Posts by gearhead

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    N2 does have a larger atomic radii as a gas than O2. But, the main reason 100% N2 is used in aircraft tires is the pressure... The loads on these tires are high and the tires are small -- so these tires are often kept close to 200 PSI. Some things will spontaneously combust in 250+ PSI air (at standard room temps) -- hence the use of 100% N2. This is due to the increase in O2 partial pressure. Sometimes this is referred to as "dieseling". Look up "fire piston" and watch videos of people using a simple plunger with a bit of cotton on the end as a lighter. People have been killed by poorly designed or faulty office chairs, where the pneumatic cylinder diesels and shoots the piston rod up through the chair (and whoever happens to be sitting on it). This is the reason a lot of the gas pistons/cylinders use non-combustible silicon oils and are nitrogen charged, to avoid dieseling explosions.

    All that said, if your tire is at 4+ ATM, the partial pressure of O2 in the tire can be equivalent to 100% O2 at standard atmospheric pressure. Hence, the reason air released from a tire smells like rotten eggs -- that O2 has been oxidizing your tire from the inside out. Some of the pressure reduction in a tire is the O2 being consumed by rubber compounds/oils in the tire (oxidation). I've used 100% N2 in my tires for decades. Science? I'm an engineer and a pilot.

    There are safety equipment choices -- and then there are insurance choices... If anyone were to take a ride with me in my Slingshot, they'd probably be the most insured they've ever been... I've got a $4M policy. For good reason. Out here in Kalifornia, most of the Hospital ER's have been closed (guess why). An acquaintance of mine had a solo accident on a bicycle in Irvine/Costa Mesa and he had to get med-evac'd out in a damned helicopter. That short copter ride set him back $10K+ and that's before the doctors even got started... An accident at higher speeds in a Slingshot or car involving multiple people -- the costs can get staggering quickly. Not to mention that many cities like Huntington Beach charge a hefty fee for accidents in their city, to cover the costs of their first-responders.

    I've used a HANS device, along with 5-point restraints... This is probably OK if you're on a racetrack -- where you're not going through intersections... A HANS device prevents you from swiveling your head to check cross-traffic. And you can forget about leaning out and taking a quick glance at what's behind you. I tried using a mirror strapped to the wrist of my left hand -- but it was simply too awkward.

    The standard 3-point safety belt on a Slingshot does allow your upper torso to pivot inwards (towards the center console) on high-G deceleration. This will avert neck snaps as your head stays in-line with your upper torso. But it also allows your helmet to smash into the steering wheel. I figure, as long as it's my helmet and not my head it's something I can live with.

    I believe Loctite 641 is used to seat the sprocket on the axle shaft. To remove mine, I slowly heated the sprocket with a giant heat gun while rotating the axle/sprocket slowly... Eventually, the 641 lets go and you can get the sprocket off. I rigged a large gear puller with pads to yank the sprocket off when the it got hot enough.

    Just my 2 cents, check one of my prior posts:

    Tires...what are you running?

    This tire will keep the rear end planted better than most anything. Note, that this is the ET-Street-R, not the ET-Street-SS... No same-same. If you want grip, you need a pliable tire. Running this tire on a Forgestar Deep Dish 12x18 +45mm wheel. This tire was originally designed for the Dodge Hellcat/Demon -- and on the drag strip, the sidewalls get a nice wrinkle (see pic).

    I've got a 2015, which came with a group 26 battery... I was looking at ways to ditch some weight and the battery was high on the list. I found that a Braille B3121 would fit, but I had to fab an adapter plate. The Braille battery is 21 lbs with 550 CCA, 1380 A at room temp.... Here's a pic of the OEM group 26 flood filled battery and the Braille B3121.

    Here's a pic of the adapter plate I milled from a slab of ABS...

    Here's a pic of the Braille installed in the adapter plate...

    And, a pic of it installed in the Slingshot:

    Now, here's the best part... Rumor has it that the Braille B3121 (around $200 retail) is actually a rebadged Deka ETX-30L (around $100 retail):

    I've had the Braille battery for 3+ years no problems. I keep it on a battery tender (AGM setting) when parked in the garage.

    Schuberth Concept Helmet. Integrated internal sunvisor which flips up/down with the flick of a switch. Anti-fog everything. Great adjustable ventilation by moving a slide, very little wind noise, designed in Schuberth's wind tunnel and has integrated turbulators. Convenient to use -- it's a flip-up helmet. The model I'm using is several years old, but if I had to replace it I'd get another:…bikes/helmets/c4-pro.html

    Niche vehicles don't need to "grow" to sell a bazillion units a year... The Morgan Auto Company has been making their niche vehicles since 1909 (including 3-wheelers)... They're still around.

    Every person that's come up to me while refueling at a gas station has asked "where do you get these?"... That says a lot about the brand recognition (or the lack of it) and dealerships. They need to locate a few Polaris dealerships in auto malls where people can compare Apples to Oranges -- and "discover" the bargain priced Slingshots.

    My 2 cents...

    The Slingshot right angle gearcase cover is a structural part, but it's also thin. This means that as the force is transmitted 90 degrees, lateral vibrations are created as the gear teeth mesh. This turns the gearcase cover into an 8" diameter convex speaker cone. This serves as a great impedence match with the surrounding air for transmitting sound. There are those who have sound insulated the trans tunnel and rear areas of the car to reduce sound levels to the driver/passenger. A better solution might be to find a way to brace the gearcase cover to either shift it's resonant frequency much higher (so that the plastic panels can deflect the sound) or have a compliant rubber contact to damp vibrations. Covering the gearcase cover with a sound absorbing mat would not be a good idea as that would retain heat.

    Just my 2 cents... For those with vibrating mirrors, I say use SlingRazor's mirror glass removal technique of using a hot air gun with nylon spudgers to carefully loosen the double-sided stick tape attaching the glass to it's plastic frame. Then, once the glass is removed, you can adjust the screw (circled) which holds the plastic frame to it's "gimbal" mount (circled). Maybe the screw has come loose, there's not enough tension, or the fit between the plastic frame and it's mount needs some adjustment with a dremel or X-acto blade... The mount may also be loose -- but you'll be able to easily determine this once everything's apart...

    My 2 cents... The small ridges/texture on the "top" of the drive belt are completely abraded away... This leads me to believe that you picked up some road debris and it got "stuck" between the frame or in your belt-guard for awhile. Then, it dropped off after a few miles. That would have rubbed off the "top" ribs/texture off the belt. As for the wear on the cogs of the belt -- that might depend on how much dirt-road driving you do. I do not believe that this is caused by any belt misalignment. I'm using a All-Things-Chrome rear sprocket (the larger diameter one on the rear axle) and have no issues with it.

    The only time I've seen this kind of wear on a drive belt was on a CNC mill drive belt... Some long chips spiraled up and around, rubbing the top of the belt. The smaller flying chip debris chewed the cogs on the drive side of the belt -- but in my mill application the cogs don't engage anything -- it acts more like a traditional V belt. It was easy and cheap to replace the belt on that mill (just a minute or two). The Slingshot's belt, on the other hand, is far more expensive and takes more time...

    Maybe we need an underbody "diffuser" guard to deflect debris away from the belt...