Zebra Board Steering Stiffness

[JulianS]

Hi guys,

due to my budget constraints, I am limited to a cheap Zebra Kiteboard right now. It’s basically a long longboard truck with a standard Kingpin. (Pictures attached). I machined a motor adapter and reused some existing kit to attach a belt drive. However the steering is quite stiff. I managed to get easier steering my loosening the kingpin nut as far as possible which gives the whole system a lot of play and makes it wobbly af. Also compensating the torque steering I get from my single motor setup is very straining for my feet. (Leaning forwards constantly).

Is there any way to make the steering easier without increasing the play? Different bushings maybe? Has anyone ever worked with one of those? Yes I know the best option is to invest in a set of Trampa spring trucks, but I dont have that kind of money right now

[Narnash]

As long as it uses normal sized bushings I would recommand going for good quality riptide bushings, if you want smooth easy turning you can experiment with some wedging, too. I think you can go with quite soft bushings (compared to regualar trucks) since the hangers are very wide thus your leverage on the hanger is small. With that single drive and those trucks you are basicly limited to “all terain” anyway, so soft bushings shouldn’t hurt stability to much.

I think, even though these are no normal trucks, that @Alphamail can try to recommend you something if you can give him the bushing sizes.

[JulianS]

Thanks!

Bushing Measurements are: Bottom Part: 25mm outer diameter, 9.4 mm inner diameter, 13.8mm height Top Part: 23.8mm maximum outer diameter (cone), 19mm minimum outer diameter, 9.4 inner diameter, 10.7mm height Washer: 10mm inner diameter, 23mm outer diameter.

I already seem to have wedges in:

I will try to put them in like so: https://www.reddit.com/r/longboarding/comments/1cgv4v/how_to_properly_use_wedge_risers/

[baxter]

You could add another motor on the other side to cancel out torque steer

[JulianS]

[pixelsilva]

I like your axel extensions. Are they 10mil thick?

[JulianS]

Not mine, came with the board its one continuous axle with spacers (grey aluminium), its 9.25mm

[Narnash]

The bushing measurements seam to be somewhat standart sized. The normal RipTide bushings are a bit taller (0.6" ->15.24 mm ) but than there are also the “street” versions which is smaller (0,5" ->12,7mm), yours are sized like ~2 steet bushings.

If we keep it simple and stay with cone/barrel combo on both ends or maybe FatCone/barrel and a tad softer than normal. That should be way easier to turn than these random and probalby super hard ones. A pivot cup uprgrade would also greatly improve that truck I guess (since there are so few good ones out of the box out there) but we don’t know which would fit.

Also RipTide has 3 kinds of urethane KranK, APS, WFB quick explanation is: KranK very high rebound, stiffen when you tighten the kingpin. APS still high rebound but more linear, they don’t really get much stiffer by tightening. WFB is lubricated and is easier to lean with than usual bushings, lower rebound than the other two. I would say “soft but fast linear feeback”

I would recommend to go for a APS FatCone/barrel setup (street version to keep the same kingpin) the duro depends … on preferance, ridestyle and weight but I guess maybe the APS barrel 90a and the APS FatCone 92,5a. (if you are around let’s say 70-80kg)

I saw that you’re from Germany, too. I’m from Osnabrück, I might have some bushings laying around (random brands … duro also kind of random and not marked) which I could give you for free btw

PS: You can also swap the back wedge for a normal riser (for stability)

[JulianS]

Wow, nice explanation! I’ll check your recommendations, and also would happily take those bushings, I’d pay for shipping of course! Send you a pm.

I’ll see if I can get a normal riser somewhere

[Narnash]

Ähem … I can also print a riser if you want, I wait for a new hotend thermistor (mail) but than it’s a few hour easy TPU print.

You can also get a 0° riser in basicly any worthy skateshop.

[JulianS]

If I get softer bushings I might consider just turning around the rear riser so it will have even less steering input.

[rusins]

@Narnash

since the hangers are very wide thus your leverage on the hanger is small.

Sorry for nitpicking, but it’s the opposite: wide hangers mean you have more leverage. Wider hangers usually sport harder bushings. (Edit: I had thought. It’s probable that nothing I said here is actually true, sorry)

@JulianS I would recommend harder bushings for more stability, and then dewedging the trucks to get more turnability.

[Narnash]

Hm … I wondering now, I thought that a wide truck with wheels far from the edge of the board is leading to a more stable but harder turn because you can’t use your weight with the small leverage of the board compared to the long hanger"arms".

[rusins]

Hmm… You raise a good point. I was looking at the problem assuming that the force would be applied to the edge of your deck, and the edge of your trucks, so making any of those wider would increase leverage. (Or maybe it’s just the smallest of the two that matter, idk)

What I did find by searching on the forum (besides multiple people simply saying that wider trucks = more stability), is this quote from a guy who works for Riptide who said

@Alphamail

your trucks are wider than your deck. Both of those features are killing the leverage you can exert over you trucks.

He probably knows way more about what he’s talking about than me, so I think you were correct in your first statement that wider trucks = less leverage, should upgrade to softer bushings. (And therefore more stable perhaps?) I apologize.

[Narnash]

What I have at hand right now and whould let go is this !

And this 3d printed 0.5" (12,7 mm) 0° riser (don’t judge it’s a test print of my first try with Extrudr TPU 58D)

If you pay shipping it’s fine (>2kg small is 3,79€ in Germany i think)

PS: I bet there is a whole box with old/other bushings somewhere on our attic (but I don’t really feel like it to search on that mess, sorry)

[Narnash]

Well in the long run, all theorycrafting is worthless, what really counts is the feel and personal preference. For me and for everyone else the best at first what you are used to, and if you don’t like what you are used to it’s simply try and error. And of course testing the setups of other people and friends.

[Narnash]

äh btw any use for these bindings?

they gather dust on my night cabinet for quite a while now

[JulianS]

I would agree that the longer trucks need more force from the deck to turn, also the turning radius is bigger then with a smaller truck.

@Narnash I really appreciate the offer, I sent you a PM already Im happy to test your 3d printed risers, whats the difference from the TPU to standard PLA? I’m also considering inverting the current riser to make the back axle even more stable.

I’m actually fairly light (~60kg), so maybe the 90A or even softer bushings are just right.

@rusins thanks for chiming in anyway, glad to see theres still places on the internet with a well working culture of open debate! I assume the instability comes from the fact that I loosened the kingpin to a degree where it started to not compress the bushings at all. I assume softer, but decently fastened bushings are a lot more stable.

Edit: The board already came with a set of bindings, but thanks for your generosity!

[Narnash]

@JulianS

whats the difference from the TPU to standard PLA? I’m also considering inverting the current riser to make the back axle even more stable.

The difference between TPU and PLA are that TPUs(thermoplastic urethane) are TPEs (thermoplastic elastomers) they are flexible rubber or rubberlike plastics. They can be formulated in a wide range of hardnesses (I have some semisoft 90A TPU filament and hard 58D TPU right now shore hardness explaination)

PLA has completly different properties than TPU, PLA has a very high harndness and is very stiff compared to most plastics, PLA can’t handle shock stress very well because it’s brittle. PLA also melts at pretty low temperature (of the shelf PLA may soften at >45°C, but can get modified to sustain a bit higher temperatures with some trade offs). TPU on the otherhand is soft, flexible, semiflexible or “hard”, the surface hardness is of course depending on formulation but overall kind of low, but TPU has a extremly high toughness(load till actual break of the material) it can (based on formulation) stretch by 350 - 600% till it snaps and it will withstand very high loads till it snaps. TPU also only softens a bit by rising temperature and only melts at way higher temperature or don’t restore it’s shape(85-140°C)

In a practical situations (mounts, risers, mechanical loaded stuff) you can’t really use PLA for any shock related or vibration related loads because it will break, TPU might deform but you basicly can’t break it. As long as it’s stiff enough to be usable in it’s application it’s way superior over nearly every print material beside maybe really high grade stuff or exotic kinds like POM, advanced nylons, PC …(mechanicly … it’s kinda hard to make nice looking prints though it “strings”, absorbs moisture like crazy, isn’t really good in printing overhangs and the shiny surface isn’t really forgiving by the naked eye)

I highly recommend to wedge/dewedge and just experiment with different kinds/hardnesses of bushings experimenting is the only way to get THE/YOUR real setup.

[JulianS]

Thanks for the explanation! Let me know when you have time to send me your payment info so I can get the shipping costs to you