TampaRiv

Harmonic Balancer, what's the deal?

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Hello Gents,   

 

      As you know I got my '63 Teal Mist started a couple of weeks ago.  There was a gawd-awful noise coming from below, and I realized that the crank pulley/harmonic balancer was as loose as a goose down there. As I went to take the thing off, I found the crank bolt was tight, but the pulley wasn't tight against the crankshaft.  It was weird.   Then as I sift through the exhaustive receipts from the previous owners, there seem to be at least 2 or 3 receipts for....you guessed it...harmonic balancers. 

 

    So, here are my questions of the day.....

           *Why harmonic balancer instead of just a simple crank pulley like every other car I've owned?

          *Is the 401 somehow out of balance by design, and therefore needs a balancer?

          *My pulley/balancer looks OK, it just appears that there's a washer missing,  allowing the damn thing to spin in a clanking wobbly orbit.

   

   Thanks guys for your help, I appreciate it. 

          

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Most ALL engines have some kind of harmonic balancer to help reduce harmonics. IF the balancer was loose you may ALSO have a front crank snout that's been worn lope sided & will ALSO need another good used crank.

I could go on for days typing with one finger about damage done from harmonic balancer bolts lose & the incorrect washers installed.

 

Tom T.

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I believe a common cause for this problem is that the bolt at the balancer and snout of the crank are not torqued to proper spec. It takes 220 ft/lb. I think a lot of mechanics don't know that and just get it as tight as they can with a conventional wench. At that torque its not unusual for the entire rotating assembly to move so you need to devise a way to lock the crank so it won't turn. If an un-knowing mechanic tightens the balancer nut at less than 220 or until the motor spins then quits, it will probably come loose. The effects of a loose balancer can be significant, primarily damage to the crank. If it were me, I'd get a new bolt/washer combination from Centerville Auto Repair (nailhead specialists), inspect the balancer and crank for damage(if OK), use a tiny amount of Loctite Green and borrow a big torque wrench that can hit 220. It might work out. It happened to me and boy does that motor run bad with a loose balancer. I survived. PRL

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Thank you Pete for the input, it's most helpful.  Here are a few photos of the unit I removed.

103_0741.JPG

103_0742.JPG

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Looks a little chewed up on the inside. Kinda difficult to see from the pic. Would definitely look at the crank. Do you have a dial caliper? If so check crank snout and id of balancer.

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Check Russ's website for a new bolt and washer.  He also sells a repair sleeve for the crank.

 

Balancer/damper bolt and washer, fits all 1957-66 nailheads and some 1955-56 engines. 3/4x16 thread. 12.00 for set new. Must be tightened to 220 lbs!

 

SRK ..Seal sleeve repair kit for all nailheads.. 17.00Others may have these for sale as well.

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Ed,

 

  That's NOT a repair sleeve for the crank but for the harmonic balancer IF the sealing surface has a groove in it from the seal.

I ALSO have those parts needed, even a good used balncer.

Tampa Riv. Need a picture from the front of the balancer looking at a straight shot at the keyway groove. 1st. clean off ALL the grease in side & out.  Then take a pic of the nose of the crank at 90* intervals especially the keyway slot.

 

 

Tom T.

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Thank you Tom.  I will clean up the unit tomorrow and get some good photos of the keyway.  I really appreciate your help.  My email is  richardreau@hotmail.com.

 

Rich

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9 hours ago, TampaRiv said:

Thank you Pete for the input, it's most helpful.  Here are a few photos of the unit I removed.

103_0741.JPG

103_0742.JPG

This balancer is junk. The keyway is broken out into the sealing surface. I can imagine what`s left of the keyway itself isnt pretty as well. Also looks like there is a crack eminating from the keyway.

Tom Mooney

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Thanks Tom.  So, where do I buy another unit?  Any special considerations in picking one out?

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24 minutes ago, TampaRiv said:

Thanks Tom.  So, where do I buy another unit?  Any special considerations in picking one out?

  Tom T. says above he should have one. If for some reason he cant help you out I have one. You basically want one with a decent sealing surface (even though that can be dealt with via a repair sleeve), a good keyway that hasnt been oversized from running loose and what appears to be good rubber between the inner and outer half.

  Better check the nose of your crank as has been suggested...that may be why the balancer has been changed repeatedly.

  Good luck!

Tom Mooney

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So the harmonic balancers between 401's and 420's are interchangable? I was under the impression that they were not being these motors are balanced with the harmonic balancer. Good to know they are interchangable.

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16 hours ago, 1965rivgs said:

This balancer is junk. The keyway is broken out into the sealing surface. I can imagine what`s left of the keyway itself isnt pretty as well. Also looks like there is a crack eminating from the keyway.

Tom Mooney

Barring any structural defect or unseen damage, that may be fixable.  Put a bead of weld over the broken area, mill it flat to create a good sealing surface, cut/ream the hole to remove any overhanging weld, and recut the keyway.

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2 hours ago, arnulfo de l.a. said:

So the harmonic balancers between 401's and 420's are interchangable? I was under the impression that they were not being these motors are balanced with the harmonic balancer. Good to know they are interchangable.

Dont know where you are seeing a reference/recommendation to interchange in this thread? Maybe I missed something....the original part numbers are different which makes sense due to the difference in reciprocating weights. Having said that, back when I was a kid and didnt know any better or have any other options (pre-internet!), I used/mixed up the balancers and didnt experience any catastrophic results...but the goal was to keep a driver in service, not to fine tune the engine balance,

Tom Mooney

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Any 401/425 balancers that you look at will have different balancing pins put in different places on the outer ring. Some may even have drill marks in the OD or ID of the balancer.  All the balancers have different balancing required depending on how the fine balance turned out at the engine plant. Even flexplates have holes drilled in them for the final fine balance of the engine assembly.

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2 hours ago, telriv said:

Any 401/425 balancers that you look at will have different balancing pins put in different places on the outer ring. Some may even have drill marks in the OD or ID of the balancer.  All the balancers have different balancing required depending on how the fine balance turned out at the engine plant. Even flexplates have holes drilled in them for the final fine balance of the engine assembly.

Yes, each engine is unique in terms of final balance but before final balance I think the 401 and 425 balancers start with different counter weighting. I seem to remember you and I comparing 401 and 425 balancers long ago and noting cosmetic differences in the basic counter weighting....same with the flex plates...or, maybe it was just a cool dream!

Tom M

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5 hours ago, 1965rivgs said:

Dont know where you are seeing a reference/recommendation to interchange in this thread? Maybe I missed something....the original part numbers are different which makes sense due to the difference in reciprocating weights. Having said that, back when I was a kid and didnt know any better or have any other options (pre-internet!), I used/mixed up the balancers and didnt experience any catastrophic results...but the goal was to keep a driver in service, not to fine tune the engine balance,

Tom Mooney

My bad , poorly worded question. Can a used harmonic balancer  from one 401 work on another 401 without any adverse affects ?

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In theory its possible it may work it all depends. Could create more damage. Because weight/balance has everything to do with it. Like stated some have drill spots etc..Think of it as a wheel weight or driveshaft. Different placement affects the balance speeds/vibration. May or may  not affect idle but can and will affect a certain rpm or possibly throughout. Vibration etc..

Edited by demon452 (see edit history)

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     OK guys, so if I understand this correctly,  each balancer is custom balanced to each crankshaft?  And how on earth would it be possible to know if any replacement balancer would be compatible with any given crankshaft, until you install it and put everything back together and start the engine?

 

    I see that the CARS guys (oldbuickparts.com) will rebuild my old balancer for $154.  That seems like a decent price.  But, given that I don't think my current balancer is original to the car, then what?  Sorry to be a PITA, I just don't quite understand all of this.

   

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IF you send that balancer to be rebuilt I think it will be rejected

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I'm an optimist. I think it can be repaired and rebuilt. IMHO, it's better to try and stick with the balancer that came with the motor since it was tuned out of the factory with that unit. Conversely, if that balancer is not original to the motor, it's a different consideration. If the car ran well with this unit until it got loose, I'd focus on repair. Otherwise, send it to a balancer shop and tell them you need to match this units spec but with a new one. Just buying a replacement balancer off the shelf is a little risky since there is mo telling how its been tuned...if at all. I do not think the 401 is interchangeable with the 425. By the way, the specs on these motors is important, but there's no need to get all doomsday about it. A finely tuned balancer is life and death critical on a high revving nitro methane burning dragster. On a low revving nailhead, not so much. PRL

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16 minutes ago, petelempert said:

I'm an optimist. I think it can be repaired and rebuilt. IMHO, it's better to try and stick with the balancer that came with the motor since it was tuned out of the factory with that unit. Conversely, if that balancer is not original to the motor, it's a different consideration. If the car ran well with this unit until it got loose, I'd focus on repair. Otherwise, send it to a balancer shop and tell them you need to match this units spec but with a new one. Just buying a replacement balancer off the shelf is a little risky since there is mo telling how its been tuned...if at all.

 

Spot on.

 

Although I believe that this balancer is a replacement, I'd absolutely go for repair first.

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5 hours ago, petelempert said:

I'm an optimist. I think it can be repaired and rebuilt. IMHO, it's better to try and stick with the balancer that came with the motor since it was tuned out of the factory with that unit. Conversely, if that balancer is not original to the motor, it's a different consideration. If the car ran well with this unit until it got loose, I'd focus on repair. Otherwise, send it to a balancer shop and tell them you need to match this units spec but with a new one. Just buying a replacement balancer off the shelf is a little risky since there is mo telling how its been tuned...if at all. I do not think the 401 is interchangeable with the 425. By the way, the specs on these motors is important, but there's no need to get all doomsday about it. A finely tuned balancer is life and death critical on a high revving nitro methane burning dragster. On a low revving nailhead, not so much. PRL

Thanks for the clarification ! I also think that is a great idea to take it to a balancer shop to try and duplicate.

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On 3/26/2019 at 8:04 AM, telriv said:

Most ALL engines have some kind of harmonic balancer to help reduce harmonics. IF the balancer was loose you may ALSO have a front crank snout that's been worn lope sided & will ALSO need another good used crank.

I could go on for days typing with one finger about damage done from harmonic balancer bolts lose & the incorrect washers installed.

 

Tom T.

Or no washer installed. And the nut on the snout not torqued to specs. A shop almost ruined my car because of incompetence. My balancer came off while I was driving. Costly second repair.

Everything is fine now. I was lucky.

Turbinator

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Thanks guys,

 

   I've gotten some great advice for everyone, and now have a replacement balancer ready to install.   I will torque to spec so hopefully the damn thing won't come flying through the hood or the floor board!

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