Gear ratio, 3.42 vs 3.73

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mcastles

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Mar 10, 2011
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7
Hi All:

Just following up on my previous post regarding choosing a new tow vehicle, http://www.rvforum.net/SMF_forum/index.php?topic=41003.0)  I have decided to upgrade to the HD truck series and the diesel.  Just as a reminder, I currently tow a boat with worth about 6000 lbs, but in very hilly, narrow roads, so I am opting for the higher power.  I do also pull interstate, but not as much.  Also, I wanted to ensure longterm capacity in the event I go to a larger boat or decide on a large tow trailer for camping.

My question is regarding rear gear.  I have found locally a 2500 HD, diesel with a 3.73 gear and a 3500 HD (SRW) with a 3.42 gear and I was wondering what would be the best option for me.  These are both 2011 Rams (please no vendor wars) and the costs difference is neglible.  I see from the specs that the 3.42 gears results in approx 4000 lb decrease in towing capacity (9900 lb vs 13900 lb with the 3.73) gear.  Honestly, it bothers me to lose 4000 lbs in towing capacity right from the beginning, but maybe I am overreacting since I don't tow everyday, mostly weekends, vacations, etc.

I highly respect the opinions of those on this forum, so please could you provide me your perspective.
 

krsmitty

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Mar 11, 2011
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Tampa, FL
Along with lower towing capacity, the 3.42 may also give you less towing power. Believe you would notice it most on the type of driving you describe, hilly etc. If you did mostly highway driving, the 3.42 may help you with MPG. I would go with the 3.73 for the extra capacity and power.
 

Gary RV_Wizard

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It's a power vs fuel economy  tradeoff, but I'm not sure what the mpg cost would be for a 3.73.  Maybe 1 mpg???  And you could always change out the 3.42 for 3.73 later.

I'm surprised there is a 4000# difference between the two for the modest gear difference. I would suspect some other difference if it is that much. Differences in cab type, wheelbase, bed length, etc. will also affect tow capacity.
 

mcastles

Member
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Mar 10, 2011
Posts
7
thanks for the replies.

Gary, I was also very surprised but here is the spec sheet for the 2500 and 3500.  I haven't actually verified the ratings on the vehicle plate, but I wil do that to ensure I am not missing something.  Here is the link to the specs.  You can go to page 22 of the pdf file for a quick view of the capacities vs gear.  I don't think I am missing something.  It is the SB, crew cab, 4x4 vehicle I am considering.

http://www.ramtrucks.com/en/pdf/2011_ram_2500_3500.pdf

 

lavarock1210

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Nov 7, 2010
Posts
446
I would go with the 3500.  As for power that is produced by the Cummins engine and not the rear end.  You gain no power with a 3.37 vs a 3.42.  The 2011 Cummins has more than enough torque to turn a 3.42.  In the end you will get much better MPG with the 3.42 and the 6 speed tranny will keep you in the required rpm range for that engine in almost all towing conditions.  There is nothing wrong with using 4th gear if that is what is needed to keep you in the rpm range needed.  For those who argue about power look up the definition.  Many confuse power and torque.
 

Derby6

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May 1, 2010
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707
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Wasilla, AK
WoW that is interesting... And from my foxhole the way they divided up the gearing with GCWR's makes no 'logical' sense....
I would continue to search and try and find a 3500 with the 3:73's.
If your heart is on one of the 2 trucks you saw, I say go with the......I can't make up my mind either.... :-\
 

Gary RV_Wizard

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Feb 2, 2005
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At our Silver Springs FL home
Gary, I was also very surprised but here is the spec sheet for the 2500 and 3500.  I haven't actually verified the ratings on the vehicle plate, but I wil do that to ensure I am not missing something.  Here is the link to the specs.  You can go to page 22 of the pdf file for a quick view of the capacities vs gear.  I don't think I am missing something.  It is the SB, crew cab, 4x4 vehicle I am considering.

http://www.ramtrucks.com/en/pdf/2011_ram_2500_3500.pdf

As I read the chart, there is essentially no difference between the 3500 SRW and the 2500 if both have the 3.42 (9900 vs 9700), which makes sense.  The chart is not very clear about SRW vs DRW in the 3500, but I guess the numbers apply to both unless there is a footnote. So, indeed the both the 2500 and the 3500 get an extra 3000 lbs because of the 3.73 plus the 3500 has an extra 1000 lb since it has a greater GCWR, so there is a net gain of 4000 lb in the 3500 SRW 3.73.  Seems odd, but I've grown accustomed to oddities in truck ratings and RVs in general.
 
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