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MPI Supercharger Pulley Failure

jsandgren10 said:
The whole point trying to be made was that pulley bolt came pre torqued and assembled from MPI. It was torqued before going to Canada. It's the fact that MPI supplied and installed a bolt too short.

And yes the nyloc helps hold tension from backing out. I NEVER see a bolt with a standard nut and no lock washer, or star washer or nyloc, or clip to keep it from backing out. The only time I see nothing is stuff that bolts in with no nut.

This thread is not about putting down MPI but showing people that even if you torque something designed to run a nyloc will back out since it isn't touching the nyloc portion.

Just wondering why you don't think some blame goes to MPI?? The part came PRE assembled, and no where in the instructions does it say to torque that bolt or even check it after a ride. So when a mfg puts something out are we all supposed to dissassemble and reassembled with what we think is the right torque? There were no torque numbers for that bolt so how do you know if it was or wasn't torqued correctly?

It's pretty much like saying well I bought a new car, so let me go buy a service manual and check torque specs for each bolt or its my fault something wasn't torqued right.
Click to expand...

It's not pre torqued from mpi. It says in step 127. "loosen the main idler bolt just enough so the idler will slide". If it was assumed that it was pre torqued from mpi when in fact it wasn't nor should it have been the nut would eventually fall off which is what happened.

In step 125. It says to install the idler bracket AND the idler wheel assembly onto the frame. It also says to use blue lock tight on each bolt. And torque each bolt to 20ft lbs.
 
irondave86 said:
It's not pre torqued from mpi. It says in step 127. "loosen the main idler bolt just enough so the idler will slide". If it was assumed that it was pre torqued from mpi when in fact it wasn't nor should it have been the nut would eventually fall off which is what happened.

In step 125. It says to install the idler bracket AND the idler wheel assembly onto the frame. It also says to use blue lock tight on each bolt. And torque each bolt to 20ft lbs.
Click to expand...

Yes I understand the instructions. The idler wheel came pre assembled on the bracket which is why there is the AND in there. But you only loctite the two bracket bolts, then after that is done you loosen the adjuster bolt and the idler bolt enough for it to slide. Then after you set tension obviously you tighten it back up, which was done in Chris's case. What you are missing is the bolt to the idler was too small so it could not grab the nyloc AFTER it was torqued.

And it only states to check the adjustment bolt every 100-200 miles, doesn't say the idler needs to be retorqued every ride. And with the idler up against the frame there is no way of knowing that it caught the nyloc without removing the assembly. I'm not saying anything bad on MPI just the fact that the bolt supplied and pre assembled was not correct. If Chris had to assemble the idler to the bracket and failed to realize that he chose too small of a bolt then yes its completely user installation error. Not saying this was a catastrophic failure its an easy fix I just don't see how people can put blame on Chris when the bolt to be used for the idler was already assembled by MPI and all you were suppose to do was loosen it AFTER you bolt the bracket up, then retorque it.

Simple mistake and an easy fix.
 
admittingly the nylock is essential.in this instance..torque holding on a static application is one thing...on an application with a rotation happening next to the shoulder of the bolt it sure wouldn;t take long for the bolt to rotate out of that nut..like real quick given all the right circumstances..

Blame..???..well maybe its society..??..who are the only people working in these packaging low paying jobs in the back rooms of Corporate Capitalistic Pigs..??..people from Asia who haven;t yet mastered the English language..

yea...can we end this thread placing the blame on poor immigrant workers...lol..??
 
Ya, Well, I don't think MPI has any poor imigrant workers in their shop so we are pretty safe on that one.

This could be as simple as the person who did the assembly grabbed the wrong M12 bolt. Might be just as simple as that.

Or it could be that some other spec in the assembly changed over time and the bolt didn't get lengthened.

Either way.
The only solution is a LONGER M12 BOLT.
 
So what if you find out MPI sold everyone that same bolt,bracket,nut,spacer and idler? Then I would guess you are just unlucky or the bolt was not tightened properly?:face-icon-small-con stir,stir,stir...

Jeff
 
Slash made an interesting comment to me.
It might be that the bolt is just fine after all.
And that the NUT is too tall.

Shave the nut by 2mm and that would solve the problem just as well as lengthening the bolt.
 
run the nylock material deeper into the nut...have a thinner bracket...use a six inch long by 3/8 LAG SCREW and hope for the best that she will grab something somewhere..
 
Why doesn't the bolt fall out of the crankshaft

Why doesn't the bolt fall out of the crankshaft on the PTO drive for the blower?:face-icon-small-con It isn't locked, it most certainly is rotating and has harmonics applied to it, the crank is spinning in a direction which would loosen it, no lock washer, no locktite, no nyloc, and it is bolted into threads which are turning and trying to unscrew themselves. The tensioner bolt just sits there dead, and it came loose? It wasn't tight. Sorry.
Tighten the idler bolt to 60 ft lbs. and all will be fine. That is for a 12mm 8.8 grade bolt.
 
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Turbo11T said:
I'd put some red loctite on it and torque it to spec.
Click to expand...
There is NO spec for torque on that bolt.

Installation manual says...

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.
 
I guess you could borrow a spool gun and WELD it back together!
**** Happens,Someone fugs up...Why is it always on a trip never in the yard?
That's what I wanna know!

Bum Deal anyway you look at it....
 
Certainly NOT life or death, didn't fail at a critical moment
Just a major Pain In the Butt an a big fun trip.

Such is life.

Thats why we carry backup sleds.:face-icon-small-hap
 
ZeeRTee said:
Why doesn't the bolt fall out of the crankshaft on the PTO drive for the blower?:face-icon-small-con It isn't locked, it most certainly is rotating and has harmonics applied to it, the crank is spinning in a direction which would loosen it, no lock washer, no locktite, no nyloc, and it is bolted into threads which are turning and trying to unscrew themselves. The tensioner bolt just sits there dead, and it came loose? It wasn't tight. Sorry.
Tighten the idler bolt to 60 ft lbs. and all will be fine. That is for a 12mm 8.8 grade bolt.
Click to expand...

hmm..ok..you win..im calling MYTH BUSTERS...
 
Follow up...

Fired off a letter and photos to MPI explaining the whole ordeal. They replied back with their normal terrific customer service of sending me all the replacement parts that were involved at no charge.

As always, for me it's all about customer service and follow through. That's the hallmark of a good company to do business with.

Mac asked me for dementional measurements on the bolt, so we should have an answer on what caused the failure next week.


Sent from my Apple iPhone 4S using the TapaTalk app.
 
FWIW.....My Apex kit from MPI last fall had the tensioner assemble put together wrong and the Oil line that are installed on the blower before the bracket is installed on the housing had the wrong length lines on them. The filter was in the wrong location as well.

The quality of the parts and machine work is top notch, thier assembly work and instructions are very poor!!!!

The installer has a BIG role in the performance of this kit. Eric
 
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SRXSRULE said:
FWIW.....My Apex kit from MPI last fall had the tensioner assemble put together wrong and the Oil line that are installed on the blower before the bracket is installed on the housing had the wrong length lines on them. The filter was in the wrong location as well.

The quality was the parts and machine work is top notch, there assembly work and instructions are very poor!!!!

The installer has a BIG role in the performance of this kit. Eric
Click to expand...

Ya, MPI takes a big hit on the instructions, and they know it.
Writing up a manual for a project like this is a MAJOR undertaking.
 
MPI just called me to confirm that the bolt that was pre-assembled on the idler was in fact the WRONG the bolt ! Someone at the shop pulled the wrong length bolt from inventory when they built up my kit last summer.

He apologized for their error and has sent me new parts.


So ends this story.
 
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