New member here. Haven't hit my reply quota to post my own thread. This one seemed to be the best fit. Hope this doesn't come off as a thread hijack.
I have a '19 TRD Pro (Fox Shocks are OEM on this model/yr). I'm getting the below list of upgrades installed and got to wondering at what load capacity should I consider upgrading the suspension?
It's worth noting I plan on doing only light offroading (logging roads etc) but with an additional 700 lbs of people, dog and gear onboard when I do.
All in it could be up to 1,185 lbs of added weight.
Upgrade list w/ weights
- Prinsu Full Roofrack +75 lbs
- CBI Sliders +140 lbs
- CBI Rear Skid Plate (alum) +50 lbs
- SSO Hybrid Winch Bumper (alum) +40 lbs
- Warn Winch (synthetic) +30 lbs?
- Truck Vault drawer system +130 lbs
- ARB Twin Air comp +20 lbs
You can calculate the height change from the added weight pretty easily.
In the front the OEM springs are about 550lb/in. There's 2 of them but they have a leverage of 2:1, so effectively the front suspension has a combined spring rate of ~550lb/in. If you add 225lb to the front, it'll sit about 1/2" lower. If you add 550lb, it'll drop 1 inch.
In the rear all 4Runners (except limiteds) have 180lb/in coils stock. And there are 2 of them, but no adjustment like the front, so combined the rear suspension is 360lb/in. If you add 360lb to the rear, it'll go down 1".
So you can calculate from there how much it'll drop depending on what you do. There are two factors that will change height - taller springs or stiffer springs. You can choose the combo that works best for you. For off road performance - it's almost always better to have a longer softer spring than a shorter stiffer one. For the ability to haul a lot of weight, then you would tend toward the stiffer spring. So you'll have to compromise with any choice between weight carrying ability and giving up some comfort.
That's why we typically end up around 600-650lb springs in the front or a little higher. That's about the sweet spot for performance and ability to handle changes in load without too much sag. In the rear, it depends again on how much you want to haul, but around 200-250lb/in is tends to be as firm as you would want without being harsh unloaded.
So... you should decide what ride height you want empty, how much weight you'll likely be carrying loaded up, and then decide what spring rates and lengths you want to match what you're wanting to do.
A lot of people use air springs in the rear to help with the extra load when they're going for extended trips with a lot of weight. I have run a couple different air spring alternatives. IMO - if you do it, I'd spend the extra few $ on the firestone set over the airlift. The firestone bags are narrower and cause less binding on the coils when empty. Both work about the same with a load.
