Riding low

Get taller tires if you want instant lift. Nothing else will ad lift under the diffs....

 

I don’t off-road but since it’s a work truck and often carries loads it routinely hit the bump stops even with lighter loads (some freeway overpasses have abysmal approach ramps) so I added air bags as a lightweight method to solve the problem. It works great for me(5 years of use) but there are other solutions that might fit your situation better. Weigh the trade offs since every option has them. Bags, Sumo Springs(a fixed spring rate version of bags), add-a-leaf springs, leaf packs(strong but heavy and stiff when you’re not loaded. Way too much to cover in one post especially by just one member so the more reading you do the better informed your decision will be. My personal opinion is weighted towards allowing the suspension to retain its ability to absorb shocks by flexing as needed without hitting the stops and Your needs will define the parameters of your choice. I’ve also seen the consequences of overloading on other vehicles and it can’t be overstated, that weight lands somewhere and can’t be eliminated. Suspension mods can at best assist the truck to operate better higher in the safe load range rather than nose high soft or nose down stiff. Don’t forget to adjust headlights accordingly.

 

It’s the springs/leafs that support the load. Shocks just control the re bound.

 

I think I know what you were trying to say, but what you said is misleading. Shock absorbers dissipate kinetic energy both during compression and extension (aka rebound).

There is a accutune article that discusses the common misconception that solving a “bottoming out issue” is about springs when it’s actually more commonly better solved by shocks. I can’t find it at the moment.

Filthy motor works has a decent video as well.

 

Ha! Well, I wanna see you revalve the stock rear shocks to prevent hitting the bumps.

 

I’d agree as far as this: If the springs are inadequate to the load then likely the shocks are as well but I wouldn’t go as far as saying that shocks can resolve the issue alone. Paying attention to both isn’t wrong though.

 

I’m not disputing that springs matter. I was trying to clarify that shocks mater during compression and also point out that people tend to focus too much on springs as the solution.

 

It’s pretty well established that these trucks in just about every stock configuration are on the soft side so yes, people focus on load management and ride height first. Threads on shock mods may get undervalued though(maybe not the wording I want). I’ve seen little in the way of recommendations for shocks that are for weight alone rather than in tandem with a lift. Same travel but larger diameter with more aggressive valving.

 

I don’t have any numbers about damping and spring rates to offer, but if you watch trophy trucks race you will notice they have a really low ride height compared to their 30+” suspension travel. That leads me to believe that they have a low spring rate. Yet they are able to catch multiple feet of air and land comfortably. That I assume is the shock absorbers doing their job, not the springs.

As far as I know, trophy trucks don’t have a progressive rate suspension geometry like on the rear of a dirt bike so the effective spring rate is constant, but I could be wrong.

I realize this isn’t 100% applicable to daily driving pickup trucks, but I do think it is food for thought on the current subject.

 

I certainly wouldn’t mind seeing more on the subject that filled in some of the missing pieces. I upgraded to Bilstiens but no further since no lift and I’ve seen no threads on any options without one. For our trucks to do anything approaching that the shock mounts would need to be massively upgraded. The usages aren’t comparable.

 

The way I understand it is that springs are going to carry the load. They are the muscle. A shock controls the dampening. It imposes a speed limit on the shock. It slows the impact and keeps a control on the rebound. For the impact stroke, the shock has little bearing on the load but with an important exception. It should be on the spring to absorb the impact and bear the weight. The exception is when the load starts approaching the max rating of the spring, which will in turn affect the speed of suspension travel, which in turn will affect the dampening rate of the shock.

A shock does not necessarily have to be beefy for a heavy load on a matched heavy spring - though I could see where the rebound would need to be matched. (In the same scenario, a heavy load on a heavy spring might have the same rate of uptravel as a light load on a light spring, but the down travel is going to be radically different.) What really kills shocks is when the piston is generating more heat than it's able to shed. So a heavy load on highway - no problem. A heavy load on washboard - big problem.

I had the same thoughts when choosing my suspension. I wanted towing shocks and a leaf pack that could handle variable weight. I've towed on the stock hitachis, and they did fine on road. Off road they were miserable, but that's no surprise to any Sport owner. That's the justification on why I bought the 6112/5160 over the 5100s. Their bigger size does a better job at shedding heat, and their digressive dampening is better suited to variable weight and towing than the linear/progressive styles of other off-road shocks.

 

A shock absorber is a damper that converts kinetic energy to heat via viscous friction. You can also think of damper as a device that applies a force that is proportional to the velocity of the mass and in the opposite direction. When the suspension is compressing, the shock absorber resists the motion. The faster the compression, the more it resists. On the other hand, a spring applies a force proportional to the displacement in the opposite direction of the displacement. The greater the compression, the more it resists. Both springs and dampers resist the compression of the suspension, but in different ways.

More info here:

https://en.wikipedia.org/wiki/Harmonic_oscillator

 

Love my medium duty Dakars. They love just a little bit of consistent weight in the back and still ride fine empty. Had issues with my OEM leaf springs as they really left a lot to be desired...

I second not going over the vehicle ratings even with a new setup... This just helps make it more comfortable and stable

 

Bilstein 5100’s and a new leaf pack would do wonders without breaking the bank.

 

Bro, what you need out back is more spring rate. Do yourself a favor and get our Add-A-Leaf, top quality Made in USA, and very affordable. Read the description and my experience with the AAL here:
https://archivegarage.com/shop-archive/ols/products/2005-tacoma-traveler-aal

There are a lot of options out there, and a lot of them have compromises.
Give us a call to help sort through the choices

 

To add a little fuel to the bump stop/shock/spring fire: Assuming that OP isn't jumping the truck, but rather facing sudden compression of the suspension due to change in road grades, he probably needs lift and shock changes for his needs. He needs to give the suspension access to travel when loaded, so that the shocks have adequate travel to bleed off the energy over a longer stroke. If you've only got 2" of uptravel from ride height when loaded, adding 1-2" of lift will increase the ability of the shocks to compensate by 50-100% even without changing shock valving. I suspect some suspension lift over factory will improve the ride when loaded.

 

I think this is the answer. When fully loaded I’m feeling like I’ve got a very short travel before a big boom on the bump stops. Been packed relatively light but two adults + a dog, moderately plush camping gear, 21 gal of water, 10 gallons of spare fuel… if I’m only going to do that once in a while it was workable but on a big fun trip the last thing I want to be doing is slowly eeking myself over really moderate trails. Sounds like I do need some additional travel, valving, and spring rate if I want to load up to the gills and have fun offroad. Gonna save up for a bilstein 6112/5160 + medium Dakar or icon multi rate AAL. In the meantime just gonna send it until something breaks . Thanks for all the help Toyota fam

 

Hitting the stops isn’t doing your axles or bearings any favors. Sumos might be a temporary option which you might pick up new/used and/or sell later and is easily diy in an afternoon. A trip full of hard hits doesn’t sound very relaxing.

 

I noticed similar driving around town on sagged factory shocks and springs. I swapped only my springs to new OME 885/895's and with factory (still ancient) shocks they did a much better job of controlling the vehicle and preventing bump stop hits.

 

I have 6112/5100s, icon aal and 255/85r16s. It's awesome. Before that I was bottoming out all the time with all my extra weight from the sliders and skids