2500 vs. 3500 (both with factory auto level rear air suspension) towing stability with 1,000 lb TW and 8,000 lb travel trailer

[AH64ID]

New question for the OP (@content): Since we have similar TT weights and 3500's, are you using a WDH? I read that whole other thread about the air suspension and wow - I have a lot to learn (also, a little worrysome about the uneven driver/passenger sides not equal?). One thing I am having trouble googling is how you are supposed to use the Alt Height when hooking up your TT, and if you are using a WDH (I know its not required for these weights but I would like to to help sway - I have the short 149" wheelbase) what order do you do everything.

In my head I was thinking the Alt Height actually *adds* air to the bags to offset the loaded hitch. But it does the opposite and LOWERS the rear height by about 1", to level it from the unloaded 1" factory rake. So you do that first. Then add the trailer. Now, if not using a WDH, do you *keep* the Alt Height set while towing, or do you return it to normal? I would think that it would currently be a little lower in rear and higher in front than when it was leveled using the Alt Height mode, but only slightly due to the fact its a 1 ton beefy suspension.

Now, I intend to use my WDH for sway help, and as a bonus return some weight back to the front and trailer axles. So I should 1) set Alt Height mode, 2) add trailer, 3) use hitch to distribute back to level, then 4) definitely keep the Alt Height mode, right?

So many videos and forum posts all over the map, many with 1500s and 2500s air suspensions or aftermarket airbags, muddying up the waters. I can't find a good TT hookup video for a 3500 except JB Reviews but of course he doesn't use a WDH and his video was a little ambiguous on whether you keep Alt Height while towing or only use it to hook up.

I'll keep researching when I get more time, but if someone in my similar situation (8K+ pound TT with a 3500+Air SRW) already knows then its worth a shot asking here first.

Thanks!
-T

Once your WDH is setup it works seamlessly with auto-level and alt ride height.

Setup is a little more time consuming than with a traditional suspension, but still pretty easy.

The easiest way I have found to setup a WDH with the auto-level is to measure the front fender height empty, hitch the trailer up without WDH engage alt height and remeasure. Now start adjusting the WDH preload until you’re about 1/2 way between the two measurements (good rule of thumb if you’re not using a scale). You’ll want to stay in alt for all of this. Once that is done check your trailer for level, and adjust the hitch height as required. That’s it, you’re done. The truck will always be at that height as long as you tow in alt, which you want to. The truck will automatically compensate for any additional payload you have in the truck and it won’t reduce the WDH effectiveness. If you do tow in normal height after adjusting the WDH in alternate you will reduce the WDH effectiveness.

It does add air to support the load in alternate height, but it first has to purge the air to lower onto the overloads. The truck the adds air as required to compensate for the payload being supported by the rear suspension. Ive seen it say “raising” into alternate height multiple times after I hitch up since it was lowered below alt height with the weight.

Lastly, the primary purpose of a WDH is to transfer tongue weight back to the front axle and trailer axles. Sway control isn’t needed on a properly built and loaded trailer.

 

[daemonic3]

THANKS! I read the manual and it leaves it totally ambiguous, as if leaving it to personal preference. In fact, both air suspension step by step and non air step by step are equal in ram 2500/3500 manual.

I totally get wanting to be level and most importantly, wanting the trailer to ride level, for a variety of reasons. What I was most confused by is my assumption that, if you drop to alt height, you are mostly on leafs with some air assist, but if you keep it normal height you are mostly air with some leaf assist? I just want to know what's best for the truck longevity and best ride! Towed with F150s for 8 years and all this air stuff will be new to me...

Your order makes the most sense, as I have seen mention that it won't allow alt height unloaded (3500 only). AND if you're saying the truck levels with air after the whole process then great! It seemed weird to risk flattening the leafs by dropping it like that.

Now I think my biggest unknown is what height (hole slots) to build my shank the first hookup. The WDH instructions say build it so the ball is ~1/8" higher than top of coupler for every 100#. Great! For my F150 I built it 1.25" higher and it squatted nicely, then leveled with spring bars (I have a weigh safe, with built in scale). With the 3500 I'm guessing it is going to barely squat at all! So I don't know which holes to use on my shank until some trial and error unfortunately. Or maybe it will squat like a half ton when alt height mode is set, I don't know!

 

[AH64ID]

THANKS! I read the manual and it leaves it totally ambiguous, as if leaving it to personal preference. In fact, both air suspension step by step and non air step by step are equal in ram 2500/3500 manual.

I totally get wanting to be level and most importantly, wanting the trailer to ride level, for a variety of reasons. What I was most confused by is my assumption that, if you drop to alt height, you are mostly on leafs with some air assist, but if you keep it normal height you are mostly air with some leaf assist? I just want to know what's best for the truck longevity and best ride! Towed with F150s for 8 years and all this air stuff will be new to me...

Your order makes the most sense, as I have seen mention that it won't allow alt height unloaded (3500 only). AND if you're saying the truck levels with air after the whole process then great! It seemed weird to risk flattening the leafs by dropping it like that.

Now I think my biggest unknown is what height (hole slots) to build my shank the first hookup. The WDH instructions say build it so the ball is ~1/8" higher than top of coupler for every 100#. Great! For my F150 I built it 1.25" higher and it squatted nicely, then leveled with spring bars (I have a weigh safe, with built in scale). With the 3500 I'm guessing it is going to barely squat at all! So I don't know which holes to use on my shank until some trial and error unfortunately. Or maybe it will squat like a half ton when alt height mode is set, I don't know!

The best ride empty comes in normal where you aren’t using the overload springs, but the best ride loaded comes riding on the overloads. At least that’s been my experience in a SRW with RAW’s up to a little over the RAWR.

The overloads that get engaged in alt height also add a lot of lateral stability, great for winding roads.

The truck will constantly level while parked as you change weight. I’ve tried disabling the auto-level while adjusting the WDH and don’t see the benefit. You want the truck at the proper ride height to get the real world weight transfer.

The truck will not sag at all, but it will lower the 1” an alt. To setup your ball height you can simply measure the top of the coupler and set the ball 7/8” above that (1/8” for coupler thickness). You’ll then settle the 1”, and stay there. The truck adds the required amount of air to stay at the same rear height under all loads, that height is selected by either being in normal or alternate height.

 

[daemonic3]

The best ride empty comes in normal where you aren’t using the overload springs, but the best ride loaded comes riding on the overloads. At least that’s been my experience in a SRW with RAW’s up to a little over the RAWR.

The overloads that get engaged in alt height also add a lot of lateral stability, great for winding roads.

The truck will constantly level while parked as you change weight. I’ve tried disabling the auto-level while adjusting the WDH and don’t see the benefit. You want the truck at the proper ride height to get the real world weight transfer.

The truck will not sag at all, but it will lower the 1” an alt. To setup your ball height you can simply measure the top of the coupler and set the ball 7/8” above that (1/8” for coupler thickness). You’ll then settle the 1”, and stay there. The truck adds the required amount of air to stay at the same rear height under all loads, that height is selected by either being in normal or alternate height.

This is all fantastic, helpful information. I can't wait to try it all out! This will be an excrutiating 4(?) month wait since I just ordered early last week. I will just have to appreciate the final months with my hybrid King Ranch... the final 4 months of having 12" full-screen android auto until I get the puny nerfed half sized android auto on the Uconnect 12" screen

 

[content]

Once your WDH is setup it works seamlessly with auto-level and alt ride height.

Setup is a little more time consuming than with a traditional suspension, but still pretty easy.

The easiest way I have found to setup a WDH with the auto-level is to measure the front fender height empty, hitch the trailer up without WDH engage alt height and remeasure. Now start adjusting the WDH preload until you’re about 1/2 way between the two measurements (good rule of thumb if you’re not using a scale). You’ll want to stay in alt for all of this. Once that is done check your trailer for level, and adjust the hitch height as required. That’s it, you’re done. The truck will always be at that height as long as you tow in alt, which you want to. The truck will automatically compensate for any additional payload you have in the truck and it won’t reduce the WDH effectiveness. If you do tow in normal height after adjusting the WDH in alternate you will reduce the WDH effectiveness.

It does add air to support the load in alternate height, but it first has to purge the air to lower onto the overloads. The truck the adds air as required to compensate for the payload being supported by the rear suspension. Ive seen it say “raising” into alternate height multiple times after I hitch up since it was lowered below alt height with the weight.

Lastly, the primary purpose of a WDH is to transfer tongue weight back to the front axle and trailer axles. Sway control isn’t needed on a properly built and loaded trailer.

Thank you for that. I'm learning too and will be coming back to this post when I am ready to hook up

 

[daemonic3]

Thank you for that. I'm learning too and will be coming back to this post when I am ready to hook up

I expect nothing less than a full youtube tutorial, you can be the first to film hooking up a moderately sized TT with a WDH and a SRW 3500!

 

[TosaInu]

It's funny to me I went through all this same decision stuff, without knowing this thread existed. But it basically confirms my decision on what I ordered last week for my needs.

I have an F150 and have been towing a 30' TT, and just updated to a 34' TT. We're still within weights (barely) with tongue scale verified 1050# and CAT scale verified total 8240#. Basically same situation as the OP. For the past 3 years we've only been doing weekend trips within 150 miles or so. We can continue this just fine with my current trailer, and if 10-day forecast predicts strong winds just cancel with a refund no big deal (the 34' length is probably not comfortable in crazy winds, though I've been fine with semis passing and whatnot). But, I can't put anything in my truck beyond myself and my wife.

Never thought I could get an HD truck of any brand until I found that Ram HD crewcab is only 6" longer than my F150. This opened a whole new world to me! I noticed that the 2500 w/cummins really limits your payload due to Ram "nerfing" their GVWR sticker at 10k. Since I want all the bells and whistles of high trim (and moonroof) I would likely be <2k payload rating. So I looked at 3500. Back (a month ago) when the "Towing capacity by VIN lookup" worked, I looked up some CCSB 3500's and their payloads, which were all around 3300-3400 at my desired trim level. Great! Cons online suggest a stiffer ride than a 2500 so I test drove a 3500, and it did not feel at all like a dealbreaker. Went unloaded on freeway, over some railroad tracks, and over some speed bumps. I honestly couldn't personally discern anything I would complain about, and perhaps the air suspension is really really helping offset the stiff leafs. So then, I noticed in inventory search that CCSB is already only about 20-30% of the entire inventory, and none near me (or nationwide!) have all the tow tech plus my moonroof plus ramboxes. So custom order it is!

Here is where the decisions come in: While you *can* get a SO cummins in a 3500, they simply don't exist on lots. Dealers overwhelmingly stock the HO cummins. But do I *need* the HO if I only want a daily driver with maybe 10% towing miles? I want the best MPG I can get, as long as I have more towing capability and payload than I'll ever need. In a 3500 CCSB, the HO only gives ~4k more towing "capacity" but eats into payload a little. You really can't take advantage of more capacity unless you go long bed or dually, which I absolutely am not able to park. Since my ultimate goal was just a 2500 with more payload than I'll ever need, that I should stick with SO cummins. It should give better MPG, especially through the lower gears with less RPMs, though at 6th gear they have equal gear ratios. Also kept the 18" wheels of standard longhorn vs "upgrade" of 20". In past research, 20" wheels add weight (rotational inertia) for slightly worse acceleration, and less comfortable ride. Likely not something I would ever notice but just going by what I've read, plus it saved $2k on my build.

Anyway, fun thread to catch up on. It confirms I'll be very comfortable with my current TT in my new 3500. And I'm future proofed for a 5er if the wife ever decides that is a must have some day (rambox and sidewinder hitch requirements aside).

Thanks for indulging,
-T

For one reason or another, you made me think about whether or not there are differences in the exhaust brake between a SO and an HO. Not sure if you know the answer or anyone else does but, when comparing the exhaust brake on my 2024 3500 to my 2017 2500, the 3500 is just way better, loaded or unloaded. I don't drive enough miles to worry about MPG but if anyone has side-by-side, real world comparisons of exhaust braking between the SO and HO, I'd be curious to hear about it...not that I will get rid of my truck, but just curious given how much better the exhaust brake is on my 3500 vs. my previous 2500 is all.

 

[AH64ID]

For one reason or another, you made me think about whether or not there are differences in the exhaust brake between a SO and an HO. Not sure if you know the answer or anyone else does but, when comparing the exhaust brake on my 2024 3500 to my 2017 2500, the 3500 is just way better, loaded or unloaded. I don't drive enough miles to worry about MPG but if anyone has side-by-side, real world comparisons of exhaust braking between the SO and HO, I'd be curious to hear about it...not that I will get rid of my truck, but just curious given how much better the exhaust brake is on my 3500 vs. my previous 2500 is all.

From what I have seen the HO and SO are programmed the same, but the 24 has lower gearing than the 17 so you’ll feel that difference.

 

[TosaInu]

I assume you are referring to the transmission gearing (68 vs. ASIN)? My 3500 has the 3.73 rear end which I believe is the same thing I had in my 2017 2500. I am one of those who uses my exhaust brake all the time, not just while towing, since I think I read somewhere at some point that it helps keep the system 'clean' but whatever, anyway, with my 2017 if I was not in tow/haul mode, the exhaust brake would cut off between 45-50 MPH whereas, my 3500 can get closer to 35 MPH. I've only done a very brief 'towing test' at this point but even then it was apparent that the 3500 exhaust brake was more effective. Appreciate your response, guess I'm just wondering if Ram/Cummins has tweaked something overall since 2017 or if what I am seeing is only on the HO.

 

[AH64ID]

I assume you are referring to the transmission gearing (68 vs. ASIN)? My 3500 has the 3.73 rear end which I believe is the same thing I had in my 2017 2500. I am one of those who uses my exhaust brake all the time, not just while towing, since I think I read somewhere at some point that it helps keep the system 'clean' but whatever, anyway, with my 2017 if I was not in tow/haul mode, the exhaust brake would cut off between 45-50 MPH whereas, my 3500 can get closer to 35 MPH. I've only done a very brief 'towing test' at this point but even then it was apparent that the 3500 exhaust brake was more effective. Appreciate your response, guess I'm just wondering if Ram/Cummins has tweaked something overall since 2017 or if what I am seeing is only on the HO.

All SRW trucks 13-18 had 3.42’s and all 19+ SRW’s have 3.73, that’s the gearing difference I’m referring to.

 

[Brutal_HO]

With the lower gearing in the AISIN HO, the exhaust brake should be working down to 2nd gear around 12-13MPH @900RPM. Mine does.