[MPKind]

What started as a clutch swap turned into a balance issue. The engine has a stock (external) balance flywheel, rotating assembly was balanced. Brought the wheel and the clutch to a shop to check balance. They added a ton of wt to the clutch. Not knowing any better, it was installed and the engine vibrated bad. Informed the shop, and they offered to remove the clutch and rebalance.

I assumed they'd just restore the clutch to factory neutral and knock the weights off, but instead they removed material from an original '65 stock flywheel, removed the clutch wts and then re-added wts...I couldn't believe it when I heard later. I didn't know at first, but when driving the car I knew something was off. Called and was told the flywheel had been modified, I knew that was a totally worng thing to do, so I called them out on it.

This threw off the rotating assembly balance of course. Car goes back to the shop a second time. They had a real stock '75 flywheel on hand in very good condition to replace the '65 wheel. This time I take the flywheel and clutch to my engine shop for a dynamic balance, instead of a static balance.

At this point I have a stock '75 flywheel w/external balance with a neutral balanced clutch. It still has vibrations. It's worse now than with the flywheel and clutch assembly neutral balanced.

I've read on forums that all stock Pontiac flywheels from '64 to '76 have the same external balance. I cannot find any documents that support that claim or any specs on them to check, and now with this other wheel on, I'm finding it hard to believe.

It looked good on paper, but it's not right.

I took the car home last night and there it sits. I couldn't leave it there forever and keep trial and erroring this just hoping it'll work. The engine shop has the bob wt card still from 15 years ago on the 455 build, but according to them it won't help to verify if the '75 flywheel is exactly the same as the '65.

This is a major bummer to my summer, so it's pretty much done. I doubt I'll be made whole by the transmission/driveline shop. They did what they could to fix it after taking it apart twice.

At this point there's only one option, remove the crank and rebalance the works.

This is another lesson on spending money and getting nowhere.

[AG]

I'm sorry you are going through this because it should have never happened. The complete rotating assembly should have been balanced together and the clutch assembly should have been neutral balanced on it's own. The stock factory imbalance on the flywheel is so little that it is easy to have it internally balanced and have the clutch neutral balanced.

[MPKind]

Yes. Should’ve never happened. My understanding of things before this all happened was minimal. Trusted others to check things and it turned into a total disaster. I’m well informed on the procedure and other things now but too little too late.

[PAUL K]

Well this sure is a poop deal. Fwiw generally changing a factory balanced flywheel with a neutral one won't produce a noticeable vibration. It may be more pronounced with a manual trans though. To further complicate things we've seen aftermarket billet flywheels with a removable weight that has the wrong weight added. Someone figured out they could use an Oldsmobile weight rather than a Pontiac to make things more profitable.

One way of attacking this issue would be to purchase a flywheel with the correct removable weight. Have a shop neutral balance the flywheel with the clutch attached and removable weight removed. Now install the balanced assembly without the weight. If all seems good enjoy. If it still has a vibration install the "removable weight" and hopefully that fixes the vibration. The weight might be able to be installed with only the removal of the inspection cover.

[MPKind]

Originally Posted by PAUL K

Well this sure is a poop deal. Fwiw generally changing a factory balanced flywheel with a neutral one won't produce a noticeable vibration. It may be more pronounced with a manual trans though. To further complicate things we've seen aftermarket billet flywheels with a removable weight that has the wrong weight added. Someone figured out they could use an Oldsmobile weight rather than a Pontiac to make things more profitable.

One way of attacking this issue would be to purchase a flywheel with the correct removable weight. Have a shop neutral balance the flywheel with the clutch attached and removable weight removed. Now install the balanced assembly without the weight. If all seems good enjoy. If it still has a vibration install the "removable weight" and hopefully that fixes the vibration. The weight might be able to be installed with only the removal of the inspection cover.

I swapped a factory for factory and it’s bad. That’s what I can’t figure out. It’s been apart 3 times now and I don’t know what to do to correct it. I could try some stuff but this is getting ridiculous.

[Vid]

Man that’s a lot of clutch removal/replacement. Sorry you have to go through that.

Just curious what damper you’re using? Sometimes dampers are taken for granted and it’s something to consider about the overall balance.

I’m running a RAM aluminum flywheel and an ATI super damper with a balanced rotating assembly and it’s smooth throughout the rpm range.


Sent from my iPhone using Tapatalk

[carbking]

Originally Posted by Vid

Man that’s a lot of clutch removal/replacement. Sorry you have to go through that.

Just curious what damper you’re using? Sometimes dampers are taken for granted and it’s something to consider about the overall balance.

I’m running a RAM aluminum flywheel and an ATI super damper with a balanced rotating assembly and it’s smooth throughout the rpm range.


Sent from my iPhone using Tapatalk

Refreshing to know I am not the only one running an aluminum flywheel on a Pontiac engine!

MPKind - NO one should have go through what you have experienced. Sorry that it has happened.

In my case, since I know absolutely NOTHING about engine balance, I sent the entire reciprocating assembly to a shop that had some pretty good results with their Pontiac racing engines.

Jon

[AG]

Do you have the bobweight sheet?

[MPKind]

Originally Posted by AG

Do you have the bobweight sheet?

I was told that the bob weight card does exist at the shop that balanced the engine 14 years ago.

[Formulas]

do you have all the parts that were smooth running but maybe worn out to start with?

[Gary H]

Just wondering if the original flywheel might have had some holes drilled in it to "neutral balance" the flywheel, before they balanced the rotating assembly? Have you looked at it and compared to the second flywheel?

[MPKind]

Originally Posted by Gary H

Just wondering if the original flywheel might have had some holes drilled in it to "neutral balance" the flywheel, before they balanced the rotating assembly? Have you looked at it and compared to the second flywheel?

The driveline shop neutral balanced it. 5 holes in it. What I don’t know is was it a stock balance before they did that or was it already slightly modified. I couldn’t guess.

[MPKind]

Originally Posted by Gary H

Just wondering if the original flywheel might have had some holes drilled in it to "neutral balance" the flywheel, before they balanced the rotating assembly? Have you looked at it and compared to the second flywheel?

That’s a great question. Not sure at this point but the engine shop may know something or have info on the bob card. May be a way to temporarily ad wt to the 65 wheel to verify its original imbalance.

[MPKind]

The 65 factory flywheel had an imbalance according to the “driveline” shop, but the “engine” shop could have taken a small amount out previously.

Kenth can you share the flywheel balance specs and how they are mapped on the part?

[Gary H]

Originally Posted by MPKind

The 65 factory flywheel had an imbalance according to the “driveline” shop, but the “engine” shop could have taken a small amount out previously.

Kenth can you share the flywheel balance specs and how they are mapped on the part?

Is this the original flywheel you took out? If so, it looks like someone, probably the people who balanced the engine, drilled holes in it to neutral balance it. Personally, I'd but a new neutral flywheel and try it. I bet that's what the engine is balanced to.

[Held for Ransom]

Originally Posted by MPKind

The 65 factory flywheel had an imbalance according to the “driveline” shop, but the “engine” shop could have taken a small amount out previously.

It wasn't Wagamon Brothers, I hope?
https://wagamonbrothers.com/

[MPKind]

Originally Posted by Held for Ransom

It wasn't Wagamon Brothers, I hope?
https://wagamonbrothers.com/

Not Wagemon Bros. Was told long ago to stay clear of them.

[PAUL K]

Originally Posted by MPKind

The 65 factory flywheel had an imbalance according to the “driveline” shop, but the “engine” shop could have taken a small amount out previously.

Kenth can you share the flywheel balance specs and how they are mapped on the part?

The balance on the flywheel in the picture is completely screwed up. Everyone involved in the project needs to be replaced with competent people.

If you know the shop that originally balanced the rotating assembly they should be able to tell you if they removed weight from the flywheel to balance the rotating assembly, it's called "standard operating procedure". If they did they need to be replaced, if they can't tell you they need to be replaced.

Plan B since you didn't like my first suggestion, would be to have the engine shop figure out what balance holes they made. Then have the clutch shop figure out what balance holes they made. Report back and we might be able to figure out what's going on.

Sorry you're going through this.

[mgarblik]

I did my best to try and read and understand everything in this thread. I have to admit, I don't fully understand everything that happened, when and by who enough to make a recommendation that I know will fix it. So, if I was faced with this situation and was committed to make it right, I would do the following. Your probably not going to like this. I would remove the engine and and the crankshaft. Have the crankshaft zero balanced +- 2 grams and verify. That completes the engine. Then I would buy a steel zero balance flywheel and a zero balance clutch. Problem solved. Time consuming and possibly a little expensive, but now it's fixed. Mixing, matching, drilling, bolting , welding, guessing, removing, installing, you may get lucky and hit the right balance, but it may be an even more time consuming exercise than just biting the bullet and doing it all one more time, correctly. I wish you the best. Very frustrating I am sure. I hope you get it.

[MPKind]

Originally Posted by PAUL K

The balance on the flywheel in the picture is completely screwed up. Everyone involved in the project needs to be replaced with competent people.

If you know the shop that originally balanced the rotating assembly they should be able to tell you if they removed weight from the flywheel to balance the rotating assembly, it's called "standard operating procedure". If they did they need to be replaced, if they can't tell you they need to be replaced.

Plan B since you didn't like my first suggestion, would be to have the engine shop figure out what balance holes they made. Then have the clutch shop figure out what balance holes they made. Report back and we might be able to figure out what's going on.

Sorry you're going through this.

I think your first suggestion was fine, it's a matter of time and logistics at this point. The car is home now, so I'm planning my next move.

I agree with the assessment of personnel. I ask questions and I get attitude that implies I'm questioning their work. As I should!

The engine shop said they have the bob weight card, what can be determined from that without the crank out of the engine? I asked if they could figure out what the original FW balance was, I was told no. I'm not savvy with what can and cannot be determined from that info. If it can be determined, how? Don't you need the crank and the bob weights to verify and measure the FW balance?