Ram Heavy Duty Forum

Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!

'21 3500 Rear Air Suspension - Smoooth Ride!

Hez

New Member
Joined
Mar 10, 2021
Messages
14
Reaction score
6
I’d like to hear from the folks who switched out their tires. Anyone get a night/day difference after a tire swap?


Sent from my iPhone using Tapatalk
 

spg993tt

New Member
Joined
Apr 11, 2021
Messages
28
Reaction score
19
just so im sure i understand what you had when you came into it and what you ended up with.... the bag on the passenger side was not firm, soft, and thats what you wanted, so you adjusted the sensor bracket on the drives side, where the bag was firm, to match the angle of the bracket on the passenger side. and you turned it from being perpendicular/parrallel to the frame, to having a few degrees of angle rearward... and the belief as experienced is that this softens the bag based on how the computer is interpreting the values and applying pressure.
where is the compressor on this system? curious if anyone checked proper operation of that compressor. is this a dual system, i think thats what they call it where each side could be at different PSI to level the bed/truck if weight is different passenger to driver side based on where the load is in the bed, or the trailer.
 

roegs

Active Member
Joined
Jan 18, 2020
Messages
247
Reaction score
178
just so im sure i understand what you had when you came into it and what you ended up with.... the bag on the passenger side was not firm, soft, and thats what you wanted, so you adjusted the sensor bracket on the drives side, where the bag was firm, to match the angle of the bracket on the passenger side. and you turned it from being perpendicular/parrallel to the frame, to having a few degrees of angle rearward... and the belief as experienced is that this softens the bag based on how the computer is interpreting the values and applying pressure.
where is the compressor on this system? curious if anyone checked proper operation of that compressor. is this a dual system, i think thats what they call it where each side could be at different PSI to level the bed/truck if weight is different passenger to driver side based on where the load is in the bed, or the trailer.
The basic answer to your question is yes - I wanted both bags to match. I started with my truck empty and full of fuel. Passenger bag very soft (deflated) and drivers bag very firm. My goal in all this was to get the drivers bag to deflate so it matched the passenger bag. To do that, I readjusted the sensor on the drivers side - basically adjusting it with the truck running to the point where it deflated the bag. The adjustment was done by loosening the two mounting bolts of the drivers side sensor. Very little change was needed for the bag to deflate and there was enough play in the bolt holes for the adjustment.

A couple updates to my first post. When I first started playing with this, I assumed that the angle of the height sensor arm should be the same for both sides. I now believe that assumption is not accurate due to tolerances in the truck build. I think we've all seen slight differences in wheel well height from right to left on just about any vehicle. After looking at a 2018 Service Manual (newest I could find at AllData) input for the air suspension is based on curb height information. Somehow a curb height is measured and then input into the air suspension control modules. RAM does not provide a way to manually adjust the sensors.

I'd love to find out more about this system, but it seems that many details are top secret. Some additional thoughts....

1. My desire for a soft rear suspension when empty assumes both bags to be empty. That's just how my simple mind is working right now. But.....based on the shop manual specifying that curb height information is entered into the system, RAM may use this system to ensure that the truck is level left to right and they may intentionally inflate one bag to level the truck. Many owners (this forum and others) have mentioned that their drivers bag is inflated and passenger is not leading me to believe that there may be a reason for it.
2. My local dealer had a brand new '21 dually on the lot this weekend so I stopped by. Sure enough, both rear bags were deflated equally.
3. If RAM does use this system to ensure the truck is always level left to right, then my adjustment to lower the drivers bag goes against RAM's intention. In my case, I'm willing to sacrifice a quarter inch difference left to right for a softer ride. This could also explain the wide range of owner reviews on this option. As mentioned earlier, some owners love the rear air, others wish they'd have never ordered it.
4. All this is based on what I've read and my own experience - This is the fine print where I say that I could be all screwed up! ;)
5. I love how my truck rides now.
6. I have not towed or run any heavy loads yet to verify loaded operation of my rear air suspension.

Last of all....if anyone has '19 to '21 service manuals, I'd be grateful if they were willing to send me an electronic copy of the rear suspension section so I could better understand it.
 
D

Deleted member 80

Guest
Interesting stuff. My dually rode what I thought was very well when I took delivery. Soon I went back for trans reflash, and they said they had to also do an RRT for the air suspension. I immediately felt a difference in ride, for the worse, and I noticed it sagged to the left. When parked on a flat surface the left side was 1-11/4" lower than the right. After several trips to the dealer, and them claiming it sat level, despite my photos of the truck being measured on a truck scale, I fiddled with the left height sensor, and got it to sit level. I have read, not sure if this forum or another, that there is another RRT out for the air suspension. Not sure if I'll give it a try, but I would like to have that initial ride quality back.
 

Brewbud

Brewmeister Meisterbrew
Joined
Aug 21, 2020
Messages
1,987
Reaction score
3,066
Location
SoCal
Are the airbags compensating for the weight of the fuel in the tank?
 

gimmie11s

Well-Known Member
Joined
Mar 30, 2021
Messages
2,345
Reaction score
3,475
If you want full adjustability, buy a set of these. They'll effectively allow you to run the bags with next to no air which should improve the ride significantly.

They'll be one of the first mods to my truck once it delivers.

 

Jak6four

New Member
Joined
Feb 5, 2021
Messages
19
Reaction score
16
I’ve only had my 3500 w/air suspension for a few weeks but I am VERY happy with the ride. It rides much better than my previous 2007 2500 and the roads around here are crap. After reading this thread I checked both my airbags by pushing on them and both appear to be deflated. Haven’t even gotten around to deflating tires some and honestly may not bother with it as it will be one less step when I load up the cab over In a few weeks.
 

Mat_HD

Active Member
Joined
Feb 3, 2021
Messages
189
Reaction score
214
After driving 500 miles in my 21 3500 w/factory air, I think the ride is great. The bags were both soft on delivery and I've aired down the tires just a touch. I'm very happy with it and now I don't even feel the need to do any of the mods I was thinking I might want to do if I didn't like the ride quality.
 

CdnHO

Well-Known Member
Joined
Nov 17, 2020
Messages
1,427
Reaction score
1,600
Location
Ontario
My old 2003 CTD dually called for 55 front and 40 rear for light loads. For ful load the tire information booklet called for 80 in front and 65 in the back. When I took delivery of this truck it was apparent after I got home that the dealer didn't bother checking the pressures. Rears were between 85 and 95psi. Fronts were around 80. The thing road so rough on the way home I thought I would need my teeth fixed. I aired them down to the 70 front and 65 rear as shown on the door label. Still rode pretty rough. So I dug up my pressure recommendations from my 2003 and brought the fronts down to 60 and rears to 40 psi. Made a huge difference in the ride. When I put the 5th wheel on this fall I will air them up to the door sticker.
 
Last edited:

roegs

Active Member
Joined
Jan 18, 2020
Messages
247
Reaction score
178
My old 2003 CTD dually called for 55 front and 40 rear for light loads. For ful load the tire information booklet called for 80 in front and 65 in the back. When I took delivery of this truck it was apparent after I got home that the dealer didn't bother checking the pressures. Rears were between 85 and 95psi. Fronts were around 80. The thing road so rough on the way home I thought I would need my teeth fixed. I aired them down to the 70 front and 65 rear as shown on the door label. Still road pretty rough. So I dug up my pressure recommendations from my 2003 and brought the fronts down to 60 and rears to 40 psi. Made a huge difference in the ride. When I put the 5th wheel on this fall I will air them up to the door sticker.
I'm guessing RAM lawyers made them pull the light load numbers - too hard to define what is light and what is heavy if something ended up in court. Safest numbers to use from a legal perspective are the maximums.

My truck was the same when I picked it up - close to 85 lbs in each tire.
 

CdnHO

Well-Known Member
Joined
Nov 17, 2020
Messages
1,427
Reaction score
1,600
Location
Ontario
I weighed the truck today and based on the inflation/load tables I am putting 65 in the front and 40 in the rear on my dually. Once I put the fifth wheel on it it will be 70 and 65 as indicated on the door sticker. These weights are full fuel, my wife and I on board and most of my towing stuff. Just two dogs were missing from the figures. And of course the pin weight of my fifth wheel.

.
 

Attachments

  • Truck weight May 4, 2021.pdf
    232.5 KB · Views: 42
Last edited:

JPNHigh

Member
Joined
Jan 9, 2021
Messages
42
Reaction score
68
Question. To all who are running a 3500 with the air assist did any have a very odd body sway? To duplicate if you are running 55 and move the steering wheel left and right quickly then center the steering wheel the body continues to sway? I have never felt anything like this to the point that I immediately pulled over on the highway. Service director drove and also felt uneasy driving. They drove another on the lot (3500 with air assist) and it performed in the same manner. Never hooked a trailer up as the truck is brand new but the feeling which can be duplicated any time is so odd and unsettling. It seems like the rear is still reacting the previous motion of the steering wheel. Dealership is escalating to engineering team and I will await the answer. Looking for some feed back. Thanks!
 

roegs

Active Member
Joined
Jan 18, 2020
Messages
247
Reaction score
178
Question. To all who are running a 3500 with the air assist did any have a very odd body sway? To duplicate if you are running 55 and move the steering wheel left and right quickly then center the steering wheel the body continues to sway? I have never felt anything like this to the point that I immediately pulled over on the highway. Service director drove and also felt uneasy driving. They drove another on the lot (3500 with air assist) and it performed in the same manner. Never hooked a trailer up as the truck is brand new but the feeling which can be duplicated any time is so odd and unsettling. It seems like the rear is still reacting the previous motion of the steering wheel. Dealership is escalating to engineering team and I will await the answer. Looking for some feed back. Thanks!
Interesting....I'll need to try it with mine, although I have standard crew cab. Did the dealer happen to try it with a non air assist truck?
 

JPNHigh

Member
Joined
Jan 9, 2021
Messages
42
Reaction score
68
Interesting....I'll need to try it with mine, although I have standard crew cab. Did the dealer happen to try it with a non air assist truck?
So far the dealer only tried a similar truck with air assist. It’s been close to a month since I initially drove my new 21 off the lot but I’ve only had it for a day due to transportation damage. It drove great for the day now after two weeks in dealership possession I hit the highway and it’s scary. Just checking other trucks. Odd the only other comparable truck drives similar. Maybe a setting not changed during transport? Hopefully ram will provide an answer. Man this has been a tough. delivery.
 

Brutal_HO

The Mad Irishman
Staff member
Joined
Feb 1, 2020
Messages
12,033
Reaction score
21,370
Location
Douglas County, CO
Thanks. Keep thinking bags are full pressure? Sensor off? In some sort of transport mode? Wish I could describe better. But stuck.

Should not be stuck in any mode, they all cancel if driven over 5MPH.

1620278008568.png
 

Attachments

  • 1620277949342.png
    1620277949342.png
    265 KB · Views: 52

Hez

New Member
Joined
Mar 10, 2021
Messages
14
Reaction score
6
After putting a level kit on my 3500 SRW with Air, I’ve had a thought regarding the Alt Trailer Height and also the Bed Lowering abilities. We are discussing keeping the airbags “deflated” for a better ride and adjusting sensors so they stay that way empty. BUT in my experience so far, the bed lowering doesn’t really work like the RAM informational video shows. And the Alt Trailer height may also be affected if the bags are not inflated prior to activating either of those systems?
When I tap on bed lowering, my bed only drops about an inch (maybe)...

Thoughts?

I did a 0.5” level kit in the front and my truck is sitting slightly higher in the front now, hoping it just needs to settle in a bit


Sent from my iPhone using Tapatalk
 

Brutal_HO

The Mad Irishman
Staff member
Joined
Feb 1, 2020
Messages
12,033
Reaction score
21,370
Location
Douglas County, CO
After putting a level kit on my 3500 SRW with Air, I’ve had a thought regarding the Alt Trailer Height and also the Bed Lowering abilities. We are discussing keeping the airbags “deflated” for a better ride and adjusting sensors so they stay that way empty. BUT in my experience so far, the bed lowering doesn’t really work like the RAM informational video shows. And the Alt Trailer height may also be affected if the bags are not inflated prior to activating either of those systems?
When I tap on bed lowering, my bed only drops about an inch (maybe)...

Thoughts?

I did a 0.5” level kit in the front and my truck is sitting slightly higher in the front now, hoping it just needs to settle in a bit


Sent from my iPhone using Tapatalk

That's the way it is on 3500. Mine does the same as do many others. Some don't see any or near as much.

The claimed 2-3 in some videos are a reference to the 2500 with full air suspension.

You need to remember that the 3500 air suspension is supplemental, unlike the 2500.

The only real way to solve any of this is to go full air on the 3500, or perhaps a man-in-the-middle sensor fooler, like the pedal foolers that can be adjusted on the fly.
 

CdnHO

Well-Known Member
Joined
Nov 17, 2020
Messages
1,427
Reaction score
1,600
Location
Ontario
Any one tried using one of the after market ride height adjustable sensor rods on the rear if a 5th gen dually? I would like the truck a little lower with the fifth wheel on it. Clearance is a bit short.
 

Users who are viewing this thread

Top