MPI Supercharger Pulley Failure

[irondave86]

m8magicandmystery is right.

I don't see how you adjusted your belt without loosening the tension pulley? you have to loosen it just a little to adjust the belt (if you loosen too much it can deflect when your adjusting the belt). Then use the adjustment screw to adjust the belt tension, set the lock nut. Then torque down the adjustment pulley. There is no possible MPI could pre-set that pulley. because its location different for every pulley combination. id86

 

[m8magicandmystery]

Chris..in the picture that you indicate"the lockbolt still firmly locked in place"..

that don;t lock that tensioner..!!..that bolt just locks/sets the tension distance..no differant then loosening your rear axle and adjusting then tightening your rear axle.??? .that center pulley
bolt is an end user issue to deal with and maintain..imo..

 

[m8magicandmystery]

Since it was factory installed I do not recall having ever touched the nut on the backside, there would have been no reason for me to have messed with it.

My only guess is that it must NOT have been fully torqued down from the factory
[/B][/I]

but you did touch it prior to the trip according to your post below...and you torqued it (from the front bolt head i assume) which would have or should have set the rear nut..so of course it would as well not be fully torqued from the factory when it had yet determined its final resting space..??..and it was torque by you..anyway i hope ya get it sorted out...first the story...was it torqued or wasn;t it....once that is determined then only can ya look at the next step


Making the first leg of a long drive back to Idaho falls today.

We DID check and torque the nut that failed before we left on this trip. With the heim joint failure on day two that got me less than 8 hours of use before failure from the last time we checked it.

Really do not understand this failure yet. Will have to wait till I get he and get the oil tank off of it so we can see it more clearly.


Sent from my Apple iPhone 4S using the AVOW TapaTalk app.

 

[m8magicandmystery]

something still not right with that tensioner..the adjusting bolt appears to push on the threaded stud of the tensioner..why isn;t that slot wider and there some sort of push block..or did the back nut have two ears that went in the slot and thats what the adjusting rod pushed on..??

 

[christopher]

The pulley wheel came from the factory bolted to the tensioner bracket.

The pulley was already attached to the bracket while it was IN the sealed package.

The bracket has a long bolt on it that is used to apply tension to the pulley.
That is a locking bolt and it was still locked in place.
So it had NOT come loose possibly allowing the pulley to get torqued and go sideways.

Ryan, my tech at Rexburg Motor Sports, said he had checked the torque on the pulley bolt before we left for Canada.

BUT...

There is NO possible way that I can see of getting a wrench in behind the pulley bracket after it has been bolted and loctited to the frame.

So I have to ask him just what exactly he did OR if he was saying he torqued to the two MAIN supercharger Pullies?? Its possible I misunderstood what it was he was telling me. I have a message in to him awaiting his reply.

 

[irondave86]

The pulley bracket is notched to hold the nut firmly. you don't need to get a wrench behind it. you only need to loosen and tighten from the front. Also i blue lock-tight mine just for added insurance. id86

 

[apex jeff]

The pulley wheel came from the factory bolted to the tensioner bracket.

The pulley was already attached to the bracket while it was IN the sealed package.

The bracket has a long bolt on it that is used to apply tension to the pulley.
That is a locking bolt and it was still locked in place.
So it had NOT come loose possibly allowing the pulley to get torqued and go sideways.

Ryan, my tech at Rexburg Motor Sports, said he had checked the torque on the pulley bolt before we left for Canada.

BUT...

There is NO possible way that I can see of getting a wrench in behind the pulley bracket after it has been bolted and loctited to the frame.

So I have to ask him just what exactly he did OR if he was saying he torqued to the two MAIN supercharger Pullies?? Its possible I misunderstood what it was he was telling me. I have a message in to him awaiting his reply.

Hey Christopher;first off sorry about your bad luck. Now take a look at the pic you posted of the sealed bag with tensioner pulley and bracket, what you dont see is the long tensioner bolt and jam nut.The long tensioner bolt is in a different bag,mpi ships 2 bolts of different length depending on adjustment required.In the instructions under-DRIVE SYSTEM INSTALL this is all explained in depth with clarity,also noted 3 times in this section of assembly is NOTE: recheck set screw torque and belt tension first 5 miles of riding! The third notation also adds ( "then recheck every 100 or 200 miles").Go back to posts #405 & #406 on your original build,also post #452 where you change to the longer bolt.Plain and simple the bolt worked loose! No permanent damage, just check it more often. Irondave86 is correct the back of idler bracket is slotted to capture nut flats for torquing. This is why everyone keeps posting that they check the belt tension and bolt torque frequently, as per mpi written instructions. So clean the aluminum off the pulley,touch up the oil tank,buy a new belt,and check tension and torque more often.

P.S. hope the kids' knee comes back.

Jeff

 

[MotoPsycho]

If the supers are the best thing in drag racing then tell me why one stop performance uses turbos on all their record setting worlds quickest snowmobiles?

What I said was "properly set up" and "on a track that short" - I guess, in the interest of symantics, I should have said was:

"2 normal everyday schmoes, normal everyday ridin' sleds, setup identically, running exact boost levels, rider weights and sled weights exactly the same, nothing different other than boost delivery method...

OSP is not even in the realm of apples and oranges... the turbo's are the size of basketballs, and they could never be ridden in day to day situations - much like you wouldn't drive an NHRA dragster to the grocery store.

 

[ZeeRTee]

The Simple Answer

Hate me if you want, but, after reading this thread, some people shouldn't be allowed to have wrenches.

I am all about someone wanting to learn about something new and working on there own machines and whatever, but when a statement is publicly made, as to a manufacturer being at fault, as in this situation because the nut was tightened before I received it, that statement is ludicrous if you know anything about how this belt tensioner works.

As far as I am concerned, some damage has been done to MPI because of this thread, I have no association with MPI other than installing a few kits which have worked flawlessly, do I love the GEMS, not really, but it works OK if you know what your doing, but other than that there stuff works good for us.

I am not against asking for advise or sharing experiences , good or bad, about a product, but I will state my opinion here as this failure is 100% installer caused.

 

[christopher]

Hey Christopher;first off sorry about your bad luck. Now take a look at the pic you posted of the sealed bag with tensioner pulley and bracket, what you dont see is the long tensioner bolt and jam nut.The long tensioner bolt is in a different bag,mpi ships 2 bolts of different length depending on adjustment required.In the instructions under-DRIVE SYSTEM INSTALL this is all explained in depth with clarity,also noted 3 times in this section of assembly is NOTE: recheck set screw torque and belt tension first 5 miles of riding! The third notation also adds ( "then recheck every 100 or 200 miles").Go back to posts #405 & #406 on your original build,also post #452 where you change to the longer bolt.Plain and simple the bolt worked loose! No permanent damage, just check it more often. Irondave86 is correct the back of idler bracket is slotted to capture nut flats for torquing. This is why everyone keeps posting that they check the belt tension and bolt torque frequently, as per mpi written instructions. So clean the aluminum off the pulley,touch up the oil tank,buy a new belt,and check tension and torque more often.

P.S. hope the kids' knee comes back.

Jeff

Man I wish I had taken some photos of it when I took it out of the bag new.
Would be super useful right now to be able to see the back side.

If there IS a cut notch for the lock nut to fit into, then that would make losts of sense and would square with my tech's comment that he torqued it down before the trip.

Let me go down and remove the bracket so I can see the backside of it.

 

[christopher]

Post 404
http://www.snowestonline.com/forum/showpost.php?p=2796989&postcount=404

Post 405
http://www.snowestonline.com/forum/showpost.php?p=2796989&postcount=405


COPIED FROM BUILD POST

128. See Figure 71. Belt adjustment. Snug M12 main tensioner bolt/ nut so that the tensioner barely slides. Adjust tension with the M8 Adjuster bolt. The long side (lower) of the belt should NOT be able to touch the other side of the belt as it runs over the idler pulley. It should require about 15-20 pounds of force to make the long side of the belt move ¼” (15 to 20 pounds of force equals ¼” of deflection). Gates and others sell an inexpensive Tension Tester p/n 7401-0076. Once desired tension is set with adjuster M8 Bolt, tighten main M12 nut and bolt. Push idler against adjuster bolt as you tighten. The idler will tend to walk out, making the belt tighter. Recheck belt tension after the M12 bolt had been tightened. Tighten M8 adjuster jam nut.

NOTE: RECHECK SET SCREW TORQUE and BELT TENSION AFTER FIRST 5 miles OF RIDING! Then recheck every 100 to 200 miles.


Using the default bolt, I cranked it all the way down and set the Lock Nut.

============

Belt tension WAS checked, and the tensioner bolt is STILL LOCKED tight in place after the ride in Canada.

 

[MotoPsycho]

Christopher -

The bolt came loose. Simple as that. No breakage = NO FAILURE

There is really NO reason to push blame on to anyone, much less have the gall to speculate the manufacturer is "100%" responsible BEFORE you have all of the facts.

The simple facts are -

The bolt utilizes a "nyloc" nut. The are only made for a single use (although we ALL use them until they don't hold - then a drop of loc-tite will suffice)

Nyloc nuts are not designed for high temp applications.

You have someone else doing your work for you. (you just split responsibility 3 ways - you, your mechanic, the manufacturer)

Humans AND parts fail. Find the commonality of the failures, and you can slow the bleeding.



What I see as the commonality in YOUR failures is 100% human error.

You chose to continue running small heim joints...
You choose to trust a mechanic to not only do good work, but to also state the truth when questioned about it.
You are ultimately the last person in the chain of custody - hence, you are ultimately responsible.

I am still a bit skeptical on the mechanic side of things - the clutching and associated components that I witnessed on your sled in Togwotee this year raised a huge red flag to me... guru, self professed expert, God to the masses - doesn't matter. He is still capable of missing things, and making mistakes.

 

[MotoPsycho]

]

============

Belt tension WAS checked, and the tensioner bolt is STILL LOCKED tight in place after the ride in Canada.

If THAT is where your bolt is seated, YOU ARE USING THE WRONG ADJUSTER BOLT!

It SHOULD NOT be bottomed out, even if it was holding proper tension upon initial install. The belt WILL stretch some, pullies will wear, and you WILL need to tighten it somewhere along the line. You cant do that with the adjuster bottomed out.

High altitude pullies almost always need to use the LONGER bolt.

 

[ZeeRTee]

Christopher are you taking any prescription medications?

I don't want to pry into anyone's personal life but seriously, are you taking anything that would cloud your thinking? If you are not, then

Some people should not have wrenches.

 

[christopher]

This one is muddied.

I see that part as supplied from the factory, pre-installed as a assembled component. There are NO torque setings listed, nor is that bolt/nut listed to be rechecked aftrer installation or riding. So far as I can tell from the manual that is a "Set it and forget it" component.



http://www.snowestonline.com/forum/...r jam nut. NOTE: RECHECK SET SCREW TORQUE andMPI MANUAL
http://www.mountainperformance.com/Files/Download/msn-1000_supercharger_nytro_10-20-10-small.pdf


These four lines cover everything related to the pulley tensioner.

125. Install the Idler bracket and the Idler wheel assembly onto the frame bracket using 2 M8x25 socket head cap screws. Use a little blue Loctite on each bolt & torque to 20 ft-lbs.

126. The jam/adjuster bolt pre-installed into the idler bracket is the correct bolt for most ratios. If you find that the range of adjustment required is different, please install the alternate jam bolt provided in the kit.

127. Once the idler is installed, back the adjuster bolt out as much as possible (the longer adjuster bolt hits the frame). Loosen the main idler bolt just enough so that the idler will slide.

128. See Figure 71. Belt adjustment. Snug M12 main tensioner bolt/ nut so that the tensioner barely slides.

Adjust tension with the M8 Adjuster bolt. The long side (lower) of the belt should NOT be able to touch the other side of the belt as it runs over the idler pulley. It should require about 15-20 pounds of force to make the long side of the belt move ¼” (15 to 20 pounds of force equals ¼” of deflection). Gates and others sell an inexpensive Tension Tester p/n 7401-0076. Once desired tension is set with adjuster M8 Bolt, tighten
main M12 nut and bolt. Push idler against adjuster bolt as you tighten. The idler will tend to walk out, making the belt tighter. Recheck belt tension after the M12 bolt had been tightened. Tighten M8 adjuster jam nut.

NOTE:
RECHECK SET SCREW TORQUE and BELT TENSION AFTER FIRST 5 miles OF RIDING!
Then recheck every 100 to 200 miles.

====================

Explanation for everyone in this thread.
The nut that failed is the M12 Nylock Nut on the back of the M12 Bolt.

Photos of this are shown on page 34, Figure 71, in the MPI PDF listed above.

 

[MotoPsycho]

Here's a gooder for ya...

You have oft given me kudos for being a guru, knowing my stuf, yada-yada B.S.

- I just went out to the shop to take a pic of how the adjuster bolt should look.

Low-and-behold - my adjuster bolt is backed all the way out, the pullies are out of alignment, and the belt is walking off the tensioner because of it...

Why?

I assure you it isn't because of the mechanical equipment.

It is simply because I cut some corners to get my sled together for the Snowest ride. I kinda "skipped" some less than important re-assembly steps, with the thought that I would tear it down later and "fix it right". Well, as luck would have it, everything stayed together the rest of the season - even though I never looked at it again.

Whose fault is all of this? It must be YOURS Chris - you did SIT on my sled for a minute or 2...

 

[christopher]

If THAT is where your bolt is seated, YOU ARE USING THE WRONG ADJUSTER BOLT!

It SHOULD NOT be bottomed out, even if it was holding proper tension upon initial install. The belt WILL stretch some, pullies will wear, and you WILL need to tighten it somewhere along the line. You cant do that with the adjuster bottomed out.

High altitude pullies almost always need to use the LONGER bolt.

This is how it looked the moment I took the pulley out as posted yesterday. The long bolt was installed early on when the short bolt proved too short to make it work last summer.

 

[jsandgren10]

Man I'm glad I never went the supercharger route. The pulleys should have to be checked and torqued on each ride. In all the cars we have supercharged never had to retorque a pulley.

Hope you get it worked out Chris, I think you would have had less headaches with a turbo.

 

[christopher]

And that is my whole point here.
This part is NOT listed as one that needs to be checked and re-tightened prior to each ride.

MPI is pretty explicit in their instructions on what has to be checked/serviced after each ride, and this bolt is not listed as one of them.


And YES, I agree with you.
When we installed a supercharger on one of our boats, the customer did NOT have to do daily checks on it before he took his boat out each time. It needed to be serviced and checked once each season.

And I have to suspect that once this supercharger is fully dialed in and "settled in" on my sled it should require less maintenance. But like the water I found in the reservoir, it is a process of figuring out what really works best and making all the little tweaks and adjustments to get from here to there.

And while the Turbos "may" be less complicated, I still prefer the ride/handling characteristics of the Supercharger.

 

[irondave86]

I have to agree with ZeeRTee, threads like this just add to MPI's already notoriously bad rep, and its not warranted. At least not in this case. I'm not trying to bash you Christopher, but to those who understand how these pulleys work its obvious that this is NOT MPI's fault. Its 100% installer error. I have over 2000 very hard miles on my s/c with few issues. And I never check my pulleys anymore. I feel that when installed correctly there's no need too.


Many on here have said this before but ill say it again. Who does the install is just as important as who's kit you buy.