Stroker engine vibration

Of course there is no way to truly diagnose this via email so one hypothesis is as good as another. I suspect the balance of the new flywheel is not consistant with the steel flywheel. Or, perhaps the new flywheel's bolt holes are drilled slightly different from the steel wheel. Or, maybe they didn't zero balance the pressure plate very well and it doesn't complement the new flywheel. Or, perhaps the bolt holes for the pressure plate on the aluminum flywheel are slightly askew from the steel flywheel creating an imbalance.

This is a frustrating problem and I have felt your pain in the past. Difficult to correct without taking the new parts back to the machinist for balance.

BALANCE IS EVERYTHING. I wrote that in capitol letters on purpose. You could swap back to the steel flywheel and see if that corrects it. Not too bad to pull the tranny. Maybe the machine shop could match the balance of both flywheels out of the car?

quote:

Originally posted by Push1267: I have a vibration issue with my 427 winsor stroker. It vibrates quite a lot all through the rpm range. Although the crank, balancer and flywheel balance should match (see below), I suspect (fear) that it’s crank imbalance. Could it be something else? Kristian

Kristian, there's an outside chance the reciprocating assembly and flywheel are just fine and the clutch/pressure plate mounting is slightly off. Depends upon how well it was centered during mounting or I suppose slight differences in mounting hole patterns on the flywheel though I would doubt the latter as it is pretty basic for such a manufacturer such as Fidanza.

Was it difficult to mount the transaxle? It is not at all uncommon for the bellhousing dowells to be off. Offset dowels are made, though the symptom here is usually difficulty assembly and possible pilot bearing failure though it also imparts a lot of stress to the input shaft. Can you discern difference in severity of the vibration when clutch is/isnt engaged? Even though the pressure plate is always attached to the flywheel, slight diffrerences in centerline of pressure plate mounting thus clutch/input shaft to the flywheel can cause chatter upon clutch engagement and vibration under power.

-Just a thought.

K

Thanks guys for you help. I really appreciate (and need) it.

quote:

Maybe the machine shop could match the balance of both flywheels out of the car?

I don't have the original flywheel so side-by-side comparison is out of the question. I bought the engine secondhand with only a few hours on it. Dynotime and a few miles on the road.

quote:

Can you discern difference in severity of the vibration when clutch is/isnt engaged?

No, vibration is the same whether the clutch is engaged or not. The clutch is a Mcleod diaphram and trans a ZF-1. Pilotbearing is an oilite custom piece by Marlin Jack. I didn't have any difficulties mounting the transmission. I thought about pressureplate centering too - there are no dowel pins in the flywheel to center it during installation - so it's done just by the bolts alone.

Another thought I had was if the engine isn't running on all 8 cylinders. The engine been sitting for 2 years so something may have occured - like a collapsed lifter? I didn't check if all the header pipes were hot as an indication of that - so I'm not really sure. Would that create a strong vibration also?

Kristian

Kristian,

If you are not sure about the engine running well, that's the first and easiest thing to check. Pull all 8 plugs and compare. If something isn't firing you will see a difference in the plugs. I hope that's all it is. Internal balance issues are tricky to address, as noted above. Good luck!

Mark

I had the same problem. I replaced my external 28oz flywheel with another and it shook like mad throughout.
You need to get the new flywheel match balanced to the old.
Will

quote:

I thought about pressureplate centering too - there are no dowel pins in the flywheel to center it during installation - so it's done just by the bolts alone.

Did you use "Pressure Plate" bolts to fasten the pressure plate to the flywheel. The correct bolts have a shank on them that locates the pressure plate correctly...

Unfortunately I don't have the old steel flywheel to match balance against. I have the the engine buildsheets showing which flywheel was originally there, but they alos state that the rotating assembly was balanced. Who knows what was done to the flywheel.

The pressure plate bolts are new ARP bolts with a shank. However, there was a small problem with 3 of the bolt holes in the pressureplate being slightly larger than the other 3. The other 3 had a tight fit. Only that particular bolt pattern fitted the McLeod pressureplate (which is std ford I think)-

I think I'll pull the transaxle first and send the flywheel/pressureplate out to check for balance. Maybe it's way off the 28.8 oz it's supposed to be.

If that's ok, I guess I'll have to pull the engine, take it apart and have the entire rotating assemble balanced.

Damn!

Kristian

quote:

Originally posted by Push1267: I thought about pressureplate centering too - there are no dowel pins in the flywheel to center it during installation - so it's done just by the bolts alone. Kristian

I was referring to the two dowel pins that locate the bell housing on the engine block. The bell housing has a a step that registers the transaxle casting to center, thus centering the input shaft. If you are going to pull the transaxle you may as well check that as well. You will need to seperate the transaxle rom the Bell housing, mount the bell housing on the engine, and then use a dial indicator to check if the step machined in the bell housing is centered on the crankshaft centerline.

This sounds less likely to be your problem since there were no assembly issues and the vibration persists whether the clutch is engaged or not. -Good luck identifying the source of the problem.

Best,
K

I agree with Marlin here.

Let me state it slightly different though. I think that it is best to tell the engine balancer person, DO NOT UNDER ANY CIRCUMSTANCES TOUCH THE BALANCE OF THE FLYWHEEL AND DAMPENER. IF YOU NEED TO, ADD MALLORY METAL TO THE CRANKSHAFT.

If you do not, they will balance the engine the easiest way for them, and that USUALLY means taking weight off of the flywheel and dampener.

If they do that, changing a flywheel or dampener will throw the reciprocating assembly into unbalance.

That is what it sounds like you have. Get the original flywheel back, any way you can. I'll bet that is the problem?

It is also a very good idea to balance the clutch as well, even a brand new one in the box.
I always have them done when I send an assembly out for balancing.

I had many engine builders tell me that you won't even see a "good" balancing job until over 7000rpm's.

I may be wrong here but if it is vibrating enough the dampener/balancer can fail on this.

In any case, best of luck with this situation.

Marlin, You are a really inteligent and helpful guy. I am extremely glad you are a part of this forum.

The dude made an honest mistake. I don't find his misfortune funny at all.

I completely agree that this could have been easily avoided with some research. Before I rebuilt my engine I did much much research. I too gave the machine shop all the parts including the flywheel, pressure plate and flywheel. I also told them that I did not want the flywheel and balancer modified so that they could be replaced in the future if required. I too have a smooth running engine because of it.

By the way "My Mommy" likes my car she lets me play with it as much as I want.

DUDE BE NICE.

It ain't my Mommy that like my car, it's my Mama. She calls me Sugar!

edited

Kristian you have my sympathy, I'm sure you're feeling pretty bad already.

The thread didn't get off track when Marlin made his comments; its getting off track when members start judging the post of another member. Lets all stay on topic, which is Kristian's Pantera motor. The topic is not our personal opinions of Marlin. That's not what some of you wanted to read is it? I may end up editing some of the comments about Marlin ... and Marlin's replies to those comments. Nobody get all bent out of shape, OK?

There are a few lessons here in regards to Kristian's motor ... here's my two cents.

The manufacturers of inexpensive crate motors are not going to use mallory metal to balance a reciprocating assembly via the crankshaft, mallory metal is very expensive, the crate motor manufacturers want to keep the retail price of the crate motors as low as possible, but they also want to make a nice profit. So they balance their motors as inexpensively as possible ... possibly using the flywheel and damper. If there are signs of that having been done, those parts need to stay with that motor.

The billet steel flywheel was the better part anyway. Its tough, durable, safe. It will last a long time without giving the owner any trouble. Aluminum has a bad tendency to work harden and crack. Aluminum is not a good material to use on reciprocating assembly parts, except in situations where the motor isn't expected to last a long time anyway.

The lure of an aluminum flywheel is to make the motor rev a little faster. But stop and think for a moment. A 500 foot pound stroker motor installed in a vehicle equipped with street tires doesn't need to rev any faster, its just going to be that much easier to break the rear tires loose, its going to make traction harder to control. A seven liter V8 with a 4" stroke crankshaft is a tire frying beast. The extra weight of the steel flywheel is actually a good thing for such a powerful motor used in a street application. The limit to the car's acceleration is going to be traction, not the weight of the reciprocating assembly.

-G

Not trying to distract anyone but in thinking about my stroker crank, when it came back from balancing, it looked like swiss cheese.

The flywheel and balancer were left factory stock and thus came back untouched.

In talking to the crank manufacturer (Eagle) they said the design takes the cost of Mallory into consideration.

They claimed their cranks are designed to come into balance with removing metal from the crank only.

The balancer took quite a bit off of the counter weights on mine. They are designed for that but longevity on any stroker crank I would suspect is going to be significantly shorter then stock.

Doug,

I was thinking the same thing ... and will check but i thought my engine was changed to internally balanced assembly ... could be wrong because I too remember the SCAT crank being made into Swiss cheese also with only metal removed. I gave him everything including the double disc clutch and aluminum flywheel assembly with the fluid damper.

Ron

Incredible .

It's just an engine, time and money - nobody died - no need to get upset!!

I posted to get thoughful insight and I got that - and little bit more. I now know what to do - thank you all for your help - let's leave at that.

Although it's frustrating, it's really not that big an issue. The engine is comming out tonight, I'm stripping it down and sending everything out for balancing. With a little luck I'll have everything up and running (smoothly) in a couple of weeks. The weather is still really bad in denmark so I'm not missing quality street time - that's good ! (for me at least).

I admit it may have been naive to think that the engine builder would always balance the crank - not the flywheel. If the engine builder was still in business I would have asked him - and if the original flywheel was available I would have used that to match balance. I don't have those options unfortunately.

I was looking through some old pictures of the engine from when I changed the oilpan. Looks like quite a lot of weight was taken out at both ends of the crank.


Kristian

That could be my front counter balance. It was the big hole that concerned me since you can measure in thousands how much material was left.

I think my rear counter balance looks the same too.

Frankly with a steel crank it must me an SOB to drill those out even on a drill press and be accurate.

My thought on the vibration is also that in my experience, you need to be really out of balance to pick up a vibration. Theoretically there is exact factory balance on the flywheel and dampener but talk to your engine balancer about that.

The thing to do in this instance is to get a new steel flywheel, install it on the engine before you tear it apart and see if it fixes it.

Location dowels in the flywheel for the clutch will sure help the situation and the clutch cover and the flywheel should be indexed.

The problem with having the clutch balanced is that no one is going to want to take it apart to remove weight from it.

Most likely what will happen is that it will get balanced along with the assembly. I'm not sure how good an idea that is at this point? I have to think about that.

Aluminum flywheels regardless of how accurately they are balanced do not absorb engine vibrations well because of lack of mass.

In any event, re balancing the entire unit will fix it, but make sure you use factory balance on the flywheel and dampener.