FAQ

How do I disassemble and re-assemble my trucks?
What are the dimensional specs of Seismic truck axles?

What mounting hole patterns do Seismic trucks support?

Why are my trucks noisy?

Should I wedge or de-wedge my trucks?

Why does one of my wheels have a gouge or tear?

How can I stop wheel rub?

Why do I see a wobble in one of my wheels?

 

TRUCK ASSEMBLY & DISASSEMBLY

If you’re having trouble assembling your trucks, first make sure that you’ve fully loosened the spring tension screws. Otherwise much more pressure is needed to align the hanger and baseplate for insertion of the pivot bolt.

If the pivot bolt doesn’t easily slide through the baseplate and catch the threads of the nut, don’t force it – you may damage the parts. Instead, place the board or truck upside-down, on the floor or a workbench. Press the hanger down and hold it in place to keep spring pressure off the pivot bolt. Then, using a 7/32" Allen wrench, give the head of the bolt a small downward push as you press it through the truck and screw it into the nut. This helps the bolt tip catch the threads of the baseplate nut.

Before disassembling the truck, the spring adjusters should always be untightened, and the hanger should be pressed down and held. Otherwise spring pressure acting on the pivot bolt hinders disassembly and creates stresses that can, on rare occasions, strip the threads of the baseplate nut as the bolt is unscrewed.

If the pivot bolt unscrews only partway and then gets stuck, the nut is probably stripped. To get the pivot bolt out of a stripped nut, first place the truck in a vice (if possible). Pound the head of the bolt back into the truck. This will force the stripped nut out of its pocket in the baseplate. Then slide a small flathead screwdriver (preferably #3) between the nut and its pocket, or grasp the nut with a strong pliers. This increases tension between the pivot bolt and the nut, and it usually helps the bolt cut through the nut’s stripped threads. After unscrewing the bolt, reassemble using a fresh bolt, nut and clip.

 

TRUCK AXLE TOLERANCES

Seismic axles are manufactured to be 7.95mm in diameter, with a small negative-only tolerance. Racing truck makers who advertise “true 8.0mm axles” generally follow a similar specification. Average brands use 5/16-inch (7.9375mm) axles

The inner race of standard wheel bearings has a diameter of 8.0mm, with a small manufacturing tolerance. Truck axles need to have a diameter slightly smaller than that, or else some bearings may not fit or even get stuck.

 

TRUCK HOLE PATTERN

Seismic trucks support both “Old School” and “New School” mounting hole patterns – a significant engineering challenge given the truck’s unique structure.

The Old School mounting hole pattern has holes that are 2.50" (63.5mm) center-to-center longways. In the New School hole pattern, that distance is only 53.5mm (2.11"). Both patterns have holes that are 1.625" center-to-center sideways.

 

TRUCK NOISE

Seismic trucks were engineered as a high-precision product, with virtually no slop in their steering articulation. So like a race car, they don’t dampen road vibrations much and may seem noisy compared to lower-precision trucks with grommets. Some skaters are more sensitive to that than others.

Actual rattling noises can occur for a variety of reasons, regardless of the trucks you’re using. The most common cause is riding on rough surfaces with loose hardware, no shock pads under the trucks, and wheels that are too hard for the surface. In addition, bearing spacers can rattle between the bearings or against the axles if they’re the wrong size, or if the wheel core tolerances are off.

Try using softer wheels with proper-sized bearing spacers, and truck risers made of urethane or hard rubber. Also check the fastening tension of your mounting hardware, wheel nuts, and truck pivot bolts. (Loose pivot bolts can also invite dirt and grime to gunk up the works, which in turn can lead to excess friction among the moving parts.)

The Seismic truck technology itself was carefully engineered to eliminate squeaking, clicking and rattling, but a few seldom-seen issues can lead to these or other noises.

Most squeaking and clicking stems from friction between the small inner springs, the main outer springs, and the long-necked “sliding” spring caps. To reduce or eliminate the noise, try rotating the spring assemblies a quarter or half turn inside the spring chambers. (Loosen the tension screws first, then just turn the springs with your fingers.) After that, tighten the tension screws at least 1.5 turns. For added measure, drop a bit of silicone or graphite lubricant inside the long spring caps.

Finally, spring tension screws that are fully loosened may occasionally rattle inside the Seismic truck hangers, though ordinarily spring pressure keeps them quite still. Try tightening them 1.5 turns. This puts them in a “neutral” position where they function as intended. The trucks won’t feel stiffer when riding, but pressure from the springs will keep the screws from rattling.

 

TRUCK WEDGING

The Seismic steering geometry is absolutely fixed and perfectly consistent - either 30-degrees (Stable-Turn) or 45-degrees (Quick-Turn). So wedged (angled) risers have a totally direct and predictable effect on performance.

To quicken steering response, orient the wedge with the thin end facing the end of the deck. Usually called “wedging,” this is most commonly done with the front truck. Just remember this reduces your leverage on the springs, so you might want to loosen them or even switch to softer ones.

To slow steering response, orient the wedge with the thick end facing the end of the deck. Usually called “dewedging,” this is most commonly done with the rear truck, especially on racing boards. Just remember this increases your leverage on the springs, so you might want to tighten them or even switch to stiffer ones.

Optimal truck mounting depends on many different variables - wheelbase, riding speed, skating style, personal preference and even body height. You’ll need to experiment to see what works best for you.

 

WHEEL CHUNKING AND TEARING

Tears and chunks are generally a matter of physics – soft urethane wheels with thin flexible lips, rolling under multi-dimensional pressures, catching and ripping on rough surface projections. This is an unfortunate reality, even though Seismic and 3dm wheels are poured using the world’s finest urethane at the world’s leading wheel factory.

Harder wheels, and wheels with rounded edges, don’t catch very easily on jagged surface elements. Softer wheels, and wheels with sharp edges, are more vulnerable to suffering tears when rolling over uneven surfaces – especially if you’re heavier or a faster, more aggressive rider.

Even small surface projections on relatively smooth roads can cause tears and chunks. A tear that runs along a significant portion of a wheel’s circumference is clear evidence that the damage occurred when the wheel rolled over a sharp surface element.

Another common cause of chunking is kick-turning on rough surfaces, which can shred the edges of thin-lipped wheels (designed primarily for carving and cruising) in the course of a single skate session. Soft urethane can even absorb sharp road residue (such as bits of glass, jagged pebbles and beer-can tabs). These objects can then work their way deep into a wheel and later split it open from the inside.

On rare occasions, an air bubble trapped in the lip of a wheel can break open under normal riding stresses. In these rare cases, the remnants of the bubble are very easy to see. However, if more than one wheel in a set of four has torn or chunked, the surface is almost certainly the culprit, since the odds of getting more than one “bad” wheel are incredibly low.

Regrettably, we cannot warrantee torn and chunked wheels, unless it’s obvious that an air bubble was the primary cause.

 

WHEEL RUB

Before skating any new setup for the first time, you should always test on carpet for the possibility of wheel rub.
Wheel rub is a “systems issue,” related to the total deck-wheel-truck combination. The manufacturers of individual components can’t guarantee that you won’t get wheel rub when combining their product with parts from other companies.

The axle height and tilt range of Seismic trucks were carefully engineered for maximum performance options. If you’re experiencing wheel rub, your best solution is to use more riser under your trucks, and/or smaller wheels, and/or a deck with wheel wells or wheel cutouts.

If your bodyweight is on the high side, another issue to consider is torsional deck flexion. Under the weight of heavy skaters, decks twist more than normal. This means that the deck actually flexes toward the wheels during turns (especially at the nose), making wheel bite more likely. Extra-large skaters should consider choosing stiffer, thicker decks, possibly with concave, to gain more torsional stiffness.

 

WHEEL WOBBLES

Wobbly wheels (wheels with misaligned cores) show up now and then, no matter what brand you’re talking about. It’s just a fact of life, even with the most modern technologies used to mold skateboard wheels. Of course, we do our absolute best to minimize the number of wheels that are wobbly. Wheels with significant wobbles – with cores so out of alignment that performance is effected – are rare. Unfortunately, we cannot entirely eliminate wobblers and still offer wheels at prices that most skateboarders can afford.

If one out of four of your wheels seems to have a significant wobble, you got very unlucky. Please contact us about the wobble (or other defect) before riding the wheels, and we’ll work with you to figure out what’s up. If the problem is real, we’ll take care of it. Just note that if you have a genuinely bad wheel, we will replace the problem wheel but not the whole set of wheels. We make no exceptions to this policy. Also, if you’ve logged a lot of miles on the wheel, it’s too late. A well-worn wheel is one that you got your money’s worth from!

The odds are incredibly low that two or more of your wheels have a significant wobble. If you think you have more than one wobbly wheel, you may be expecting too much. Aerospace tolerances are impossible to deliver at affordable prices. Miniscule wobbles – the type that you have to strain to see, the type that you can’t notice in any way when you’re riding – are common and do not effect performance. In fact, they normally disappear or diminish as wheels break in.

If you’re unsure about one or more of your wheels, first check to make sure you have bearing spacers of the correct size (0.400-inch) installed between the bearings. Bearing spacers help keep the bearings aligned in the wheel core; neglecting to use them can make good wheels appear wobbly.

Also note that appearances can be deceiving. Even with good bearings and bearing spacers, some wheels with perfect core alignment may look wobbly when spun by hand. How is this possible? When wheels are popped out of the molds, the urethane sometimes settles unevenly as it cools, leaving small excesses around the edges. Also, sometimes the “flash” (excess urethane) on the inside lip is trimmed off unevenly after molding, creating an edge that appears to wiggle as the wheel spins.

These two factors – uneven cooling and asymmetrical trim – can make good wheels appear wobbly when free–spun. To distinguish these from true wobblers (wheels with misaligned cores), look at the inside and outside edges separately during a spin test. In a true wobbler, the inside and outside edges will oscillate with a perfectly even rhythm, and the middle of the wheel will probably not stay level.
Wheels with high spots, or wheels with an uneven trim, will usually show only one edge wobbling during a spin test. If a wheel has multiple high spots, both edges may look wobbly, but the middle usually stays level and the oscillation will not have an even rhythm. Again, such wheels are generally perfectly fine to use.