Clutch Chatter & Flywheel run-out

[BRENT in 10-uh-C]

We are exploring a fairly rough clutch chattering situation on a vehicle that has been mechanically restored prior to this person owning the vehicle. Initially we removed the transmission thinking we would see a worn pilot or main drive gear end that engages into the pilot bearing. All of that appears to be new and not the culprit. The flywheel has been converted to the V-8 clutch style P/P and has a new pilot bearing. We just indicated the housing and it is between 0.004" - 0.005" with the majority of the run-out on the lower portion. Not sure how much the physical weight of the transmission would lessen that amount (-if any) when it is installed.


The flywheel face still has the grinder marks, and although they are a little rougher than what most would like by today's standards, it does appear the clutch is engaging uniformly for the most part and probably not the culprit. The flywheel face appears to have approximately 0.008"-0.009" of run-out in it and was indicated on the outermost portion of the flywheel face near the pressure plate holes. I suspect this was introduced when the flywheel was machined, HOWEVER I also do not know if this much run-out is really a problem either. I know there has been a number of something like 0.005" maximum runout for a flywheel offered numerous times here however if I recall correctly, that number is taken as a spec designed for the multiple-disc clutch and may or may not necessarily be applicable for the 6375B flywheel.


So where my question(s) would be is exactly how much flywheel face variance/runout is acceptable before it would actually give a problem? Why I am asking for opinions is kinda two-fold in that this flywheel has been balanced along with the P/P. If I were to set it up into the flywheel grinder to take off the 0.005" to true it up, then I potentially would need to rebalance the flywheel and P/P. Not a big deal if it were to cure the issue but it would be perceived as a wasted expense if not the culprit. Thoughts??
.
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[Patrick L.]

Hmmm, interesting. My thoughts are that there is too much runout in that wheel. I've always thought that about .002" was the accepted number. How much more than that would cause your problem, I guess I'm not too sure. But, I think your .008" is way too much. That said, taking off the few thousands to true it up, I wouldn't think it would need to be rebalanced. Personally I would try that. I understand your predicament, time is money and we know how much time it takes to pull these critters back apart. I'm sure we'll all be interested to hear about the outcome.

[BRENT in 10-uh-C]

Originally Posted by Patrick L.

Hmmm, interesting. My thoughts are that there is too much runout in that wheel. I've always thought that about .002" was the accepted number. How much more than that would cause your problem, I guess I'm not too sure. But, I think your .008" is way too much. That said, taking off the few thousands to true it up, I wouldn't think it would need to be rebalanced. Personally I would try that. I understand your predicament, time is money and we know how much time it takes to pull these critters back apart. I'm sure we'll all be interested to hear about the outcome.

Ok, some additional food for thought.....


If I take 0.002" off of the flywheel, how much do you think that removed material will weigh? Using a clock face for a visual reference for this illustration, theoretically if I take 0.002" off the flywheel face, then I will be taking approximately 0.001" off from the 4 o'clock to the 5 o'clock position along with 0.001" from the 7 o'clock to 8 o'clock position and approx. 0.002" from the 5 o'clock around to the 7 o'clock position, ...or about 120° of the flywheel. The remaining 240° of the flywheel perimeter is not to have any material removed. While I can probably calculate the weight of that material which would be removed, by guess I feel like it would be at least 10 grams, ...which in the world of balance should/would be noticeable on a flywheel.


Since you mentioned recalling the 0.002" runout number, I went to the source to find exactly what that number is. On page 218 of the Service Bulletins, it mentions a number of 0.005" as the maximum number for being eccentric and without wobble. It states to measure this at the hub and rear face of the large diameter. The issue with this number is we are speaking of a multiple disc flywheel that is only been machined in the clutch hub (...in the center). So if the "wobble" is to be measured on the multiple-disc hub, it is only ½ the distance to the outer perimeter of the flywheel. Therefore, if we use the 0.005" maximum of wobble on a multiple-disc flywheel, then on a regular Model-A flywheel that max number would likely double if the radius of the flywheel measurement were doubled too. With that mindset, then 0.010" would be the maximum number of run-out. Would it not??

[Jim Brierley]

Brent, I don't think that .008" would cause your chatter problem, nor removing it would be cause for re-balancing. I chased the same problem in my tudor. I replaced the float-o-motors with original mounts, helped a little but no cure. I later changed engines, with a fresh-ground flywheel and V8 PP, not enough improvement to speak of. The last change was to a diaphragm clutch, that helped immensely, for all practical purposes it cured it but occasionally (rarely) a bit of chatter could still be felt. I don't know why some A's chatter, but that's my story. BTW, changing to stock motor mounts did not affect the overall smoothness one iota!

[Patrick L.]

I don't remember ever seeing a spec for an 'A' flywheel. The number I posted is a generally accepted spec for most stuff. Some are spec'd much tighter, [I have read some specs in the past that were less than .001".] If I cut one or had one cut I'd expect it to be within that number.
I don't think the 10grams could be considered to be removed from one spot on the wheel, it would be spread out. I think I'd still run it without balancing, but as said, it would be just time for me to remove it again if I had to. I wouldn't be very happy about it, thats for sure.
If the other measurements seem good including the finger heights, crank end play and motor mounts etc then I'm at a loss. Maybe the disk or pressure plate has a problem.

[BRENT in 10-uh-C]

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Thanks Jim. This engine has stock rear mounts. By diaphragm clutch, you are speaking of a diaphragm pressure plate and not the fingered Borg & Beck style P/P, -correct??


The reason why we have not suspected the flywheel per se' is sometimes even pressure plates will have their plate release/engage at a slight angle that would be at least 0.008-0.010 or more.


Here is some of the talk we have had in-house. Theoretically, the transmission main gear (input) shaft should be running very close in concentricity since the pilot bearing and shaft end are very tight in fit, ...and there is a new bearing in the transmission case holding that end where the disc cannot jump out of centerline when it is engaged. It also appears the clutch housing is piloting correctly on the front bearing retainer however maybe something is off there? We have discussed mounting the clutch housing onto the bed of the mill and indicating/sweeping the flange however my mill table is only 9", so I am not sure how accurate we can measure with the equipment I have. I do have access to a surface plate that maybe we can check it with.


One other theory we have discussed is that clutch discs have some spline to shaft clearance to allow the hub of the disc to float on the shaft during pressure plate disengagement. I do not have a print on the transmission shaft nor on the clutch to reference sizes, but is it possible that with a few thou. of clearance in the fit that the clutch disc (-which likely is never balanced) can move slightly out of centerline enough to create just a small amount of chatter?

[john in illinois]

The foreign made new V8 clutch pressure plates have an extensive history of chatter on Ford Barn V8.

John

[john in illinois]

...

[BILL WILLIAMSON]

Brent,
Use a smooth, idling, second gear take off, for a Month. This smoothed out Minervas' clutch perfectly.
Bill W.[/B][/B]

[BRENT in 10-uh-C]

Originally Posted by john in illinois

The foreign made new V8 clutch pressure plates have an extensive history of chatter on Ford Barn V8.

John

Interesting. Does anyone know why?

I have not experienced it with the flywheel conversions we have done. The only thing that I have heard is they possibly do not have enough clamping force on tall(er) geared vehicles.

[1931 flamingo]

How many miles on this disk?? From where??
You might try contacting : Fort Wayne Clutch, and try a new disk. FWIW JMO
Paul in CT

[Phil Brown]

If your flywheel mounting surface and clutch face surface are not parallel its going to chatter. Or if you have got high and low areas on the clutch face side of the flywheel the highs hit the disk first during the engagement and chatter.
No burrs on the end of the crank or under the flywheel holding it from mating together flat ?
I would surface it and not worry about and VERY small imbalance that it might create because driving ANYTHING with a clutch that chatters is NO fun
If you feel like doing the math a 1" dia slug of steel 1/8" long is 13 grams

[robib]

Flamingo is on the right track, Fort Wayne is excellent. Many clutch discs today are made with not enough "air gap". The gap I am speaking of the gap between the clutch disc itself and the friction material. There is a marcel spring between the disc and the friction material which is there to "soften/dampen" clutch engagement, preventing chatter. Good friend built an A with a flathead and 5speed. Chattered so bad he could not drive it. Called Fort Wayne, they sent a new clutch disc and all is well.

[KR500]

I agree with some as to the disc possibly causing the chatter. If a disc became overheated and weakened the torsional springs or if the springs were never up to tension in the first place, I would want to try a different disc. I was under the impression that a clutch disc should be included in the balancing job when doing the pressure plate and flywheel. If you have ever driven a vehicle with an oil or grease soaked disc you know how they can chatter.

[Dick Steinkamp]

Originally Posted by KR500

I was under the impression that a clutch disc should be included in the balancing job when doing the pressure plate and flywheel.

The disc ends up in a different position every time the the clutch is engaged. How would it be done to balance it with the PP and flywheel?

[BRENT in 10-uh-C]

Originally Posted by robib

Flamingo is on the right track, Fort Wayne is excellent. Many clutch discs today are made with not enough "air gap". The gap I am speaking of the gap between the clutch disc itself and the friction material. There is a marcel spring between the disc and the friction material which is there to "soften/dampen" clutch engagement, preventing chatter. Good friend built an A with a flathead and 5speed. Chattered so bad he could not drive it. Called Fort Wayne, they sent a new clutch disc and all is well.

I have dealt with Ft Wayne clutch on numerous occasions, and you both are correct on their expertise.

I will do some research on this 'air gap' that you are mentioning.

[DJ S]

I'm no expert on this issue but I do recall reading about someone who was experiencimg a similiar issue. Everything was new and within tolerance. They were able to resolve the issue and the culprit was a poor reproduction clutch disk.

[PC/SR]

I have the same thoughts as Bill W and a couple of others to try another clutch disc. I had a flywheel from a prominent machinist that was .022 off, that a local machinist was able to get milled down to .012 face differential and it was not a problem. Dont recommend it, but it drove fine. (It was also out of round, but was able to balance that out.)

[Tom Endy]

There are two .010 horse shoe shaped brass shims that install in the two ears of the clutch housing where it attaches to the rear of the engine block and where the accelerator mechanism is installed. Quite often they are found missing and will throw off the alignment of the transmission to the clutch. Also the thickness of the gasket that installs between the block and the clutch housing are all over the map, depending on the supplier, and is also a factor. The shims and the gasket should be in harmony with each other. The cardboard gasket should be slightly thicker than the metal shim in order to align the housing correctly.


Tom Endy

[roy green coupe]

Originally Posted by BILL WILLIAMSON

Brent,
Use a smooth, idling, second gear take off, for a Month. This smoothed out Minervas' clutch perfectly.
Bill W.[/B][/B]

I think Bill is on to something here. I have also had the experience of
a new disc and pressure plate needing some wear to work smoothly. It was mentioned that the flywheel had grinding marks. When a good working clutch is taken apart the surfaces will be polished smooth. Chattering is caused by the surfaces trying to grab instead of slipping until the clutch is fully engaged. Compatability of the surface finish and the lining material is critical to smooth operation much like disc brake rotors. I would try to improve the finish on the flywheel and pressure plate and clean well and break it in like Bill said.
As someone that has worked on alot of stuff over the years I have to say you can really make yourself crazy if you get too carried away with dial indicators and micrometers and such. These cars are very simple and can tolerate alot of runout or imbalance and still function pretty well. Most problems like this ultimately trace back to china and subpar aftermarket parts.

[BRENT in 10-uh-C]

Originally Posted by Tom Endy

There are two .010 horse shoe shaped brass shims that install in the two ears of the clutch housing where it attaches to the rear of the engine block ...

Hey Tom, I as unaware that the clutch housing attaches to the engine block.

Just kidding, ...I believe you are speaking of the the flywheel housing, and if you re-read my first post, we actually put an indicator on the center of the flywheel and swept it in, and it read less than 0.005" which is within spec.

[BRENT in 10-uh-C]

Originally Posted by roy green coupe

I think Bill is on to something here. I have also had the experience of a new disc and pressure plate needing some wear to work smoothly. It was mentioned that the flywheel had grinding marks. When a good working clutch is taken apart the surfaces will be polished smooth. Chattering is caused by the surfaces trying to grab instead of slipping until the clutch is fully engaged. Compatability of the surface finish and the lining material is critical to smooth operation much like disc brake rotors. I would try to improve the finish on the flywheel and pressure plate and clean well and break it in like Bill said.

As someone that has worked on alot of stuff over the years I have to say you can really make yourself crazy if you get too carried away with dial indicators and micrometers and such. These cars are very simple and can tolerate alot of runout or imbalance and still function pretty well. Most problems like this ultimately trace back to china and subpar aftermarket parts.

This vehicle has about 2,000 miles since a frame-up restoration and the problem is still there, -so I'm not sure Bill's thoughts are truly applicable in this situation, as surely it has been driven enough to cure this by now. Additionally, can you imagine the response that a new Ford owner would get it they brought their new Ford automobile back due to chatter and the mechanic told them to use Bill's method to repair it?

I also want to make sure I understand what you are saying. You are saying that 'chatter' is caused by rough surfaces? I can believe that a 'grabbing' clutch would be caused by this but not one that shudders. My experiences with a shuddering or chattering clutch has been that the disc is not within the centerline of the spinning flywheel which causes the disc to momentarily spin eccentrically until it can work itself to be concentric. Generally the causes of this is any one or combination of a worn input shaft tip, a worn pilot bearing, a worn front transmission bearing, or a grossly misaligned flywheel housing, HOWEVER generally speaking, when those symptom are found, the transmission will generally jump out of 2nd or High gear on deceleration. This vehicle did not do this, which is partially why we have been puzzled. You may very well be right, but I guess I need to think on that one for a day or two.


So based on thoughts above, it seems most feel like it is the clutch disc. I will look it over on Monday to see if something is obviously wrong. I am pretty sure I do not have a copy of a print of the disc, ...and even at that I would specifically need several prints including the hub, and the plate itself. I am wondering if the repro discs that are having issues are found to have too large of tolerances in the hub area where the disc has a sloppy fit on the main gear (input) shaft splines? I am wondering exactly is different causing them to chatter?

[roy green coupe]

I could be wrong but I thought original ford discs had solid hubs with no cushion springs. I dont think that a person should have to break in the clutch but if the surfaces are too rough it might be a solution. Bills method accelerates the process. The combination of a disc grabbing and slipping compounded by the hub springs recoiling is what I am describing. For the clutch to work properly it needs to slip smoothly at the beginning of engagement.

[Terry, NJ]

FWIW, When I was doing my fly wheel Lightening act. I tried for a 0-0 set up in a universal chuck. The chuck was worn and it required shimming (About .002 IIRC) I managed to get it pretty close. So close that it only required about a 5/16 X 5/16 hole to rebalance the fly wheel. Estimate the weight of a cast iron plug .312 X .312. It ain't much! So for me, Indicating the flywheel as closely as possible is the answer, The clutch face, I don't know! I never had the issue. Tom W. says he get good results with a palm sander. I can appreciate how Bill W's solution might seem realistic to an owner, but not really feasible for a professional restorer. Paying customers don't want to hear "Just drive it for a while and it may get better!", however well the advise may be. Good luck with it!
Terry

[Jim Brierley]

Brent, The PP I'm talking about is multi-fingered, commonly used in Chevy's for many years. Not a Borg and Beck style. They require a rounded TO bearing or the release is not constant. The first one I did made for a performance Mustang, I put it behind my 4-port Riley, which has a lot of torque. The second one was, I think, off a Ford Ranger pickup. It required less pedal effort to release although the Mustang was not bad. I understand Clutch-Masters out here now stocks a lightened, machined flywheel, PP, disc and TO brg.

[Jim Brierley]

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p.s., Bill's idea of some 2nd gear starts may work too. Also, keep the RPM low on take-offs.

[BILL WILLIAMSON]

My thinking is that the original chattering caused HIGHS & LOWS, in the disc lining. Each chattering take off makes them DEEPER. The slow, idling take off, in SECOND, doesn't chatter & helps EVEN out the HIGHS & the LOWS. That took care of Minervas' chattering, PERMANENTLY!
Bill Smooth

[KR500]

I am addressing Dick S. comment about a clutch disc being out of balance and it starting and stopping in a different position would negate balancing it. A tire wheel assembly after taking a number of right and left turns put the assemblies in different positions, but it doesn't change the fact that a tire and wheel assembly's balance has changed. Lets not forget static balance and dynamic balance.

[Y-Blockhead]

Originally Posted by KR500

I am addressing Dick S. comment about a clutch disc being out of balance and it starting and stopping in a different position would negate balancing it. A tire wheel assembly after taking a number of right and left turns put the assemblies in different positions, but it doesn't change the fact that a tire and wheel assembly's balance has changed. Lets not forget static balance and dynamic balance.

I guess there are two ways of looking at this. Balancing a disk by itself (like your tire example) or balancing the disk with the assembly (flywheel, disk, pressure plate) which I believe Dick was referring to when he stated it would do no good because the disk would likely land in a different place each time.

I just had my flywheel and pressure plate balanced and the machinist told me to leave the disk at home... They marked the two so they would always be reassembled the same way.

[Dick Steinkamp]

Originally Posted by KR500

I am addressing Dick S. comment about a clutch disc being out of balance and it starting and stopping in a different position would negate balancing it. A tire wheel assembly after taking a number of right and left turns put the assemblies in different positions, but it doesn't change the fact that a tire and wheel assembly's balance has changed. Lets not forget static balance and dynamic balance.

"A tire wheel assembly after taking a number of right and left turns put the assemblies in different positions, but it doesn't change the fact that a tire and wheel assembly's balance has changed."


I'm not sure I'm following you. I'm not seeing how making turns puts the assembly (tire/wheel) in different positions. The tire is always in the same position relative to the wheel (unlike the clutch disk relative to the flywheel/pp combo). I also don't think the wheel assembly's balance (static or dynamic) has changed by turning corners.

Flywheel/PP's are balanced dynamically...just like wheels/tires are done (currently).

I may be missing something in your explanation. It's happened before with others

[BRENT in 10-uh-C]

OK, a little Monday morning update. The clutch disc seems to be wearing uniformly and the edges all mic pretty close measuring about 90° apart. Unfortunately, I do not have a mic with a deep enough reach that I can measure the lining towards the center to see if it shows something different, but just based on how tight it is one the input shaft, and the wear pattern, I am not suspecting it is the disc.


Something that I have found this morning (-that is very likely the problem) is the pressure plate mounting holes are not concentric with the center pilot bearing hole. The flywheel is not reamed for shoulder bolts, and the bolt fit is pretty sloppy but when I sweep the thread holes with a longer bolt bottomed into the holes, it appears there is approximately 0.010-0.012" at the furthest point (-all bolt holes in the circumference are drilled at different locations on either side of the circumference centerline.) What I need to do next is figure out in my mind whether the offset mounting of the pressure plate is what is causing the chatter -or if it is still something else. Conventional wisdom would say that needs to be corrected however from a balance issue, the pressure plate cover already has holes drilled into the pressed steel P/P cover to compensate for the imbalance, so theoretically it being offset is not going to harm the engine. Also, it would seem the pressure plate itself while being offset is still within the centerline established by the transmission input shaft and the pilot bearing, so does it matter if it is offset??


As I mentioned above, the car owner purchased this vehicle already restored by someone else, and he does not know who actually rebuilt the engine either. Deep down, I now am suspecting the flywheel is the root of the problem, and I think we will replace the flywheel, clutch and p/p, -and then reassemble to see what that changes. My only other fear in my plan is, ...based on the craftsmanship we have seen thus far on the flywheel is, imagine if we replace his flywheel with a whole new lightened flywheel, clutch, and P/P, and assemble it only to find the engine was balanced with the crank, pressure plate, and flywheel as one unit. Imagine the feeling when we correct the chatter problem but now have a new harmonic balance issue with the engine!! Oh well, any other thoughts or suggestions are welcomed.

[Dick Steinkamp]

If you haven't done so already, you might want to check and see if there is a counterweighted crank in there. If so, there might be a higher probability of the crank/flywheel/pp/pulley being balanced as a unit.

I don't know if this is possible, but it would be great to learn what is causing the chatter. If you replace the disc, PP, flywheel, and correct for the slight out of concentric pp, and drill for shoulder bolts, and rebalance the rotating assembly, it probably will correct the chatter, but we can only guess at which of those factors was causing it.

Being a CAMAO (cheap ass Model A owner) and with my free labor, I'd probably start by taking a palm sander to the flywheel and pp faces and installing the best disc available and giving it a try.

[Tom Wesenberg]

I did this about 25 years ago. My newly purchased 29 Tudor shook like a paint mixer, and no amount of easy engagement or slipping the clutch would help. I didn't want to do the job twice, so I installed a new disc I bought at a swap meet, along with a good looking used pressure plate. I also sanded the flywheel with my 1/4 sheet palm sander and dialed in the flywheel cover. So, I don't know what fixed it, but now it's as smooth as an automatic.


The disc I removed was new, as the lining wasn't fully worn to touching yet, and the pressure plate also looked good. There was no oil on the disc or flywheel, but as I recall I found the flywheel cover was a bit off when I dialed it in.

[BRENT in 10-uh-C]

.
.UPDATE:

So here is what we did. We put the flywheel into the grinder and supported it off of the hub area and indicated it off of the flywheel ring gear to verify it was parallel to the stone. The face was only out by about 0.004-0.005, so it was a quick clean-up there. This was a relief to know the initial uneven reading was not due to a crankshaft flange run-out problem.

Next, we mounted the flywheel on the Bridgeport and indicated off of the pilot bearing hole to find true center. We laid out the V8 pressure plate mounting holes using the DRO, and just rotated the flywheel enough to move to an undrilled area on the flywheel. We drilled & tapped six new 5/16-18 holes and reamed the top of the holes for Mr. Gasket (Part #: 911) shouldered pressure plate bolts to properly locate the pressure plate. We then balanced the flywheel, -and then the flywheel and the customer's pressure plate as an assembly. Since there were several ½" lightening holes previously drilled into the pressure plate cover where they originally balanced it, we used a TIG to tack-weld a one inch diameter slug that we punched from some 11 gauge just to get us somewhat close(r), and from there it was balanced with the flywheel as an assembly.

The flywheel housing was left as-is and was never removed from the vehicle/engine, -and the flywheel was reinstalled along with the customer's original clutch and pressure plate. Once reassembled enough to test-drive it in and out of the shop, we found that engaging the clutch in forward and reverse revealed no more chattering. Yes, I know it was a gamble not replacing the pressure plate and disc, however if truth is told, I initially had planned to replace the disc however I got side-tracked as they were reassembling it and they already had the transmission and rear end installed by the time I handed them the disc, -and after a quick discussion whether to go on or disassemble, because we had not seen any evidence of looseness on the hub, nor unevenly worn areas on the linings, I chose to forgo pulling it apart just to change the disc simply because we felt the disc was not hurt or defective. The gamble paid off (-this time! ). So ultimately, it was either the poor flywheel face finish or the pressure plate being off-center that was causing the chatter issue. My opinion is the chatter was probably more likely due to the pressure plate being drilled off-center of the flywheel, but who knows. So as Paul Harvey would have said, --Now you know...…
.


.

[Dick Steinkamp]

Thanks for the epilogue, Brent.

[Patrick L.]

Good, nice to hear about the fix. Knew you would figure it out. How far off center was the plate ?

[BRENT in 10-uh-C]

Originally Posted by Patrick L.

How far off center was the plate ?

Around 0.010" the best I could tell. Not sure how it was mis-drilled but I am going to guess it was done on a rotary table that was not perfectly centered.


The bottom line is whoever did this conversion was pretty sloppy/crude with their craftsmanship IMO. The scary thing about this is the engine rebuilder probably knew this was going to be installed, --or possibly it was done by the engine rebuilder. One good thing was the engine did not vibrate when we test drove it up the road, so either the crank & assy. was balanced --or at least the crank, flywheel, and P/P was not balanced as an assembly. Who knows the real story is behind all of this but if the car was mine, I'd be doing an inspection on that engine just for peace of mind.

[Patrick L.]

Amazing, you never what you'll find. I'd feel the the same way about the engine. Nice to hear its fixed.

[Terry, NJ]

Agreed! It was a pretty sloppy method! However, In a shop only dealing with a few parts, it would behoove you to machine a center pin for quick and precise locating. Just locate the center of the Flywheel and dial off the radius.
I think that this is a good example of why I want my parts balanced separately. Balancing together may be ok for some, but whatcha gonna do when the time comes that you need to change the PP? Rebalance the whole shooting match?
Terry

Originally Posted by BRENT in 10-uh-C

Around 0.010" the best I could tell. Not sure how it was mis-drilled but I am going to guess it was done on a rotary table that was not perfectly centered.


The bottom line is whoever did this conversion was pretty sloppy/crude with their craftsmanship IMO. The scary thing about this is the engine rebuilder probably knew this was going to be installed, --or possibly it was done by the engine rebuilder. One good thing was the engine did not vibrate when we test drove it up the road, so either the crank & assy. was balanced --or at least the crank, flywheel, and P/P was not balanced as an assembly. Who knows the real story is behind all of this but if the car was mine, I'd be doing an inspection on that engine just for peace of mind.