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Discussion Starter · #1 ·
Is it normal for the balancer "assembly" to wobble at idle?

I've just installed some under drive pulleys and the balacer wobbles at idle. Anything off idle and it smoothes right out. At idle, when wobbling, it doesn't seem like the engine is excessivly rough (Comp 304 cam), but it never did that BEFORE.

Symptoms? Suggestions? Sollutions?
 
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Discussion Starter · #3 ·
I have the BBK crank pulley and it does the exact same thing as you described. I have had it on the car for 1.5 years now.
 
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Discussion Starter · #4 ·
Joe - that's what I thought, "This can't be good!" That's why I came here imediately, looking for experience of others.

Jumbo - Have you seen others that do this? I'm glad to hear it's not an isolated occurance.

Thanks. Anybody else?
 
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Discussion Starter · #6 ·
I have not seen another Impala with a pulley yet. I took the pulley off a few times and also had my mechanic reinstall it with the same out come. The pulley I have replaces the balancer but they also have 25% underdrive Harmonic balancers for a few more $$. This may be the solution in the future. For now I'll live with the wobble at idle.
 
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Discussion Starter · #8 ·
The pulley may not be true... Also If the centrality of the holes are not correct, you will get wobble.. If you have access to a surface plate(perfectly flat level surface) you could check out the truness of the pulley. A good machine shop may be able to check this unit out..

If it were me, I'd send it back for another one.

-Tom
 
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Discussion Starter · #9 ·
I've been running that ASP underdrive harmonic balancer for several years and like it. The engine rev's quicker with it.
 
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Discussion Starter · #10 ·
The balancer has about 60K miles on it. I don't know it this would be considered a lot or not (I normally wouldn't), there are quite a few of those that are HARD miles (Auto-x, drag racing, etc.). Everything is bolted up tight and the balance was re-installed in the original orientation (pointer set up). I'm going to give it a try up to the gas station and see what it feels like on the road.

Thanks for the input. I'm curious to hear others' experiences with under drive pulleys.
 
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Discussion Starter · #11 ·
The balancer on my wife's L99 runs out a good 1/8". It came out of the factory like that... but if your's always ran true I would probably try to keep it running true. The risk would not be worth the reward in my opinion.
 
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Discussion Starter · #13 ·
Well the short trip reveals a slight vibration that was never there before, and after about 3300 rpm, it's serious enough for me to take it all apart again to see what's what.

This is the March under drive pulley "set" (alternator too).

I'm pretty aggrevated that I couldn't auto-x today too. Dang it ...
 
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Discussion Starter · #14 ·
You mention in the first post you have a comp cams 304. Was this done at the same time?
Is it possible someone used a hammer on the damper, or didn't realize the damper hole is blind and put so much force on a puller that they bent an ear on the damper hub?
You have three parts to check.
Damper, hub and reduction pulley. One of them should show the problem if you look at them carefully. Does the under drive pulley wobble too. Look at the damper closely. Is it the inertia ring only or is the centre hole wobbling also.
Run the engine with just the hub. Is it wobbling too?

The idea of spacing the damper out further is not the greatest idea to me.
It is asking too much of the assembly I believe. Any discrepancy can allow the damper to attempt to whip causing nothing good.
I felt strongly enough to do mine with the damper moved back and the reduction pulley in front.My damper installRegards, Gerry
 
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Discussion Starter · #15 ·
It's the whole "assembly" that wobbles, not just the balancer. I plan on dis-assembling it all and checking things out. I've already ordered a new hub from Dal on suspicion of a bent ear. I may even get a new balancer to make the whole deal brand new.

The balancer BEHIND the pulley looks like a pretty good deal, just a bit "involved" for your garden variety tool pusher like me.

I'll post my discoveries.
 
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