WTF is up with dynafit toe pieces?

**XXX-er** · 02-23-2009, 07:02 PM

I believe the foam is the glue reacting to moisture ,PU glue needs moisture to react and cure

**splat** · 02-23-2009, 08:01 PM

Originally Posted by sfotex

I think epoxy is going to be my new approach to this problem in the future.

keep that fire extinguisher handy.

**Buzzworthy** · 02-24-2009, 03:15 PM

Originally Posted by sfotex

First pair was high societies, 2nd pair was moment bibby pros.

Jebus, how many pair of skis do you have? I saw you Sunday with another plus your almost lost Praxis............you feeding you kid right? Wait, mom has that duty for now. Kid has clothes and diapers? No wonder you are 155, spending all money on skis and no food.

I wonder about you sometimes.....

**skifishbum** · 02-24-2009, 03:23 PM

He justifies it all as SAR gear

**MultiVerse** · 02-24-2009, 03:36 PM

I blame it on every FKNA review posted on TGR because I’ve got the disease too. I just bought a pair of used Wailer 95s that will be mounted with Dynafits’ and it would be nice if I could use my own epoxy but still have them mounted at a shop.

The shop guys always say that epoxy is not recommended because it can break down the fiberglass or carbon resin… total BS; it’s not solvent based, and I cringe a little when I see the Elmer’s Glue bottle and think about how much torque is applied against the toe-piece.

**skifishbum** · 02-24-2009, 03:45 PM

I've mounted a few hundie rental skis with elmers never seen a pullout a few cracked cores but never a pull out without.
I mounted my dynowhompes with gorilla and the core of the carbon lhasas
cracked just above the toe but didn't pull out.

**MultiVerse** · 02-24-2009, 04:20 PM

^^^ I should add that I’ve never had a problem. But I also lack SFBs’ crazy-mad-single-ski-BC-skillz, although, one ski wouldn’t be a total disaster, at least not in the Wasatch playground.

**mittens** · 02-24-2009, 05:28 PM

I'm the one splat said emailed him. I have now ripped out the other toe piece on the original Euro made 183's. Splat sent me a slightly used replacement for the first one and told me to send the othe one back for replace also. Now that is customer service!
I am not light weight, 230lb 6'3'', Bindings shop mounted by a reputable dynafit dealer in Seattle. There were less than ten days on the skis. i know the snow has been hard around here, but I thought it shouldn't be a problem.
I guess there is some comfort knowing I wasn't the only one. However, if it had happened in a no fall zone, it could have been bad. Shakes my confidence with the setup. Last thing I need to worry about is if my equipment will hold up during a decent.
I'm interested to see what the guys can find out at PMGear once they get my skis.

**Lani** · 02-24-2009, 05:47 PM

I'm intrigued by this thread. I've always mounted with epoxy and never had this problem. I've broken quite a few skis and a few dynafit heel pieces in various ways. I've also cracked part of the plastic base for a toe piece and broken the front plastic clicky thing that locks the toes pieces. I've even broken the plastic housing the toe piece fitting in the boots. But never pulled a dynafit toe. This is with 7 years of heavy dynafit usage.

I haven't seen the issue myself and I've mounted something like 30 or 40 setups over the years with dynafits now.

I'd like to add another "wtf" regarding the threaded dynafit toe piece plastic bases to those of Big Steve and pechelman.

**Jonathan S.** · 03-25-2009, 09:38 PM

I also use Titebond for all my binding mounts, Dynafit or otherwise. My understanding of using glue is just to lubricate and seal the hole. (Yes, I know Lou advocates epoxy, but I still think that is some weird holdover from tele-pullout days of old.)

I also tap all my binding holes, regardless of ski construction.

I've never had any Dynafit screws pull out, even on my Trab Duo Sint Aero skis, whose cores seems to be made of something very soft -- quite noticeable when drilling and tapping.

**sfotex** · 03-26-2009, 09:25 AM

Well,
I beat the hell out of my dynafits in Canada (15 feet to a flat hard windslab landing, etc) and didn't destroy anything.
Guess ski gear is like cycling - when you get one flat you know there's 2 others right behind it.

**sfotex** · 03-01-2010, 09:08 AM

Bumping this up,
I know SFB ripped a toe piece out of his skies this season, Trackhead ripped one out last season.
Someone just posted up this thread:
[ame="http://www.tetongravity.com/forums/showthread.php?t=186748"]Dynafit+Pro Rider+moguls=fail? - Teton Gravity Research Forums[/ame]

I've started to heli coil the front screw under the lever in the tie piece from the git go to see if that helps. And other ideas? Dyna-duke plate?

**harpo-the-skier** · 03-01-2010, 09:28 AM

FYI, Dyna is getting rid off the 5th, front screw hole on the toepiece next year........ Stock up on the old ones if you think the 5th hole helps keep the toe piece on the ski.

**sfotex** · 03-01-2010, 09:57 AM

I'm no mechanical engineer, so maybe one can chime in, but I remember reading an article in Popular Science or something a long time ago, about how sometimes adding things to a design to strengthen it sometimes makes it weaker (with some case studies of spectacular failures of course). Anyways, I wonder if the 5 screw ends up taking most of the load when the heel piece hits the back of the boot causing it to lever out (vs. all 5 screws sharing the load) effectively weakening the toe piece.

Thoughts?

**jondrums** · 03-01-2010, 10:16 AM

^^ no, not in this case. The 5th hole should provide some extra support. They must be changing the structure of the toepiece if they're going to 4 holes

Tapping your holes when mounting should definitely result in a more secure mount.

**Solesides** · 03-01-2010, 10:50 AM

I ripped out at an FT12 toe piece on Coombacks recently...heli coils in there now and hoping that's a long term solution. It's hard to say what caused the screws to pull out..at the time I was burning wax off the skis on a groomer before a tour. Got the skis up on edge, slight chattering and that's when they ripped. I'm standing there with the toe piece clamped to my foot and no ski. Pretty horrifying when you no longer have confidence to make turns on hard pack... I'm wondering if water penetrating the front screws could have loosened them over time.. The feedback in this thread addresses bits and pieces of the problem, but I still think those who ski dynafits in bounds constantly are asking for trouble.

**frorider** · 03-01-2010, 10:57 AM

some observations from someone who uses tele and AT gear..

there are some similarities. skinning with the dynafit toe locked, and you encounter a creek gully...and ski down and across the snow covered creek, with some tricky moves on a big log. these small incidents add up to repeated stress on a relatively inelastic interface to the ski.

pull-outs typically involve a first phase of 'working out' i.e. slowly, over time, some of the key screws start rotating out a small amount. often the skier doesn't even notice, since the other screws are keeping the binding on the ski pretty well. there have been measurements posted showing that the virgin pull-out strength of an epoxied and tapped binding screw is no greater than a tapped-mount screw...and these measurements completely miss the point. the reason epoxy works well for binding mounts (especially bindings that inherently have a limited amt of lateral elasticity, such as a locked dynafit toe, or a non-releasable tele binding) is that the epoxy makes it very difficult for the screw to rotate even an 1/8th of a turn.

it's that first 1/8th of a turn that you want to prevent, since it paves the way for the screw to work loose a bit more and a bit more, which then leads to widening of the core hole diameter (i.e. the inner diameter of the hole, which ideally is the same as the non-threaded screw core) and also chews up the spiral threads in the ski core....paving the way for an eventual pull-out.

the only negative brought up re: epoxy mounts is the need to replace a binding (or remove and reinstall on a ski) in the field. ok fine, just bring a bic lighter and heat the screwdriver head and keep pressing it / heating it / pressing it on the screw, and you can get the screw hot enough to partially break that epoxy bond. if it works for me in the garage, it can work in the field.

**frorider** · 03-01-2010, 11:17 AM

btw, regarding the threaded dynafit baseplates: i've thought about this, and taken into account the fact that dynafit design engineers show plenty of evidence of not being stupid...and concluded that they threaded the baseplate in order to create a (mild) lock nut effect. helps increase resistance to rotational movement of the screw. anyone have a better explanation?

it's never bothered me in practice; easy enough to get just one of the 5 screws protruding a slight amt, line it up, mount to ski using plenty of downward force on the baseplates, then do the rest of the screws.

an alternative and perhaps better (?) approach would be to have serrated teet on the underside of the screw head, and matching serrations on a metal mount plate.

**Nordic75** · 03-01-2010, 12:52 PM

Pulling out the toe piece is bad enough, but when the entire ski delaminates after remounting with heli coils really weakens my confidence in Dynafit. I think they should make the baseplates a little bit wider to reduce the forces on the screws.

**jondrums** · 03-01-2010, 10:22 PM

it is a pretty narrow mounting pattern in the toepiece, so I can see how there's a lot more force on the screws than some other bindings. Either making the baseplate of the toepiece wider, and/or making the hole pattern wider would reduce the pull-out force on the screws.

frorider- I agree - I assumed that dynafit made the holes small for a "locknut" effect. In practice, I'd guess that it contributes to messed up mounts more than it helps lock the screws in place. Personally, I've chosen to drill out the plastic holes in mine and those that I've mounted.

**Shorty_J** · 03-01-2010, 10:41 PM

Originally Posted by sfotex

Dyna-duke plate?

Maybe Jondrums can chime in here, but I would think this would help prevent rip-outs. The mounting pattern of the plate to the ski is much wider and longer, so the plate is very unlikely to rip out... and now the narrow mounting pattern of the dynafit is mounted to metal with many threads in contact. Just make sure the M5's don't losen up (check them regularily and use loctite).

Does this make sense?

**XXX-er** · 03-02-2010, 12:10 PM

if you are worried about not being able to remove a screw mounted with 2 part slow set epoxy just crack the screw's after after the epoxy has cured to break the bond of the epoxy on the screw

you will still have made the bomber screw threads in the ski but the screw won't be sticking to the epoxy ...wiping the screw with an oily rag works too

**displaced** · 03-02-2010, 09:48 PM

i've seen people with some pretty unorthodox kickturn styles when making switchbacks - especially deep snow or icy skin tracks-. sometimes I wonder how on earth the toe piece of a binding can hold up to that force? not trying to say you're making shitty kick-turns, but just a thought.