at the speed limit then 3. 54's would save some fuel.