Bennett KP Breaks Again

Parson Adams · Bennett KP Breaks Again

Well, this is two stock Bennett KPs in one month. I think that I'll just start swapping out KPs when I order new Bennetts. It is the same kind of break--right at the splines. Luckily, this time, I was only doing 12 mph and didn't hit my head.

dmccoach · Re: Bennett KP Breaks Again

Can you post a pic of the broken pin perhaps a few close ups of the break itself?

Thanks

Parson Adams

Actually, it looks just LIKE the previous broken KP.

These are the original pics posted from the first KP. I remember someone else stating that they, too, (ah, alliteration) snapped a KP in the same spot on the splines.http://picasaweb.google.com/jamesdsimpson/Broken

pavedwave

Jim, that's pretty wicked you've managed to bust two of these already. I'm glad you're okay because KP breaks--falls can really suck. it's worth taking up Aikido just to learn to fall in those split-second crashes Neutral

i'm dying to see your pump technique on video, as well as knowing all the particulars of your setup and typical riding terrain. i know from experience that riding over any kind of "cattle guard" type structure or sidewalk cracks with regularity contributes, but there could be something entirely new at play here.

where your pins are snapping is not a big surprise, but the fact it's snapping with this much regularity is, not having yet broken a front Bennett yet. whenever I've busted or seen pins busted, it's always been where a compromise to the bolt is made -- either threading, splines, or an area where the hangar was able to grind into the pin repeatedly.

my strategy here would be to pop out the stock pin, replace it with a grade8 bolt of the same or just slightly shorter length, that has a smooth shaft from the head of the bolt to where the threads start. I would put the bolt through the plate just like the stock was mounted, and use JB Weld to hold the head in place, letting it set for an overnight or two, then mount up like normal. This would be somewhat like the method samhell has used, but I would lean toward keeping the bolt's head and smooth shaft end in the baseplate end. if this makes no sense, I'll try to snap a pic sometime later.

camel

Yup, killed mine in the same place as well. right at the splines, below the level of the baseplate. Replaced with a 2.5 grade 8 and haven't had a problem since. I won't run another stock Bennett bolt in the front again. Wish the company had an email address or phone number. I can't even tell them there is an ongoing problem. Smile

Belegnole

bennettskateboards@yahoo.com

camel

Yeah, I tried that one too. I even asked JP to find me one. He couldn't get ahold of them at the time either. But thanks for the effort. Smile

Belegnole

I figured that you would have tried that one, but threw it up just in case.

pavedwave

pavedwave

camel

I haven't had any reason to get a hold of them lately. I replaced that pin and said screw it. I think that I am just going to replace all my Bennett kp's. I didn't even know they had changed owners.

model.citizen

they haven't, Buddy's just made the shift from CEO of Tracker to them as "President". same owners.

pavedwave

Mr. Bennett and I had some really great emails before his disappearance last fall, and he was generous in giving $100 to one of the Livestrong Ultras, on top of donating wheels for the cause which I auctioned off. Then I think he changed email accounts or something.

More recently I sent a couple mails to Buddy Carr at Tailtap, the first at beginning of February, then another a couple weeks ago -- but still haven't heard anything back. To not get any reply was a bit disappointing to say the least, but I'm not going to stew on that just yet.

...

What's more interesting to me at the moment is a discovery I made by popping out a few kingpins, getting ready to take them to a local shop for some replacements (finally)

I've been baffled as many know here, how I've not yet broken a Bennett pin -- while others are starting to do so with some regularity. I can safely say without exaggeration I've put several thousands of miles on my Bennett 4.3 truks, the ones that I first bought back in 2006 when Gareth and Brian first started chatting about LDP and my testing out his stuff. I instantly dug the truks and continued to like the 4.3 -- and continued to ride these two I have into the ground.

My beat up kingpins from the old 4.3's are still holding up, and now I think I know WHY. Check the photo:

The pin on the left is the old 4.3 one and the black baseplate that matches it. The pin on the right comes from a newer 5.0 one with a silver baseplate. Ignore the middle one for now.

Note how the older pin's splines at the bottom are WIDE and the newer bolt's splines are NARROW and thus there are many more of them -- which collectively creates more of a horizontal "cut" into the shank of the bolt, right at the stress point. The baseplates are of course grooved to match. I would suspect the newer bolts are fundamentally weaker.

scooterdad

Very interesting... It also appears that there is a bit less threading on the old pin which might explain some of the longevity(less shredding) you've experienced with your bushings compared to what many others have found with the newer pin.

Alec

It also doesn't have any markings on it. So what grade is it?

pavedwave

Good point Landy. That's what I'm aiming for with the middle one, hoping that the local shop will have that same size bolt, but with far fewer threads.

As for the grade question on the old pin, not sure, maybe Buddy will respond to someone else? sk8info@tailtap.com Wink

LDPanda

On the shredding issue, just a quick note. When i switched from a very non-standard bushing setup (two cones in an hourglass with a sliver of a barrel glued on there) to a more conventional one (blue cone superglued to white barrel, no cutting) i eliminated all bushing wear. My bushings look brand new now. I cant really explain it, i used to chew thru bushings like crazy and now they look great, id say if youre having shredding problems it might be worthwhile to change bushing combos to something more standard and see what happens.

pavedwave

The four pins on the left are those that Dave and I had made from our trip to Tacoma Screw the other day. We're going to try mounting them up this weekend. Originally 3" in length, we had cool dude Rick grind the tips off, leaving just enough threading for the nut and lots of smooth shank which should help solve the bushing wear problem.

To hold the bolt head in place, we're going to test this loctite compound first, which Barry has done with some success, then try an epoxy, per Camel's recommendation. The best mod here of course would be a little baseplate machining, creating a hex-shaped catch underneath. I'll leave that one to Bennett...

model.citizen

i'm sure you could slap a bead or two of alloy weld into the baseplate cavity using a MIG welder to hold the KP head (or nut, if you're inverting) in place.

pavedwave

For me at least, no inverted bolts, no nuts in the baseplate. IMO, that would undo all the logic of this strategy -- given the threaded portion of the bolt loses 18% of its strength compared to the smooth shank, and so far all these bolts are breaking down in that area just above the baseplate clearing.

Is alloy weld like "JB weld"? I'm open to all ideas. We're just going to try some of this loctite the first round, then maybe return the bottle that we don't open, if it doesn't seem to hold (Dave and I each bought a bottle -- stuff is NOT cheap!)

model.citizen

hmmm....true dat. i guess i had my head more around preventing bushing death due to the long threads. but of course if you're replacing the KP with a less-threaded one then this is moot.

by alloy weld i mean actually MIG or TIG welding a bead or two of alloy welding wire into the alloy baseplate, to anchor the KP head.

the weld doesn't need to be much, just a couple of blobs that prevent the head from turning...just enough to penetrate the baseplate alloy (and, since cast alloy is generally "dirty" and often contains alot of air bubbles, you don't want to weld too hard in there so as to prevent weakening the baseplate)

if you use a high enough amperage on your MIG welder, you can even stick alloy to steel (after a fashion) using plain steel welding wire.

if you're using JB weld, make sure you use the runny 2-pack affair, rather than the all-in-one kneadable crap (doesn't stick so well). before applying, rough up the surface of the baseplate (a centre punch is best to create little dimples) which well help the JB adhere better.

another option is to drill and tap a 4 or 6mm hole into the baseplate near where the KP head sits, and screw in a grubscrew so that it sits against the KP head and prevents it from turning. just pop a bit of Loctite on the grubscrew first so that it doesn't vibrate out.
if you don't have access to a set of taps and dies, then you could always force a thick short wood screw/machine screw into the hole you've drilled (with a bit of Loctite for good measure).

it's the engineer and fabricator in me coming out! Very Happy

Ian the Groove Worshipper

I have done the KP swap on several Bennett baseplates now, using the Loctite shown above. A few of the KPs came loose, and needed repeat applications of Loctite, but now seem to be sticking. So you know, I indeed had prepped the surface prior to applying the Loctite with Acetone and 600 grit sandpaper.

While they are sticking for the time being, if they continue to come loose, I was considering trying JB Weld.

I've never used JB Weld before. For those of you who have, how permanent/strong is it? Would it still be possible to remove the JB Welded KP without causing damage to the baseplate for future KP changes?

model.citizen

JB weld just needs a hammer and a screwdriver to remove it - not difficult. Kinda like Loctite. doesn't eat into surfaces, but if applied correctly lasts almost forever.

it'll generally remove as a chunk, that's why you need to really prep the surface (not just clean and abraded) before using it, otherwise under vibration it can just come free.

camel · Is that your final answer?

This is ALL you need guys. I have been using it for over a year. (It says it is for China and Porcelin, that is just because it dries "off white". It is WAY more than you would ever need for that kind of repair.)

Devcon 2Oz White 2-Ton Epoxy S30

"Bonds and repairs metal, wood, concrete, glass, ceramics, porcelain, china, tile/fixtures and fiberglass. Sandable and paintable. 2500 psi bond strength. Sets in 1 hour."

http://www.hardwareandtools.com/invt/6393680

I have never had this come loose, it has a slight bit of flex that keeps it from breaking loose. Slather it around in the kp hole and the inside of the baseplate. Wrap the threads tightly with saran wrap, push through the hole. Assemble the truck after cleaning excess and leave it overnight. In the morning you will have a permanent bond between kp and baseplate. Works like a champ every time...

LDPanda

I put together a bennett 5.0 baseplate with the new KPs that james and i had made. I used red loctite 262 (the same one pictured above). The KP is a little shorter than im used to, i couldnt fit my current bushing combo on there but i made something work for now. I probably wont use it for the ultra considering its so close and i dont want to dial in a new bushing combo. Anyway, as far as i can tell, the red loctite is working just fine. I was able to put the nut on fine without any slippage or slop. I rode it around the neighborhood for a second but its kinda wet out and i didnt want to push it. The KP clearance is nice, very little of the bushing is on threads, over all im pretty satisfied. I think the loctite worked fine despite its many opponents Smile

LDPanda

Finally got around to mounting that new baseplate on my pulse and im glad i did. The stock bennett kingpin in the baseplate i took off showed visible signs of metal fatigue arond the base and audibly jiggled around the plate. Im just glad it didnt break during the ultra! My standard bushing combo worked out just fine, i dont know what i was talking about before, i must not have tried very hard (or the bushings have worn in a bit). The loctite is still working fine, i had it mounted with a 5.0 hangar on my mistress and took it out for a few rides before. Its certianly more secure than the old one! The KP is slightly shorter and adds a tiny bit to kp clearance. I like the shiny top Cool

Heres the old one. the fatigue doesnt show up real well in the photo but here it is anyway.

Bennett KP Breaks Again

Re: Bennett KP Breaks Again

Is that your final answer?