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

[alnukem]

I've been driving my 90 LPE 475 Package car for 5 years now. , now, for the last few days I've been driving a couple of cars with Cams & Single Mass Flywheels........Don't know if I like it. What are the Advantages/Disadvantages of each. Are there limitations on the dual mass & running cams?

[KILLSHOTS]

The heavy dual mass was used to enhance balance and quiet the rattle that's inherent in the ZF6, which is basically a bulletproof truck transmission adapted to work in our cars. If you remove it and move to a lighter single mass, the advantage is that the car will rev much more quickly and will basically mimic an increase in HP. The disadvantage is that the transmission will most likely sound like it's about to fall out of the car. It won't; it will just sound that way. Not ALWAYS...some guys manage to get theirs balanced pretty well and I hear that increasing the idle speed helps somewhat. But my understanding is that MOST ZF6s with lighter single mass flywheels rattle like hell.

[efnfast]

I've been driving my 90 LPE 475 Package car for 5 years now. , now, for the last few days I've been driving a couple of cars with Cams & Single Mass Flywheels........Don't know if I like it. What are the Advantages/Disadvantages of each. Are there limitations on the dual mass & running cams?
No experiance, but lots of reading.
Single mass is lighter = better acceleration.
Dual mass quiets the gear rattle in the tranny. Rumor has it this rattle does no damage, but at idle, sounds like a bucket of bolts.
I'm on the fence on going to a push throw out, and single mass flywheel.

[Demps]

Jerry has an intermediate solution with a heavier-than-Fidanza single mass. If/when I ever change again it will be with one of Jerrysgaskets products.

HPDE car loves the light Fidanza.

Getting off of the line at the strip is "tricky" with the light Fidanza. Street starting and stopping isn't really fun...plus the rattle. BUT, ah, the quick revs.

To me, the Fidanza was a great mod. Now, I think Jerry has the ultimate solution.
Ted

[Paul Workman]

I have the 13# Fidanza with essentially stock cams, NO secondaries, with some custom phasing. The idle was run up to 850, and with the new Accel injectors, it is hardly noticeable.

See what you think...

http://www.youtube.com/watch?v=y1YFa8ruh8A

13# aluminum Fidanza:

It is a little trickier to launch at the drag strip, whereas the dual mass stores sooo much energy it is easier to launch, and smoother between gears (does more damping)
inertia dyno indicates the equiv. of approx 15 rwhp when comparing results. (However, the effective rwhp might be significantly higher than that due to the fact the 15 hp value is the effect in 4th gear. The equiv. may be significantly higher than 15 in low gears where the rate of rotational acceleration speed is significantly higher! Just sayin.)

The dual mass:

the dual mass is 46# (vs. 13# for the Fidanza) and makes for a smooth shifting between gears
little or no transmission rattle with stock cams, and much reduced rattle with big cams.

The best of both worlds might be a steel single mass weighing in at around 22-25#. That might be a compromise, especially for LT5s with cams with aggressive phasing.

With good injectors, plugs, and idle at about 850 on a stock cam motor, I don't think there is much to complain about. I like the extra seat of the pants snap, especially in the lower gears!

Your mileage may vary!

[A26B]

.........The best of both worlds might be a steel single mass weighing in at around 22-25#. That might be a compromise, especially for LT5s with cams with aggressive phasing..........!

Paul,

I had 2 different, custom weight ALUMINUM billet flywheels made, 18lb & 22lb, to cover the spread between the uber-light 13# & the uber-heavy, stock dual mass. Now, energy conservation can be matched to gearing and desired purpose, i.e. street driving, drag, autocross and road course.

Both new flywheels are dimensionally identical to the stock dual mass to preserve the same clutch geometry with the stock, pull-release clutch. Both flywheels can also benefit from the installation of a push-release clutch with the RAM style Hydraulic Release Bearing.

[alnukem]

Paul,

I had 2 different, custom weight ALUMINUM billet flywheels made, 18lb & 22lb, to cover the spread between the uber-light 13# & the uber-heavy, stock dual mass. Now, energy conservation can be matched to gearing and desired purpose, i.e. street driving, drag, autocross and road course.

Both new flywheels are dimensionally identical to the stock dual mass to preserve the same clutch geometry with the stock, pull-release clutch. Both flywheels can also benefit from the installation of a push-release clutch with the RAM style Hydraulic Release Bearing.

Sounds good.....have you had any seat time behind them yet?

P.S. Jerry, thanks for your contributions to the LT5 world & helping to keep our cars running!

[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.

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

[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.

http://i126.photobucket.com/albums/p110/HAMMERHATE/BAD-ATTITUDE-EH-PIER_zpsb5e9a6f2.jpg

http://i126.photobucket.com/albums/p110/HAMMERHATE/502cidscblowermotor400p_zps5c256118.jpg

http://i126.photobucket.com/albums/p110/HAMMERHATE/b16aed1a-86ed-443d-95d1-956c109b9908_zps04a9b24c.jpg
THE FOX RIVER IN MY BACK YARD
READY TO GO AT AN INSTANT

[LGAFF]

With a sprung clutch disc from an LT-1 Camaro no rattle.....I went to a normal LT-5 Disc and rattles with clutch in

Honestly I think the perceived issue of driving with the 13# flywheel is overplayed, I have had no issues at all

[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]

"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.

http://i126.photobucket.com/albums/p110/HAMMERHATE/BAD-ATTITUDE-EH-PIER_zpsb5e9a6f2.jpg

http://i126.photobucket.com/albums/p110/HAMMERHATE/502cidscblowermotor400p_zps5c256118.jpg

http://i126.photobucket.com/albums/p110/HAMMERHATE/b16aed1a-86ed-443d-95d1-956c109b9908_zps04a9b24c.jpg
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'

http://i126.photobucket.com/albums/p110/HAMMERHATE/BADATTITUDEANDBLACKLIGHTNING_zpsb6a86a5c.jpg

http://i126.photobucket.com/albums/p110/HAMMERHATE/THE-42-FOUNTAINmontage-4.jpg

[efnfast]

I carumba that's a lota boat. NICE.

[Paul Workman]

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.


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-roof_combustion_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.

[Paul Workman]

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.

You are correct. "Effective power": During acceleration, energy transfers to the mass of the drivetrain, and that left over goes to the wheels. By reducing the drivetrain mass, e.g., a lighter weight flywheel, the effective result is as tho the engine had more power. Actual crankshaft output, or "true" horsepower is not changed. Using a Fidanza flywheel will not increase power at the crank, or when pulling a load at a steady pace. Only when rpm is accelerating (or decelerating) will the effects of a massive flywheel be a factor.

[alnukem]

Thanks Paul....I'm still into "if Dick had 2 Rocks & Jane had 3 Rocks"!!!!!

I wonder where the sweet spot is, maybe one of Jerry's flywheels with a sprung hub?????? I have a factory DMF, so that's probably how I'll go.

[-=Jeff=-]

All I know is when I I had my 89 I had a Centerforce single mass flywheel it was almost as heavy as the DM Factory one. I swapped to a fidanza and I hated driving the car ever since. the technique for driving the car around town changed dramatically.

I did not realize Jerry had 18 and 22# SM flywheels, I would probably do a 22# and hope that the car does not completely change. but for now I will keep the DM.

When I bought this car I came to the realization that there will always be someone faster than me.. I am good with that, I now just enjoy driving the car

[5ABI VT]

What are the chances a lighter weight dual mass could be made to work? many cars use them these days

[LGAFF]

If anyone is looking for a replacement Dual Mass Flywheel, I just shipped three over to Power Torque systems. He is going to give them the once over, light resurface....

Two under 8K miles and no visible wear, one with 17K miles

[5ABI VT]

Here is how I look at it. If you put on a 40 lb back pack you are no stronger or weaker. But if you try and run with it on.. it will affect your acceleration !

[XfireZ51]

Here is how I look at it. If you put on a 40 lb back pack you are no stronger or weaker. But if you try and run with it on.. it will affect your acceleration !

And conversely the more mass, the harder it is to stop or change direction. There's a reason race cars go for lightweight. Unlike =Jeff=, I preferred my
84 w the Fidanza and ZF-6 combination. Same is true w both ZRs.

[Locobob]

I think I preferred my old 20lb-ish LPE (McCloud?) flywheel over the Fidanza I have now. The abrupt speed at which the engine winds down when you get off the gas is a little much and kind of annoying during normal driving.

[XfireZ51]

I think I preferred my old 20lb-ish LPE (McCloud?) flywheel over the Fidanza I have now. The abrupt speed at which the engine winds down when you get off the gas is a little much and kind of annoying during normal driving.

LB,

That's easily addressed by slowing down the IAC.

[Paul Workman]

I guess I'm just lucky. I have very little rattle if any in neutral (evident by the video I linked to). Lee reminded me too that in addition to the 850 rpm idle, Accel injectors, new plugs, I also have a Centerforce, Camaro LT1 sprung hub (Centerforce # 381039 from Summit Racing).

I noticed a difference in technique when pulling away from a stop, i.e., a little more feathering perhaps than was needed with the heavier FW. But, after just a couple hours in traffic, I no longer notice it.

As for deceleration, maybe because mine is a 90 and typically is slow to return to idle (that was later "fixed" in subsequent calibrations) I can't say it has been a problem - decelerating to quickly*.

*I notice tho that when decelerating from speed, as in during the Mountain Run 2, the engine stalled - an old problem that seemed to return that had disappeared for a couple years. The stalling isn't the fault of the flywheel, I don't think. I rather suspect it might be something like oil in the MAP tube - which was an issue once when I first got the car in 2007.

I had already purchased the oil separator to address oil getting into the MAP and fouling the valves and combustion chambers. So, now that it has been installed, we'll see if that was the issue. However, the flywheel weight isn't a serious consideration, at this time.

[rkreigh]

If anyone is looking for a replacement Dual Mass Flywheel, I just shipped three over to Power Torque systems. He is going to give them the once over, light resurface....

Two under 8K miles and no visible wear, one with 17K miles


glad to hear you say that. I have a lightly used stocker that I'd like to have checked out it's been sitting for many years and has surface rust

everyone says you can't "fix" these flywheels but I don't believe it

like to get a "lighter dual mass" if I could

maybe some machining on the factory wheel would work or Jerry's deal with a dual mass center

I KNOW I'm getting tired of gear rattle

anyone know if the dual disk setups from RAM quiet down the rattle?