I finally have time to get back into this build. I started cutting the brackets off of the Y61 axles in order to prep them for custom
So I have been playing around with 4-link calculators and reading up on designing the 4-link setup. Whilst I understand the terminology in principle I am still at a loss as to what numbers/setup I should be shooting for in terms of Anti-Squat/Dive, Roll centre and instant centre and so forth. Also I donít know when it comes to a 4-link setup on the front Vs rear is it beneficial to have more or less of the any of the above.
I appreciate that any design or setup is basically going to be a compromise between what the ďperfect numbersĒ are, what is physically feasible on the truck and then with the Ultra4 factor (high speed rough stuff vs low speed technical climbs and obstacles)
I'm going to throw out my understanding of the principles and how I understand them to affect handling. If anything is wrong, please correct me. My understanding is purely from reading up online.
1. Roll Centre
I understand that a high roll centre will have less body roll than a low roll centre. Which would be good for off camber situations and help keeping body roll in check which would make the rig more stable. I also understand that a low roll centre will articulate more freely transmitting more force into the shocks vs a high roll centre that will transmit more force into the body. So for high speed whoops or rough hill climbs a low roll centre would be better.
To confuse things a bit more the roll centre isn't just a point but also an axis. So it's possible to have it horizontal, sloping up or down. From what I have read a flatter roll axis will have less roll induced steering when articulating.
Based on the above Iím thinking that for my application i want relatively low roll centre with a flat roll axis, I canít see any benefit to roll induced steering. The reason I am thinking low is that I want to be able to soak up bumps on hill climbs and the rough stuff at higher speeds. I am also thinking a decent sway bar could help combat excessive body roll from having a low roll centre. Am on the right track with this?
2. Anti Squat (AS)
Ok so, Anti Squat refers to the ability for the suspension to resist the tendency for the shocks to compress under acceleration. 100% AS means that acceleration wont input any force into the shocks. So a bit of squat can help the trees dig down and find traction. Too much can result in wheel hop. Not enough can make it harder for the rear wheels to find traction.
Iím thinking a bit of squat is good, but not to the point that if Iím trying to climb up a steep rocky climb the back end is going to squat down and pitch the front end up leading to backwards roll overs. What I donít know is how much is good? I know itís fairly easy to adjust AS at the chassis end so when I build the mounts Iíll put in a few additional holes to be able to adjust it up or down. But how much should I be shouting for as a starting point?
3. Anti Dive (AD)
So this is the ability to resist diving under braking. Iím thinking excessive diving under braking, especially on steep downhill sections wont be good and could pitch the truck over. I canít think of any benefit to not shooting for 100% anti dive or at least as much as I can build into the system. Am I missing anything?
4. Instant Centre
I donít have much to say on this. I know the further forward or further backward it is determines the AS and AD numbers.