Forum Discussion

scottkeen's avatar
scottkeen
Explorer
Jul 30, 2017

Changing Axle Ratio from 3.73 to 4.10 and GCWR

I'm looking to get a used 2004-2007 Dodge Ram 3500 truck.
The specs I've found for 2004-2007 Ram 3500 Quad Cab 4WD LB DRW:

3.73 axle ratio = 21,000 (GCWR) 13,350 (max trailer)
4.10 axle ratio = 23,000 (GCWR) 15,350 (max trailer)

Pretty much all I can find on the used market are ones with 3.73 axle ratio.

My questions:
1) How costly is it to change out the gears to 4.10?
2) How can I get the truck re-rated/re-certified to 23,000 GCWR after the gear change?
3) If I have 4.10 gears but my truck sticker says my GCWR is still 21,000, will I have a legal problem if I'm made to weigh my rig and my trailer is 14,500 lbs (truck is 7,500)?

I'm new to all this, so maybe I don't understand. I read about people pulling trailers in excess of their rating. I don't want to do that without changing the gears so that it's safe. But how do people pull trailers around the country with trailers in excess of their truck's rating? Aren't they made to weigh their trailers at weigh stations? Does highway patrol make people weigh their rigs and verify GCWR compliance?
Tow Vehicles
  • Tiger02's avatar
    Tiger02
    Explorer
    Jul 30, 2017
    Scott,

    I would get the truck you want with the 3.73, and wait to see how it tows for you. You may find it just right for your needs. 4.10s are nice, but not a necessity for sure. If after some time towing you still feel the need then it may be worth the $1000 to $2000 for you.

    Don't worry about the weights other than your F/RAWR and the GVWR along with your tire capacities. People re-gear vehicle all the time, and it's no big deal.

    Good luck in your search.
  • Me_Again's avatar
    Me_Again
    Explorer III
    Jul 30, 2017
    You would be much better to invest in a newer truck with a 6 speed automatic, preferably a DEF model. A 2004-2007 5.9 will have the 4 speed 48RE tranny. I towed with a similar tranny for 11 years and found it very gear bond to do a really good job like my new RAM with the Aisin tranny.

    So you will spend 1-2K for gears and mostly 3-6K for a tranny rebuild/upgrade with a 2004-2007. Put that money on a newer truck.

    Chris
  • Tyler0215's avatar
    Tyler0215
    Explorer
    Jul 30, 2017
    Changing the rear axle gears will probably cost 1K to 1.5K. It will not affect the GCWR on the truck. State weigh stations only weigh commercial vehicles.
  • carringb's avatar
    carringb
    Explorer
    Jul 30, 2017
    1) Gear changes run about $700-$900 per axle depending on your local labor rates.

    2) Your owner's manual will tell you the maximum recommended combined weight for an available gear ratio. Note that you may install gears outside of those charts, but you may not be able to easily calibrate the truck's computers if you go beyond factory options. Keep in mind, these are only recommendation, mostly pertaining to performance and longevity.

    3) You can print your own sticker if it makes you feel better. Seriously. You don't have a sticker now, and there are no laws pertaining to Combined Weight ratings, other than your combined weight can't exceed the truck's GVWR + trailer's GVWR. You could legally pull 23,000 pounds with a F150 as long as the driver and truck were properly licensed for the load being hauled, and federal bridge limits are not exceeded.

    That all said..... going from 3.73 to 4.10 is a pretty minor change. I wouldn't do it for the cost. If 3.73s aren't cutting it for you, even lower gears might be worth considering.
  • Jim-Linda's avatar
    Jim-Linda
    Explorer II
    Jul 30, 2017
    You are not commercial! Commercial vehicles are the one getting weighed, not RV's. I seriously doubt changing gearing will matter one whit to any agency.

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