gtistile

Where to begin?

I'll cut strait to it. I cannot keep a serpentine belt on this car to save my life. I have pinpointed the issue to the alternator bracket. When the motor is under load, the belt is walking towards the front of the idler pulley on the alt bracket, and feeding down on to the crank pulley at least 1 full rib off. Under super heavy load, WOT in 1st or shifting in to 2nd, the belt either comes all the way off or feeds misaligned in such a way that it snaps, nearly every time.

So I purchased a brand new GM alternator bracket with pulley and installed it. the belt would still move when you revved the engine, but maybe 10% of what it had been doing with the old bracket. I wasn't loosing belts anymore… Then I went to the track and broke one, and the pulley alignment was right back where I started again. I've broken 2 more belts since. Seemingly I am either bending or twisting the alternator bracket itself, the bolt that holds the pulley on, or crushing the hole in which the bolt threads to hold the pulley on.

Has ANYONE ever seen this issue? My initial solution was to try and find a smooth idler pulley with flanged edges, but I have had no such luck. I have seen one, I know they exist but cannot find any info about it. It was on a LS7 Crate engine and the owner told me it was sent to him that way and was not modified to changed in any way.

Another potential solution I have seen is a billet alternator bracket online which claims to be stronger than the factory one. Is this an issue anyone has heard of? Is the blower putting more strain on that pulley/bracket than it can handle? I am at a loss on what to do, but replacing these belts is not only frustrating, but I''ve now spent literally 3-400 on belts alone trying to get this resolved. HELP!

my photo bucket isn't working, ill try to post pics in a few

jkel1124

iTrader: (3)

Have you tried checking everything with a laser alignment tool? I was having similar belt issues and bought a Dayco Belt Diagnostics Kit from Advance Auto-parts for about $100. My issue ended up being the ECS tensioner needed shims.

gtistile

I havent, i just know when I initially replaced that part, the belt was tracking correctly again and I had no issues... Now it's right back again. So my logic says that the same exact problem has occured twice now, and the belt only walks on that one smooth pulley. It's blatantly obvious just by eye balling it that its the culprit. Of course photobucket is screwed up and I cant post the pic

Becker

iTrader: (4)

Check into the laser alignment. Also I'm sure your routing is correct but I'd double check. I've seen threads in the past where they experienced similar belt issues and their routing was wrong. Your setup is a bit different than stock though that sucks you can't use that power! Maybe you could modify the pulley and smooth it out if you want.

gtistile

So When I do the lazer alignment check, and find out that the idler pulley on the alternator bracket is sagging and causing the belt to come off the front, what do I do next?

serik21

My mmoney is that your crank balancer is shot

DMM

+1 something's worn to cause the belt to walk. Usually bad tensioner/idler pulley bearing or waterpump, however the crank balancer is the most likely culprit here.

gtistile

How would I go about determining that is the case without just replacing.

This thing has 4,000 miles on it as well. ATI balancer

gtistile

Tensioner is also brand new as well

serik21

If its a ati balancer I don't think it's the balancer. The stock balancers are notorious for going out.

gtistile

I mean… the thing runs true as can be, not so much as a TINY wobble on it. I've seen the wobble on the factory ones (my stock V does that)… This cars appears flawless though

Becker

iTrader: (4)

see if you can post some pics of the alignments and the routing, might help.. Laser alignment just ensures your tracking straight from pulley to pulley, could also use a level or straightedge.

gtistile

Are you guys pulling the whole front end off the car to put a strait edge/level on the pullies?

Becker

iTrader: (4)

is it not feasible to get some sort of straight edge on the alt pulley and idler or crank pulley that you believe is the culprit? Snap some photos and post em so we can see if there is a obvious issue.

gtistile

It's tight in there. Damn photobucket where my pics are hosted is having serious issues. Ill try and get em up today

gtistile

Best pic I have of how it rides on the pulley. at least 1 rib off center, and then when you stab the throttle it walks off… Sometimes it doesn't break, but its really a coin toss at this point. I don't like coin tosses.

Becker

iTrader: (4)

definitely a rib off, why is it misaligned?

gtistile

Same reason its tossing the belt. The only spot it is misaligned or moving is on that alt. bracket pulley.

This pic was taken before I replaced the alt. bracket and idler pulley. After I replaced it, the belt was lined up correctly. Now, a couple months later, the belt is now out of alignment again on that same bracket/idler pulley.

Becker

iTrader: (4)

Why is that bracket / idler pulley moving after months of abuse? have a better stronger bracket made?

gtistile

I was hoping to find out that at least one other person has witnessed this issue at least once before. Everything I've read is that guys go TO the lower mounted alternator bracket as a solution to having problems with the upper mounted style when making big power. There are plenty of cars with blowers on them that arent ruining low mount alternator brackets. Is it really possible that these massive aluminum brackets are being bent on my car, while everything else remains unphased?