Lt1 engine -- harmonic balancer wobbles at idle -- ok with throttle? - Hot Rod Forum : Hotrodders Bulletin Board
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Old 02-27-2012, 12:28 PM
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Lt1 engine -- harmonic balancer wobbles at idle -- ok with throttle?

Hi guys,

I replaced my old harmonic balancer because i noticed a little wobble after replacing my optispark. I figured that since the old balancer had been on the engine since 1994, it was time to replace it anyways. I replaced the balancer with a brand new part, and the slight wobble is still there at idle.

If i apply any throttle to the engine, the wobble goes away. I have read varying posts -- from no wobble allowed to a tiny bit being OK. Is there a consensus on this? I don't want to destroy the engine (that's already happened once!) Should i send this balancer back to amazon and replace it with a different one?

I'm not throwing any belts, at least not yet... any help would be much appreciated!

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Old 02-27-2012, 02:29 PM
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sorry

hey man i feel ur pain and wish i could help u i had alota bad luck with my buddies lt1 all i can say is sorry. someone will get to you soon
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Old 02-27-2012, 02:51 PM
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The balancer should not wobble at all. If it does either its not properly installed, a faulty part, or your crank is shot. If its your crank then a lot more will be fubared. What balancer did you use?
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Old 02-27-2012, 03:12 PM
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i got it off of amazon -- i believe the brand is AIT. It wobbles at idle, but once any throttle is applied it looks like its completely smooth. I don't think it's the crank, but i suppose it's possible -- i don't feel any serious vibrations thought.

I'll try another dampener and see if the wobble at idle goes away. I don't think it was installed improperly either -- i simply mounted it to the hub, tightened the bolts finger tight and moved around the hub with the torque wrench until i hit spec torque.

is it possible that it's just because the engine is shaking, that it looks like the dampener is wobbling? i don't know why that would be the case because i noticed that the accessories don't wobble at idle.

Very frustrating...
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Old 02-27-2012, 06:17 PM
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I'm surprised it hasn't eaten up the edges of the belt yet. It shouldn't wobble at all.
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Old 02-27-2012, 07:08 PM
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yeah, hasn't eaten the belts yet -- like i said the wobble isn't extreme, but it is noticeable by eye -- when i give it some throttle, the wobble disappears (by eye anyways).

should i just get another balancer and test it? if the second balancer is still wobbling, then it must be something else...
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Old 02-28-2012, 04:56 AM
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Yep, i'd swap it out for a different one. It would make quite a mess if it were to snap the snout of the crankshaft off.
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Old 02-28-2012, 05:05 AM
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When you installed the new balancer did it slide on with little effort or was the fit tight and you had to use a installer?
If the balancer just slid on without much effort then what will happen is the wobble will work against the bolt and break it off in the crank.
The balancer must have a tight press on interferance fit.
Some years ago I installed a 8 inch balancer on my 4.3 V6. The fit wasn't that tight and the balancer slid on without issue so I torqued the bolt and left it. The balancer had a slight wobble to it and after about a year I was going down the road doing 45 when I heard a loud pop then some clanging under the truck. I pulled over and inspected everything but didn't think to check the balancer bolt which was stupid of me as I had been in a vehicle that had did this same thing before and found it to be the balancer bolt.
So I kept driving it and after about 3 days the balancer started making it's way off which threw the belt off. I pulled the balancer off and found it cracked. I inspected the crank snout and found the keyway was sheared off and it removed a chunk of the crank snout with it. So I had to yank the engine and get a crank kit, plus get it balanced all over again. That $50 balancer with the loose fit ended up costing me $500 and the engine at the time only had 10,000 miles on it since being overhauled. Needless to say my mistake taught me a important lesson.
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Old 02-28-2012, 10:16 AM
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Quote:
Originally Posted by tylerwerrin
Hi guys,

I replaced my old harmonic balancer because i noticed a little wobble after replacing my optispark. I figured that since the old balancer had been on the engine since 1994, it was time to replace it anyways. I replaced the balancer with a brand new part, and the slight wobble is still there at idle.

If i apply any throttle to the engine, the wobble goes away. I have read varying posts -- from no wobble allowed to a tiny bit being OK. Is there a consensus on this? I don't want to destroy the engine (that's already happened once!) Should i send this balancer back to amazon and replace it with a different one?

I'm not throwing any belts, at least not yet... any help would be much appreciated!
X2 DoubleVision, right down to having the damper come off a 454 some years ago.


Do you mean it says AIT or is it ATI (i got it off of amazon -- i believe the brand is AIT) . First I worry about stuff from China, they often copy or imitate name brands for their knock off parts.

ATI would be a part hopefully from the longstanding company that makes these things. If an ATI, it is probably the multi-piece unit that uses many O rings between the major parts. These are given to wear and fitment issues, my recommendation is to contact ATI http://www.atiracing.com/products/products.htm and discuss it with their tech line http://www.atiracing.com/contact/contactati.htm look under Email.

Bogie
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Old 02-28-2012, 11:29 AM
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It had the same crossover part number as a dorman, only the dorman wasn't in stock. I'll pick up another balancer and swap it on.

To answer your question about it sliding on, yes, it slid right onto the crank hub, which is pressed onto the crank snout and secured by a bolt.

The harmonic balancer is bolted down by 3 5/8" bolts to the hub. THey are torqued down to 70ft/lbs (very snug).

If this next balancer is wobbling then i'll know i have another problem somewhere else -- my next guess would be the hub itself.
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Old 02-28-2012, 01:25 PM
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The hub should be a very tight fit, the balancer secures to the hub. If the hub is not tight, that is NOT good. That will cause the wobbling issues.
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Old 02-28-2012, 01:45 PM
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Da Hub

Tyler, I'm gonna suggest that you possibly don't have the hub on all the way. Or perhaps if you're using a stock hub with the ATI three bolt balancer there may be a tolerance issue causing a bad fit. Also the ATI balancer requires a spacer washer when used on later LT1's. For the benefit of others, the LT1 doesn't use a traditional small block balancer, its two pieces and looks like this;
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Old 03-12-2012, 05:10 PM
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Hi guys,

Sorry for the delay in replying, been waiting on a new balancer to arrive... looks like this one is messed up too!

I used a dial gauge indicator to make sure the face of my crank hub was OK. It was all even so that lead me to believe it's just a defective balancer. Finally the new balancer arrived in the mail, but it failed my visual test -- this balancer is very obviously cockeyed and not true.

So tonight, I'll try my third balancer (off my old Impala SS.) The part numbers are the same so I assume this will be okay.

I don't think that the crank is bent -- the engine runs smooth and doesn't shudder or shake. It is a possibility though. I just wish I had looked at my original balancer before taking it off to see if this was just how the engine was.

Does anyone have a video of their balancer in action? so i can see exactly like how it's supposed to look? I'll try and get a vid uploaded ASAP.

Thanks guys!

PS -- the brand that i purchased from Amazon isn't ATI but in fact ATP -- it's also on rock auto.
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Old 03-12-2012, 06:21 PM
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Since the original balancer had a problem, and the replacedment balancer had the same problem, I think your problem is with the hub or crank.
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Old 03-12-2012, 06:25 PM
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the original balancer was pulled off using a 3 jaw puller which may have disrupted the rubber ring (it was the original balancer.) isn't it possible the replacement one was just slightly off?

I just don't know what other option I have in terms of checking to see if the hub is true -- once i know what the culprit is, i can replace the part, it's just determining what it could be.

So far it sounds like my entire rotating assembly could be bad (which seems unlikely because the car drives smooth), the hub is damaged somehow, or the balancer is messed up (again.)

Is it possible that the T56 is causing the problem? Like a vibration from the tranny?
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