I haven’t really gotten into making videos. but here are some pics… And sure you can give me some props 
The main thing I did was just build the rig up from scratch. Lots of bones names …and fine positioning. UGHHH
I’m working on a 4x4 game so I expect a lot of roll overs. The simple vehicle worked fine but looked horrible with the wheels floating a foot away from the axle.
I also wanted leaf springs as I am making some old vehicles. Wasn’t sure that was going to work but it did.
I’ll probably need another rig for bigger/newer vehicles… That’s be a wishbone set-up.
Main issue was figuring out which bones did what.
So the:
Lower Arm dictates the radius the suspension rotates around. For my rig (as the axle is solid) I put that basically in the center of the axle.
Kingpin is attached to that. It always stays vertical (theoretically the top of it is attached to the top swing arm). In Unreal it doesn’t really matter, that’s all in code I believe. The hub, vis and phys wheel follow it to stay upright.
Upper arm is mainly for looks. The bottom of the shock follows it in it’s arc. Wasn’t working right for me, but my case is a little different. Visually on a wishbone it should be same length as lower arm and straight above it so the arms and the kingpin always stay together. ( I didn’t follow that and maybe that’s why rigging to the lower shock didn’t work for me)
A lot of the bones are unweighted, it’s all code stuff and they all follow each other accordingly.
The ‘shock’ bones (shock_bl, shock_fr) are sitting at 0,0,0. I thought maybe they were part of the code, so I included one. I don’t think they do anything. I also deleted the driveshaft as I have no exposed drive shaft to turn.
The steering linkage up front is purely visuals.
The main issues were:
Trying to reuse the old rig, and heavily reconfigure it and not getting bones zero’ed out. Working too long straight and just getting tired and confused and chasing my tail in circles.
Then I tried mirrored bones, another fail even after zero out.
Trying to weight my axles to the lower shock.
Putting collision models on my viswheel, instead of the Physwheel. (it was working but it seems like I was trying to tow a house, not traction barely moving.
Forgetting to set my attached wheels to anim BP.
And having my main BP be an anim instance, not a vehicle anim instance. (class settings)
So for my leaf suspension I just set the axle weights to the kingpin. The middle of the axle is 50/50% on both kingpins. This makes it follow them really nicely. I’m also going pretty low poly so I didn’t include a ton of details. The leafs are weighted to the kingpin 100% in the middle and fade off to the body at the ends.
In the wheels I ‘think’ the Suspension Force Offset is basically how soft it is. at +40 I seem to get no body roll. - 40 is a lot. 0 is probably a regular car.
Max raise is the sag (how much the car sinks into it. Max drop is how far the wheels extend.