Sizing leaf springs

I would like some help sizing replacement leaf springs for load without lift. Completely bottomed out with trip gear, OK for standard driving but saggy hauling any significant building materials.
Read a lot about spring rates and pounds level load without understanding how to select for my purposes clearly.

I want to minimize lift as my handicapped wife has trouble getting in as it is.
Would the Hellwig adjustable helper spring (EZ990) do the trick?

Also: will the OEM shocks work or does the travel distance change and require replacement shocks as well?

Newer 2023 Tacoma SR5 4wd auto 6ft bed dual cab 3.5L,
all stock except for full aluminum skids and factory continuous running board/steps. Also Sumo bump stops under leaf springs. Say 100#.

Driver and passenger 300#. Do we include or exclude in calcs?

Standard load 80% of year: DCU contractor cap, rubber mat, everyday tools- about 400#
If I size springs for hauling materials I would say a 600# load.

Trip load 20% of year but 50% of yearly mileage: base load 400#, add 600# gear plus 280# hitch load, making gross load #1280 or more. Toyota is coy about max load but with passengers we're right on it.

Looking at helper springs, replacement springs, and progressive replacements.
Air Lifts were suggested but I read they are not a replacement for proper spring sizing. Is that correct?
I'm very disappointed with Toyota as my 2012 bare tacoma stock setup handled the exact same loads just fine with spring to spare. This 2023 is a real lightweight in many respects, lots of plastic.

 

Airbags would be my choice for what you want. No increase in stock height but when aired up can handle the extra weight no problem.

Also as far as your 2012 Tacoma, was it a double cab long box as well? They all use the same leaf springs so saying a 2023 is a lightweight is wrong.

Edit: a 2012 single cab 2.7 weighs 3300lbs. 2023 double cab long box 3.5 weighs 4000lbs. So your new truck bone stock is 700lbs heavier than your old truck

 

Sumo Springs, air bags, overload springs, take your pick, pros' and cons to each. Most other spring options will have some lift depending on how loaded the truck stays. I'm kind of in the same boat, I need extra capacity, don't really want a lift and I've probably got 200# between the topper and some other stuff I keep in the bed. I just want better carrying capacity and know the stock setup sucks for that. I'm going with a set of heavy duty springs (500#) It'll be a little stiff when there nothing else along, but I'm not a fan of airbags although they work well for varying loads. The setup I'm getting is going to raise the rear up to 1.5" which was lost when a topper was added to the stock springs. If you carry 500# around all the time you probably wouldn't notice any height difference.
https://springworks.com/products/20...rerunner-heavy-duty-rear-leaf-spring-90-297hd

 

Appreciate the suggestion. If I aired these up four times a year for trips and aired down for normal driving that seems like a sound solution.
looking at https://suspensionconnection.com/firestone-2407-ride-rite-air-bag-helper-springs

Is there a downside to these airbag lifts? Anyone running something similar on a similar frame? Any issues?
Rather than installing an air pump system can I hard pipe an extension to a 1/4" NPT air fitting for manual adjustment several times a year.

The 2012 OEM had four active leafs leafs plus the bottom leaf. 4wd single cab basic model, not SR. Added the Sumo spring bump stops.
When I installed the skids on this truck first thing I noticed was it has thinner springs (just mic'd at 0.32") and three active springs. Added the same Sumo spring bump stops right off.

 

Photo of springs with minimum load. Are the Sumo springs the cause of going flat/negative bend?
Had the same setup on my 2012. Springs were arched.

 

I would say airbags are going to be your friend in this situation. Variable weight capabilities little to no lift.

 

Roadmaster Active Suspension is a good option too. Have been using for year and zero maintenance.

 

thanks folks! The Firestone Airbags look like a great solution and more affordable than a full leaf set. Would use an external pump.

Back to one of my original questions: If pump them up to the 5.5" to 6.5" height their instructions call for (Sumos are 3.5" high) what does that do to my OEM shocks?
Will the shocks work right or am I looking at shock replacement as well?

Roadmaster looks good too. I like the idea of the airbags as I can adjust different left-right loads. On trips we are pretty unbalanced with heavy gear on passenger side and handicapped transport on left (lighter.)

When I do this work, can I add a leaf to the OEM springs? They are totally flat now.

 

I had airbags on my last truck. messing with them wasn't that fun and I didn't care for cutting the bumpstops. Using road master now on my current truck. Only installed them this weekend, so far happy but no serious use on them

 

I think the truck rides better with them. What is your thought?

The have worked fine for me with unbalanced loads too.

 

So far seems fine. I also just replaced my shocks and lifted the truck so I dont have a good base line to start with. I changed too much at once but I dont see any negatives from RAS yet. The only thing I have put on the truck is two mountain bikes

 

You seem to want to return to stock height with a heavy load, so stock shocks will be fine, although not the greatest in the world. I suspect you will find about 20psi to be good for around town regular driving and about 40psi good for loaded trips. Stock shocks will be fine, if you want better damping upgrade them down the road

 

The airbags are only intended to bring the ride-height back to original (rather than create a lift), even if loaded. So entry height should be exactly the same.

Since you do not change the total travel (no lift), OEM shocks will be OK length/travel wise. However you may find that they are too weak if you are heavily loaded. If the rear is unsettled (bounces excessively after bumps/dips) when heavily loaded, you may need an after-market set.

- The airbags come with a valve fitting meant to be bolted through a panel. I drilled 2 holes next to the rear license plate and installed the valves over there. Floor pump (e.g. a bike pump) worked great.
- I ran these and removed them, but my reasons may not apply to you:
- I offroad a lot, and I installed the Daystar cups (allows the bottom of the airbag to be disconnected from the axle, for articulation). The added stack height of the airbags, mounts and cups consumed a lot of my available travel and therefore the setup bottomed, unless air pressure was perfectly set. Was not a problem on road.
- You need to remove the bumpstops to install the airbags, and I did not like that (did not like using the airbags as bump-stops). Again, an off-road problem, not an issue on road.
- Finally, I disliked the way the rear rebounded after heavy compression - the non-linear behavior of air springs caused violent rebound. A problem on big, high-speed bumps off-road, not much of an issue on-road.

Adding a leaf will be no issue. Try Headstrong Offroad. https://www.headstrongoffroad.com/

 

Appreciate these very helpful responses. Ordered the airbags.
Do the air bags essentially replace the leaf spring function or do I still need appropriately sized leafs?
I don't like that they're currently flat with no load. Are they so weak the Sumosprings are flattening them? Worried about breaking a leaf spring under load while on a trip. In the many past years it's happened twice but I don't haul the same machinery and millwork now.

I looked up some stats on old and new truck from the owner manuals. Various online references were sometimes different (erroneous.) What I could not find in my manuals was the Curb Weight for the 2023 and have inferred it from Kelly Blue Book listing.
Looks like I'm over payload limit on the new truck when on trips!

 

Its pretty normal for the leafs to be flat on tacomas. dont stress about that too much

 

Here is the jumble of crap Michigan Truck Springs 2cd day shipped to me. Rejected for potential damage, with rubber bellows being slammed by sharp metal edges.
MTS repackaged and shipped a previously damaged box in a second box sleeve, original contents protections appear to be missing. I went with MTS precisely to avoid the sort of Returned Goods shipments endemic to Amazon and the like.
I have to assume manufacturer Firestone includes some sort of wrapping and protection on the rubber and plastic components for shipping.
Can anyone who has bought these confirm that is the case?

 

I do not remember as mine were like 10 years ago but I dont think that they would pick any meaningful damage up being packed like that. the rubber is pretty heavy duty.