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Roller Derby Forum Discussions about banked-track and flat-track roller derby events, teams, skaters, and training methods.

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Old May 22nd, 2011, 01:05 PM   #1
Salamanda
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Thumbs down Reactor kingpin fail

One of our refs experienced a minor inconvenience yesterday during a bout (he lurks here sometimes so if he's reading this, Hi Sutton! ) when the kingpin on his Reactor snapped. I think this plate is about 12 months old, possibly less. To my very inexperienced eye it looks like that the brass pivot cup has started to wear out and that may have caused the truck to pop out and snap the pin?
By the way I do realise that kingpins snap on all brands of plates, not just Powerdynes. I'm posting this as more of a public service announcement to check your stuff for wear and tear regularly.
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Old May 22nd, 2011, 06:00 PM   #2
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Thumbs up Looks like a good assessment to me..

Although "starting to wear" is being quite generous on the pivot cup wear (I would have replaced any that were starting to hint at looking like that.) Looks to me like a typical pivot cup failure attributable to running the suspension loose and/ or not lubing the bushing.

When he fixes the pivot get some new bushings as well.. The new Riedell "Magic" cushions seem to be of good quality.. at least they are all showing the same durometer for the same color which cannot be said for the originals.
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Old May 22nd, 2011, 06:08 PM   #3
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I also noticed that it seems to have snapped just where the allen screw in the base of the pin seems to finish. Weak point? I'll mention the new cushions to him. If the Reactor will take SG supers I can just give him some. Do I need to do any modifying?
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Old May 22nd, 2011, 06:15 PM   #4
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Exclamation Its BRASS Not Oil-lite Bronze. You need to lube it.

All the aftermarket and Hong Kong Phooey BRASS PIVOT CUPS are not made like the original Pro-Line Pivot cups.

The Original proline PIVOT cups are made from OIL LITE Bronze and are impregnated with Graphite. When you rub it (the oil lite bronze) out comes the dry graphite and lubes your metal pivot ball.

You know what this stuff is (oil lite bronze) Ever car generator 6 volt and 12 volt use it on the commutator brush ends instead of ball bearings. The carbon brushes would wear the abrasive dust and get in the bearings. So the manufactures (Delco Remy) used the Oil Lite bronze because in could function in a dirty location etc. Lube the shaft etc.

SO,If you have anything other than a proline cup,you should put some grease lube in your cups. The best for this is Disc Brake wheel bearing grease. Reduces friction and gives smooth working action.

It does not hurt to lube you bronze pro lines either. Any friction you can reduce in the pivot area will aid in turning truck action.

As soon as you see excess play ,slop in this area,you should change/fix immediately. If not sheared off king pin soon to happen.

You can identify if you have Oil Lite Bronze or Brass by taking a real close look and a pocket knife. The Oil lite bronze is more grey color and under a bright light you can see the small grooves that retain the graphite. Just like your ball bearings in your skates. little grooves.

The Hong Kong Phooey replacements that are All Brass, there real shiny and you can actually cut with a pocket knife. The Brass is softer. Wears fast with out lube.
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Old May 22nd, 2011, 06:27 PM   #5
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Thumbs up Bronze Pivots,Orginal Pro Lines

You can see they are much darker color from the Brass ones.

Also the aftermarket ones do not have the exact same ball socket radius as the originals. They will still work if there greased though.

If you use dry and no lube they put much more pressure on your cushion action.
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Old May 22nd, 2011, 07:01 PM   #6
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Cheers Okie. So lightly lube the pivot cups and the cushions? I'm assuming where they sit on the kingpin?
I think these pivot cups will be replaced with the delrin ones. One of our other Refs had his brass pivot cups on his Reactors disintegrate about a month ago and he replaced them with the delrin ones. We have one other Reactor in the league which I think has brass pivot cups so I'll pass the info on.
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Old May 23rd, 2011, 01:53 AM   #7
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Default Reactor geometry...

Every Reactor I have put together has had geometry issues!!! I have to "custom" cut the pivot cups in every set. They do not sit in the plate deep enough especially in the front. I have to trim the bottom of the pivot cups to get the proper depth. The plate referenced above has 2 issues... Old style brass pivot cups with the revised truck and the pivot cup does not sit down in the hole enough. The revised truck has a larger pivot ball and a retaining sleeve that comes down on it from the top. There is virtually zero clearance for travel when this happens. I have seen it countless times while working on the Dallas Derby Devil's setups. All of the action is applied at the pivot when the pivot cup sits up to high and causes premature wear of the pivot cup. Riedell tried to address this with the new delrin pivot cups. The new delrin cups fit the truck pivot better but the plates are still not drilled deep enough half the time. When I set them up with the proper depth of the pivot cup and knock the tops off to clear the revised pivot balls on the truck all issues have gone away with the brass cups. The girls used to kill the pivots in just a few months. I just did a tune-up on some that I did two seasons ago and the pivots are still good! It's all about setting them up properly! If I didnt have a lathe I could not do this properly...
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Old May 23rd, 2011, 08:48 AM   #8
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Anyone else find it funny how towards the end of the king pin the break occurred? It would seem the should occur closer to the plate.
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Old May 23rd, 2011, 03:41 PM   #9
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Quote:
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When you rub it (the oil lite bronze) out comes the dry graphite and lubes your metal pivot ball.
Robot pr0n!!!
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Old May 24th, 2011, 12:08 PM   #10
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Sounds like a quality-control issue to me. How many failures like this have there been in the skating community among Reactor owners?

I've always wondered about the possibility of machining kingpins from titanium alloy.
Quite difficult, and very expensive, but what price for a kingpin that's stronger than steel whilst almost as light as aluminium, and would virtually eliminate the risk of a face-plant...
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Old May 24th, 2011, 12:30 PM   #11
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Quote:
Originally Posted by Nick V View Post
Sounds like a quality-control issue to me. How many failures like this have there been in the skating community among Reactor owners?

I've always wondered about the possibility of machining kingpins from titanium alloy.
Quite difficult, and very expensive, but what price for a kingpin that's stronger than steel whilst almost as light as aluminium, and would virtually eliminate the risk of a face-plant...
Titanium kingpins are available.
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Old May 24th, 2011, 12:59 PM   #12
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Snyder Titanium Kingpin, fits Laser so cant see why it wouldnt fit many other plates.

Very cost prohibitive.
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Old May 24th, 2011, 02:18 PM   #13
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Titanium kingpins are available.
+1, I have a couple pairs of Snyders with them. Evidently the Ti used in skates will bend easier than steel, but weighs a lot less.

I am pretty sure Reactor kingpins are aluminum.
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Old May 24th, 2011, 03:15 PM   #14
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If the truck mount is bogus and it is flopping around too much on the kingpin,excess stress will be going onto locations where it does not belong, instead of onto the plate body.

The SPLIT END kingpin with wedge screw to lock the action nut is a poor design for resisting the excess stress that a flopping about truck can apply there. Aluminum is rather weak for resisting fatigue (cyclical) loading. With the sharp bottom of the V cut from action nut thread and the 2nd internal sharp V cut of the wedge screw hole's thread, these both combine with the long slits that make the "wedge fingers" to give a break spot that can easily become over-flexed by the messed up action. So imagine a force pushing left & right on these fingers with every stroke. This cyclic force initiates tiny cracks forming at the point of the thread's V groove at base of fingers. The continuing left-right wiggle gradually makes the crack expand and travel all the way across the base of the finger until it meets with the internal thread's V groove and breaks. When one finger breaks, this overloads the other two, and instantly the remaining two are also cracked away from the solid part of the kingpin, allowing the truck to fall off.

I have said it before and I say it again POOR DESIGN. A solid kingpin and a regular NYLOC NUT adjusting scheme is a WAY BETTER & MUCH SAFER design. The split finger+wedge screw concept is a perfect example of OVER-ENGINEERING something that does NOT need to be so complicated.

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Old May 24th, 2011, 04:05 PM   #15
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Thumbs up NICK V, Titanium King Pins (real Titanium) The Good Stuff

See Post #5.

In this picture you see 2 Proline American made,6061T6 King Pins.

In this Picture you see a BOLT. This bolt is a Aircraft grade Titanium (mil SPEC) with 1/2 X 20 threads that will screw into a Proline Plate. Your not going to thread these if there not already what you need very easy. Eats the dies and they must be the adjustable dies.

These bolts are used to attach and hold together the Rotary Nuclear CRUISE Missile LAUNCHER. THE ONES THAT HAVE WINGS AND FLY LIKE A AIRPLANE.

The launchers are mounted in side the B2 STEALTH BOMBER bays.

There is no stronger Ti made in the World. So after spending a week and probley 50 carbide lathe tool bits,dies,taps, I did make 4 out of these bolts.

There is little weight saved vs the 6061. They never have broken yet. In my spare plates. Under the bed.

Was it worth it?? Who knows. But if a skate plate has the tru correct action and does not load the king pin. You will hardly ever break one. My Proline Plate new in 1991 and still on the same aluminum pins. But I do regular maintenance and check ever thing before I go Warp 9. Change cushions ever year. And I lube cushions so they do not grip the metal and make friction when turning.

Only 2 plates in the real world that I have checked for accurate swing thru the full action are the Pro Lines and the Roll Line brand. Ever thing else is a comprise. Complicated by the use of adjustable pivot pins.

Now you know where we found this brand of Ti. Roswell " Alien flying saucer" crash in New Mexico,1947. Thats what they say in the museum there. Brings in lots more customers. They have some bolts and metal skin there from the Flying Saucer.

More fun going there though on your motorcycle,mountains,banked curves all the way,leaning and doubling all the speed signs IE 45 go 90. Lots of leaning and giggling,but it you have a BIG AH SH*T. Over the side down the mountain,won't be to good.

If you want to check your own plates etc. You can make some sponge cushions. Dish wash sponges have the stiffness to cut with a Xcacto knife and you can make to duplicate your cushion shape. Install and move through the turn observing what happens as you do it. This is off your foot and at work bench if you desire. You can see what the difference is if Pivot pin is 2 long or 2 short etc
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Old May 24th, 2011, 10:52 PM   #16
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I just had the same thing happen to me (also during a bout), but I have late-model Reactor plates (9 months old) with the plastic pivot cups. They don't appear to be that worn, but I'll try to post pictures when I install my new set of Magic Cushions.

My kingpin (front right) broke the same way, all the threads, clean off. Do I have to worry about the geometry of the truck with plastic pivot cups? What exactly am I looking for?

Also, if I'm getting this (hang in there with me), I should use a little lube (any kind?) on the cushions and cup? I'm still a little new at this (+1 year back on skates), but any advice to help prevent another breakdown would be appreciated.

Here I was just thinking it was just bad kingpin.
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Old May 25th, 2011, 03:50 AM   #17
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Originally Posted by Laddie View Post
I just had the same thing happen to me (also during a bout), but I have late-model Reactor plates (9 months old) with the plastic pivot cups. They don't appear to be that worn, but I'll try to post pictures when I install my new set of Magic Cushions.

My kingpin (front right) broke the same way, all the threads, clean off. Do I have to worry about the geometry of the truck with plastic pivot cups? What exactly am I looking for?

Also, if I'm getting this (hang in there with me), I should use a little lube (any kind?) on the cushions and cup? I'm still a little new at this (+1 year back on skates), but any advice to help prevent another breakdown would be appreciated.

Here I was just thinking it was just bad kingpin.
Use silicone grease on the cushions, retainers, trucks (also comes as dielectric grease). However be aware that it does neutralize the torsional (twist) snap back that the cushions can provide, since they will now slip instead, but with steep kingpin plates, this torsional snapback is not so significant. With a DA-45 plate I would not grease my cushions.

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Old May 25th, 2011, 08:44 AM   #18
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Default kingpin

The design isn't poor in general. The reactor kingpins from what I have noticed doesn't have a seperate jam nut as proline or snyder. I set my trucks and then see how many threads stick out after. Then I take and screw the kingpins down untill only 1 or 2 threads at the most stick out. The split end works better when it is in the adjusting nut. It is really easy to over tighten the wedge screw and flare out the kingpin causing it to be week. Plus we all know aluminum doesn't really bend it likes to break. I have been on prolines for almost 20 years and have yet to break a kingpin. With that said it seems that if you have a reactor and the nut is cranked down there is a chance that this can happen to you.
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Old May 25th, 2011, 01:17 PM   #19
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The design isn't poor in general. The reactor kingpins from what I have noticed doesn't have a seperate jam nut as proline or snyder. I set my trucks and then see how many threads stick out after. Then I take and screw the kingpins down untill only 1 or 2 threads at the most stick out. The split end works better when it is in the adjusting nut. It is really easy to over tighten the wedge screw and flare out the kingpin causing it to be week. Plus we all know aluminum doesn't really bend it likes to break. I have been on prolines for almost 20 years and have yet to break a kingpin. With that said it seems that if you have a reactor and the nut is cranked down there is a chance that this can happen to you.
After your opening statement, you proceed to confirm why I say it is a poor design. It is FAR too complicated for what is needed --- just a plain 3/8-24 thread and a thin Nyloc nut of aluminum. If everything is perfectly tuned with the suspension, I have no doubt they can last many years, but things can become messed up too, and when they do,this scheme is NOT very forgiving.

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Old May 25th, 2011, 11:52 PM   #20
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I am sure some of you on here have had more problems with reactors then just king pins and pivot cups, I have had mine snap long ways up the mounting plate and separate completely twice.

I have also went through dozens of trucks,I would shear them off at the pivot ball regularly,after many years they have since revised that issue thank goodness,i have still broken them but far less, I used to snap the king pins but I had some pro-line hardened steel king pins laying around and never had that problem again.

I was sponsored by Riedell for 7 years as a Jamskater and gave them all the feed back in the world on issues like these and imo they didnt seem to care to change anything to fix the quality.

I will stick with my Pro-Lines and Advantages :-)
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