What gear for 37s - Dodge Cummins Diesel Forum
2013-2018 General Discussion General Chit Chat About the 2013 model year differences 6.7L 4th generation Cummins - NO ADVERTISING - Sponsored by: StarLite Diesel

 27Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 122 (permalink) Old 09-04-2019, 11:13 PM Thread Starter
Cummins Enthusiast
 
Join Date: Jul 2017
Posts: 239
Thanks: 6
Thanked 3 Times in 3 Posts
iTrader Score: 0 reviews
Going to regear my truck and need you help.

What gear ratio should I run? I'm thinking 4.10s.

I do not ever intend to run anything smaller than a 37" tire.

What brand is most quiet? From what I read AAM is closest to factory and preferred.

Did a search on telephone number to order and could not find....anyone have a number?

I have the factory limited slip....should I upgrade or factory is perfectly fine...I do not off road.

What is the break in period? I read 500 miles and 55 mph...

I'm in the gulf coast area....anyone have any recommendations on installers?

Thanks for reading and thanks for all the help.


2018 Ram 3500 Limited, Single Wheel, 6.7L Cummins, Aisin Transmission
Cummins_Michael is offline  
Sponsored Links
Advertisement
 
post #2 of 122 (permalink) Old 09-04-2019, 11:22 PM
Diesel Head
 
nick00less's Avatar
 
Join Date: Nov 2014
Location: Aww-Bree
Posts: 8,138
Thanks: 3,535
Thanked 1,862 Times in 1,280 Posts
iTrader Score: 1 reviews
Anything over 4.10 for 37’s is unnecessary.

AAM and G2 and nitro get my vote for silence.

Break in is 500. Avoid sustained highway speeds for your first trip.

'18 6.7 S472-5 Blade 2018 Build
nick00less is offline  
post #3 of 122 (permalink) Old 09-04-2019, 11:35 PM
Diesel Head
 
K9Kodi's Avatar
 
Join Date: Dec 2011
Posts: 5,198
Thanks: 9
Thanked 699 Times in 499 Posts
iTrader Score: 0 reviews
4.10

--2015 2500, Crew Cab, Long Bed, 4x4, G56, Maximum Steel
- To Do List, 6" suspension,37" tires,4.56 Gears
--2006 2500 4x4 4 door long bed auto, 8" BDS, 37s
K9Kodi is offline  
Sponsored Links
Advertisement
 
post #4 of 122 (permalink) Old 09-04-2019, 11:52 PM
Cummins Fanatic
 
5.7 Hemi's Avatar
 
Join Date: Jul 2019
Posts: 121
Thanks: 0
Thanked 4 Times in 4 Posts
iTrader Score: 0 reviews
The factory limited slip sucks! No getting around the cheap copy of a Detroit True Trac. If your happy with it, leave it. I’m not, I like the clutch style sure grips, work all the time and you don’t need to use both feet to get it to work. Although the diff fluid requires an additive, no biggie.
5.7 Hemi is offline  
post #5 of 122 (permalink) Old 09-05-2019, 12:06 AM
railer and bailer
 
elephantrider's Avatar
 
Join Date: Mar 2008
Location: round rock tx
Posts: 11,515
Thanks: 475
Thanked 1,045 Times in 846 Posts
iTrader Score: 10 reviews
usual rule of thumb is 3.73 for 35's and 4.10 for 37's.

jason

closet poster

'19 2500
elephantrider is offline  
post #6 of 122 (permalink) Old 09-05-2019, 12:45 AM
Diesel Head
 
dillonjm's Avatar
 
Join Date: Jun 2009
Location: Wichita Falls, TX
Posts: 2,655
Thanks: 69
Thanked 342 Times in 280 Posts
Garage
iTrader Score: 5 reviews
For others reading this, I’ll pepper the opinions with “it depends on your transmission.”

G56 has a higher (numerical) OD than the autos.

That said, for your specific application, if I towed occasionally I’d go 4.10. If I regularly towed heavy, 4.56.

That said, if I regularly towed heavy, I probably wouldn’t be running 37’s. My 2 cents.

I think the guys have covered your other questions.

Either route, I think you’ll be happy.
4everlearning likes this.


19 2500 Longhorn Mega 4x4

11 SRT8 Challenger M6 - Corsa; 295 Nittos

dillonjm is offline  
post #7 of 122 (permalink) Old 09-05-2019, 11:04 AM
Diesel Head
 
Join Date: Nov 2010
Location: Bend
Posts: 1,823
Thanks: 249
Thanked 150 Times in 126 Posts
iTrader Score: 3 reviews
I am going to do 4.10s. I only have 35s now, but will probably upgrade to 37s. If not, I will enjoy the better towing capability of the 4.10s.

AAM are factory gears, that is what I will be replacing with

'18 3500 Mega Aisin, Carli suspended
’13 3500 CCLB Aisin, Carli suspended
'11 2500 Mega, Carli suspended
kylant is offline  
post #8 of 122 (permalink) Old 09-05-2019, 10:42 PM
Diesel Freak
 
Join Date: Mar 2015
Location: OccupiedKommieFornia
Posts: 972
Thanks: 28
Thanked 116 Times in 95 Posts
iTrader Score: 0 reviews
4.10 - 68RFE or 69AC

Doesn't matter the trans, they both benefit from the 4.10 gear ratio and 37's.

2017 2500 MegaCab Laramie 4x4
SoCalAdam is offline  
post #9 of 122 (permalink) Old 09-05-2019, 10:48 PM
Diesel Head
 
Gator1's Avatar
 
Join Date: Feb 2015
Posts: 4,694
Thanks: 109
Thanked 312 Times in 293 Posts
Garage
iTrader Score: 0 reviews
Unless you're towing really heavy I'd say 4.10 also.

03 QCLB- 19 to 25 mpg with electric parts, and engine mods....
Gator1 is offline  
post #10 of 122 (permalink) Old 09-05-2019, 10:55 PM Thread Starter
Cummins Enthusiast
 
Join Date: Jul 2017
Posts: 239
Thanks: 6
Thanked 3 Times in 3 Posts
iTrader Score: 0 reviews
Thanks for all the replies.

Couple more questions.

What rear end do I have? 11.5 or 11.8? My truck is a 3500 srw.

Also....any of you ever thought about 4.30s or 4.10 the better route?

2018 Ram 3500 Limited, Single Wheel, 6.7L Cummins, Aisin Transmission
Cummins_Michael is offline  
post #11 of 122 (permalink) Old 09-05-2019, 11:07 PM
Diesel Head
 
nick00less's Avatar
 
Join Date: Nov 2014
Location: Aww-Bree
Posts: 8,138
Thanks: 3,535
Thanked 1,862 Times in 1,280 Posts
iTrader Score: 1 reviews
You have an 11.8 however a 11.5 will fit. Both are in the same 14 bolt housing. They just use different bearings for their associated R&P
MSquare likes this.

'18 6.7 S472-5 Blade 2018 Build
nick00less is offline  
post #12 of 122 (permalink) Old 09-05-2019, 11:12 PM
Diesel Head
 
nick00less's Avatar
 
Join Date: Nov 2014
Location: Aww-Bree
Posts: 8,138
Thanks: 3,535
Thanked 1,862 Times in 1,280 Posts
iTrader Score: 1 reviews
Also don’t go getting all caught up in the numbers race.

4.10 vs 4.30 vs 4.44 vs 4.56

I see guys on here all the time debating over which is best. Trust me when I say this. Your rear end (your butt) will not feel a difference between those 4. The only difference will be final RPM +/- 100-300 RPM.

I’ve had 4.56 in my last 2 trucks and I now have 4.10’s. Guess what, they feel the same. The only thing you gain by going marginally higher is a higher final RPM, which as mentioned earlier is only suggested if you want to “comfortably” tow heavy 24/7.

But even then in order to get your power band back all you need is 3.8 something. Since none such gear exists the next best step is up, not down, that being 4.10. So now since you have more gear than you need, 4.10 is plenty to tow max #’s these trucks are capable of towing. The only reason go higher gear is to tow more “comfortably” not more weight.
MrJibbs, MSquare and G. Mcpherson like this.

'18 6.7 S472-5 Blade 2018 Build
nick00less is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Dodge Cummins Diesel Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome