3500 SRW suspension

[AH64ID]

I did but my truck functioned the same with the factory suspension.

The only way it wouldn’t move with the factory suspension is if you were already resting on the overloads, which means that your truck wasn’t properly setup from the factory. The spring rate of the two main leaves is soft enough the truck sags onto the overloads when the bags are deflated for bed lowering or transport mode.

Now with the different spring rate, likely higher than the two main leaves on the OEM springs, there will be less movement… but should still be some if the system is properly setup with the new suspension. You should be able to hear the bags deflate when you go to bed lowering mode, and even feel/hear the air dump out the hose between the bed and cab.

 

[Brutal_HO]

My 3500 will lower ~3/4" at the hitch when empty. I use bed lowering mode when I hitch/unhitch my 5th wheel. It also serves to "lock out" the air system so it doesn't move around during hitching operations. I then switch to ALT ride height and it really doesn't move again.

That said, I do have a crossover toolbox and gear in it, but it certainly isn't close to 600lbs. The hitch shown here is ~35 lbs solid bar stock. I believe this image was taken without my 5th wheel hitch (160lbs).

However, Bed Lowering mode has absolutely no technical/programmed requirement to have weight in the bed to function. It dumps the air in the bags. Period. There IS always some air in the bags unloaded. Depending on how/where your wheel position sensors are adjusted on each side may alter your specific truck's behavior. I have gear in my truck, I have a 50gal fuel tank. Etc.

ALT Trailer height DOES have a load requirement to MAINTAIN lowered height. It will lower, then raise and post a message if there's insufficient load.

FWIW, this was also taken on a cold day in Dec 2020 as evident by the snow.

 

[Ionicbrick]

As promised here is the video of my 2022 air suspension lowering the bed with little load in it. Certainly less than 650 pounds.

Sent from my iPhone using Tapatalk

 

[roegs]

I started a thread on this back when I purchased my '21 (link below). My experience and understanding of the air suspension aligns with what BilletWilson is saying. Others who participated in that thread seemed to see the same. The thought is that when the truck is empty, the rear of the truck rides only on the lighter spring pack that is part of the optional air suspension. Air only comes in play when the rear lowers due to weight, and the bags re-level the truck. I found that my empty truck rides better when your thumb can easily press into the sides of the bags (deflated). As for correct factory calibration....many new trucks come from the factory with one bag (typically drivers side) firm and the other bag supple. I find it hard to believe that is correct.

As I stated in the thread below, I'd love to hear from a RAM suspension engineer on what the correct operation of this suspension should be. I've searched high and low without any information officially from RAM. The only other source might be a RAM factory service manual. That may provide some insight in the section on calibrating the suspension.

Since both my rear bags are empty when there is no load in the bed of my truck, nothing happens when I go into bed lowering mode (or alternate bed height). Also overload springs are not in play when my truck is empty.

https://hdrams.com/forum/index.php?threads/21-3500-rear-air-suspension-smoooth-ride.4477/

 

[roegs]

As promised here is the video of my 2022 air suspension lowering the bed with little load in it. Certainly less than 650 pounds.

Sent from my iPhone using Tapatalk

Thats a great video for sure! My thinking is that you're riding on air because of the load you have in your truck, but hey, that's just my opinion. I'd be more than happy to be corrected by an engineer from RAM. Thanks much for taking time to put the video together!

 

[AH64ID]

I started a thread on this back when I purchased my '21 (link below). My experience and understanding of the air suspension aligns with what BilletWilson is saying. Others who participated in that thread seemed to see the same. The thought is that when the truck is empty, the rear of the truck rides only on the lighter spring pack that is part of the optional air suspension. Air only comes in play when the rear lowers due to weight, and the bags re-level the truck. I found that my empty truck rides better when your thumb can easily press into the sides of the bags (deflated). As for correct factory calibration....many new trucks come from the factory with one bag (typically drivers side) firm and the other bag supple. I find it hard to believe that is correct.

As I stated in the thread below, I'd love to hear from a RAM suspension engineer on what the correct operation of this suspension should be. I've searched high and low without any information officially from RAM. The only other source might be a RAM factory service manual. That may provide some insight in the section on calibrating the suspension.

Since both my rear bags are empty when there is no load in the bed of my truck, nothing happens when I go into bed lowering mode (or alternate bed height). Also overload springs are not in play when my truck is empty.

https://hdrams.com/forum/index.php?threads/21-3500-rear-air-suspension-smoooth-ride.4477/

The main, normal, springs are soft enough that with no payload and no air in the bags they compress onto the overloads on every auto-level truck I’ve played with.

Since you have tweaked your sensors to a feeling in the bags of no air are your main leaves riding on the overloads? You say they aren’t, but that’s not my experience on multiple trucks. If they aren’t, how much clearance is there? Have you tested it with a full vs empty fuel tank?

With your tweaked sensors and a dump of the bags (bed lowering or transport mode) do you hear/feel air blow out the vent?

Both my 3500’s were well above the overloads in normal, but dumping the air from the bags manually would drop the truck onto the overloads with no added payload.

The drivers side bag should have more air than the passenger side bag due to fuel, DEF, and driver… standard weights the passenger side doesn’t have. The leaf springs have the same rating so the airbags are what keep it level side to side. There are trucks that were improperly setup from the factory thou, like they did the calibration with the wrong fuel weight… makes me wonder it has anything to do with the 50 gallon tank option and basic weights for programming, even on trucks that don’t have the 50 gallon tank.

I also don’t think that LB vs SB is a difference as the CCSB version of my truck only has a published RAW of 30lbs less than my CCLB, and CCSB Rambox has a higher RAW. The only truck with a significant difference is the RCLB truck.

 

[BilletWilson]

Sorry guys, the video was taking a while to upload and I needed to go to my daughters for dinner. Here is the video showing normal ride height, bed lowering mode, and alternate ride height.

Edit: The video is still currently processing so video quality will be poor until it's complete

 

[Ionicbrick]

Thats a great video for sure! My thinking is that you're riding on air because of the load you have in your truck, but hey, that's just my opinion. I'd be more than happy to be corrected by an engineer from RAM. Thanks much for taking time to put the video together!

Only my truck acted the exact same way at the PDI. I spent over two hours checking everything out because I had heard that the air suspension sometimes isn’t set right at the factory. This was from a buddy of mine who doesn’t have air suspension in his rig. It’s worked this way since it really was empty.

In fact, I had it loaded with 750 pounds of tile the other day… the bags filled to bring the truck level, but lowering the bed for unloading didn’t drop it any more than the 1” or so I’m accustomed to.


Sent from my iPhone using Tapatalk

 

[AH64ID]

Sorry guys, the video was taking a while to upload and I needed to go to my daughters for dinner. Here is the video showing normal ride height, bed lowering mode, and alternate ride height.

Edit: The video is still currently processing so video quality will be poor until it's complete

So something is definitely not working correctly with your truck. You should not be able to get into alternate ride height without a drop in height. You should get “selected ride height not permitted due to payload” if the truck doesn’t sense an adequate drop.

It also said alternate trailer height achieved too fast for no payload. With the ignition on and truck off when you hit alternate ride height you should hear a valve open, air dump, then air flow back into the bags, the compressor may run and the tank may purge. The whole process form selecting alternate ride height to it failing from
insufficient payload is over 15-20 seconds, not instant.

Did it work like that with alternate ride height before the lift?

 

[Ionicbrick]

Guys. There has to be some air in the system at all times. Just with aftermarket bags, if you run them with no air and load up the truck the compression on just the spring could squish the bag out of place. Same reason crawling with a vehicle that has 10psi won’t take the tire off the rim, but 0psi will surely kick the bead.

When we load these trucks, the auto doesn’t come on to fill bags until after the truck has been “turned on” either by opening a door or starting it.
So when the forklift drops 2000lbs in my bed the weigh sits on the springs AND the lower pressure air in the bags. Once I climb in the truck it lifts to accommodate the weight to level.


Sent from my iPhone using Tapatalk

 

[Ionicbrick]

Sorry guys, the video was taking a while to upload and I needed to go to my daughters for dinner. Here is the video showing normal ride height, bed lowering mode, and alternate ride height.

Edit: The video is still currently processing so video quality will be poor until it's complete

I saw your video just fine. Sweet truck BTW. Love those tires.
Anyway. I think you should have your system looked at. I could do another video on mine, but when I hit alternate trailer height, my truck says it can’t be accomplished, and to increase the payload and try again. Or something like that. It definitely doesn’t say alternate ride height achieved.

Now, when I pull my TT with 1100 pounds on the hitch, it WILL go into an alternate ride height. And I can actually feel that difference. The trailer is sleeping for the winter or I’d show you that.


Sent from my iPhone using Tapatalk

 

[roegs]

The main, normal, springs are soft enough that with no payload and no air in the bags they compress onto the overloads on every auto-level truck I’ve played with.

Since you have tweaked your sensors to a feeling in the bags of no air are your main leaves riding on the overloads? You say they aren’t, but that’s not my experience on multiple trucks. If they aren’t, how much clearance is there? Have you tested it with a full vs empty fuel tank?

With your tweaked sensors and a dump of the bags (bed lowering or transport mode) do you hear/feel air blow out the vent?

Both my 3500’s were well above the overloads in normal, but dumping the air from the bags manually would drop the truck onto the overloads with no added payload.

The drivers side bag should have more air than the passenger side bag due to fuel, DEF, and driver… standard weights the passenger side doesn’t have. The leaf springs have the same rating so the airbags are what keep it level side to side. There are trucks that were improperly setup from the factory thou, like they did the calibration with the wrong fuel weight… makes me wonder it has anything to do with the 50 gallon tank option and basic weights for programming, even on trucks that don’t have the 50 gallon tank.

I also don’t think that LB vs SB is a difference as the CCSB version of my truck only has a published RAW of 30lbs less than my CCLB, and CCSB Rambox has a higher RAW. The only truck with a significant difference is the RCLB truck.

AH64ID....thanks for the info. This is a perfect time for me to do some checking as I just filled with fuel. Mine is Crew Cab Standard Box...everything factory including stock 20" wheels and tires. No Rambox.

Crawled under the truck this evening and saw the following. I have 1/2 full def and full fuel tank. Truck bed is totally empty other than tonneau cover.

1. Both bags can be pushed in with my thumb.
2. On both driver and passenger sides, the rearmost overload rubber cushion is just touching the lighter weight primary leafs.
3. On drivers side, the frontmost overload rubber cushion has a very slight gap to the lighter weight primary leaf. Gap is like the thickness of a quarter.
4. On passenger side, the frontmost overload rubber cushion has a 1/4" gap to the lighter weight primary leaf.

When I go into bed lowering mode, I hear the compressor system go through its cycle, but in the end there is no change in height. Bags feel exactly the same when I press them with my thumb.

Questions.....
I believe you're in the camp where bags should always be firm, and when empty the truck is riding on both the bags and lighter weight primary leafs.

1. What overload rubber cushion gaps would you expect to see on an empty truck? (sorry if you already posted this)
2. What process do you use for setting the sensors on each side of the rear suspension?
3. Have you ever been able to see what the calibration process is in the RAM service manual for our trucks?


Thanks!

 

[AH64ID]

AH64ID....thanks for the info. This is a perfect time for me to do some checking as I just filled with fuel. Mine is Crew Cab Standard Box...everything factory including stock 20" wheels and tires. No Rambox.

Crawled under the truck this evening and saw the following. I have 1/2 full def and full fuel tank. Truck bed is totally empty other than tonneau cover.

1. Both bags can be pushed in with my thumb.
2. On both driver and passenger sides, the rearmost overload rubber cushion is just touching the lighter weight primary leafs.
3. On drivers side, the frontmost overload rubber cushion has a very slight gap to the lighter weight primary leaf. Gap is like the thickness of a quarter.
4. On passenger side, the frontmost overload rubber cushion has a 1/4" gap to the lighter weight primary leaf.

When I go into bed lowering mode, I hear the compressor system go through its cycle, but in the end there is no change in height. Bags feel exactly the same when I press them with my thumb.

There is the reason you don’t lower when going to bed lowering mode, the overloads are engaged enough to support the truck.

You adjusted your setup too low, and that’s why your getting your results.

Questions.....

I believe you're in the camp where bags should always be firm, and when empty the truck is riding on both the bags and lighter weight primary leafs.

Firm, no. They should have positive air pressure in them thou. Think about bike tire. I can easily compress a bike tire with 10 psi in it, and 10 psi in airbags supports a bit of weight.

1. What overload rubber cushion gaps would you expect to see on an empty truck? (sorry if you already posted this)

I’ve had around 1/2” on both my auto level 3500’s, but haven’t ever measured it exactly. I just know there is a decent gap. That gap is where the bed lowering comes from.

2. What process do you use for setting the sensors on each side of the rear suspension?

I haven’t, but based on what I’ve experienced on multiple trucks I would adjust the sensors to a 1/2” gap and then equal height side to side.

3. Have you ever been able to see what the calibration process is in the RAM service manual for our trucks?

No, but I would really, really like to!

 

[roegs]

I’ve had around 1/2” on both my auto level 3500’s, but haven’t ever measured it exactly. I just know there is a decent gap. That gap is where the bed lowering comes from.....

I may play around with this tomorrow. When you say 1/2" are you referring to the frontmost cushions vs rears? On my truck the rear cushions on the overloads definitely touch before the front cushions.


Its been a few years since I posted my experiences. I had hoped that by this time I'd have somehow been able to access the suspension section of a RAM service manual or read some technical details from RAM, but no such luck. Seems to be top secret within RAM!

 

[AH64ID]

I may play around with this tomorrow. When you say 1/2" are you referring to the frontmost cushions vs rears? On my truck the rear cushions on the overloads definitely touch before the front cushions.

I believe mine is the same, you want that around 1/2”.

At the end of the day what you want is for the truck to drop less than 1” when empty, but a 600-750lb payload will put enough weight on the springs/overloads that you can drop 1” and have minimum pressure in the bags for alternate ride height to work.

Its been a few years since I posted my experiences. I had hoped that by this time I'd have somehow been able to access the suspension section of a RAM service manual or read some technical details from RAM, but no such luck. Seems to be top secret within RAM!

I’m not sure if it’s top secret or just not really discussed as there aren’t many issues with the HD systems.

I’ve been researching the system since 2015 and driving one since 2019. There just isn’t much out there.

 

[loveracing1988]

I test drove a 22 3500 SRW short bed with air suspension. I was impressed with the ride and put a deposit down to buy it but the dealership had to fix a couple things first. After 3 months they never got it fixed and sent it to auction and refunded my deposit. I can't find another similar truck close to me but did find one with everything I want except the air suspension that is 8 hours away. Is the difference in the ride as significant as I suspect between the two suspensions? I can't find a 3500 SRW near me to test drive and compare myself. I have driven a 3500 drw with standard suspension and it's too harsh for my purpose but I suspect the dual wheels is a big part of that.

Where are you located? There are plenty of people around who would probably take you for a ride in their 3500 both air and non air equipped. I have a non air equipped 3500 and it rides better than the 2014 coil 2500 I traded in. If you were located in Michigan I'd offer to show you.

 

[BilletWilson]

So something is definitely not working correctly with your truck. You should not be able to get into alternate ride height without a drop in height. You should get “selected ride height not permitted due to payload” if the truck doesn’t sense an adequate drop.

It also said alternate trailer height achieved too fast for no payload. With the ignition on and truck off when you hit alternate ride height you should hear a valve open, air dump, then air flow back into the bags, the compressor may run and the tank may purge. The whole process form selecting alternate ride height to it failing from
insufficient payload is over 15-20 seconds, not instant.

Did it work like that with alternate ride height before the lift?

It worked this way stock as well. When I hitch up or have a load in the bed everything functions perfectly.

 

[AH64ID]

It worked this way stock as well. When I hitch up or have a load in the bed everything functions perfectly.

Maybe something changed for ‘23, but it still seems off as it didn’t even try to go into alternate ride height. It takes longer to open a valve than it took to say alternate ride height achieved. It would have been interesting to know if you rode on the overloads with the stock springs or not.

It will be harder to get Ram to look at it with the Carli springs installed.

 

[Ionicbrick]

It worked this way stock as well. When I hitch up or have a load in the bed everything functions perfectly.

I’d still have them look. You’re losing the functionality of the lowered bed option, and your truck is telling you stuff is happening that isn’t. Like someone said, maybe programming changed, or they might not do anything with the aftermarket stuff… still worth a mention during a recall or maintenance.


Sent from my iPhone using Tapatalk

 

[BilletWilson]

Maybe something changed for ‘23, but it still seems off as it didn’t even try to go into alternate ride height. It takes longer to open a valve than it took to say alternate ride height achieved. It would have been interesting to know if you rode on the overloads with the stock springs or not.

It will be harder to get Ram to look at it with the Carli springs installed.

When it was stock, the bags had just enough air to not be empty and could easily press a thumb about 1/2" into them. As soon as any kind of weight lowers the suspension the bags instantly air up to level. At that point the system functions as it should including the messages you described. It's almost like the bags are non existent until the sensors detect a load then the system wakes up and assist.