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| Truck Reviews (15215 Posts)
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Dear Fitz
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On 12/15/2006
Chris Chaput
wrote in from
United States
(71.254.nnn.nnn)
The compression of the bushings is retained when you take the hanger off of the baseplate. In order to remove/replace the hanger, you simply take off the two 1/2" pivot nuts and the whole thing slides right out. You leave the 9/16" kingpin nut alone, and the crosspin never comes out. This way you can quickly and easily take the hangers off of one board and put them onto a different deck that has only baseplates on it, and the bushing compression is unchanged. It's all done with a skate key in about a minute.
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crosspin ,out?
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On 12/15/2006 herbn
wrote in from
United States
(152.163.nnn.nnn)
it doesn't look like you have to take the pin out,ever. you can take the kingpin out without removing the pin, the pin is just the cheapest way to let the kingpin float vertically to balence the bushing tension,and keep it from turning ,so the bushing tension can be adjusted with out a second tool. ie if the pin falls out nothing really happens except when you try to adjust the truck the whole kingpin just spins,and you need to line the flat up with the pin hole and stick an allen key or something in there to keep the kingpin from turning. Today I was thinking about making a "fyre seismic" , it would be splitaxle machined from billet with one of the ball joints between the axles,hmm.
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Fyre Truck Clarity
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On 12/15/2006
fitz
wrote in from
Australia
(211.31.nnn.nnn)
I should have phrased it better when I said "kingpin preloaded".
What I meant was the kingpin locknut adjustment on the bushings or preload.
I was under the impression the king pin could be removed after the cross pin was taken out. That way you would never have to change the lock nut position or the feel in the trucks if you were to interchange hangers to different angled baseplates. Thats provided you used the same bushes of course.
Thats when I came to the point where it would be difficult to do this as the preload would make it difficult to disassemble/reassemble. Esp if you liked tight trucks.
Maybe with some thought, that principle could be used? The tapered cross pin was just a idea at the time but maybe another simple method would work.
I'll let you use that one for free Hehe. All in the name of getting kickass end product.
Keep em coming Chris. Can't wait till they're available. Esp the DH version.
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Fyre Trucks Q & A
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On 12/15/2006
Chris Chaput
wrote in from
United States
(66.116.nnn.nnn)
Fitz asks: "With the king pin preloaded for the right feel. How do you assemble the dowel pin into the king pin by hand? Some people prefer tight trucks. The pressure required to crush the bushes down so that the dowel can be inserted may be too much by hand. I thought on this longer and a taperd dowel could be used but then it'd need to be retained on the thin end with a nut which would defeat the purpose of quick release."
I don't really understand the question. I have what I call a "crosspin" that is press fit into the baseplate at the factory. Although it can be removed, that shouldn't ever be necessary. It doesn't go "into" or through the kingpin. It just sits there off to the side and creates a "D" shaped hole so that the flat spot on the side of the bottom of the kingpin will rest against it and prevent it from twisting when you tighten the locknut. The compression of the bushings will not have much of an effect on how easily the kingpin can slide in and out of the hole in the baseplate. Compression of the bushings is dome between the locknut washer and the washer that rests on the "ledge" where the kingpin goes from a 3/8" OD to 1/2".
Perhaps you were thinking that the crosspin went into the middle of the kingpin and under some kind of pressure. It doesn't. Check the image below. Newer kingpins will have a flat spot on both sides of the base of the kingpin so that a 3/8" open end wrench, or a crescent wrench, or a vise can hold it once it is slid out of the baseplate.
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fyre trucks
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On 12/14/2006
fitz
wrote in from
Australia
(211.31.nnn.nnn)
so do i get a reply to my previous question about these trucks?
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Big Fyres
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On 12/14/2006
Chris Chaput
wrote in from
United States
(66.116.nnn.nnn)
I'm making some hangers between 160mm and 190mm to test out for Downhill and cruising. The basic size, height, and width of the first Fyre Trucks are for Slalom, but the design can be scaled up for heavy duty applications. The image above is the 7" version that I'll be testing soon. I'll be working on "grind-friendly" designs for general purpose longboarding, where the kingpins and pivot pins are different or better protected.
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Fyre trucks
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On 12/12/2006 seom dude
wrote in from
United States
(69.143.nnn.nnn)
do the Fyre trucks Chris Chaput just put out come in a bigger size or are they just a slalom truck?
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C.C's efforts
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On 12/11/2006 Oldtimer
wrote in from
United States
(71.164.nnn.nnn)
And C.C, your renderings are always VERY helpful, hats off to you for them, but they don't always portray the true dynamics of the mechanism as it exists. Engineering almost always works on paper, but executing what's on paper doesn't always occur, leaving the designers and users scratching their nuts, thinking... Hmmm, it worked in the model.
P.S I;m gonna be a owner of a few sets of the Fyres when you get them out to the general public!! Love the concept and thought put into them, as with most all quality components!! Thanks again for your commitment to the industry
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Geezer's observance
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On 12/11/2006 Oldtimer
wrote in from
United States
(71.164.nnn.nnn)
Precisely my point GeezerX!! That is why I like the adjustable length pivot pin! I tested Radikal,you tested G.O.G. Neither apply the load to the center of the pivot, which is where most of the schematics I've seen allude to. Don't get me wrong here..I really like the performance these trucks offer but..They could be a much refined, and true to mathmatical effect, if the geometry was actual to the plans! Bara..I mentioned more than once re: Gullwings brackets.
When the forces are applied to either the kingpin, or the pivot in a lateral direction, you create binding and shear, which results in structural failure, sooner or later.
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One more thing...
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On 12/11/2006
Geezer-X
wrote in from
United States
(65.127.nnn.nnn)
On my G.O.G., the tip of the hanger does NOT bottom in the bearing in the baseplate. Virtually 100% of the load is being borne by the kingpin.
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The Year, 2007...
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On 12/11/2006
Chris Chaput
wrote in from
United States
(66.116.nnn.nnn)
Oldtimer, At 45 degrees, the load on the pivot cup is NOT the same as the load on the kingpin. You're not looking at the complete picture here. The Radikal front, GOG front, and Randal truck is designed in such a way that the hanger is a lever. The top of the bottom bushing acts as the fulcrum on which the hanger would teeter, had the pivot rod not been constrained by the pivot cup. The axle is positioned on the far side of the kingpin, and the weight of the rider will force the hanger to go down onto the bottom bushing, and force the pivot rod to go up in the pivot cup. As shown in the rendering above, the distance between the pivot cup and the kingpin, and the distance between the kingpin and the axle, will have an effect on amount of leverage. Increasing the baseplate angle will increase the load on the pivot cup, while decreasing the amount of force on the lever, but that's never been a problem for us. Soft urethane pivot bushings take these loads without any problems, and spherical bearings (ball joints) are way, way, more than capable of handling these loads. Another factor is that the bushings themselves provide a certain amount of friction on the hanger, which tends to put more of the load on the kingpin, and less on the pivot cup.
The problem that we're having with these trucks is that TOO MUCH OF THE LOAD IS BEING PLACED ON A CANTILEVERED KINGPIN AND THAT THE KINGPIN DESIGNS INCLUDE A STRESS RISER. The solutions will be found in doing one (or more) of the following three things:
1. Reduce the load on the kingpin
2. Don't use a cantilevered kingpin
3. Don't put a stress riser in the kingpin
Now take a look at the trucks that don't snap kingpins. What do we know about them? On Tracker and Indy style trucks, the axle is position above the area that is between the pivot cup and the bushing seat, so it's not acting as a lever. Most of the load is down into the pivot cup, especially when steering is wedged in. These trucks are free to turn very quickly because there isn't much of a load on the kingpin and the bushings. They tend not to break, or don't break at all, and there are no problems in the pivot cup. For the rear, we stabilize these trucks by taking out some steering and moving the axles away from the pivot cup. It's not that putting the axles inline with the kingpin is "magic", it's that better stability is acheived on a "hinged" truck when you've put the load on the bushings instead of on the pivot cup. Even though they still employ a cantilevered kingpin, they don't break. So it would make sense that the reasons for this are:
1. The reduced load on the kingpin
3. The absence of a stress riser in the kingpin
There's nothing "wrong" about making a bracket per se. You can either support the kingpin at both ends, or support the hanger at both ends. If you choose to support the kingpin, the truck is still both a hinge and a lever, and you're forced to put a spherical bearing between your bushings, and you have to live with angles that change when you tighten your truck or use different height bushings, and assembly is tricky at best. If you support the hanger at both ends, the truck is neither a hinge nor a lever, you don't need a bearing betwwen your bushings, and you preserve the baseplate angle and steer on a true axis of rotation. This is why I went a "different than old-school" direction with the Fyre Trucks.
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gullwing brackets
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On 12/11/2006 herbn
wrote in from
United States
(64.12.nnn.nnn)
gullwing kingpins were very long and had threads on the baseplate side of bolt,for thatbit of an angle adjustment. I made a pair of trucks with a billet bracket and a hollow 7075 kingpin (that's aluminum)they havn't broken. My design threads the kingpin into the bracket with an allen key socket , and the other end,is 3/4 in diameter and is clamped in the baseplate,i have to loosen the the allen bolt in the baseplate to adjust the bushings and it's backwards,loosen to tighten.
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what's old is new again
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On 12/11/2006 bara
wrote in from
United States
(204.78.nnn.nnn)
ok...i cant even pretend to be an engineer...and i know some of you guys posting up here really know your poop....but didnt gullwing go thru the same thing with the splits and phoenix's years ago?.....the problem was simply too much weight bearing down on a pin that couldnt take the stress....why not just have a hanger bracket like the old gullwings had?...maybe even something with a hinge so you could remove the kingpin without removing the whole truck...with all the Rads out there, and with now GOG's coming out, with all the debate on how to fix the "problem", i'm surprised nobody has even brought it up...Even as an aftermarket item, i have to imagine somebody with machining skills could sell a ton of them...
no?
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Points for Chris
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On 12/11/2006 Oldtimer
wrote in from
United States
(71.164.nnn.nnn)
You're correct on some things! At 45 degrees the weight is evenly shared between the 2 points in theory, (pivot/bottom bushing) Every degree you wedge increases the load placed on the pivot. The percentage isn't an even factor tho, due to the differing resistances of the 2. What are the sphericals rated for in the direction the weight is applied?(Linear vs. lateral)?
Hmmm..... lots to be considered here. You almost need a mechanical testing machine to replicate stresses and duration to the point of breakage to get the answer as to success.
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Fyre trucks
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On 12/10/2006
fitz
wrote in from
Australia
(211.31.nnn.nnn)
Question...
With the king pin preloaded for the right feel. How do you assemble the dowel pin into the king pin by hand? Some people prefer tight trucks. The pressure required to crush the bushes down so that the dowel can be inserted may be too much by hand. I thought on this longer and a taperd dowel could be used but then it'd need to be retained on the thin end with a nut which would defeat the purpose of quick release.
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I Disagree
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On 12/10/2006
Chris Chaput
wrote in from
United States
(66.116.nnn.nnn)
Hey Oldtimer, I think that you have it exactly wrong.
OT: "An entire function and axis of the spherical bearing is lost."
C: Yes. It's the function of the bearing that currently loads the kingpin too much that is lost. This is a good thing to lose.
OT: "...robbing Peter to pay Paul..."
CC: We haven't weakened Peter, we've only strengthened Paul.
OT: "It would also place 100% of the load on the pivot bearing/bushing, taxing it past it's limits."
CC: No it wouldn't. It just allows the pivot cup to share more of the load. It doesn't even come close to overloading the pivot cup bearing, which is insanely strong.
The whole point of the "slot" is to allow the pivot cup to share more of the load, because trucks design that way don't have snapping kingpins.
I envision a fix similar to Gullwing's bracket of the 70's where the cantilevered truss is supported at both ends(no longer truly cantilevered) Or a variable length pivot arm, such as TTC's or Splits where an individual assembles, then adjusts the length to be snug in the cup/bearing.. The 1st fix of a bracket would be fairly inexpensive, made from stamp proccess or if prefered CNC'D then press breaked..No re-tooling to the base or hanger needed.. Some-one's going to suffer severe injury or worse if it goes un-tended!
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C.C's Cure all
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On 12/10/2006 Oldtimer
wrote in from
United States
(71.164.nnn.nnn)
I don't know Chris, but your latest solution detracts from one of the main reasons of having a "precision truck" An entire function and axis of the spherical bearing is lost. It's a good idea, but robbing Peter to pay Paul usually ends with a broke Peter. It would also place 100% of the load on the pivot bearing/bushing, taxing it past it's limits. I envision a fix similar to Gullwing's bracket of the 70's where the cantilevered truss is supported at both ends(no longer truly cantilevered) Or a variable length pivot arm, such as TTC's or Splits where an individual assembles, then adjusts the length to be snug in the cup/bearing.. The 1st fix of a bracket would be fairly inexpensive, made from stamp proccess or if prefered CNC'D then press breaked..No re-tooling to the base or hanger needed.. Some-one's going to suffer severe injury or worse if it goes un-tended!
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broken Seismic "kingpin"
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On 12/10/2006
k-lee
wrote in from
United States
(71.222.nnn.nnn)
I broke a Seismic kingpin (pivot pin) once. It was on one of the older German models, back in 2000. I was just mellowly cruising around campus, and the back hanger went rolling away, after the pin broke. Good thing I wasn't bombing a hill. Go figure.
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Thinking out loud
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On 12/10/2006 Michael
wrote in from
United Kingdom
(87.114.nnn.nnn)
hmmm......what if the 'channel' was actually a roller?
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And another way?
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On 12/10/2006 Michael
wrote in from
United Kingdom
(87.114.nnn.nnn)
CC, that picture reminds me of part of my gear linkage in my van.
How about that 'channel' each side was replaced on each side by easier to source cylindrical bars. Two each side, parralel to each other, as runners? These would also be able to be replaceable, and screw inable.
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Another way to skin the cat
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On 12/10/2006
Chris Chaput
wrote in from
United States
(71.254.nnn.nnn)
That oblong shaped ring doesn't exist, and it would probably be cost prohibitive to manufacture in small runs. The parts really only need to pivot in one direction with a relatively tight tolerance, and to allow travel in one direction. A couple of concave "tracks" could be inserted around the shrere to do the job.
I actually have made several prototype hangers with an oblong hole in each, and I put a nylon sphere between two special bushings that hold it in place. The hanger itself acts as the outer ring of the spherical bearing. They work great.
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Oblong hanger bearing sleeves for the Radikal/GOG
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On 12/10/2006 Pauliwog
wrote in from
United States
(71.193.nnn.nnn)
OLDTIMER AND CHAPUT- Thank You, both of you!
Chaput- That's the same idea I had a while ago and talked with Fluitt about but did'nt really push it because I did'nt know if that kind of sleeve was a manufactured item already or not. Good to see someone else seeing the same thing. I agree, it would allow play in the direction you need play in and keep nice tight precision in the axis where it is needed. Also, the idea of a kingpin with a "big plug" base with a good sized fillet likely would be big structural advantage - Similar to what Wallgren suggested with a threaded kingpin with a flared base made from some sort of auto engine valve related mechanism(which would put the compression on the flared base and put the threads 100% into tension as they should be.
OldTimer- Thanks for doing the test(I'm assuming you did the test on a Radikal) with the putty and confirming what I have long suspected - 100% vertical and lateral loads onto the Radikal kinpin from the hanger being suspended on the kingpin and the pivot being not fully seated in the base of the pivot.
This has been a good and interesting thread. Adios - Paul
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Location, Location, Location
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On 12/10/2006 Michael
wrote in from
United Kingdom
(87.114.nnn.nnn)
Exactly.
Its not WHERE the bits are made. But HOW they are made and designed.
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seimics/radikals etal.
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On 12/10/2006 oldtimer
wrote in from
United States
(71.164.nnn.nnn)
The reason Seismics don't suffer the same ails as other "non taditional" trucks is that the hanger is nearly butted up to the fulcrum and contacts the king pin over a larger area. GOGs Radikals and such have the weight of the rider suspended/supported on a much narrower contact area, that is further out from the fulcrum, resulting in a more leveraged situation.I'm thinking instead of harder materials, softer might allow the kingpin to conform/bend a tad. allowing the load to be re-directed more to the pivot pin. I placed a tiny bit of putty in the pivot cup to see if the was indeed no direct vertical load on the pivot. After a short ride,I disassembled the trucj and found approx. 1/16" of an inch of putty. meaning ALL the load was applied to the king pin.
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Oh yeah
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On 12/9/2006 herbn
wrote in from
United States
(64.12.nnn.nnn)
when i made mounting hardware , i made the bolts with the least number of threads as possible and just long enough for a flipper board and a 1/8 inch riser. When buying 50,000 bolts they'll do that at no extra charge,it is less work,but it is off standard. To do kingpin sized bolts to your spec it may be lower numbers, i don't think slalom truck companies are buying 50000 kingpins.
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