Leveling the rear with lots of hitch weight

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vtl

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Hello,

5 of us are taking a long trip to Newfoundland this summer in 22 Sequoia TRD PRO (thousands of miles of mostly paved roads).

With the third row up, the cargo is good for maybe two twelve-packs, so I've got a Yakima EXO system with two 100 lbs storage boxes. I'm also transferring Yakima LoadWarrior roof steel basket with two extensions from my Volvo wagon. Now, with all that added weight, I know up front the Tree will be squatting in back. To counter that up, I bought Timbren SES. But the more I think about it, the lesser I like the idea of riding atop rubber shocks. So the only way out is replacing rear coils with the heavy duty version.

And here I need a second opinion. I'm planning to go with Dobinson 1.75" coils, which claim to have a factory compression rate. The idea is that with all extra load on hitch they will sag to about a factory ride height. However, having experience with HD springs in past, they imminently butcher the quality of ride, even after taking extra weight, which I'm definitely not looking for. What people think about their Dobinson coils? Is your rig riding much firmer or it's about the same?

One more option would be to keep the factory coils and install spring spacers, like Wescott Design. But I've been there as well with my other rigs and would love to avoid going this route if possible.

What fellas think I should do?
 
IMO - air helper springs are better than rubber overload springs. It's just a better way to fix the same issue. And cheaper. No need for a compressor or any fancy electronics. The $120 Firestone kit and a bicycle pump is all you need. And you can deflate when not hauling heavy and get back your normal ride quality. When inflated they both add additional spring force but also expand out to somewhat bind the coil springs so you end up with a significantly firmer rear end. It's kinda ideal for hauling heavy stuff and towing on the highway. It's not my ideal choice for offroad hauling of heavy stuff or to use for a low cost lift. For that - swap springs. I often swapped springs and/or air springs for different uses.

If you buy a set of the compact spring compressors, it makes installing the air springs super easy. But you don't really need anything but a blunt tool like a tire spoon to jam them into the coils. I'd plan on maybe 2 hours to have plenty of time to put them in, plumb the air lines, etc.

My only tip is to buy the Firestone kit instead of the Airlift one. I've been through 4 different sets of air helpers in different vehicles and I find that the firestone are just a little better. Not a lot. But hardware and fit is a bit nicer and the bags have less friction on the coils when empty due to narrower diameter in the applications where they go inside the coils. So I would pay the extra $5 or so between the two options for the Firestone version.

Good luck.
 
The 1.75" Dobinsons coils are most definitely stronger than stock. See attached comparison. I don't get ride quality complaints unloaded on those.

If you don't need lift, I would just add airbags inside the stock springs.

Spacers wouldn't help, they would just add height.

Sequoia-d.png
 
Jetboy said:
IMO - air helper springs are better than rubber overload springs. It's just a better way to fix the same issue. And cheaper. No need for a compressor or any fancy electronics. The $120 Firestone kit and a bicycle pump is all you need. And you can deflate when not hauling heavy and get back your normal ride quality. When inflated they both add additional spring force but also expand out to somewhat bind the coil springs so you end up with a significantly firmer rear end. It's kinda ideal for hauling heavy stuff and towing on the highway. It's not my ideal choice for offroad hauling of heavy stuff or to use for a low cost lift. For that - swap springs. I often swapped springs and/or air springs for different uses.
Click to expand...
Yeah, I was considering those. The big downside is I live in New England where in winter we get a few snow flakes packed between all the layers of road salt. Any unpainted metal rusts in a blink of an eye. I'm afraid those air bags will rub against the coil's paint and accelerate rust, which will eventually cause coil to snap. I've seen those snapped.
 
I'm sure it'll rub on the springs. I imagine it'll also polish the rust off. But I'm not sure how much it'll shorten the life. I've never had an issue with spring rust, but it's just not a thing anywhere I've lived.

Coil springs are cheap and easy to swap. But it'll be a pain if they fail when you're not expecting it.
 
I wish I could buy Nivomats for Sequoia... Installed them on my Volvo wagon, they are awesome both in simplicity (no compressor, no nothing), comfort and load capacity.
 
Nivomats seem like an interesting idea. Not necessarily what I'd want, but I can see the utility for some vehicles. I'd bet there is a version of the monroe air shocks that would work. I don't think the shock damping is all that great. But neither is the OEM shock, so it might not be a big difference.

I wouldn't recommend this for temp use, but I have done it. You can OEM air bags to fully replace the rear coils. I ran GX460 air bags in my 2015 4runner for a few years. It takes some custom fabrication to adapt the air line to a common air brake line size to then go into your compressor manifold. I can describe how I did it if you wanted to do that. I have a writeup somewhere on it. But it's a lot more involved than simple air helpers. You'll need to either buy an air ride system or design your own and if you want self leveling, you'll need a set of sensors and a more complex control unit. The way I designed mine was with a compressor and a custom manifold that had set of wireless solenoids to adjust each rear side, a solenoid to open a cross vehicle air path with a flow restrictor for when I was offroading and wanted max articulation, and a dump valve for each side also with a flow restrictor slowly. The result was the ability to adjust height, side so side, and also open or close cross vehicle transfer. IMO this only really works well with something like KDSS though because you still need that big heavy sway bar to help with body control. And I found that I didn't love the highway ride because the air bags are very progressive and shocks with damping profiles for linear springs had too much rebound damping and not enough high speed compression damping for a comfortable ride. It was soft - but also uncomfortable. Hard to explain, but overall I loved it off-road, didn't love it on road.
 
Unfortunately, her ride is TRD PRO, which means FOX shocks with external reservoirs. It rides super nice both on and off pavement. For day to day use I would love to keep it as close to stock as possible.
 
Jetboy said:
IMO - air helper springs are better than rubber overload springs. It's just a better way to fix the same issue. And cheaper. The $120 Firestone kit and a bicycle pump is all you need.
Click to expand...

I‘m all ears on where you can get Firestone bags for $120. I have Timbrens in my truck now, but usually run air bags. I’ll take a few sets at $120!
 
Oh. Those aren’t what I’d call airbags. I mean, they are, but I was thinking of actual bags that mount to the axle and frame, rather than the coil helpers.
 
joseywales said:
Oh. Those aren’t what I’d call airbags. I mean, they are, but I was thinking of actual bags that mount to the axle and frame, rather than the coil helpers.
Click to expand...
There's no other way to do it on this type of axle with coil springs, not unless you want to fab some stuff up. These operate basically the same way as what you're describing.
 
crikeymike said:
There's no other way to do it on this type of axle with coil springs, not unless you want to fab some stuff up. These operate basically the same way as what you're describing.
Click to expand...
I realize that. I’ve never bagged a rear coil truck, so was unaware that style was so cheap. The lack of needing any brackets obviously saves a ton of cash.
 
YMMV - I have Timbrens on my 2012 sequoia and tow a large camper + 6 people. Works great. I have no love for aftermarket air bags due to my experience as an auto tech removing / replacing / maintaining them for customers. With timbrens, just install them and forget they were ever installed. They work when needed, truck acts normal when the vehicle is not loaded.

I had the dobinsons springs on order for many months, but they are on forever backorder, due in the USA in June/July 2023 was the last I was told. Dobinsons are great, I sure wish they were actually available in the USA when needed.
 
Ok, Dobison 1.75" are out of stock now, 2.5" with 600 lbf/in rate might be too much, so I just put an order for ARB 2684 2" springs with 320 lbf/in rate. Hopefully 2" will not squat more than 2" under the load.

Btw, this is the stock TRD PRO springs (are they any different?) with Yakima EXO and two empty 10 sq.ft boxes. The rear lost about 1/2" already.

1.jpg
 
vtl said:
Ok, Dobison 1.75" are out of stock now, 2.5" with 600 lbf/in rate might be too much, so I just put an order for ARB 2684 2" springs with 320 lbf/in rate. Hopefully 2" will not squat more than 2" under the load.

Btw, this is the stock TRD PRO springs (are they any different?) with Yakima EXO and two empty 10 sq.ft boxes. The rear lost about 1/2" already.

View attachment 3308817
Click to expand...
Good luck. Those springs you ordered are Land Cruiser springs for a straight axle, and you have IRS which requires a strong spring rate for how and where the springs are mounted. That's why they're half the rate, because they're not made for it.
 
crikeymike said:
Good luck. Those springs you ordered are Land Cruiser springs for a straight axle, and you have IRS which requires a strong spring rate for how and where the springs are mounted. That's why they're half the rate, because they're not made for it.
Click to expand...
Darn... Asked to cancel the order. Thanks for catching that!

So, the only two options are Wescott Design 1" spacers and 2.5" Dobinson coils. Hmmm...
 
vtl said:
Darn... Asked to cancel the order. Thanks for catching that!

So, the only two options are Wescott Design 1" spacers and 2.5" Dobinson coils. Hmmm...
Click to expand...
Yeah, I'm not aware of any other brand making a proper spring for them. The fella up above said he has the Timben SES and that has worked well for him, so that's another option.
 
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