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Belt chirping / pulley wobble

 
Old 02-02-2019, 12:03 PM
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aaronc7
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Default Belt chirping / pulley wobble

I posted this up in my "build thread", but I'm looking for some insight and thought this might gather more views.

A&A, 8 rib direct/secondary drive setup, V2 TI. New kit, new install.

Drove the car around 3 hours total, after which it suddenly started belt chirp on a cold startup. Noted belt dust around blower. Blower pulley has black mark on side towards engine and rib closest to engine. Bought laser alignment tool, suspected crooked main bracket due to non OEM water pump.

Aligned tool, alignment on blower side more or less checks out.... checked the secondary drive side and alternator is spot on, PS pulley is off by a hair but hasn't caused any issues yet and it's a different belt.... more just wanted to verify the laser tool more than anything.

Only thing weird I can find is the blower pulley appears to have a wobble. If I spin the pulley as a hold the laser stationary pointed at the crank, it walks around a bit. I tried this over 10 times and the other side of the pulley etc and it's repeatable every single time. Laser spot wanders left/right 1/4-1/3 a rib maybe? Doesn't seem like a ton, but maybe it gets worse with belt tension.

I contacted A&A, but it's the weekend and figured I would see what I could gather from the interwebs.

Anyone else ever seen this or looked for play at the blower pulley itself?

Thanks for any info/comments/thoughts. It's frustrating being so close yet so far to having this install 'done'.

The pics show the laser pattern with the blower pulley rotated ~180* apart... best vs worst case.








Last edited by aaronc7; 02-02-2019 at 12:06 PM.
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Old 02-02-2019, 02:52 PM
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neutron82
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how can you hold the laser stationary on the blower pulley while turning it?... just curious but I'm not sure if I would trust that reading because any small movement will change the position of the laser and the farther away you are aiming the worse that reading will get... have you shot from the crank to blower and then rotate the blower pulley?... that might be a more accurate reading in my opinion, you will probably have to remove the ribbed idler in order to do it this way though
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Old 02-02-2019, 05:14 PM
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I mean initially I just rotated the pulley 45 degrees....check laser.....45 more degrees etc. That's when I noticed the laser spot wasn't consistent. I was skeptical that the tool just wasn't being consistent, but I got it down to where it was consistent. I just later figured out I could hold the laser in place steady while i slowly rotated the pulley under it and it showed the same thing, just in a nice smooth motion fashion.

I didn't shoot from the crank as that looked like I would have to pull a good bit of stuff off.... didn't want to go there yet if I didn't have to.

But I think my test is valid-- as the supercharger pulley spins, the angle/axis that it is on is changing. If the main bracket was cocked but pulley was true then the laser spot on the crank pulley should be off, and even if the laser tool was off, it would still be a consistent spot.

I did start the car up with the belt off and shined the laser on the crank... I'm confidence the crank isn't wobbly or something weird going on there. It lit up a peak and didn't budge while running.

Random thought I had was maybe I tightened the manual tensioner too much or something, so I put a new belt on and didn't get it as tight and let the autotensioner take up a bit more slack. Started it up and no noise etc....but that's how it all began the first time anyways.

Drove around and did some logging, 30-45 mins and did a few WOT runs to 5500 rpm, ~9psi. No noise.

There's already some belt dust accumulating right around the blower pulley. You can see some wear on the outer edge of the belt already too. I have a feeling it will start chirping here before long, I'll try to gather more useful data as I go this time.


Last edited by aaronc7; 02-02-2019 at 07:19 PM.
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Old 02-02-2019, 09:46 PM
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Took a video, stabilized it and slowed it down. Looks like a wobble of some sort, what do you guys think?

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Old 02-02-2019, 09:55 PM
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can't see the video... well hmm, I don't think it could be the waterpump or bracket since that seems like it would be a constant out of alignment issue and not a wobble like you are explaining... maybe it's isolated to the blower pulley or blower hub... is there any kind of spacer behind the blower pulley?... I wonder if the pulley isn't machined perfectly flat, just throwing out ideas
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Old 02-02-2019, 10:02 PM
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Originally Posted by neutron82 View Post
can't see the video... well hmm, I don't think it could be the waterpump or bracket since that seems like it would be a constant out of alignment issue and not a wobble like you are explaining... maybe it's isolated to the blower pulley or blower hub... is there any kind of spacer behind the blower pulley?... I wonder if the pulley isn't machined perfectly flat, just throwing out ideas
All good ideas thanks. I feel like the likelihood of the issue being with the blower itself is pretty low, but that video sure makes it look like the pulley and shaft are wobbling.

Stuff you mention is def worth checking out.

I'll try the link without https and see if you can see it then or copy/paste at least

youtube.com/watch?v=7BDNqxEwTvk
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Old 02-03-2019, 12:27 AM
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Bent shaft? Wobble is pretty noticeable in that video.
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Old 02-03-2019, 11:31 AM
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Have you tried a different pulley?
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Old 02-03-2019, 12:46 PM
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To my eyes it looks like both the pulley and shaft are moving about.

I want to talk to A&A or vortech about it first, but trying a different pulley first, making sure spacer isn't jacked up like Neutron mentioned is common sense first step I think. And would be easy to take another laser measurement/another video and compare.

I was thinking about a smaller 3.47" pulley and I'm not even tuned yet............. lol
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