It took some time...

[Marcus Seyffarth]

...but then the kingpin gave up.



Now how the hell do I replace it? There's nothing to grab or hold on to.

/Marcus

[Gary Saenz]

First put thin lube on the thread area to loosen it up. Then get a reverse drill bit and drill into the center of the bolt. The drill bit will most likely catch and start to back the bolt out.

[Dave Gale]

If not..then get the proper sized E-Z out to follow the drill hole...presto

[Wesley Tucker]

Marcus,

Were you hurt when that happened or did it just get wobbly and you stepped off?

[Dave Gale]

Is that mounting hole in the baseplate whallered out?

[Eric Brammer]

As someone who works with metals, is a machinist, and skates, that Radikal 'gave up' at the kingpin from these likely causes; The truck was insecurely mounted, likely on a wedged pad, and it was always twisting under sideload (wear at mounting holes); The bushings were in upside-down with the Flat side towards the hanger (this will cause slop between the hanger at the Spherical pivot, and the bushing). I note this as there's no 'imprint' on the baseplate from the bushings. Proof is NOT conclusive. ; The kingpin wasn't tightened into the baseplate quite far enough. (not likely, but possible, NO proof in photo, but the Kingpin may have exposed threading on the upper shank, which would be something to consider) ; The spherical ball joing wasn't lubed, and 'froze'. (again, NO proof here, but a possibility nonetheless.)

I know none of the above is comforting, but I've seen lightweight riders do similar things to these (early production/Proto) trucks, yet have also seen this truck company completely respond in re-engineering and fabricating to help eliminate issues of this kind. It shouldn't occur, but metal being what it is, it'll fatigue and 'give' out rather suddenly. Yet, something was likely an added coercive acting force to compromise an otherwise overbuilt part of the truck. Maintenance is most likely to be that extra issue that'll cloud the finding of a root cause here.

In getting the kinping out, an EZ-Out is the best bet. Whether that's really best, I dunno. I'd say send the baseplate with notice to Radikal, and start with a new, un-used baseplate. In the meantime, google the Sheer Strength ratings for Titanium rod in 10mm or 3/8" Diameter. I'll bet you won't believe the force needed to bend that size of rod! Yet, there it is. Hence, I believe that premature metal fatigue is likely in this incident, and some of the above contributing factors may have had a role herein.

[Marcus Seyffarth]

Thank you for all the input!

Wesley - thanks for the concern, but no one was hurt when the kingpin broke from what I know. Fact is that Adel broke his kingpin at the worlds 2006 so I borrowed him my spare truck. Then he gave it to Corky, who was the one skating the truck when the kingpin gave up some month ago.

I have no idea why the mounting holes are so worn, they used to be ok. I guess the people using the truck for the last year have used Khiros soft wedgepads or not tightened the mounting screws. Same thing with the bushings, I have no idea what bushing was used at the time of breakage. I only use different radikal bushings that I have shaved or so.

Why would the busing used make any difference?

What I do know is that the insert is of the old kind, and that the kingpin also is of the old kind so its not such a big surprise that it gave up. I do have another old kingpin so I can still get the insert out once I get the remains of the broken kingpin out. But in order to do that I need to know what a E-Z tool is...

Perhaps I'll just try and drill the schmuck out of the insert.

[Dave Gale]

First off..Radikals are designed to maintain the exact geometry that their bushings create. You are not supposed to adjust tension, but change durometer instead(ie: to be tighter or looser turning) An E-Z out resembles a thread cutter, but reversed, so that when it is treaded into the hole drilled for it, it tries to counter rotate the bolt(king-pin) They are usually rather brittle high carbon, so it's important to drill the correct size hole for the desired E-Z out. And even then, make sure you don't "pry" or angle the E-Z out into the bore hole..

[Noah Heinle]

You won't be able to get the newer kingpins into the older inserts. The threads won't match. Gotta replace them both.

[Marcus Seyffarth]

I know, thats why I'll use my old kingpin. That is given I get the broken part out...

[Wesley Tucker]

Marcus,

You're signed up for North Carolina, right? Would it be too long to wait to just bring it with you and let Keith swap it out?

[Marcus Seyffarth]

I'm signed up but unfortunately its not very likely that I'll be there. I'll give it a go to fix it myself. Its no biggie really since its my spare truck, but its better to have a functional spare truck than a broken one...

[Claude Regnier]

Marcus you should heat the baseplate up in the oven around 450 or 230 c for around 20 minutes or more.

Then try to remove the whole piece it may be a little easier to remove the kingpin section, maybe not? You need to breakdown the locktight.

Good Luck see you in N.C. You got to go. I owe you one from last years Worlds:) [/i]

[Wesley Tucker]

I just thought of something.

Is that kingpin Titanium?

And if it is, will one of those back-out bits bite into it or just skip around on top?

[Marcus Seyffarth]

Wesley, how would you know if its titanium?

Claude - I thought I owed you one...

[Pelle Gustafsson]

hej mac! min gick åxå av likadant. ring mig så fixar jag de för jag köpte special verktyg till de
har du kingpin? annars går de med annan som jag kan fixa åxå

[Dave Gale]

A good quality high speed steel bit should work no matter. To see if it's titanium, see if a magnet will stick to it. It may be difficult since the insert is attached, but you may be able to isolate the attraction. Titanium is non-magnetic.

[Eric Brammer]

If the kingpin is Titanium (which being an older one, is likely), using a Titanium-coated drill jobber and lots of oil and patience, you should be able to get a hole that an E-Z out can latch onto. Start with small diameter bits, not too much down-pressure, get a 'pilot' divot, go gradually larger in bit size until you match the E-Z out's diameter. A 1/4" or 6mm E-Z out should be big enough to get some traction, especially if you 'bake' the baseplate as Claude suggested. A few dabs of high-quality penetrating oil (once it's cooled from baking) before you drill wouldn't be a bad idea, either. If no penetrant oil, use a soak in gasoline to break down the LocTite. E-Z out will screw into the hole you'll drill, and let you torque counter-clockwise to un-thread the nub of the kingpin. The take some down-pressure to work, so clamp the baseplate down when you try getting the E-Z out to work. Go Slow, and don't hammer the E-Z out unless it slips. Tap it with a dead-blow to re-engage it if it does slip. If none of this works, ship it back, let Sparky have at it.


As for bushings, it's the spherical pivot in the hanger that's the issue. Notice how Radikal bushings have a flat side, and a curved side? The curvature is needed to fit around the spherical pivot and maintain constant contact between the bushing and hanger. Put a Rad bushing in flat-side towards the hanger, and the hanger will 'flop' loosely until it bumps into the bushing. That extra 'slop', with your weight on it, is gobs of sudden Torque against the kingpin once the hanger meets the bushing. This sudden jolt, repeated a few thousand times, equals metal fatigue, which leads to failed kingpins. Use the bushings correctly (and not over-tensioned), and there's almost no chance of kingpin failure. Realistically, there's no design flaw with the truck, but there's ample opportunity to have the end user misuse the bushings and create the metal-fatigue issue.

If you decide to use other bushings on Radikals (something I'm sure they wouldn't recommend), hollow out a divot about 12mm in diameter that's at least 5mm deep right outside the existing hole in the bushing. This divot, or contoured cavity, fits around the spherical pivot, and keeps the flat surface of a bushing in full contact with the hanger. Again, don't tighten down the kingpin locknut much, as you don't want compressed/deformed bushings on this truck. The idea is instead to not have 'slop', and to let the bushing reactively compress under turning loads only, not to have the bushing 'pre-loaded' by overtightening the locknut. Hence, picking the right durometer of bushing becomes pretty important. I've done a 'reshaping' on probably 50 bushings, where I trim the outer diameter to effectively change the turning resistance a bit, which gives a Radikal user a few more options in 'steering feel'.