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'21 3500 Rear Air Suspension - Smoooth Ride!

CdnHO

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My links were the same length at the shortest length as the stock rods. I cut .75 (3/4") inches off the link rods. The original stock rods are 6.7 inches between socket centers. I installed the links at 3/4 shorter than stock. Have not tested it loaded yet.
 

Linked4door

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My links were the same length at the shortest length as the stock rods. I cut .75 (3/4") inches off the link rods. The original stock rods are 6.7 inches between socket centers. I installed the links at 3/4 shorter than stock. Have not tested it loaded yet.
Awesome, thaks man. Just cut mine down.
 

Vr6mole

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Has anyone with a heavy load/trailer (2500+ pounds) been able to test if the air will raise the rear to unloaded height? or does it sit a tad lower?

Trying to figure out how much I want to level the truck when it arrives. I worry that with the minimal factory rake I can't go more than a .5 inch lift in the front or I will be squatting with a 3k pin weight 5th wheel and I'd like to avoid that.
 

Dunn08

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Has anyone with a heavy load/trailer (2500+ pounds) been able to test if the air will raise the rear to unloaded height? or does it sit a tad lower?

Trying to figure out how much I want to level the truck when it arrives. I worry that with the minimal factory rake I can't go more than a .5 inch lift in the front or I will be squatting with a 3k pin weight 5th wheel and I'd like to avoid that.

I think you’ll be fine. You can always get longer links for the air sensors if needed. I lifted my front 3.25” and rear 2” and my truck sits fairly level with bags empty and no load. I get my truck back tomorrow for the detailer I plan to hook up to my 5th wheel tomorrow or Sunday to see how she levels out and play with the sensor arms if need be.
 

Vr6mole

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I think you’ll be fine. You can always get longer links for the air sensors if needed. I lifted my front 3.25” and rear 2” and my truck sits fairly level with bags empty and no load. I get my truck back tomorrow for the detailer I plan to hook up to my 5th wheel tomorrow or Sunday to see how she levels out and play with the sensor arms if need be.
Please let me know how it goes. My next question was going to be how much higher can you get the bags to level the truck without throwing the payload error.

How did you raise the rear of the truck? Was it strictly using the longer links for the air sensors? If so how is the ride quality if the bags are more inflated?
 

Dunn08

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Please let me know how it goes. My next question was going to be how much higher can you get the bags to level the truck without throwing the payload error.

How did you raise the rear of the truck? Was it strictly using the longer links for the air sensors? If so how is the ride quality if the bags are more inflated?

2” leaf blocks and 2” air bag spacers in the rear. Using the arms to keep the bags deflated unloaded for the best ride possible.

Turns out the shop isn’t done installing the PPF and coating on the truck. Getting frustrated, they had it all week. So unfortunately I can’t get any data this weekend but as soon as I can I’ll post it up.
 

Vr6mole

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2” leaf blocks and 2” air bag spacers in the rear. Using the arms to keep the bags deflated unloaded for the best ride possible.

Turns out the shop isn’t done installing the PPF and coating on the truck. Getting frustrated, they had it all week. So unfortunately I can’t get any data this weekend but as soon as I can I’ll post it up.
Who makes the blocks and the airbag spacers?
 

Linked4door

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2” leaf blocks and 2” air bag spacers in the rear. Using the arms to keep the bags deflated unloaded for the best ride possible.

Turns out the shop isn’t done installing the PPF and coating on the truck. Getting frustrated, they had it all week. So unfortunately I can’t get any data this weekend but as soon as I can I’ll post it up.
Please post pics when you get it back. I want to do the carli leafsprings that are a little over 2" and would love to see the stance of your truck with a 2" lift.
 

Dunn08

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Please post pics when you get it back. I want to do the carli leafsprings that are a little over 2" and would love to see the stance of your truck with a 2" lift.

Carli 3 and 1/4” springs up front, 2” blocks rear.
If you do 2” springs in the front I’d use the 1” billet blocks carli makes. Readylift makes the leaf spring blocks and air bag spacers I used. The air bag spacers for for model year 18 and below but nothing has changed they work perfect with 19+

cd1b58f5f048f62a3eb50bce45a7530a.jpg
 

JABAR357

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Thought I'd give an update to my original findings. I'll once again preface by saying that these are my findings only. I'm all ears if someone is able to provide additional information on how this system operates. I'd also be grateful if anyone is able to provide the section describing Rear Air Suspension from the RAM Shop Manual.

I'm very satisfied with how my truck (see sig) rides both empty and loaded. Loaded in my case is a Grand design 2930RL S-Class Solitude with approx 2500 lbs pin weight. While some may say 'its a 3500 and is supposed to ride stiff - get over it' my reply is that its also my daily driver and I know that with some work these trucks can be made to ride better.

My definition of a smooth unloaded ride? Prior to any of the things I did, I noticed that the rear was much stiffer than the front. When going over a bump the front would be fairly smooth while the rear would jolt my behind. After the adjustments etc, my rear suspension now feels just like the front. While it will never ride like a half ton, the sharpness of the ride is much more reduced.

Since I last wrote in this thread, we've towed the 5th wheel approx 500 miles which has allowed the rear suspension to settle. While my drivers side bag was still soft, it was not as supple as the passenger bag was. My assumption all along has been to have the bags empty when the truck is empty with full fuel. In my case the drivers bag has always been more firm than the passenger bag. To get the drivers side height sensor to let more air out of the bag, I needed to elongate one of the mounting holes. I used a dremel to remove a small amount of material as shown in the photo. After doing this, the drivers bag is now as supple as the passenger bag. Note that I've never anything to the passenger side of the suspension - my goal all along has been to get the drivers side the same as passenger via adjustment of the height sensor.

In summary, my combination for a very acceptable ride empty is the following:

1. Height sensors adjusted so that both bags are supple when truck is empty and fuel full.
2. Rear tire pressure is 42 lbs or less - note that I have the 20 inch wheels on mine. Either way, take advantage of the load range charts. There is no reason to keep the rears at 80 lbs! Front air pressure is 60 lbs.
3. Keep a full fuel tank - this seems to give the best ride.
Your research and explanation has been very helpful. Thanks for the Information.
 

RTillery

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I wondered why my airbags both were tight and was intrigued when I read the OP's results. I went out and checked again, hard as a rock. I loosened up the passenger side and cocked the bracket and sure enough, I could hear air releasing and I could deflect the bag with my thumb.

Different story on the driver's side. There was not enough play in the holes to get it to deflect so I drilled them out with a 13/32" bit and that was enough to allow a little more angle on the bracket. Both sides are soft and that's with a full tank of fuel and empty payload. My first trip around the neighborhood seems promising. Looking forward to a 4000 mile trip on my 56,000 mile 19-HO SRW. Hope my CP4.2 makes it to next year;).
 

Vr6mole

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I wondered why my airbags both were tight and was intrigued when I read the OP's results. I went out and checked again, hard as a rock. I loosened up the passenger side and cocked the bracket and sure enough, I could hear air releasing and I could deflect the bag with my thumb.

Different story on the driver's side. There was not enough play in the holes to get it to deflect so I drilled them out with a 13/32" bit and that was enough to allow a little more angle on the bracket. Both sides are soft and that's with a full tank of fuel and empty payload. My first trip around the neighborhood seems promising. Looking forward to a 4000 mile trip on my 56,000 mile 19-HO SRW. Hope my CP4.2 makes it to next year;).
Aw man. Are you saying you went 56k miles before you found this thread?
 

RTillery

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C'mon man, I got hairy legs, gimme a break.
Most of that 56K was before this thread started. I had back surgery in May, and I had foot surgery two weeks ago. "Mighty Whitey" has spent most of the last 7 months sitting around beside the house. I did this mod today still wearing my surgery boot. Super easy to do.
 

Scvette

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1st off your truck looks great. So now that you have it back from getting the ppf and ceramic coating and spent some time with it, can I ask you another question? So you went with the 3”+ lift/leveling kit and added 2” blocked to the rear and you say it’s pretty level. As we’ve talked on that other forum you know I’m going with the 2.5 Carli leveling kit. I know I’ll need to add the bag spacer and axle spacer, my question is, what do you think the better way to go would be, I already ordered the 1” spacers, do you think they’ll be enough? Should I send them back and get 2”? I don’t want the air bags to fill up to keep me level and have a rough ride when not towing.
Carli 3 and 1/4” springs up front, 2” blocks rear.
If you do 2” springs in the front I’d use the 1” billet blocks carli makes. Readylift makes the leaf spring blocks and air bag spacers I used. The air bag spacers for for model year 18 and below but nothing has changed they work perfect with 19+

cd1b58f5f048f62a3eb50bce45a7530a.jpg
 

Dunn08

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1st off your truck looks great. So now that you have it back from getting the ppf and ceramic coating and spent some time with it, can I ask you another question? So you went with the 3”+ lift/leveling kit and added 2” blocked to the rear and you say it’s pretty level. As we’ve talked on that other forum you know I’m going with the 2.5 Carli leveling kit. I know I’ll need to add the bag spacer and axle spacer, my question is, what do you think the better way to go would be, I already ordered the 1” spacers, do you think they’ll be enough? Should I send them back and get 2”? I don’t want the air bags to fill up to keep me level and have a rough ride when not towing.

I wish I had it back, lol. That pic was at the alignment shop the day before it went to the detailer. By the time I pick it up Friday they will have had it for 13 days. They’re making the delay right though so I can’t complain. Besides, it’s storming like crazy in Vegas and it’s staying clean in there facility instead of sitting in my driveway.

I think you should try the 1” spacers first. Unless you want a little rear end rake than go with the 2”. Even IF your rear end is a little low (I don’t think it will be) you can use the revel arms to make your air bags not fill up. Or you can buy 2” spacers and change them out for cheaper than buying the revel arms. Either way, I say try the 1” first.
 

Scvette

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That’s what I’ll do, just go with the 1” since I already have them here. I wish I had your weather, look at western Washington weather…. It really sucks here. Been raining for like forever.
I wish I had it back, lol. That pic was at the alignment shop the day before it went to the detailer. By the time I pick it up Friday they will have had it for 13 days. They’re making the delay right though so I can’t complain. Besides, it’s storming like crazy in Vegas and it’s staying clean in there facility instead of sitting in my driveway.

I think you should try the 1” spacers first. Unless you want a little rear end rake than go with the 2”. Even IF your rear end is a little low (I don’t think it will be) you can use the revel arms to make your air bags not fill up. Or you can buy 2” spacers and change them out for cheaper than buying the revel arms. Either way, I say try the 1” first.
 

Vr6mole

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I wish I had it back, lol. That pic was at the alignment shop the day before it went to the detailer. By the time I pick it up Friday they will have had it for 13 days. They’re making the delay right though so I can’t complain. Besides, it’s storming like crazy in Vegas and it’s staying clean in there facility instead of sitting in my driveway.

I think you should try the 1” spacers first. Unless you want a little rear end rake than go with the 2”. Even IF your rear end is a little low (I don’t think it will be) you can use the revel arms to make your air bags not fill up. Or you can buy 2” spacers and change them out for cheaper than buying the revel arms. Either way, I say try the 1” first.
Maybe a dumb question but what is the downside of just doing a 1 inch spacer? Is there any loss of payload etc? How come they say it only works on the 2018 trucks and not the newer ones?

I assume the idea of the spacer is taht you are just lifting the leafs up 1 inch and bags 1 inch so everything in theroy should just work the way it does like a stock system? It's just that the new "level" is now 1 inch higher?
 

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