Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×


Reply
 
Thread Tools Display Modes
Old 01-19-2022, 12:55 PM   #1
Junior Member
 
Join Date: Jan 2022
Posts: 8
Dynamax 5 28SS Gear Ratio

I noticed that Dynamax orders the Ram 5500 chassis with the 4.89 gears or 4.88 as listed. I have owned 12 of the Ram Cummins powered trucks. I don't think the 28SS needs 4:89 gears. The stock 4.44 gears should be more than enough. With a 10,000-pound hitch weight it would give the RV GCWR of 29,500. It would be hard for me to believe you could exceed the capabilities of the truck with the stock 4.44 gears. I can see this on larger models but on the 28SS? I'm thinking with the 4.89 gears you would be close to 2,700 RPM's at 75 mph?
V7Sport73 is offline   Reply With Quote
Old 01-19-2022, 02:23 PM   #2
Senior Member
 
CyberShanks's Avatar
 
Join Date: May 2014
Location: Top of a hill (in Iowa) surrounded by corn.
Posts: 400
My 2010 Ram w/ 6.7 Cummins is running 3.73 gears and a G56 manual with heavy clutch disks. I've been 23k combined with it and went over rockies without leaving 6th gear. It may be slightly tuned though.


Jim
__________________
2021 Dynamax Dynaquest XL 3400KD
2021 Aluma 8220H Tilt flatbed to carry:
2012 Jeep JKU Rubicon or 2001 Jeep TJ
CyberShanks is offline   Reply With Quote
Old 01-19-2022, 02:46 PM   #3
Junior Member
 
Join Date: Jan 2022
Posts: 8
We use the Ram trucks for dump trailers and roll-off containers. We haul the containers to the landfill. There you must weigh in and out again when leaving. 26,000 pounds GCW is easily pulled with 4.10 gears on our 3500 Ram trucks. Our 5500 Rams have the 4.44 gears and it's overkill. Even if you exceed the weight rating of 10,000 on the Dynamax 5 28SS hitch, which in my opinion 10K is more than enough for just about any trailer or boat, it would still pull the load just fine with 4.44 gears. So why the 4.89 gears?
V7Sport73 is offline   Reply With Quote
Old 01-19-2022, 09:06 PM   #4
Member
 
Join Date: Aug 2021
Posts: 94
What are we talking about 200-300 RPM difference?
1HasBeen is online now   Reply With Quote
Old 01-19-2022, 11:09 PM   #5
Senior Member
 
Desert Boat's Avatar
 
Join Date: Jan 2021
Location: Fort Mill SC
Posts: 289
Now you got me curious how to check the final gear ratio. The only call out on my RAM window sticker (2019 chassis for 28ss 2WD) relating to axle ratio is:

Quote:
Max Tow Package (Increases Axle Ratio)
Where do I dig around in documentation or on the vehicle to find this?

Quote:
Originally Posted by V7Sport73 View Post
I can see this on larger models but on the 28SS?
It would be illuminating to see if Dynamax is interested in different axle configurations within the Isata 5 line since the usual thought is minimizing configuration differences helps ease production in many ways.
__________________
2021 Isata 5 28ss 4x2 / 2020 JLU Rubicon
Prior: 2016 Lance 1995 / Ram 1500 Eco Diesel
2012 Lance 1575 / 2015 Jeep JKU Rubicon
Desert Boat is online now   Reply With Quote
Old 01-20-2022, 07:59 AM   #6
Junior Member
 
Join Date: Jan 2022
Posts: 8
You can run the VIN through the one of the many VIN decoder websites.
V7Sport73 is offline   Reply With Quote
Old 01-20-2022, 08:02 AM   #7
Junior Member
 
Join Date: Jan 2022
Posts: 8
Quote:
Originally Posted by 1HasBeen View Post
What are we talking about 200-300 RPM difference?
On a Diesel, 300 RPM is a lot. At 70 MPH with 4.44 gears you are running the engine well above it's sweet spot 1800 to 2100 RPM. With the 4.89?
V7Sport73 is offline   Reply With Quote
Old 01-20-2022, 08:06 AM   #8
Junior Member
 
Join Date: Jan 2022
Posts: 8
Quote:
Originally Posted by Desert Boat View Post
Now you got me curious how to check the final gear ratio. The only call out on my RAM window sticker (2019 chassis for 28ss 2WD) relating to axle ratio is:



Where do I dig around in documentation or on the vehicle to find this?



It would be illuminating to see if Dynamax is interested in different axle configurations within the Isata 5 line since the usual thought is minimizing configuration differences helps ease production in many ways.
You can run the VIN through the one of the many VIN decoder websites. If you have the max tow package then the gears are 4.89
V7Sport73 is offline   Reply With Quote
Old 01-20-2022, 08:54 AM   #9
Member
 
Join Date: Aug 2021
Posts: 94
Quote:
Originally Posted by V7Sport73 View Post
On a Diesel, 300 RPM is a lot. At 70 MPH with 4.44 gears you are running the engine well above it's sweet spot 1800 to 2100 RPM. With the 4.89?

I am well aware, and have owned and driven diesels for a long time. I ordered my dually with 4.10s, because I pull at 65, so it puts me basically right there. It's a balancing act, I get it.
1HasBeen is online now   Reply With Quote
Old 01-20-2022, 06:45 PM   #10
Junior Member
 
Join Date: Jan 2022
Posts: 8
Here is one example. This is a run today with my Ram 2021 3500. With a 4.10 gears it handles 26,000 pounds no problem. With our 5500 Ram trucks and the 4.44 gears, you can't even tell the trailer is back there. I tried to get a shot of the scale on the way in but the photo didn't show the weight. The 15,600 is when the truck and trailer is empty. I estimate the trailers we pull are around 6,500 empty. As far as I'm concerned the Ram Chassis are some of the best out there. However, I really question the need for 4.89 gear sets. I pull an ATC 32' toy hauler 5th wheel as well. It weighs about 14,000 loaded. The ATC's have the aerodynamics of a huge brick. You may as well pull a parachute all day. I get 9 mpg pulling the ATC. I average about 11.5 pulling the trailer shown in the photo. Perhaps Dynamax puts 4.89 gears in the RV because of aerodynamics? So those of you that have the Dynamax 5, what RPM are you running at 70 MPH? Any idea's on average MPG in the Dynamax 5?



V7Sport73 is offline   Reply With Quote
Old 01-21-2022, 09:15 AM   #11
Senior Member
 
Desert Boat's Avatar
 
Join Date: Jan 2021
Location: Fort Mill SC
Posts: 289
Quote:
Originally Posted by V7Sport73 View Post
I get 9 mpg pulling the ATC. I average about 11.5 pulling the trailer shown in the photo. Perhaps Dynamax puts 4.89 gears in the RV because of aerodynamics? So those of you that have the Dynamax 5, what RPM are you running at 70 MPH? Any idea's on average MPG in the Dynamax 5?
14000 miles in last year, 10.6 average towing JLU Rubicon, by spreadsheet (not the dash gauge, which can be off by up to 1.5 MPG either high or low), usually cruise around 68. Will check RPMs today.

Quote:
Originally Posted by V7Sport73 View Post
You can run the VIN through the one of the many VIN decoder websites. If you have the max tow package then the gears are 4.89
No joy, either don’t recognize the VIN, return just basics (6.7 diesel, GVWR, and a few other generalities), or want $.
__________________
2021 Isata 5 28ss 4x2 / 2020 JLU Rubicon
Prior: 2016 Lance 1995 / Ram 1500 Eco Diesel
2012 Lance 1575 / 2015 Jeep JKU Rubicon
Desert Boat is online now   Reply With Quote
Old 01-21-2022, 10:25 AM   #12
Senior Member
 
milkman55's Avatar
 
Join Date: Aug 2016
Location: Canyon Lake, Texas
Posts: 1,792
Try this lookup tool. Worked for my VIN.

https://windowstickerlookup.com/
Attached Thumbnails
Click image for larger version

Name:	859D22EB-F510-42FB-BB14-7AA8DBF7A56A.jpg
Views:	36
Size:	352.1 KB
ID:	268031  
__________________
2021 Isata 5 30FW
2014 Honda CR-V
milkman55 is offline   Reply With Quote
Old 01-21-2022, 10:44 AM   #13
Junior Member
 
Join Date: Jan 2022
Posts: 8
Quote:
Originally Posted by Desert Boat View Post
14000 miles in last year, 10.6 average towing JLU Rubicon, by spreadsheet (not the dash gauge, which can be off by up to 1.5 MPG either high or low), usually cruise around 68. Will check RPMs today.
That's pretty good mileage. Much better than the 8 MPG I see often with my ATC 5th wheel.
V7Sport73 is offline   Reply With Quote
Old 01-21-2022, 11:03 AM   #14
Junior Member
 
Join Date: Jan 2022
Posts: 8
Quote:
Originally Posted by milkman55 View Post
Try this lookup tool. Worked for my VIN.

https://windowstickerlookup.com/
Thanks! That is a great link!
V7Sport73 is offline   Reply With Quote
Old 01-21-2022, 03:37 PM   #15
Senior Member
 
mjbenedict's Avatar
 
Join Date: Oct 2015
Posts: 387
I average between 8-12 mpg at 70mph depending on wind direction, towing my Ram1500 limited loaded with kayaks, bikes, etc. I think the gear ratio is perfect given there are few times it needs to downshift and I don't have to work it on the hills. A couple things to remember:
  1. The max tow package changes the gearing
  2. The transmission is different than what comes on 3500
  3. Dynamax orders these rigs so they can build to order when the orders come in
I don't know if the AISIN transmission comes with different gearing, it could.
Dynamax doesn't know how many orders for each different rig they will get in the future so one rig fits all is better for them and us. They could put your smaller rig on backorder and allow me to jump line if they have the larger rig chassis available. I'm not sure anyone would like that, except for the ones getting pushed ahead.
__________________
2020 Dynamax Isata 5 36DS 4X4 (Super C)
2020 Ram 1500 Limited
Sold: 2015 Rockwood Ultralite 2604WS
No longer mine: 2006 Rockwood Roo 23SS
All pop-up and tent camping before...
mjbenedict is offline   Reply With Quote
Old 01-21-2022, 04:28 PM   #16
Member
 
Join Date: Aug 2021
Posts: 94
Other than, potentially, the programming, the AS69RC in the 3500 pickups is the same as what is in the 4500/5500.
1HasBeen is online now   Reply With Quote
Old 01-21-2022, 06:45 PM   #17
Senior Member
 
Desert Boat's Avatar
 
Join Date: Jan 2021
Location: Fort Mill SC
Posts: 289
Quote:
Originally Posted by milkman55 View Post
Try this lookup tool. Worked for my VIN.
Quote:
Originally Posted by Desert Boat View Post
Now you got me curious how to check the final gear ratio. The only call out on my RAM window sticker (2019 chassis for 28ss 2WD) relating to axle ratio is:

Max tow package (increases axle ratio)

Where do I dig around in documentation or on the vehicle to find this?

As previously posted, I have the window sticker. It doesn’t list the axle ratio. And the one you posted doesn’t either, just has the same statement about max tow.
__________________
2021 Isata 5 28ss 4x2 / 2020 JLU Rubicon
Prior: 2016 Lance 1995 / Ram 1500 Eco Diesel
2012 Lance 1575 / 2015 Jeep JKU Rubicon
Desert Boat is online now   Reply With Quote
Old 01-21-2022, 06:52 PM   #18
Senior Member
 
Desert Boat's Avatar
 
Join Date: Jan 2021
Location: Fort Mill SC
Posts: 289
Quote:
Originally Posted by V7Sport73 View Post
So those of you that have the Dynamax 5, what RPM are you running at 70 MPH? Any idea's on average MPG in the Dynamax 5?
on our 2wd 28ss:

60 MPH is 2000 RPM

70 MPH is 2300 RPM
__________________
2021 Isata 5 28ss 4x2 / 2020 JLU Rubicon
Prior: 2016 Lance 1995 / Ram 1500 Eco Diesel
2012 Lance 1575 / 2015 Jeep JKU Rubicon
Desert Boat is online now   Reply With Quote
Old 01-21-2022, 07:01 PM   #19
Senior Member
 
milkman55's Avatar
 
Join Date: Aug 2016
Location: Canyon Lake, Texas
Posts: 1,792
Quote:
Originally Posted by Desert Boat View Post
As previously posted, I have the window sticker. It doesn’t list the axle ratio. And the one you posted doesn’t either, just has the same statement about max tow.
FCA shows it on their data sheet, page 5

Axle Ratios: 5500 — 4.44 (DMK)
— 4.89 (packaged with Max Tow Package

https://www.fcausfleet.com/content/d...ChassisCab.pdf
__________________
2021 Isata 5 30FW
2014 Honda CR-V
milkman55 is offline   Reply With Quote
Old 01-21-2022, 10:34 PM   #20
Senior Member
 
Desert Boat's Avatar
 
Join Date: Jan 2021
Location: Fort Mill SC
Posts: 289
Quote:
Originally Posted by milkman55 View Post
FCA shows it on their data sheet, page 5

Axle Ratios: 5500 — 4.44 (DMK)
— 4.89 (packaged with Max Tow Package

https://www.fcausfleet.com/content/d...ChassisCab.pdf
That is a useful link. I had found a shorter version of this, but not the detailed one. And now we know max tow includes a 12” axle along with the 4.89 gear.
__________________
2021 Isata 5 28ss 4x2 / 2020 JLU Rubicon
Prior: 2016 Lance 1995 / Ram 1500 Eco Diesel
2012 Lance 1575 / 2015 Jeep JKU Rubicon
Desert Boat is online now   Reply With Quote
Reply

Tags
dynamax

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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 Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Disclaimer:

This website is not affiliated with or endorsed by Forest River, Inc. or any of its affiliates. This is an independent, unofficial site.



All times are GMT -5. The time now is 05:21 PM.