[grivera]

Originally Posted by grivera

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

Originally Posted by lust4speed

This reads about the same as following the pea moving around under walnut shells. I probably missed it but most shops in my area zero balance cranks for a performance build. It seems that the assumption was made that the crank was still needing the 6 inch ounce external balance, but the vibration indicates that a stock flywheel is causing problems.

There were only two choices that should have been made by the original builder - either stock balance retaining the external balance or a full internal balance requiring a neutral balanced flywheel. If a presumed good external balance flywheel vibrates, then the only other choice should be a neutral balanced flywheel.

That’s what I alluded to earlier but OP has clarified the assembly was externally balanced

[scott70]

Originally Posted by mgarblik

Chances are the engine shop that balanced the crank would know "how" they balanced it. Most shops have a standard way they balance various crankshafts by application. If a customer presents a Pontiac crankshaft for balance, most shops would be aware of the slightly different way "partial" internal balance crankshafts are done. They would have asked the customer if they wanted a "full internal balance using a neutral balance flywheel", or a stock balance. At my school, we like to do a full internal balance because it opens you up to any one of many options for flywheels and pressure plates in the future. If we do a stock balance, we balance with the flywheel only added to the rear, no pressure plate. Once that's good, we bolt on the pressure plate and spin it again to see if the balance remains correct. Then if needed, fine balance the pressure plate with tiny magnets to get it just right. Mark the location, weigh the magnets, switch the magnets to washers and weld them to the pressure plate. Good quality pressure plates generally don't need any attention other than a check spin.

Engine shop just emailed me and said it’s ready. He said he couldn’t find the balance card so he made the new flywheel like the old by adding a weight.

[mgarblik]

That's good news and a good catch on your part.

[scott70]

They had to add weight to the new flywheel to get it to match the old flywheel. And still have to index the PP because the new McLeod PP was off quite a bit from neutral balance. He said if I don’t put it where it needs to be it will off by around 11 grams. I noticed also the new flywheel isn’t as thick as the original so let’s hope the starter and everything lines up. Sorry for jumping on your thread but it seems like it might be helpful and related

[Formulas]

i had these parts out so i took a pic for referance

PRW wheel i indexed a auto flex plate on top and marked the factory balance holes with a sharpie

they come out opposite of the PRW inst. weight so there approach is factory balance by adding weight opposite where factory removes weight


so for theoretical neutral balance you remove PRW weight... BUT you end up with empty bolt holes with nothing opposite to counter those holes which are 5/16 dia by about .430 deep and no mention about filling them.

i put in 5/16 × .375 set screws in with a bit of
lead fishin weight to make up for the hole in set screw for allen key.... should be close enough no to be a problem

btw there is 3 different sets of clutch holes two sets are 3/8 dia for both GM and another set for 5/16 holes all threaded Borg and Beck?

[MPKind]

The latest is that they want to restore the flywheel by welding the 8 holes up. The fw will be preheated since it’s cast iron. Fill with steel and get a skin cut on the engine side in the outer machined surface to even things out. Going back to the previous Centerforce clutch. The McLeod may be compromised with all the welding and weight removal. Twice. In retrospect we could’ve changed the clutch fork and fw bolts and life would’ve moved on. But no.

[b-man]

Welding on a cast iron flywheel.

Maybe if it were last one on the planet otherwise never.

Run far away from those hackers.

[Held for Ransom]

What year is this one?

[MPKind]

Originally Posted by b-man

Welding on a cast iron flywheel.

Maybe if it were last one on the planet otherwise never.

Run far away from those hackers.

Bart is 100% correct. Why take the risk? There no way to be 100% certain welding didn’t compromise the flywheel.

[MPKind]

Update: The place that destroyed my flywheel won’t replace it with a new steel wheel. They offered up a used cast one from who knows where. I’m out of ideas. It runs and drives but don’t step on it or it gets shaky.

Some say you can determine a flywheel balance using the bob weight card. Others say no way. Not sure how you use the numbers to reverse engineer the proper fw imbalance. If anyone knows please advise.

The only thing left is to pull the crank and start over. Like to avoid that if possible.

So in the end a simple process to verify a new clutch was zero balanced that cost me $80, turned into this disaster and will likely cost me $3-5k. All they did was burn up 15 hours of labor which they’ll write off as “training”. Lucky me.

[Schurkey]

Originally Posted by mgarblik

My information came from an old GM film that showed the build process of Pontiac engines at the plant. I was almost sure I was watching the final dynamic balance being performed on rotating engines and just small amounts of finish balance material being removed externally. I remember thinking that was really bizarre as that would sort of marry the flywheel to the crankshaft which would be wrong. How in the world did they drill cast iron counterweights on an assembled engine without leaving metal in the engine?

That film was substantially longer; it's been cut down to just the engine section in that Youtube video.

The drilling on the Pontiac engine would be done with nothing but assembly lube in the crankcase--I imagine that the counterweights were completely dry. The drill swarf/chips wouldn't stick to the dry metal, and a little compressed air would leave it reasonably clean.

Buick on the other hand screwed the balance pooch. Their connecting rods don't have big-end/little-end balance pads. The balance pads are on the beam of the rod, ("center-of-mass" balancing) so they get all the rods to weigh the same, with no regard to matching big-ends and matching little-ends.

And then they final-balance this mess with the oil pan in place by either running the engine (early) or motoring the engine with compressed air in the cylinders (later)--they pound steel rods into holes in the damper in front, and punch holes in the flexplate/drill holes in the flywheel to get the rear in balance. So, when you replace a Buick damper, you have to take note of the keyway, remove the steel pin(s) from the old damper, and cram them into the new damper in the same relative positions. And you're just screwed on the flexplate/flywheel unless you're willing to drill the thing to match the OEM lightening holes.

Originally Posted by PAUL K

That's the correct way to do it.... If you can believe it, Chevrolet missed that memo.

Chevy engines of this general time frame used neutral-balanced dampers and flexplates/flywheels except for the 400 small-block, and the 454 big-block--which did use locating dowels between crank and flywheel/flexplate. The neutral-balanced flexplates/flywheels don't need an offset bolt pattern because it doesn't matter which of the six possible positions it can be installed in, they all balance-out and function the same. Once Chevy went away from neutral-balance on the parts, there were offset bolt patterns or locating dowels.

[Held for Ransom]

So, the picture of your latest flywheel ('75) looks like 11" bolt holes for pressure plate/clutch disc. I thought the smaller than 455 CIDs liked the 10.4" units. I have a '73 flywheel, but it's not for sale. I'll look to see if there are others.

[slowbird]

Originally Posted by MPKind

Update: The place that destroyed my flywheel won’t replace it with a new steel wheel. They offered up a used cast one from who knows where. I’m out of ideas. It runs and drives but don’t step on it or it gets shaky.

Some say you can determine a flywheel balance using the bob weight card. Others say no way. Not sure how you use the numbers to reverse engineer the proper fw imbalance. If anyone knows please advise.

The only thing left is to pull the crank and start over. Like to avoid that if possible.

So in the end a simple process to verify a new clutch was zero balanced that cost me $80, turned into this disaster and will likely cost me $3-5k. All they did was burn up 15 hours of labor which they’ll write off as “training”. Lucky me.

Reading through this thread post 4 seems like a good approach

[MPKind]

Originally Posted by Held for Ransom

So, the picture of your latest flywheel ('75) looks like 11" bolt holes for pressure plate/clutch disc. I thought the smaller than 455 CIDs liked the 10.4" units. I have a '73 flywheel, but it's not for sale. I'll look to see if there are others.

That pic is the ‘65 wheel. I don’t have a good pic of the ‘75 since I didn’t take one before it was installed….like an idiot.

Both are 11”.

The a-hole of the trans shop said he’d track down another 11” wheel. He found one, but it’s been tense. I think in the end a new steel wheel will go on with a full rebalance. I don’t see a sure path forward where there’s still doubt about how it’ll react.

[PAUL K]

Originally Posted by Schurkey

Chevy engines of this general time frame used neutral-balanced dampers and flexplates/flywheels except for the 400 small-block, and the 454 big-block--which did use locating dowels between crank and flywheel/flexplate. The neutral-balanced flexplates/flywheels don't need an offset bolt pattern because it doesn't matter which of the six possible positions it can be installed in, they all balance-out and function the same. Once Chevy went away from neutral-balance on the parts, there were offset bolt patterns or locating dowels.

I'm with you, but have never worked on a Chevrolet V-8 engine which had an offset bolt pattern. Just dowel pins.

[Held for Ransom]

I was looking at the pictures posted in #17 and #48, Both are of the '65 flywheel? Must be a 421 engine, I forgot they'd use the 11". I wouldn't have one of those.

[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

[MPKind]

Epilogue

Proven Force / Midwest Transmission did the old “plausible deniability” escape ploy. They basically knew nothing about the flywheel they permanently changed (ruined), then blamed the customer for not knowing more than they knew.

To recap:

1. for flywheels you must know about the engine’s balance setup it came from before even thinking about f’ing with it. Appears it never entered their mind. A pro would know that’s a critical piece of information before doing anything and be 100% sure of what they’re dealing with.

2. If you commit to balancing a flywheel, it’s typically trying to make a zero balance more precise. So any changes would be tiny. Fine tuning an external fw is not recommended, EVER! It’s part of the cranks balance.

3. If the driveline guy tacks a pair of 50cent pieces on the pressure plate and says it’s balanced, tell them to try again...better yet, take your s*** to someone else. The PP is always zero balanced from the factory to a level of precision within their spec. It can be optimized for its “best” clocked position on the fw to achieve same balance as the flywheel alone, whether zero or external balanced. Any change in PP balance would require a very tiny amount of weight tacked on.

Factory and aftermarket parts in general shouldn’t need any to very little change in weight/balancing to work in spec in most street applications.

Another costly series of events, by others.

[scott70]

Any updates?

[MPKind]

Updates? Looks like a short winter in Minnesota, so I can get a jump on correcting the mess Midwest Transmission/Proven Force created. The car is still in storage, but it may be good to drive it soon. Roads are clean and dry already...snow is mostly gone.

This time the rotating assembly will be fully neutral (zero) balanced. New billet steel FW, maybe a different clutch. While it's apart, it'll get inspected thoroughly for any unusual wear.

For clutches, I've tried the Centerforce II that got a bad rap before I saw the stupid ARP flywheel thick head bolts rubbing on the clutch damper springs. I think the PP is fine, but I'd likely replace the disc. Also had a McLeod Super ProStock for a short time last summer. Ceramic disc really can do a number on a cast iron flywheel. The machine shop welded wts on the PP cover and later ground them off...no big deal they said. I wouldn't use it again. So that's money gone...again. What clutch set do you like for a heavy car, 3.42 gears, 400 HP, 500 Ft-lbs? I'm open to suggestions.


I'm still pursuing some relief from the Proven Force. I'll be getting in touch with Mr. Peter Fink - CEO of Certified Transmission in Omaha. If you're from there, you probably know who he is. The business in Minnesota is a current acquisition of Certified...an umbrella company (franchise) that sells and services their parts. That may produce some relief or go nowhere. We'll see.

Still exploring the specs for the stock 11" flywheels. Henderson & Osterstock say "about 6 inch-ounces" in the Blueprinting booklet. What years does that cover? 64 and up? I measured the mass removal on my old '65 wheel. Only has 2 (unmolested) holes. They're close together at 5.875 inches from center. Using the unit wt of cast iron the moment is 5 in-oz. Post #17 has a pic of it. The other holes are 120 degrees away and don't seem like existing holes were already there.

I still can't figure out how back in the day if your FW went bad, they just slapped in a new one from the parts dept. and it worked. I understand the tolerances were not super tight, but still. I don't think any 2 stock flywheels are the same with regards to the location of weight removal. I've seen many and there's anywhere from 2 to 5 holes, spacing is different and location is not the same. Did Pontiac match every flywheel to the crank with a specified balancing procedure or did they "batch balance" flywheels using an average imbalance based on the batch of cranks at the time? Sounds time consuming.

Same goes for aftermarket FWs. This guy swapped a stock FW for a new billet steel external balance for Tremec transmission upgrade at this stupid shop I used. Early 70s T/A. Plug and play. I can't imagine it's a smooth operator...no way it doesn't vibrate, right? BTW, that FW the guy removed is currently in my car, not even close to imbalance that WAS on my old '65 FW. The theory of being able to swap one stock FW for another not holding up very well.

McLeod and Centerforce make external balance FWs but they specs they publish for counterweight don't make sense to me. Centerforce uses 4.22 in-oz, which is kinda close to 5-6 in-oz. McLeod uses a bolt on wt. Sheet says 12...12 what? Grams, ounces? Cmon. 12 grams is less than 1/2 ounce. How is that helpful? 12 oz is too much. 2 12 grams wts would come close to the 5-6 in-oz at about 6 inches from center of wheel.

That's all for now.