Dual Mass vs. Single Mass Flywheels, Advantages/Disadvantages??????????

[WB9MCW]

"Honestly I think the perceived issue of driving with the 13# flywheel is overplayed"

I concur - I like the very quick ramp/rev up with the 13# - you sure can tell the difference.

BTW I went out last Saturday for a romp since is was my B-day and I am always telling others to do the same (on their B-days) and had a great time enjoying the Z all afternoon.

[efnfast]

Originally Posted by WB9MCW

"But my understanding is that MOST ZF6s with lighter single mass flywheels rattle like hell."

I have the F 13# and it does rattle a lot at low RPM in 1st and 2nd when you are lugging the motor.

At a stop as well but only when the clutch is not depressed in.

With my ceramic clutch the combo is great IMO and worth the PITA noise.

I kept my DM so I could always convert back if I wanted to.

Along with my secret supplier ECM chip I get some extra spank from the LT-5.

All else is stock on my Z.

I got my set up from Carolina Clutch but this was long b4 Jerry had his offerings = no doubt I would go with Jerry if I were to do it today.

Someday I may go with headers and an exhaust system for more bang but I figure I am on borrowed time with my stock injectors and vacuum system.

So far the "corn squeeze" has not got to my injectors - I do fire up the motor every 30 days all through the winter(s) and use seafoam as well.

62K now and I put about 500 miles on a season. I am a go fast boat guy first and a fair weather Sunday ZR-1 owner 2nd.






THE FOX RIVER IN MY BACK YARD
READY TO GO AT AN INSTANT

Very nice Brian, but my Z will do 75 in second gear. Funny how boats take so much HP.

[WB9MCW]

"Funny how boats take so much HP."

Well you know what they say ---

It is like doing a brake torque with your car all the time.

In fact the worst strain on the drive in a boat is when you are just holding plane and slow putting along. Well that is other that the initial hole shot to get up on plane.

BTW if you think waxing the Z is a PITA try 28' of fiberglass and in the case of my best pal Mike's 42'

[efnfast]

I carumba that's a lota boat. NICE.

[Paul Workman]

Originally Posted by tf95ZR1

What about us top end (Mile) guys?
I have heard a heavier flywheel has
more momentum/inertia available at
high RPM that acts like more torque.

Just the opposite...*

Newton's First Law of Motion: A body at rest tends to stay at rest, and a body in motion tends to stay in motion (unless an external force acts upon it).

Essentially, a flywheel resists changes in rotational velocity. And, the heavier it is, the more force required to act upon it.

Acceleration = Force/MASS

So, as the mass of the flywheel is increased, the acceleration must decrease, if the Force engine torque remains the same.

*IF there were a hill to climb at the end of the mile, a hill (gravity) that would, when combined with the air and mechanical resistances, overcome the power produced by the engine, causing it to decelerate, the flywheel would tend to resist that change in momentum caused by the slowing - and would continue to assist the motor as long as the rotational velocity was slowing.

Back in my modified "stock" (dirt track) racing days, we'd run without any flywheel - the crank was coupled directly to the drive line "in and out" box, thus eliminating any lag between the engine and the wheels!

The cars were push stared, and when in the pits (transmission disengaged) they would idle at around 2000+ rpm until the switch was turned off. The motors would stop instantly - going from 2000+ rpm to zero at the snap of a finger. BUT! When you dropped the green flag and hammered the gas, 100% of the engine's torque went to the differential, and NOTHING was lost by spinning up the mass of a flywheel.

Originally Posted by tf95ZR1

What would be the difference between a
single mass & dual mass of the same weight?
I think dual mass just dampens the vibration more?

Although they may both be of the same weight, the dual mass is divided into two discs, coupled by springs and friction surfaces. This tends to dampen and absorb shock and vibration that would be transferred to the transmission from the engine better than the single mass will.

[KILLSHOTS]

Although they may both be of the same weight, the dual mass is divided into two discs, coupled by springs and friction surfaces. This tends to dampen and absorb shock and vibration that would be transferred to the transmission from the engine better than the single mass will.


Good point, Paul. I think in some cases, guys may think that if they go with a heavy (40#, for instance) single mass, then they'll have the same resistance to rattle as the stock dual mass. But this is not necessarily the case; it's not ALL about the weight of the dual mass. Its dampening ability is primarily due to the fact that it's a two-piece unit.

[Kevin]

I've heard ones that are a slight rattle, others sound like a rod is coming out of the block

[WB9MCW]

I have said the sound for mine is more of a Rut-rut-rut sound and when lugging the engine in 1st or 2nd it becomes a long ruuuuuuuuuuuuuuutttttttttt sound. When I do the 90 on my private road to get home it always makes that long ruuuuuuuuttttttttttt around the corner. This is why when you are pulling up to a spot at a show and you are doing the curvy back in to your slot it is rather embarrassing when folks ask about the sound and what is wrong with the Vette. I just tell 'em it is the Hi-Po ceramic clutch rather that the long drawn out full actual explanation. That always leaves 'em in a quandary. Once I pop da hood they start asking other questions. Like is that a HEMI - then you tell 'em all about the Pent-roof design and how it is better than a HEMI.

http://en.wikipedia.org/wiki/Pent-ro...ustion_chamber

[alnukem]

Actually, my car is pretty quiet at idle, Pete just tuned it. The noise I don't like is when lowering speed, as in a construction zone. I am use to my dual mass car being fine with it. I "daily drive" my cars daily, I am 99.9% street guy & I think at the first good opportunity, I am going to do "something". Not to mention, when pulling out in normal driving....I have to pay attention to how I come out, not a good scenario in hilly country like I live, buttheads driving & other distractions. I think for my type of driving it may not be the compromise I want. I think the tuners back in the day probably did it to help with "the number" foremost.

Paul, I tried studying on flywheel weight before....I thought I came up with the HP was mainly due to the way a dyno measures & not a "true" number, as if you had heavy wheels on your car & it dynos less with no difference in the engine. I do realize if you drop off weight it will accelerate faster.

[XfireZ51]

I have a Fidanza, used one in my 84 transplanted to a ZF-6, and it will rattle when hot and sitting at idle. Otherwise it's as quiet as the DM. I also use the
LT-1 sprung hub disc which helps keep rattle to a tolerable level. Finally, the rattle is a product of the trans gears and the greater imbalance from the motor, the greater the rattle. If the engine runs smooth, the rattle is minimal. At cruise, even in the 12-1300rpm, there simply is no rattle. BTW, helps to use the BMW Castrol trans fluid IMO.