broken drive shaft

[RKT]

well, if the glue wasnt needed then why did polaris put it in there? and if it was a material thickness/strength issue then why hasent everyone of them failed? its an extruded shaft, meaning very very consistent..if there was inconsistencys in the tube, the failures wouldnt all be almost identical.....as for your socket analogy, yep your right ..the bolt cant spin in the socket..yep absolutely...but the bolt can slide right out of the socket..and is exactly what will happen when the tube gets clamped and the glue fails..the glue is the one constant when it fails..the shaft fails.

WOW. How can it slide out when it is bound at each end with the tunnel??

The failure occurs at an angle NOT laterally.. The pics show this CLEARLY>..

The OTHER constant IS the material strength.. The GLUE is NOT just the 1 constant.. Material does not just "tear" like these are doing unless there holding strength has been overcome...

As for me saying glue is not needed??? AAHHH.. please see 2 posts above where I clearly state.. IT IS NEEDED.

 

[RKT]

I just noticed that the pics I posted show the exact same failure ( extrusion tearing) YET, they are from 2 different failed sleds..

 

[whoisthatguy]

The upward pull of the belt, causes about a 1400 lb-in moment on the glued joint. The belt tension causes about a 100 lb-in moment on the glued joint. The engine torque causes torsion of about 1400 lb-in of torque on the glued joint which does not tend to pull the fence post cap out of the end of the aluminum center section. Therefore, it would appear that the 700 lb belt tension is the primary driving force that prys the red hot fence post cap out of the end of the aluminum center section, after the glue fails. I wonder how well that glue holds up to 180 deg F. I'll bet that it is not rated for those kind of temperatures.

 

[snowmobiler]

fifty dollar china bicycle's are built better

 

[mountainhorse]

The upward pull of the belt, causes about a 1400 lb-in moment on the glued joint. The belt tension causes about a 100 lb-in moment on the glued joint. The engine torque causes torsion of about 1400 lb-in of torque on the glued joint which does not tend to pull the fence post cap out of the end of the aluminum center section. Therefore, it would appear that the 700 lb belt tension is the primary driving force that prys the fence post cap out of the end of the aluminum center section, after the glue fails.

What about the serious varying tension on the track, and subseqently the driveshaft, as the suspension cycles though it's range? Add to that, radically shifting torque feedback from varying traction and power input.

 

[mountainhorse]

The failures shown in the pics above do not show the stub "popping" out of the shaft extrusion...but rather it shearing through the extrusion.

I would be surprised if the tunnel, at the bulkhead, with the extruded/bonded aluminum fwd. wall of the tunnel acting as a strong reinforcement, is spreading to any significant degree to allow the stub to pop out of the shaft.

In both photos I dont see much adhesive residue remaining on the stub/cap. Seems the adhesive bonded well to the more porous alumium of the shaft... but not to the stub/cap. In fact, the stub/cap looks kind of shiny.

Seems it may have been a lack of adaequit surface prep... an etched or blasted finish on the steel may have made the connection much stronger.

 

[mountainhorse]

If the adhesive connection of the stub/cap to the aluminum extruded shaft assembly fails, then the force of the cap overpowers the dimensional stability of the shaft (ie. The shaft wants to go "round" rather than remaining a hex)... Much like rounding off a thin walled wrench-socket does when using too much torque on a tough fastener...

Once this heat treated, rigid aluminum driveshaft "balloons out"... the end comes very quickly for the shaft assembly.
You can see that the shaft extrusion is ballooned-out in the photo above.. it is no longer a hex, but mostly round... That cap spun in the shaft BEFORE it tore out.

The stub/cap fractures the shaft and the track tension, pulling aft, finishes the job of tearing out the stub/cap from the shaft extrusion.

At least that's my theory.

The factory had such good luck with the Demo fleet... all had the aluminum shaft.
I personally (with the help of Phatty and Turbolover) abused this driveshaft by running the sled with a piece of log jammed in there for 30 minutes of riding.
Those shafts were hand built in a low production environment.

The production of thousands of driveshafts for consumers sleds MAY have been different.
Which is also a good reason why some people that I know that have already put on some good mileage on their 2013's have not experienced a problem.

I'm sure that the vendor that assembled/supplied these shafts is catching he!! over this right now.

I don't think the design of the shaft is poor... I think the assembly of these units that HAVE failed was done poorly.





Pic of the chunk of log that was wedged in the tunnel for 30 minutes of riding (heck.. its a demo, huh)

Well... I had a Vibration in the driveline that felt much like driver that was not meshing well with the track. For 30 minutes I rode it that way... but I thought to myself... "It's a rental".... drive it into the ground... ride it like a rented mule...I thought that I'd "break it" and show those guys in Roseau their Achilles heel... NOPE!

Well after coming back to "base" and telling Jared to "ride that sukka and tell me what you think" ... He flopped it over and found a two-hour piece of firewood wedged against the bulkhead... took some work to get it out..but we did..

That sled would stop as soon as I got off the gas...the clutches were smoking... and I was convinced that the belt drive was stripped out...

Well.. we pulled the log out and rode around... no problem and no broken belt... And we hammered that thing... I drove the same sled back 10 miles to the lodge with zero issues and no vibration.

 

[AKSNOWRIDER]

pretty much..but it all starts at the glue failing..as for the tunnel spreading..not much in a factory setup..but it will if any form of clamp is pit over the tube..because then when the glue fails, the hub cant fail sideways thru the joint..it is going to climb out of the tube..bowing out the clutch side of the tunnel..

 

[modsledr]

Personally, I think the both "theories" are partially correct.

The Lords adhesive IS structural. The nature of assembly lines is that there are assembly tolerances...no 2 are exactly alike, but ALL are close. That is why some have more glue coming out of the rivet holes than others. It also is 1 possible explanation of why some will fail earlier than others.

Now, some of the "less glued" units are failing early, and it's possible that some of the "more glued" units MIGHT fail later. It's also possible that the "more glued" units will be able to handle the stresses put on them (time will tell).

Once the glue fails, regardless of what forces are causing it, it is allowing the "plug" to rotate in the shaft, and the rest is history.

 

[AKSNOWRIDER]

Mod, I will use kelseys bolt and socket as an example....if you slide a bolt into a socket and then weld the socket all the way around the end right to the bolt hex(just like this driveshaft is with glue) and then lock the bolt down and torque the socket to fail..what will happen as long as your weld(glue) is good? the socket body will fail..in the middle, since the ratchet end is to solid to fail, and now the bolt end is...same as this shaft..if the joint holds and too much force is applied..its going to fold the driveshaft tube right in the middle where it is weakest.(go back 4 pages, there is a pic of a twisted truck driveshaft) the fail on all shafts pictured so far all show the hub joint failed at the glue first...everything else was secondary to the glue failing...

 

[skibreeze]

Mod, I will use kelseys bolt and socket as an example....if you slide a bolt into a socket and then weld the socket all the way around the end right to the bolt hex(just like this driveshaft is with glue) and then lock the bolt down and torque the socket to fail..what will happen as long as your weld(glue) is good? the socket body will fail..in the middle, since the ratchet end is to solid to fail, and now the bolt end is...same as this shaft..if the joint holds and too much force is applied..its going to fold the driveshaft tube right in the middle where it is weakest.(go back 4 pages, there is a pic of a twisted truck driveshaft) the fail on all shafts pictured so far all show the hub joint failed at the glue first...everything else was secondary to the glue failing...

Agreed.

 

[AKSNOWRIDER]

Agreed.

thanks Ski....

 

[smwizzz]

Cool thoughts...

since 06 I've had 06 m7, 07 m8 ,08 m10, 10 m8 turbo, 11 m8 turbo, never had a diamond drive failure, and that's not buying and selling every year, I presently have 2 turbos in my shop. Im leavin green cause I don't like the direction they've gone and crappy dealers. In my 39 yrs of owning sleds I've only been able to dream of having a 160 hp sled that's 400 lbs, but I'm on the fence right now, I was even guilty last nite of spending 2 hrs on the xm forums tryin to convince myself y I should or shouldn't buy one. I've always called the brps a desposeable machine, now it might be lookin the same way with the pro..

One can say the same about Cat... or Gm vs Ford... or Dodge....

I've seen older Cats plastic blow off in snow cross at -35 deg C and the rest seemed to hold together. That didn't mean cat didn't make a reasonable machine. I heard rumors of Doo's bending in half and Yammy has always been the cast iron sled that lasts forever.... .

If you are concerned wait and let everyone test them first. All new stuff has a few issues. Hopefully the warrantee stage takes care of this and hopefully grand failure doesn't happen way back in the hills where it is a major pain to get it out. Bottom line is if they take care of the customer and fix the problem... if there is one then it is still a good ride.

No one wants to tow a sled out for sure, especially me!!! I've pulled and been pulled on more than enough occasions. It sucks!!! Honestly, I've pulled every brand out at one time or another. I have had mod sleds that were pulled out on occasion. I guess the good thing is you aren't pulling a 450 - 500 lb ride out. Still doesn't make it fun to pull anything.

Lets wait a day or two until the real snow flies and everyone starts to really ride. Time will tell!!!

 

[FCR112]

If the warped/torn/damaged shaft is grinding on the stub immediately following failure it may be difficult to determine where the adhesive bond was thickest or strongest at the time of failure by looking at what's left.
It may also get hot spinning around in there which may weaken the Lord's and help it to come off the stub after the failure...


There's my contribution to the speculation.

I think you guys are on this, now let's hope the Polarry warranty program gets on it too.

 

[RKT]

Mod, I will use kelseys bolt and socket as an example....if you slide a bolt into a socket and then weld the socket all the way around the end right to the bolt hex(just like this driveshaft is with glue) and then lock the bolt down and torque the socket to fail..what will happen as long as your weld(glue) is good? the socket body will fail..in the middle, since the ratchet end is to solid to fail, and now the bolt end is...same as this shaft..if the joint holds and too much force is applied..its going to fold the driveshaft tube right in the middle where it is weakest.(go back 4 pages, there is a pic of a twisted truck driveshaft) the fail on all shafts pictured so far all show the hub joint failed at the glue first...everything else was secondary to the glue failing...

YUP.. But you are forgetting 1 thing.. The shaft AT THE CAP ENDS, does NOT have the internal renforcement (see the pic) and EVERYWHERE else inthe shaft will have the 3 point internal reennforcement bracing.. So, the ENDS of the shaft are weaker than the rest of the shaft...
They have machined back the internal re-enforcement of the shaft to allow fo r the end cap insertion...

In any case, clamping around the shear points on the END of the shaft will , NO DOUBT, stengthen this area and the amount of force required to rupture/fracture this area will be greater than if there was nothing there at all..

Can it fracture elsewhere?? YOU BET.. Will It?? Don't know... Why? because the shaft is stronger due to its internal bracing. and the forces at play are not as strong the further you move inward on the shaft body.

This is the basis of the kit I offer..

Take a pencil and grab it at each end and try and snap it.. It snaps in the middle quite easily. Now, put a hose clamp around the center of the pencil and try it again.. It breaks at one side of the hose clamp...> Why?? Because the clamp strengthened the arae it surrounded..

 

[modsledr]

Mod, I will use kelseys bolt and socket as an example....if you slide a bolt into a socket and then weld the socket all the way around the end right to the bolt hex(just like this driveshaft is with glue) and then lock the bolt down and torque the socket to fail..what will happen as long as your weld(glue) is good? the socket body will fail..in the middle, since the ratchet end is to solid to fail, and now the bolt end is...same as this shaft..if the joint holds and too much force is applied..its going to fold the driveshaft tube right in the middle where it is weakest.(go back 4 pages, there is a pic of a twisted truck driveshaft) the fail on all shafts pictured so far all show the hub joint failed at the glue first...everything else was secondary to the glue failing...

I generally agree with this...but it seems like you're saying 2 different things...with the different analogies.

If the glue holds, are you saying that the shaft is twisting/breaking?

Personally, I agree with your last statement that everything is secondary to the glue failing.

If we assume that a certain amount of glue is required to meet the structural engineering requirements of the application, and there are a certain % of units that are "under glued"...then the glue fails first, then the insert spins and blows out the sides.

One of the first pics posted of a failure in snobyrd's post showed a shaft where the insert had spun, but had not yet broken out.

Personally, I don't believe the insert can spin without the glue failing...Just my opinion.

It IS possible that if properly glued, the shaft will work as advertised/engineered.

I really like NM's solution. Even if the glue is subject to failure, it till keep everything held tight.

 

[smwizzz]

Hmmm...

Lets say that I was out snowmobiling by myself in 3 feet of fresh powder over a 5 foot soft base. It is 10 degrees F and night is coming within 2 hours. I can easily ride the 20 miles to the trailer, if my sled holds up as per manufacturers claims. Except, some bonding glue between steel and aluminum in the main drive system, suddenly fails due to no fault of mine. Then I die in the process of attempting to hike out in snow conditions that are impossible to be hiked. Is this life or death scenario figured into the engineering calculations that designed that driveshaft joint? What is Polaris going to say about all this? "Snowmobiler died because of a bonding glue failure, where it should never ever have been used?" No. They won't say anything because they will never be asked, which is why cutting corners to build a lighter sled, occurred in the first place. Glue is not a long term and viable structural element in any structural system, especially the main drive system for which no backup exists nor can one be fabricated in the field from branches and duct tape. Welding is long term. Solid metal is long term. Glued joints are not. Jet planes that use carbon fiber and presumably glue, are inspectioned by professionals on a regular basis. Snowmobiles that rely on glue to keep the rider alive, are not. Polaris really screwed the pooch on this one, in my opinion.

I will suggest a riding partner. If you die because you have to hike out then you must be riding alone. I don't think this is a wise choice whether it is in the mountains... or anywhere for that matter.

Not trying to be miserable but doors on vehicles and body panels are and have been glued for years with no problems and possibly stronger than welds. Hilti and other fastener manufacturers make bonding products that are amazing and even used in structural buildings and such... which have people inside... and have a failure rate of??? I don't know, I have never heard of a failure.

Personnaly I like welds. I own a metal fab shop and if one is a skeptic, it is probably me. I have just been around long enough to see the potential for great products even though they are glued. I have also learned that one should have survival gear and ride with a partner so we don't die because of a driveline failure.

 

[AKSNOWRIDER]

mod, what I am saying is if the glued joint holds as far as the glue goes, the joint will hold and the tube will fail somewhere else(most likely twist up in the center as the truck driveline did)..ideally if you have a big powered sled(turbo bigbore, i think a 11-12 steel shaft would be the best bet) on a stocker..well I would get some milage on it(with anything I think I would need for a tow just in case in the truck) and inspect it closely on every ride..once it got miles on it..I would gain trust in it..but thats me...

 

[RKT]

If the adhesive connection of the stub/cap to the aluminum extruded shaft assembly fails, then the force of the cap overpowers the dimensional stability of the shaft (ie. The shaft wants to go "round" rather than remaining a hex)... Much like rounding off a thin walled wrench-socket does when using too much torque on a tough fastener...

Once this heat treated, rigid aluminum driveshaft "balloons out"... the end comes very quickly for the shaft assembly.
You can see that the shaft extrusion is ballooned-out in the photo above.. it is no longer a hex, but mostly round... That cap spun in the shaft BEFORE it tore out.

The stub/cap fractures the shaft and the track tension, pulling aft, finishes the job of tearing out the stub/cap from the shaft extrusion.

At least that's my theory.

The factory had such good luck with the Demo fleet... all had the aluminum shaft.
I personally (with the help of Phatty and Turbolover) abused this driveshaft by running the sled with a piece of log jammed in there for 30 minutes of riding.
Those shafts were hand built in a low production environment.

The production of thousands of driveshafts for consumers sleds MAY have been different.
Which is also a good reason why some people that I know that have already put on some good mileage on their 2013's have not experienced a problem.

Eric,

If for the shaft to go from hex to round.. there must be some "flexing" or movement in the out shell. Even if for a moment and slight enough that it does not fracture.. I think it has to flex outward.

I also think that we can and do have at least 2 possible and different failures that can occur..

1) Glue does not fail but forces internally, due to extrernal angular forces, overpower what the external extrusion can handle and it "breaks out" causing failure.

2) Glue does fail and outer extrusion wall flexs due to the end cap trying to move internally . The end cap eventually wins and the two are seperated completely..
There are certainly more scenarios that can happen..

I think anything one can do to help strengthen the critical areas will increase its resistence to total failure..

 

[mountainhorse]

Here is a vid typical of how Lord 406 is injected into an assembly like the driveshaft.

Holes on the shaft are injection points... not weep holes.

The cap has, what appears to be, a channel in it for the adhesive to flow around the circumference of the cap during the injection process.

You will see in IEATSRT'S pic that the adhesive seems to have an even amount of squeeze out around the cap... a bit less where there is no hole.

Fast Fwd to 2:25 in this vid and you will see this injection method.

I'm curious why there is not an injection hole on EACH flat of the hex?

Again... this leads me to believe that the design of the shaft is good.. the application of the adhesive and surface prep of the stub/cap ON SOME UNITS seems suspect to me.

It also may be possible that during the bonding processing of the driveshaft ... there was not enough time after the injection prior to moving the shaft which might disturb the bondline.

Cheers,
MH

​

Here are a few pics of my shaft with 230 miles on sled. Loads of glue in there oozing out holes and seam, other ones I have seen that have failed don't appear to have near this amount of glue, if any glue at all. Why I think it is a manufacturing problem, some just weren't glued as well. If mine hasn't blown with what I've done with it for first 230 miles not sure what I would have to do to it to get it to fail. Glue is good and hard also. And hey, my belt is holding strong.... go figure.