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Just pulled into a gas station to fill up my 96 RMW, and noticed the PS piump wasn't kicking in to help me turn the car. And then the alternator/charge light came on. I popped the hood and noticed the belt was very loose, but still turning the pulleys. Once home, jacked car up and found a very surprising issue! The lower part of the main 'half moon' bracket that attaches alternator, PS pump, and AC compressor (and the belt tensioner) had literally snapped off in two sections at the very bottom. As if the belt tensioner was putting stress on the bracket (which it was not). the only thing holding the belt tensioner anywhere close to the right place was the bolt connecting the transmission cooler lines to the severed bracket.

Has this ever happened to anyone else? My car has 280,000 miles - this bracket looks like a PITA to remove (I had to take alt and PS pump off once, when replacing the pump a few years ago).
 

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More interesting than anything about a bracket is just asking whether anyone has even got a car with 280,000 miles on it! ;)
Seriously, that's some archive worthy documentation of damaging effects of harmonic fatigue. Or, is there any sign of physical damage? - from road shrapnel or something?
 

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Suspect alternator braces not present. Replacing bracket isn't that bad really. Easier with shop manuals.
 

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On my Impala, I was running the Corvette accessory bracket due to the SVI centrifugal setup I had.
I had two of the Y body brackets fail in similar fashion.
I did have the first failure welded, but that repair didn’t last more than 2 or 3 years. More recently, when a second bracket cracked on me, I used it as an excuse to buy a more modern blower set up that brought me back to running a proper b-body accessory bracket. I’m hoping I have no issues with the stock bracket.

To be clear, the supercharger was on an independent bracket and unrelated to the Y body bracket failures.
 

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Suspect alternator braces not present. Replacing bracket isn't that bad really. Easier with shop manuals.
Great point. I am using the upper alternator brace, but due to my headers left off the lower brace. That is more concerning now.

OP, were you running with the factory alternator braces?

Thank you.
 

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Some time back I reintroduced one of the back braces to the first hole in head....
Virtually all headers do not use. Adding a spacer to get even with header flange. 3/8-18 threaded rod into hole... Add spacers until brace sits as it should. Bolt to threaded hole in back of alternator ,and nut to threaded rod. Tighten after alternator is firmly in place.
 
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Discussion Starter #7
My alternator rear/side brackets still a-ok. My main bracket broke right at the very bottom, opposite end of where alternator is. Almost like the vibration of tensioner stress fractured the area where it was mounted.
 
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My alternator rear/side brackets still a-ok. My main bracket broke right at the very bottom, opposite end of where alternator is. Almost like the vibration of tensioner stress fractured the area where it was mounted.
Thank you for bracket confirmation.
Sorry to hear this.
I went to fleabay and paid $120.00 to get a nice b-body bracket (with bolts) circa February 2020.
 

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Yah those doubled up alt. braces always struck me as overkillI and I certainly heard plenty of guys 'deleting' them with headers. But I figured GM sure wouldn't have wasted the money on them if not seriously called for. So, with the Tri-Y II I kept them on, but had to take a grinder to one to clearance it and recall stacking washers on the other to line it back up right.
 

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It's aluminum; easy to have it welded back together, and have the shop reinforce it while they're there.

On the alternator braces; there are three of them; it's by far the heaviest and highest-inertia accessory on there, and these alternators don't have the overrun pulley many later model applications do which is a lot easier on the accessory drive. I'm with 1slow96, I would never run without those braces. Many of those brackets have cracked, making them sought after nowadays. The C4 Y-body brackets have a similar cracking issues.
 

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Discussion Starter #11
Thank. Mine cracked at the bottom where the tensioner mounts. All the secondary braces at the top up by alternator are A-OK. It's pretty involved taking it off, right?
 

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Well @ 238+k mi....long life for anything on the car. Broken accessory brackets were not uncommon for people who deleted the 2 rear ALT (thus bracket) support braces. Generally motors making more power than stock and drag racing

Accessory brackets are specific to B, F & Y body gen 2 LT1 so if getting one from junkyard, get a B body

R&R is not horrible. You will need to pull the pully from PS. Most auto part stores have the loan-a-tool for it.

Check to confirm your AC compressor did not lock up causing belt to add severe pressure=broken bracket...

For anyone running headers its easy to maintain the 2 rear ALT brackets/ Either a threaded stud or long bolt/spacer works and a longer header bolt for #4 cyl (pics)
alt bracket 1.jpg

alt bracket 4.jpg
alt bracket 6.jpg
 

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Thank. Mine cracked at the bottom where the tensioner mounts. All the secondary braces at the top up by alternator are A-OK. It's pretty involved taking it off, right?
Yes, but while we're talking about cracked brackets, it's worth mentioning the alternator issue because it's more common. I always thought the tensioner mounts were a little on the skimpy side, and those little 10mm head bolts can strip easy if you overdo it.

To BALLSS's point, racing applications have much greater RPM transient rates which are very stressful on accessory drives. The same is true with manual transmission vehicles.
 

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To BALLSS's point, racing applications have much greater RPM transient rates which are very stressful on accessory drives. The same is true with manual transmission vehicles.
Yeah I check both those boxes and also have a McLeod twin disc clutch which is not forgiving and run a MT slick.....so I chose to maintain the 2 real alt/Accec Bracket braces

Odd Op's broke but at his mileage maybe "fatigue" finally set in or maybe it was a slightly compromised casting and just finally crapped.

I would confirm none of the accessories are locking up (AC)
 

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The bracket on my 96 SS was found to be cracked on rebuilding motor after 250,000 miles. had it welded and reinforced, the reinforced corners worked very nicely. $35.00 plus the time to R&R all the accessories.
Haven't had further problems, but it's only been a year and low miles since being repaired.
The bracket braces are a good idea. Thanx for the photos.
 
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