Aluminum flywheel owners !!!!!NEED INPUT

[Stapl3]

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?

What's wrong with 1g 7bolt block design? DSMJIM just posted a pic of why they're better in some reguards.

1g 7 bolt motor is NOT the same as the 2g one. 1g 7 bolt motor doesn't get the credit it deserves, I personally feel it's the absolute best option for a block you plan to fill with aftermarket parts.

 

[Defiant]

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

I don't follow what you mean. The flywheel's rotational mass will take more energy to change its rotational velocity regardless of whether it's coming from the crank or 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.

Because a lighter flyweel can't contain as much momentum as a heavier one, making the torsional load on the crankshaft more direct. Which still has no effect on the thrust bearing.

I don't understand where you mean that my example is backward.

 

[!^3]

What's wrong with 1g 7bolt block design? DSMJIM just posted a pic of why they're better in some reguards.

1g 7 bolt motor is NOT the same as the 2g one. 1g 7 bolt motor doesn't get the credit it deserves, I personally feel it's the absolute best option for a block you plan to fill with aftermarket parts.

How many have you built? What are the specific differences between the 1g 7 bolt and the 2g 7 bolt? I mean that is great if that is your personal opinion, but as far as I know the 1g 7 bolt IS the 2g 7 bolt so there is no real benefit of one over the other.

 

[Amar1995]

What's wrong with 1g 7bolt block design? DSMJIM just posted a pic of why they're better in some reguards.

1g 7 bolt motor is NOT the same as the 2g one. 1g 7 bolt motor doesn't get the credit it deserves, I personally feel it's the absolute best option for a block you plan to fill with aftermarket parts.

It is the same short block as the 95 to 99's. The only difference is when they went to the t-25 in 1995 they changed the cylinder head. That is the only difference, don't be so defensive no one said it was a bad engine

 

[Tevenor]

1G 7-bolt block is NOT the same as a 2G 7-bolt block. And there are 2 styles of 2G block 95-97 and 98-99.

 

[Turbonium]

as to the flywheel thing it goes both ways... it'll either have more shock on the tranny or more shock to the engine depending on what your doing. i would think a heavier clutch would amplify the shocking effect as there is less slippage and more grabbing? as for the light flywheel my opinion is that its easier on the tranny but rougher on the engine because the engine has less rotational mass so its "jerked" around alot faster than with a heavier flywheel. couldn't tell ya what negative effects it would have maybe none. my .02
ryan

 

[bjones18]

Interesting paper

Crankshaft 42 modes, Block 38 modes, viscous oil film prevents accurate FEA...


http://www.tytlabs.co.jp/japanese/review/rev372pdf/372_027inagaki.pdf

 

[bjones18]

as to the flywheel thing it goes both ways... it'll either have more shock on the tranny or more shock to the engine depending on what your doing. i would think a heavier clutch would amplify the shocking effect as there is less slippage and more grabbing? as for the light flywheel my opinion is that its easier on the tranny but rougher on the engine because the engine has less rotational mass so its "jerked" around alot faster than with a heavier flywheel. couldn't tell ya what negative effects it would have maybe none. my .02
ryan

I am wondering more about axial and bending modes of the crankshaft/flyweel lining up with axial and "no-one-can-even-imagine-block-modes" to destroy the viscous barrier at the thrust surface.

I would think the easiest way to alter the crankshaft modes would be flywheel mass, main bearing radial & axial clearances, and timing belt tension.

Bob

 

[Defiant]

I still wonder what happens if you saw the center (thrust bearing) cap free from the girdle on a 7-bolt. It's one of the obvious differences between the designs, could it be the obvious cause? Is trying to restrain the thrust bearing why the surface is overloaded to the point of lubrication failure?

 

[bjones18]

I still wonder what happens if you saw the center (thrust bearing) cap free from the girdle on a 7-bolt. It's one of the obvious differences between the designs, could it be the obvious cause? Is trying to restrain the thrust bearing why the surface is overloaded to the point of lubrication failure?

This is possible, and on my list of things to try as last resort...cut the girdle legs from the center main cap. It might be best to make a small cut 1/8" and sandwich urethane between the girdle segments (offer some axial support).

Not sure I want to go this far quite yet, since the block/girdle was designed as a system.

Is there anyone out there who is really-really-really good with strain gages and has a data acquisition card in a PC? I would like to see four strain gages on the back side of the thrust bearing surface. This may give data on what kind of loads, constant, cyclic, max are in action.

 

[paul s]

I have been using Fidanza flywheel with ACT 2600 for the past 4 years and it works awsome. The whole rotating assembly has been balanced. All this on a build 7bolt.

 

[Jon Lane]

My question is:

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

I have no in-the-motor experience to back up what I'm going to say, but I seriously doubt the harmonics theory, simply because the harmonic excursions in iron structure like a crank can't be but a few magnitudes less than what it would take to cause contact. Pounding a crank with a sledge won't cause enough <i>vibrational</i> ringing energy to run any portion of the thrust surface completely through the oil film and into the bearing, much less disturb the entire thrust face on the crank as a cohesive unit to cause it to all penetrate the oil film at once. I think we need to differentiate between substantial dimensional displacement, which walks cranks, and harmonic displacement, which rings the bell but doesn't move the entire crank these huge relative distances.

If a crank were this elastic, it's contact all bearing surfaces, not just the thrust. Even more so if the clearances in the thrust were initially greater than they are in the rest of the crank's bearing surfaces.

Unless I miss the hypothesis: Is there a mechanism to vibrate the entire crank far enough and hard enough to penetrate the entire thrust film, and is this what you're asking? Seems such a condition would plague a significant ratio of engines then, since harmonic modes must vary about as much as engine designs do, which is to say, quite a lot.

This is just a intuitive shot at the question, but considering that the excursions in even a badly ringing crank would be almost molecular, and not consume thousandths of inches, I think it deserves a second glance.

 

[Jon Lane]

1G 7-bolt block is NOT the same as a 2G 7-bolt block. And there are 2 styles of 2G block 95-97 and 98-99.

So I've also heard. Is this relative only to the modified thrust bearing, and did the late 2G thrust bearing design match the 4G64?

 

[bjones18]

I have no in-the-motor experience to back up what I'm going to say, but I seriously doubt the harmonics theory, simply because the harmonic excursions in iron structure like a crank can't be but a few magnitudes less than what it would take to cause contact. Pounding a crank with a sledge won't cause enough <i>vibrational</i> ringing energy to run any portion of the thrust surface completely through the oil film and into the bearing, much less disturb the entire thrust face on the crank as a cohesive unit to cause it to all penetrate the oil film at once. I think we need to differentiate between substantial dimensional displacement, which walks cranks, and harmonic displacement, which rings the bell but doesn't move the entire crank these huge relative distances.

If a crank were this elastic, it's contact all bearing surfaces, not just the thrust. Even more so if the clearances in the thrust were initially greater than they are in the rest of the crank's bearing surfaces.

Unless I miss the hypothesis: Is there a mechanism to vibrate the entire crank far enough and hard enough to penetrate the entire thrust film, and is this what you're asking? Seems such a condition would plague a significant ratio of engines then, since harmonic modes must vary about as much as engine designs do, which is to say, quite a lot.

This is just a intuitive shot at the question, but considering that the excursions in even a badly ringing crank would be almost molecular, and not consume thousandths of inches, I think it deserves a second glance.

I don't know what you are saying. Have you taken a ME vibrations class? You do not wake up one day with 0.045" of crank displacement...it is eaten away bit by bit from the initial 0.005".

Your sledge hammer example doesn't make sense to me. Have you read any papers which describe oil wedging? and how difficult it is to wedge oil on an thust surface? What is the required displacement to disrupt an oil film when the throwout bearing is applying a force? Not much. What would happen if the clutch were disengaged and the crank vibrated axially (at aligned modes)? We do not know what the root cause for crank walk is.

Please read the paper in the thread above and this one below.

http://naca.larc.nasa.gov/digidoc/report/tn/80/NACA-TN-1280.PDF

1947! crank vibration issues are not new...interesting....high performance 4 cylinder...

If you haven't taken a MechE vibrations course, and never dis-assembled an engine I am wasting my time.

 

[bullettdsm]

I have been using Fidanza flywheel with ACT 2600 for the past 4 years and it works awsome. The whole rotating assembly has been balanced. All this on a build 7bolt.

Thanks for getting back on topic. I am curious about this due to the fact that I am about to work a 7 bolt with 100k on it. I have the Fidenza and I am an inquiring mind.
MB

 

[dsmpower1]

hey before my rebuild i had a 7bolt which reached 110,000. i had 2600 and fidanza flywheel. it was on there for 20,000 miles. it never gave me any problems. the only thing that eventually led to the rebuild was bad synchros in the tranny, and head gasket leaking. but i don't think i had any problems with c-walking.