Vibration/shutter only with supercharger belt on

Foxbodyguy49

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Jul 30, 2019
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So my 91 mustang has a powerdyne supercharger and it’s been on for a few years now. I rebuilt it a couple months back after a weird noise in between shifts and after the rebuild it’s been fine up until now. So the problem is when I have the supercharger belt on and under tension I can feel a vibration or a shutter when letting the clutch out. This only happens when comming our of first and second and also in 5th gear at highway speeds you can feel a noticeable vibration like something is spinning un-even. I noticed this started to happen only after removing my transmission mount to add the mid-pipe hanger. After that the car threw off the supercharger belt and I didn’t notice until the next time I drove the car the shutter was gone but I wasn’t making boost leading me to find the charger belt had been thrown off. Now without the charger belt on the car feels fine no symptoms. Now I’m not sure if the charger is the problem or if it’s making the problem more pronounced. My first thought was the balancer but it looks in good shape visually but I’m not ruling it out. Cause I can see the crank pulley has a slight wobble to it but I’m not sure if that’s just the engine itself goin back and forth ever so slightly . The drive shaft u-joints are only about a year old so I don’t think that they are to blame. Any insight would be great. Thanks
 
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Foxbodyguy49

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Jul 30, 2019
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I would investigate that wobble in the crank pulley first.
I’m not really sure it’s actually wobbling if I grab it when the car is off and try to move it there is zero play but what I did notice with the car running and the supercharger belt on the belt for the charger actually is fluttering on the non-tensioned side so maybe I need to put more tension on the belt. I’ve just never figured the belt could cause this type of driveline vibration.
 

Foxbodyguy49

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Jul 30, 2019
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Powerdyne has ceramic bearings with no lubrication. Very troublesome.
Yeah deffinitly but it’s been very reliable to this point and I’ve rebuilt it before for very little money and it’s easy to do. So I can’t complain about the powerdyne even tho I’ve heard many of horror stories
 

Foxbodyguy49

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Jul 30, 2019
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So it ended up being the harmonic balancer snout was cracked in the key way area! The supercharger was making it worse! Thanks again guys
0161BCCF-1058-42B5-90AC-60860900A3D3.jpeg
 

2Blue2

will be trying this sex one when I can find it
Mar 5, 2019
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Wow! Haven't seen that one before.

Way to be tuned into your Mustangs twitches.
Nicely done!
 
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TOOLOW91

If you're the village idiot what's that make me?
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Wow! Haven't seen that one before.

Way to be tuned into your Mustangs twitches.
Nicely done!
Blower stuff does some bad stuff esp with a single key waywhen you have that belt tension .
 
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