In my downhill days, I used to run JimZ speedhangers with spherical bearings. They were probably the most precise, no-slop trucks I’ve ran. I did run them on 35 degree baseplates, and I think because of this I never really had any problems pushing 55mph+.
Last night I swapped out my TB218 stock pivot cups with some 100a riptide wfb cups. The difference these make is phenomenal… It was unexpected how much better responsiveness these provide, and how leaning really does just = turning now… No more wiggle in the cup. Combined with my nylon surf key things, precision washers, these are nearing as precise as I would ever want, even compared to using sphericals in the hanger like my old dh setups.
So, all this got me thinking… I haven’t experienced serious wobbles in years. Last night some wobbles tossed me off my board when I was going pretty quick. I feel like had I not replaced the pivot cups, I wouldn’t have had nearly that bad of wobble at the speed I was going, as wobbles I’ve gotten on the old pivot cups at that speed were never uncontrollable.
It’s my opinion that precision is great, but maybe only to a certain extent. That small bit of slop I feel like would have absorbed, or nullified the start of the wobbles. Once these started though, even my normal noodle legs, relaxation, leaning, none of it had any effect- it just immediately took over and threw me off in a split second… I don’t even see how I could have absorbed the start of those wobbles last night.
Since I love the responsiveness, I’ll keep the pivot cups. Since I love the turning, I won’t be de-wedging my rear more. I’ll be gearing down to max out at a more reasonable speed instead of introducing more slop just to feel safe going fast.
What are your guys thoughts? Ultra precise turning for safety or does some slop actually help cancel out the imperfections of human control?
My thoughts are if your trucks took over, your bushings are too soft and kingpin is to tight with a soft bushings. So the bushing likely binded and we’re amplified by any torque vectoring from the motors
Step up the duro of your bushings.
Evo on 180 trucks I run super loose setup. Like pretty much all my decks
86a wedge board side with flat washer. 86a barrel rear roadside precision cups, 83a front roadside precision cups.
Pretty much most of my electric builds are 89 or 90a all around with same kingpin tightness as above setup.
Every time I’ve gotten wobbles, it is due to a bushing over compressed trying to compensate kingpin tightness for motor torque vectoring (amplifying the slop). And stepping up a duro from what I’d normally run analog fixes it every time.
I don’t like truck slop either…but I like loose setups, rear wheel drive does some weird voodoo and can over amplify something you would normally carve out on a rail analog.
For your anecdote w/ your pivot cups, less slop in the pivot should reduce wobbles and promote control.
I think its probably some other factor, or coincidence, that caused the wobbles to happen.
I just understood Chinese while he was explaining the slop thing! Anybody here can explain this better? So hes trying to say that the truck hanger moves say 8 degrees on either side w.r.t. the kingpin and then you loose 4 degrees at 45 deg baseplate angle? Is slop a dead movement? Thought the slop is a shift, mostly due to a less restrictive bushing seat …
So what happens is when you’re turning you actually put huge amounts of side loading on the hanger, so even though getting it to move takes a lot of force on a table top, when you actually have your wheels down on the road the hanger is going to be moving the same way, depending on how hard you are into a turn.
So even though its not free movement, thats still slop.
And its not just from sliding in the bushing seat, its also from sideways compression of the bushings, compression of the pivot cup, or even the kingpin moving around in the baseplate. That last one is why people will sometimes use a knurled kingpin
That loss of turning from slop isn’t so much relevant when talking about going straight and getting speed wobbles, but more about the responsiveness while holding lines, or your minimum turning radius.
So for instance a 45 degree truck without any slop might have a turning radius similar to a 50 degree truck with slop, but while still maintaining the same leverage advantages and stability of a lower angle truck.
So what happens is when you’re turning you actually put huge amounts of side loading on the hanger, so even though getting it to move takes a lot of force on a table top, when you actually have your wheels down on the road the hanger is going to be moving the same way, depending on how hard you are into a turn.
Yeah, that’s what I understood.
So even though its not free movement, thats still slop.
And its not just from sliding in the bushing seat, its also from sideways compression of the bushings, compression of the pivot cup, or even the kingpin moving around in the baseplate. That last one is why people will sometimes use a knurled kingpin
Well completely forgot about the rest :). Would it be still an issue if you press the KP into the baseplate (e.g. very tight tolerances)?
That loss of turning from slop isn’t so much relevant when talking about going straight and getting speed wobbles, but more about the responsiveness while holding lines, or your minimum turning radius.
So for instance a 45 degree truck without any slop might have a turning radius similar to a 50 degree truck with slop, but while still maintaining the same leverage advantages and stability of a lower angle truck.
It does make the thing a little more clear. So, in order to minimize slop you wanna preload the pivot cup (and use appropriate materials), restrict the bushings and have higher tolerances on the actual KP. An insert bushing should also reduce slop, right?
An insert bushing can reduce slop of a poorly designed bushing seat that is oversized and doesn’t properly hug the bushing. But a proper bushing seat is > then a insert/spherical.
