[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.

[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

[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.

[AG]

Do you have the bobweight sheet?

[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.

[b-man]

If starting over with another flywheel step up to a steel aftermarket one.

It’s never overkill when protecting your only 2 feet.

[242177P]

Not sure which year the register size
changed, but it's worth a mention?

[Kenth]

"The engine has a stock (external) balance flywheel, rotating assembly was balanced."

So, the rotating assembly was balanced with the external flywheel ON, as it should be?

"They had a real stock '75 flywheel on hand".

Really? An untouched 1975 flywheel? Was it verified untouched?

Hard to believe since your engine ran fine with your original external balanced flywheel, and not so fine with it when it got neutral balanced.
Going back to an external balanced original Pontiac flywheel would make the engine running fine again, i would think.

[MPKind]

Originally Posted by Kenth

"The engine has a stock (external) balance flywheel, rotating assembly was balanced."

So, the rotating assembly was balanced with the external flywheel ON, as it should be?

"They had a real stock '75 flywheel on hand".

Really? An untouched 1975 flywheel? Was it verified untouched?

Hard to believe since your engine ran fine with your original external balanced flywheel, and not so fine with it when it got neutral balanced.
Going back to an external balanced original Pontiac flywheel would make the engine running fine again, i would think.

Yes in 2010 it was balanced with the flywheel and HB.

Yes they had a factory Pontiac wheel on hand. A customer with a 75 Trans Am swapped to a Tremec and did not want it back. Looked very nice. 75 date code. Had the typical 2 factory holes on the back side.

It ran great, then as I wrote before the shop took it upon them selves to balance a flywheel to neutral when it should never have been touched.

Back to a factory balance wheel is what was installed now. It was dynamically checked at a DIFFERENT shop to verify it had the factory balance. The engine shop I used in 2010 did it. Clutch PP was neutral balanced. So in theory it should’ve been close enough to its original configuration.

But it’s not.

Unknowns

1. I don’t know what the imbalance was on the factory 65 wheel. Has the 2 factory holes then 5 more 90* away that neutral balanced it.

2. Without knowin the 65 wheel specs, can’t compare to the 75 wheel specs.

3. Was the 65 wheel tweaked back in 2010 when balanced with the crank? I’m looking into that.

4. What affect is the clutch having in all this? It had all the weights that had been welded on at the driveline shop removed and brought back to factory neutral balance. No extra anything on it.

So yeah. This is a bad deal. Never should’ve happened like this and after 7 weeks the issue has not been resolved. I doubt I’ll be made whole on this. That’s what really sucks and the fact it blew up the end of the car season.

[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.

[grivera]

Maybe I missed it but have you already tried a neutral balanced FW along with the neutral balanced clutch assembly?

[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/

[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.