Pulley replacement

Tech discussions on the L77 6.0L V8.
white12
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Pulley replacement

Post by white12 » Mon Apr 30, 2018 7:26 pm

Hey, so I'm new to the forum and just as new to chevy products. I've been searching older posts but haven't found a clear answer.

My crankshaft pulley (harmonic balancer i guess...) has a pretty good wobble, so it needs replacing. And if it needs replacing it needs upgrading. I found a few on summit but not sure on quality. Anyone have links to a better pulley? L8ghter would be great. Possibly underdrive.

xcidmigs
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Location: SE PA

Re: Pulley replacement

Post by xcidmigs » Mon Apr 30, 2018 9:11 pm

There is a TSB on those depending on the year, obviously a bad GM part I had mine done 10K miles ago no wobble still...

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kevink
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Re: Pulley replacement

Post by kevink » Mon Apr 30, 2018 9:40 pm

Powerbond's 25% underdrive balancer works great on my car. I have no charging issues, but my idle is pretty high at 800-900 RPM. Part# PBU1117-SS25.
2011 9C3: 11.48 @118.

white12
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Re: Pulley replacement

Post by white12 » Mon Apr 30, 2018 9:54 pm

TSB? I'm not familiar with the term.

I saw the powerbond at summit. I may go with their own then, since it's about 1/3 the cost. Has the underdrive made enough of a gain to justify the money?

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kevink
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Re: Pulley replacement

Post by kevink » Mon Apr 30, 2018 10:21 pm

white12 wrote:TSB? I'm not familiar with the term.

I saw the powerbond at summit. I may go with their own then, since it's about 1/3 the cost. Has the underdrive made enough of a gain to justify the money?
I have no idea on power gains since I changed a lot of parts at once, but if it's a 5-10 HP gain as some say, it's a good value in terms of dollars per HP. If you can find a used one, it's an even better deal. I think I paid just over $100 for mine.
2011 9C3: 11.48 @118.

CrashTestDummy
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Re: Pulley replacement

Post by CrashTestDummy » Tue May 01, 2018 3:24 am

$10 per HP is the going rate for aftermarket replacement parts updates. So if they claim 10 HP, and charge about $100, then you are on par. Try to find reviews where others have at least tried dyno tests, though, just to be sure.

I have an underdrive crank pulley on our 96 SS though, and can attest it helps. I’d do the same if we needed a replacement on the 9C1.
Gene Beaird,
Pearland, Texas
2012 Caprice 9C1
1992 B4C 1LE Camaro
2010 Tahoe PPV (her car)
1995 DGGM Impala SS
1996 BBB Impala SS (11-second DD)
1985 Firebird - 310 LS1 C Prepared autocross car.
And some others
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white12
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Re: Pulley replacement

Post by white12 » Tue May 01, 2018 6:39 am

If its only 100 then it's definitely worth it. Summit was charging 230. I'll see if I can find it elsewhere.

Pursuit
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Re: Pulley replacement

Post by Pursuit » Tue May 01, 2018 3:12 pm

white12 wrote:TSB? I'm not familiar with the term.

I saw the powerbond at summit. I may go with their own then, since it's about 1/3 the cost. Has the underdrive made enough of a gain to justify the money?
TSB stands for Technical Service Bulletin. All of the manufacturers will release these as a "description/fix" of an acknowledged problem. There are searchable sites for TSB's. I apologize for not having that available..

Regards,

Maurice
Maurice Sheil

mhsheil@gmail.com

2011 Caprice Phantom Black 9C3
2012 Impala 9C1
1995 9C1 Caprice
1996 GMC Sierra C1500
1996 Chevrolet K2500 Extended Cab, long box, 454, 91,000 rust free miles
1974 SJ Grand Prix 455 well optioned with factory moon roof

xcidmigs
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Location: SE PA

Re: Pulley replacement

Post by xcidmigs » Tue May 01, 2018 3:34 pm

If your car qualifies for the TSB then any GM dealer does the replacement for free.

On the under drive pulley scene how would installation work with the factory belt? and I don't understand why it would effect idle since that's a PCM function. I've always heard that the prob with them is unsteady IDLE volts from the alternator since the idle is the same but the RPM of the belt is actually slower meaning it turns the alternator pulley slower?

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kevink
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Re: Pulley replacement

Post by kevink » Tue May 01, 2018 4:20 pm

That's right, they turn the alternator slower, but since my idle is set higher than stock, my alternator speed should be back at stock speed at least. With the Powerbond pulley, you need to use shorter belts. I have the numbers somewhere if anyone needs them.
Last edited by kevink on Tue May 01, 2018 4:34 pm, edited 2 times in total.
2011 9C3: 11.48 @118.

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