Aluminum flywheel owners !!!!!NEED INPUT

[bjones18]

Can I get a poll from 7bolt (2G) owners using an aluminum flywheel?

If you have had crankwalk on a 7bolt using an aluminum flywheel please respond (pm prefered, or add to the thread). (indicate if engine was rebuilt or not and if it had proper endplay upon rebuild).

I have a thread out there suggesting possible aligned modes between the crankshaft and the 7bolt block/girdle. A simple litmus test may be the reduced mass of using an aluminum flywheel. I'm not sure if CW is modes lining up, or if the reduced flywheel mass is enough to separate the modes...but it will be interesting to see if aluminum flywheel users report crankwalk as often as the rest of us 7bolt clowns

Bob

 

[DSMraver]

Maybe everyone still misses the major difference between the 6 and 7 bolt motors?

The OIL SQUIRTERS. Crankwalk is thrust bearing failure. What is the main cause of bearing failure? Insufficient oil pressure/oil starvation. The 2g oil squirters have been proven to get jammed open or lose spring pressure with age, and bleed off pressure at and above idle. Combine that with sitting on the clutch at a light, and there goes the thrust bearing.

Why are we thinking that this is a harmonics problem? The simplest answer is usually the correct one.

 

[Tevenor]

Maybe everyone still misses the major difference between the 6 and 7 bolt motors?

The OIL SQUIRTERS. Crankwalk is thrust bearing failure. What is the main cause of bearing failure? Insufficient oil pressure/oil starvation. The 2g oil squirters have been proven to get jammed open or lose spring pressure with age, and bleed off pressure at and above idle. Combine that with sitting on the clutch at a light, and there goes the thrust bearing.

Why are we thinking that this is a harmonics problem? The simplest answer is usually the correct one.

Without data to prove or disprove any hypothesis, regardless of commen sense or simplicity, any theory will stay a theory. This is why what causes crankwalk will always be speculation.

As far as CW goes, I don't believe CW is caused by any single issue or fault, similar to how there are multiple "flu" strains but they are all give you the same symptoms. Certainly squirter issues could be an issue as proved by Marco at Magnus Motorsports. However there are other alternative that could be just as likely. For instance diverging harmonics in an undampened crank could distrupt the oil surface tension, and voila, CW. Or larger pressure plates transmit lateral forces to large for the oil bearing to resist, especially if you add harmonics and lack of oil volume to the equation.

In other words, good luck nailing a single culprit. It seems the casualities are to random and to spread out to gather any meaningful data.

 

[bjones18]

Maybe everyone still misses the major difference between the 6 and 7 bolt motors?

The OIL SQUIRTERS. Crankwalk is thrust bearing failure. What is the main cause of bearing failure? Insufficient oil pressure/oil starvation. The 2g oil squirters have been proven to get jammed open or lose spring pressure with age, and bleed off pressure at and above idle. Combine that with sitting on the clutch at a light, and there goes the thrust bearing.

Why are we thinking that this is a harmonics problem? The simplest answer is usually the correct one.

You might be saying that I haven't done my home work. The Magnus report is an excellent study...kudos to Magnus for sharing the info, however it does not prove a failure mode as you have stated. Where is it proven, that oil squirters stick open as you have stated? Magnus showed differences in opening pressure for nine oil squirters. I didn't see any data presented that squirters stick open, only a suggestion. Magnus' report seems to point more toward "questionable" oil pumps than "open"oil squirters or combo's of. Show a shortblock with an "open squirter" and crankwalk, or fix one to stay open and follow it's performance.

I do not sit at lights with the clutch in, and I start my engine without depressing the clutch. I had 0.045" of crankwalk.

If you think the major difference between a 6 bolt and 7bolt block is the oil squirters I would suggest you disassemble some for yourself. Look at what is holding the thrust bearing in place THE BEARING CAP! There is a MAJOR difference between the bearing cap on a 6bolt and 7bolt.

As for simple answers....simple problems tend to be fixed rather quickly by OEMs...unless major tooling $$$ is required for the fix.

check Thread: Crank Walk, is it modes lining up? for additional info on this

 

[DSMraver]

You might be saying that I haven't done my home work. The Magnus report is an excellent study...kudos to Magnus for sharing the info, however it does not prove a failure mode as you have stated. Where is it proven, that oil squirters stick open as you have stated? Magnus showed differences in opening pressure for nine oil squirters. I didn't see any data presented that squirters stick open, only a suggestion. Magnus' report seems to point more toward "questionable" oil pumps than "open"oil squirters or combo's of. Show a shortblock with an "open squirter" and crankwalk, or fix one to stay open and follow it's performance.

I do not sit at lights with the clutch in, and I start my engine without depressing the clutch. I had 0.045" of crankwalk.

If you think the major difference between a 6 bolt and 7bolt block is the oil squirters I would suggest you disassemble some for yourself. Look at what is holding the thrust bearing in place THE BEARING CAP! There is a MAJOR difference between the bearing cap on a 6bolt and 7bolt.

First off, I never said you didn't do your homework on this one, no disrespect was intended.

I can see your point, I can conceed the point that there could be other factors involved with CW. But if you look at the variety of milage timeframes that CW has happened within, I don't see how CW could be caused by harmonics. The oil squirters in the 2g are drawn off of the bearing feed instead of the main galley like the 6-bolts.

With the main-caps being a possible issue, on the 6-bolt there is no girdle, so I couldn't see how the 7-bolt could be any *more* vulnerable since the 6-bolt's cap is floating. Yes, I've had these apart before and looked at them.

If the bearing cap shifting was the problem, you'd see one half of the bearing wear more than the other. What I've seen instead, was even wear in most of the cases that have posted pictures. It would be interesting to get a definitive answer however.

 

[DSMJim]

The only one floating on a 6 bolt is the center. The outter two are connected together. Not exactly like a girdle but better than nothing.

You must be logged in to view this image or video.

You can only see the one on the right because of the oil pick up but it's pretty obvious the first two and end two are connected in this pic. I was surprised it doens't have a girdle of some type and no windage try or anything.

 

[DamionGST]

Lets not forget 6 bolt motors crank walk to. I have seen atleast 3 with my own two eyes, (and about five 7 bolts).

 

[bjones18]

My question is:

Is there an "axial resonance" of the crank-assembly which disturbs the thrust-surface viscous barrier for the 7 bolt?

 

[tlcoolj]

I put a ACT flywheel and new oem clutch in my car resently. (Prior to this my car ran fine except for the slipping clutch of course..) While i was in there before i changed anything i grabbed ahold of the flywheel and noticed a back and forth movement when i pulled on it... but once the flywheel and clutch were put in then the engine finally crankwalked for good. Basically due to the lightened mass the new pressure plate was able to move the crank back and forth when the clutch was pressed and depressed, prior to that the old pressure plate didn't have enough strength. I'm definatly not saying that the clutch or flywheel had anything to do with causing the crankwalk, the engine was crankwalking before their installation, they just made the symptoms much more apparent.

 

[DSMraver]

before i changed anything i grabbed ahold of the flywheel and noticed a back and forth movement when i pulled on it...

but once the flywheel and clutch were put in then the engine finally crankwalked for good. Basically due to the lightened mass the new pressure plate was able to move the crank back and forth when the clutch was pressed and depressed, prior to that the old pressure plate didn't have enough strength.

Your car was a CW victim before you changed the clutch, this is true.

However, the lighter flywheel did NOT contribute to anything. The pressure plate doesn't "overcome" the weight of the flywheel, they are attached.

Now it's possible that the new pressure plate's spring was stronger than your old clutch, seeing that it was brand new, so the force required to disengage the clutch (from the clutch fork actuating the TOB) went up, and finally killed the thrust bearing 100%, but the flywheel has nothing to do with it.

 

[ITSME4G63]

Holy shit jim when did you become a wiseman?

 

[Mirage2LTurbo]

I run a Fidanza alum flywheel on my 6bolt. I know this threads about CW, but I love mine. You have to shift quickly though, as it will spin down a lot faster.

 

[ITSME4G63]

I run a Fidanza alum flywheel on my 6bolt. I know this threads about CW, but I love mine. You have to shift quickly though, as it will spin down a lot faster.

I got the act 12.5lb flywheel for my awd, I was afraid to break my shit with such a lightweight flywheel as the findaza, the 12.5 act one almost feels like stockish.

 

[Mirage2LTurbo]

What/Why would you break?

 

[ITSME4G63]

What/Why would you break?

because its lighter, wouldnt there be more preessure applied on a lighter flywheel, hell I don't know, maybe causing too much stress? paranoia

 

[DSMraver]

because its lighter, wouldnt there be more preessure applied on a lighter flywheel, hell I don't know, maybe causing too much stress? paranoia

There is less chance of breakage, since the flywheel doesn't have as much momentum since its got lower mass.

Transmissions/axles usually break due to shock loads, which a heavier flywheel would contribute to. Think about this, what has more force: a bicycle wheel spinning at 20mph, or a semi-truck wheel and tire spinning at 20mph.

 

[ITSME4G63]

There is less chance of breakage, since the flywheel doesn't have as much momentum since its got lower mass.

Transmissions/axles usually break due to shock loads, which a heavier flywheel would contribute to. Think about this, what has more force: a bicycle wheel spinning at 20mph, or a semi-truck wheel and tire spinning at 20mph.

Damn I was stupid to buy that flywheel then? How much does a stock one weight?

 

[Mirage2LTurbo]

I don't like ACT clutches, so that's why I went with Fidanza. I didn't realize the Fidanza was lighter until after I made my purchase.

 

[Defiant]

There is less chance of breakage, since the flywheel doesn't have as much momentum since its got lower mass.

Transmissions/axles usually break due to shock loads, which a heavier flywheel would contribute to. Think about this, what has more force: a bicycle wheel spinning at 20mph, or a semi-truck wheel and tire spinning at 20mph.

What? A heavier flywheel would absorb more "shock loads" due to its greater inertia. Which is a baseball bat going to affect more, a kickball or a bowling ball?

Anyway, this thread of foolishness is on the verge of being killed anyway. It's starting to get just too deep.

 

[ITSME4G63]

What? A heavier flywheel would absorb more "shock loads" due to its greater inertia. Which is a baseball bat going to affect more, a kickball or a bowling ball?

Anyway, this thread of foolishness is on the verge of being killed anyway. It's starting to get just too deep.

godamnit, smark ass remarks, stay out of it just for once please

 

[Stapl3]

The only one floating on a 6 bolt is the center. The outter two are connected together. Not exactly like a girdle but better than nothing.

That's pretty much the reason I'd choose a 1g 7 bolt to build over a 6 bolt.

 

[DSMraver]

What? A heavier flywheel would absorb more "shock loads" due to its greater inertia. Which is a baseball bat going to affect more, a kickball or a bowling ball?

Negative. It would absorb more shock load to the motor, not the transmission.

The shock comes when the momentum of the flywheel is rapidly applied to the clutch disc (via pressure plate engagement), and then subsequently the transmission's input shaft.

You're looking at it backwards in your example. You can feel the difference when you launch a stock-flywheel car vs. an aluminum flywheel car. You need higher revs to get the same launch on the aluminum flywheel car.

 

[!^3]

That's pretty much the reason I'd choose a 1g 7 bolt to build over a 6 bolt.

Considering that almost none of the big-name tuners that put down more power than anyone here will ever dream of with 1g 6 bolt motors have no issues.

First you have bad motor design=7 bolt motors

Second you have bad motor assembly=everything

I could be wrong, but isn't the 1g 7 bolt motor the same as a 2g 7 bolt motor?

 

[Amar1995]

Yes, Mr. Emmet you are correct. They switched to the 7 bolt in the 93 model year.

 

[!^3]

Yes, Mr. Emmet you are correct. They switched to the 7 bolt in the 93 model year.

Sir! You may not post on any DSM forums until your car is running!

BTW, happen to have a 1g CAS sitting around? I think mine died