Long Travel BS Thread

Caster change helps bump steer. Caster change also changes tie rod angles. The anti dive is how I was able to achieve true zero for bump steer. I was able to design the steering around caster/camber change to make it that way.

Without any change at the outer pivot, you will always have some degree of bump steer. While it may be an inch or less total under a perfect scenario. Bump steer will exist.

Caster and camber change have great impact on bump steer. As crazy as it sounds. Caster/camber need to work together with the steering to create perfect geometry.

I’m not a good teacher in this department so I apologize for my poor explanations. But I have a very, very good handle on how the geometry works and what impacts what. IFS gets pretty gritty when you get deep into it. Far far more complicated than any link setup etc.

 

I will have to keep learning I guess because that is hard for me to follow with my current understanding. Maybe with the inner tie rod mount being back from the outer mount it is able to match the combination of movement arcs at the hub?

anyway, I think it would be cool if you could put in a few bolt hole options for the upper so that people could play with antidive on their own. As long as changing that pivot slightly doesn’t trash other aspects of performance.

With a prototype it would be nice to just test what you like. And in production say someone has a different wheelbase, ride height, tire size, cog etc. they will have a little adjustability to get similar performance for different setups.

 

Bear with me here. Loooong post and my understanding of the concepts is there but my writing skills are not lol. I'm gonna take a step back and start with the concepts and then get back to how they apply to the answer yall are looking for.(this is more of a post but the quotes were part of my motivation for explaining as this will answer your questions)
There's two main concepts/principles behind suspension design. They're kinda one n the same with how much they interact as a vehicle is in motion, but the more things can get broken down, the easier it'll be to understand all the factors at play:
1. Suspension of the vehicle(and brakes) exists to turn the kinetic energy of the vehicle in motion into heat as a way to manage or get rid of it.
2. A vehicle is most efficient (read fastest) when the pressure/forces and all 4 tires are as equal, and thus minimal, as possible. Greater or uneven forces on any number of the tires causes an increase in friction. An increase in friction causes loss of speed and unsettling of the vehicle.
A vehicle takes fuel (heat/potential energy) and turns it into motion (kinetic energy/excess heat as a byproduct) as a way to move things like people and stuff. Because of things like war and the profitability of oil/electricity production we've really really quickly gotten really really good at producing the motion part of it with things like ICE engines and electric motors. Everything else about the vehicle is about slowing down that motion or controlling it for efficiency and to keep the vehicle and it's occupants steady. Suspension (comfort and efficiency) isn't as profitable. Hence we are still a hundred or two years behind. Hell some parts like leaf springs even predate the motion creation but are still in use in almost exactly the same way.
Now we get into how we design suspension to achieve these functions! There's two ways. Again they're both used together most of the time but to make it easier to understand i'll break it down:
(A) Mechanically
(B) Hydraulically

(A)Mechanical solutions(F1 suspension, most on track racing) use elaborate levers, linkages, and mechanical resistance (friction from binding, plastic deformation from twisting) to absorb and get rid of the energy. Think torsion bars, sway bars, springs, etc.. ...yall know most examples. They are the most commonly used because they're somewhat necessary, you need at least a few mechanical connections for suspension function, and because they're EASY to deal with and understand. All the parts are right there. They bolt together and apart. You can see and understand the ways they function by just watching the parts move. It's obvious when they don't work; parts wear, or go snap and bang, or throw the vehicle around.
But mechanical solutions aren't good at the job. The more you try to achieve with them, the more complicated they get physically and the more difficult packaging becomes. A lot of the functions that they rely on to work cause the materials and parts they make to break down. !!Most importantly, materials with qualities that avoid breakdown of parts, like great toughness, tensile strength, and thermal conductivity, don't store energy well so they don't provide a large window for controlling how and when the kinetic energy is absorbed and released!! For example a leaf spring (without a hydraulic shock) that's tough enough to hold up for a while will not provide much control because it absorbs energy well but doesn't release it well. A coil spring is better because it has a much greater surface area by volume of material so it will shed the energy as heat better but still not great on it's own. Every joint holds energy from friction so they're all wear items eventually, the less directly they transfer forces the worse this effect is. Engineers will often lean into this and design joints in a way that they intentionally bind and/or use softer less thermally conductive materials so they sacrificially absorb more energy. (@906taco and @Evenflow this is the start of answering your question) We see this all the time with our trucks to the point where we mention you need the time and the money to replace joints more often when people ask about long travel. All those joints can only receive so much energy and heat cycles before reaching plastic deformation. Especially joints like the UCAs that are intentionally set out of alignment to create more friction and absorb more energy during certain vehicle motions like dive.

(B)Hydraulic solutions(Mclaren, Citroen) use hydraulic resistance to absorb the vehicles kinetic energy into heat and then radiate that heat to get rid of it, or are used as pastes and lubricant to control the spread of heat(yes grease and oil on joints are a hydraulic form of controlling the kinetic energy of a vehicle). They aren't used as extensively or developed as well yet because they aren't as easy to deal with. The fluid has to be contained; doing so reliably is very difficult. Because of that it's not as easy to just look and see how well they're functioning. The systems must be pressurized to avoid cavitation. Problems like leaks can creep up on you and be hard to detect if small, catastrophic and messy if big. Tuning and development is mostly trial and error as fluid dynamics aren't as simple or well understood as mechanical forces. There's probably more i'm forgetting by now.
But they're great at the job. It's easy to transfer energy to a fluid as heat by creating hydraulic resistance with valves. Fluids have low specific heat capacity so they store energy well and regulate pressures extremely well -- this offers a very broad range of control and adjustment of energy transfer through volume, viscosity, added pressure. Energy losses during transfer of energy are very low compared to mechanical joints. Packaging constraints are minimal since tubing allows energy and pressure to be transferred easily.
To understand the differences further think about aircooled vs water cooled cars, motorcycles, computers. It's all just heat control and mediums for doing it with. Suspension is going that same direction but the development just isn't there yet cause it doesn't need to be or isn't profitable. We're on our own in the offroad community

So to get to the answer of why people shit on taking a mechanical approach to antidive. It's just that it's not as great of an option for controlling it as it seems anymore now that it's not really the only one as hydraulic approaches are getting better like bump stops and bypass bump zones. It works and has some adjustability but adds a now unnecessary sacrificial part. I don't think it's that big a deal either but i can absolutely see while people want to chase as 'clean' of travel as possible and i see that being sought out more in the future as suspension design develops.

As for the trophy trucks. TBH they're on some hillbilly shit compared to most other high level motorsports with a lot of things like materials, aerodynamics, and in some ways even suspension. BUT there's a couple things they do really well like safety and using a blend of mechanical and hydraulic systems with their suspension. This is just speculation from here but the idea to start using big shocks is credit to the guy behind Fox and pushed later by the guy behind Custer. iirc both were successful engineers so i like to think those moves were planned ahead. Like they knew they were gonna need shocks at least somewhat, so may as well try some steps forward with em even though the development of hydraulic systems was even more far out in their times. But i don't think the modern suspension blend they use was as planned ahead. To me that seems like it's more of a product of chasing reliability. Which is what the trophy truck guys do best by far, and i think is how they've come to the conclusion to use mechanical antidive but only a small amount. It's probably a very slowly developed approach with trying different angles, uniball sizes, shock tuning, and is what they've come to for the best trade-off of performance and reliability for one race at a time. Again just speculation from me but i think it's a safe guessplanation
Anyone that read all this, thank you

 

IFS/IRS 4wd with 30" of travel. Street legal

 

Has anyone successfully made a internal roll cage that isn't loud? Filling it with foam or wrapping it? Is it possible?

 

It’s not happening. And if you fill with foam you’re absolutely effed if you ever need to add something or do repairs.

Cages add lots of noise. All there is to it.

 

Yes but only when paired with noise cancelling headsets or helmet.

 

I would have such a hard time with headsets I feel lol. I’ve spent my entire life driving manuals strictly based on sound. It would be a hard one to overcome lol

 

100% true. It took a while to get used to. But now I absolutely love it.

 

this is the way... can't drive my truck without them on....lmao...doesn't help that i ripped the stereo out of the truck as well.

 

Then you got me over here with all 4 windows down and avoiding using my AC cause it changes how the engine sounds

 

I cut my noise level in half by adding 2 inch foam covered in fabric on top of 2 layers of kilmat. But the clicking noises of the rear bypasses though a bit quieter now still never quit clicking. Just gotta get used to it. You can see in the pic some of the rear wall foam before I covered it.

 

tell me more about that absolutely smashing king hat

 

They sell them at pretty much any event where they are a vendor. Think it was either 20 or 30 bucks. Now You Know!!!

 

I may have to give this a go at some point. Conversation is not happening at 55+. And hardly at 35.

Engine cage definitely doesn’t help matters. I can hear fluid entering my assist ram next to my head.

 

Anyone have feedback on the uniball lower ball joint conversion from TC for 1st gen tacos/3rd gen 4Runners? Are folks really blowing through ball joints that easily?

 

@chrslefty should have some feedback. I know he’s running something similar.

 

Yes they are. And 100% the best thing money can buy to prevent it. Such a cool design. Makes it nearly impossible to shit out.

 

Can’t decide if the change in tie rod angle worries or excites me without having one to cycle. Hopefully someone can chime in on that. I’ve seen some guys tweaking factory brackets to accept uniballs. Guess that’s the only other option out there.

 

Lbj failure is common for this platform.

If you maintain it, I think it is not a massive issue. Use a torque wrench on the bolts and use the black oem bolts with washers torqued to 39ft-lbs. most people preach oem joints, but they get loose as fast as some aftermarket ones so I don’t think it really matters.

I have never had a failure in 100k miles on the platform and beating up on this thing, uniball also doesn’t prevent bolt failures which I think happen just as often especially offroad when you may have to undo the bolts often.

Would be interested to hear @theesotericone thoughts… he put this platform through more than most and I think he had a few failures.

I consider doing the upgrade mainly so I can swap to full heim tie rods.