Replacing LT-4 flywheel
Thread Starter
Instructor
Joined: Mar 2012
Posts: 201
Likes: 10
From: Kennewick WA
Replacing LT-4 flywheel
Since Chevy doesn't produce a 350 DM flywheel anymore in looking for one I got these two hits.
http://www.ramclutches.com/Specialty...Conversion.htm
http://www.ecklerscorvette.com/corve...4-1989-96.html
I know nothing about flywheels
other than I've got clutch chatter from a hotspot and that I'd like as close to the original weight/performance as possible. Do either of those hits mean anything?
Thanks to those who know how these things work.
http://www.ramclutches.com/Specialty...Conversion.htm
http://www.ecklerscorvette.com/corve...4-1989-96.html
I know nothing about flywheels
other than I've got clutch chatter from a hotspot and that I'd like as close to the original weight/performance as possible. Do either of those hits mean anything?Thanks to those who know how these things work.
Drifting
Joined: May 2005
Posts: 1,336
Likes: 12
From: Chicago Executive Airport, formerly known as Palwaukee
No-IL Events Coordinator
St. Jude Donor '12-'13-'14-'15-'16-'17
There are many companies which manufacture and sell different flywheel & clutch combinations.
I would do a search here to find tons of information about what you are trying to do.
I would do a search here to find tons of information about what you are trying to do.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Team Owner
Joined: Aug 2005
Posts: 34,988
Likes: 515
From: Riverside County Southern California
Co-winner 2020 C4 of the Year - Modified
2018 Corvette of Year Finalist
2017 C4 of Year
2016 C7 of Year Finalist
St. Jude Donor '09 thru '20
Consider their own disclosure.
Eliminating the dual mass flywheel and using the semi-rigid hub in the RAM disc will cause some gear rattle in the driveline under light load.
I just replaced the single mass out of my DD. Trust me, that rattle was annoying. It drove me nutz.
Eliminating the dual mass flywheel and using the semi-rigid hub in the RAM disc will cause some gear rattle in the driveline under light load.
I just replaced the single mass out of my DD. Trust me, that rattle was annoying. It drove me nutz.
Thread Starter
Instructor
Joined: Mar 2012
Posts: 201
Likes: 10
From: Kennewick WA
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
The flywheel used with an LT4 isn't unique. It uses the same flywheel as the earlier LT1 and L98 ZF6 cars. The throwout bearing will be different depending on black tag vs blue tag transmission.
Last edited by 96GS#007; Dec 17, 2012 at 07:48 PM.
Drifting
Joined: May 2005
Posts: 1,336
Likes: 12
From: Chicago Executive Airport, formerly known as Palwaukee
No-IL Events Coordinator
St. Jude Donor '12-'13-'14-'15-'16-'17
Just for that you made me re-phrase my statement in my prior post
Race Director
Joined: Sep 2001
Posts: 14,676
Likes: 751
From: NEwhere Ohio
A lightweight flywheel is an upgrade. I've never heard of more mass being better in the drivetrain.
If you have chatter (beyond the slight noises in too high of a gear, or a light tapping at neutral (clutch pedal out - which you don't drive like that normally), then you have something else wrong with your transmission.
Explain to me why I like my 12 lb al fidanza flywheel so much?
Even if an ice cream getter is the only purpose of your car, I still can't see how anyone would think the slight extra noise increase is bad.
I use this car to race cars of all different types and taking out the heavy useless slug of mass called the dual mass flywheel is one of the best things you can do.
The only caveat is you must use a sprung hub clutch and not a stock style (non sprung hub). The springs do the job (with less weight) that the dual mass did.
Ecklers is most certainly right that they can market it as an upgrade which it is.
Last edited by dizwiz24; Dec 17, 2012 at 09:24 PM.
Race Director
Joined: Sep 2001
Posts: 14,676
Likes: 751
From: NEwhere Ohio
Was your ram disc a sprung hub clutch?
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Heavier billet FW is easier to drive plain and simple.
Better manners
I wouldnt tolerate a chattery noisy clutch for a second.
Unless its a track only car doesnt make sense to me.
Ive driven Vettes with those clutch/FW setups and they suck.
How much clutch really do you need to hold 3-400hp? Not much.
Better manners
I wouldnt tolerate a chattery noisy clutch for a second.
Unless its a track only car doesnt make sense to me.
Ive driven Vettes with those clutch/FW setups and they suck.
How much clutch really do you need to hold 3-400hp? Not much.
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
Dizwiz, the answer to your question regarding the "extra mass" lies in the internals of the ZF trans. The gears are cut in such a way that they tend to rattle in neutral a bit more than some other transmissions do. That was GM's reason for the dual mass FW in the first place.
The extra rotating mass helps to keep the gears from vibrating as much. So along with a traditional sprung hub clutch disk, it will keep it relatively quiet. But still more than the stock FW.
The other point for an extra mass FW is in normal, city driving conditions. The extra mass keeps a certain level of inertia allowing for easier starts from stop lights in traffic and such. A light FW, i.e. aluminum requires a higher rpm at start due to the loss of rotating inertia. This takes some getting used to and can be a p.i.a. in heavy, rush hour type traffic. Plus the light weight FW will allow the gears to vibrate more and chatter quite a bit in the ZF.
It's really a matter personal preference. Not everyone has the sole desire to make their Corvette faster than it already is. For them, a light weight FW with all of it's characteristics is more a liability than an asset. For those that track the car, especially autocross and road course, it's an asset.
The extra rotating mass helps to keep the gears from vibrating as much. So along with a traditional sprung hub clutch disk, it will keep it relatively quiet. But still more than the stock FW.
The other point for an extra mass FW is in normal, city driving conditions. The extra mass keeps a certain level of inertia allowing for easier starts from stop lights in traffic and such. A light FW, i.e. aluminum requires a higher rpm at start due to the loss of rotating inertia. This takes some getting used to and can be a p.i.a. in heavy, rush hour type traffic. Plus the light weight FW will allow the gears to vibrate more and chatter quite a bit in the ZF.
It's really a matter personal preference. Not everyone has the sole desire to make their Corvette faster than it already is. For them, a light weight FW with all of it's characteristics is more a liability than an asset. For those that track the car, especially autocross and road course, it's an asset.
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
Now, as the original poster referenced it, I'm not hijacking. But I am curious about the Eckler's FW. Anyone use it? Good quality in terms of replacement. I know the Spec FW would be better, but for the money, is the Eckler's any good. I mean $160 for the flywheel seems like a good price.
Race Director
Joined: Sep 2001
Posts: 14,676
Likes: 751
From: NEwhere Ohio
Dizwiz, the answer to your question regarding the "extra mass" lies in the internals of the ZF trans. The gears are cut in such a way that they tend to rattle in neutral a bit more than some other transmissions do. That was GM's reason for the dual mass FW in the first place.
The extra rotating mass helps to keep the gears from vibrating as much. So along with a traditional sprung hub clutch disk, it will keep it relatively quiet. But still more than the stock FW.
The other point for an extra mass FW is in normal, city driving conditions. The extra mass keeps a certain level of inertia allowing for easier starts from stop lights in traffic and such. A light FW, i.e. aluminum requires a higher rpm at start due to the loss of rotating inertia. This takes some getting used to and can be a p.i.a. in heavy, rush hour type traffic. Plus the light weight FW will allow the gears to vibrate more and chatter quite a bit in the ZF.
It's really a matter personal preference. Not everyone has the sole desire to make their Corvette faster than it already is. For them, a light weight FW with all of it's characteristics is more a liability than an asset. For those that track the car, especially autocross and road course, it's an asset.
The extra rotating mass helps to keep the gears from vibrating as much. So along with a traditional sprung hub clutch disk, it will keep it relatively quiet. But still more than the stock FW.
The other point for an extra mass FW is in normal, city driving conditions. The extra mass keeps a certain level of inertia allowing for easier starts from stop lights in traffic and such. A light FW, i.e. aluminum requires a higher rpm at start due to the loss of rotating inertia. This takes some getting used to and can be a p.i.a. in heavy, rush hour type traffic. Plus the light weight FW will allow the gears to vibrate more and chatter quite a bit in the ZF.
It's really a matter personal preference. Not everyone has the sole desire to make their Corvette faster than it already is. For them, a light weight FW with all of it's characteristics is more a liability than an asset. For those that track the car, especially autocross and road course, it's an asset.
You are right on the car being easier to drive.
Example, its more difficult to stall it out due to all that inertia.
Next, if you go down a hill and there is an uphill right there, the inertia of the 'heavy' flywheel can sometimes carry you over the crest of the next hill without requiring a downshift.
In my car, it will chatter a bunch (i gave that example, going up a hill in too-high-of-a-gear) until you downshift which will eliminate the chatter.
Definitely a little more work to drive it.
Finally, it is trickier to launch at the dragstrip, but still manageable. I have two drag radial assisted 11.95 sec 1/4 mile launches with 1.8 60 ft times that I managed on the lightweight flywheel.
I believe that the freer reving nature of the lightweight flywheel overwhelms the 'good inertia at launch' benefit of the heavy flywheel at the 1/4 mile dragstrip. But thats an argument that each person will have their own opinion on!
So I take back my 'ice cream getter example'. The dual mass flywheel is the better flywheel for the most relaxing drive possible.
Thread Starter
Instructor
Joined: Mar 2012
Posts: 201
Likes: 10
From: Kennewick WA
Interesting debate. So is the consensus of opinion that SPEC with extra mass is the way to go? Anyone actually done it?
http://www.lmperformance.com/5266/24.html
http://www.lmperformance.com/5266/24.html
Melting Slicks
Joined: Jan 2009
Posts: 3,482
Likes: 196
From: folsom california
Interesting debate. So is the consensus of opinion that SPEC with extra mass is the way to go? Anyone actually done it?
http://www.lmperformance.com/5266/24.html
http://www.lmperformance.com/5266/24.html
second, I have a Sec lighteight billet steel flywheel and stage three plus clutch and I love it.
third, if dampening out the maximum amount of transmission noise and ease of drivability is of paramount importance, a Spec heavy weight billet steel flywheel would be the way to go.
A Spec "heavy" flywheel is a relative and somewhat confusing term; its about the same weight as the usual nodular iron flywheel of the same diameter used in a zillion stock chevy manual transmission / v8 drive combo's. No big deal; the main difference is that the flywheel is (a) made from billet steel and that (b) the surface is cut down 0.090 inch to accommodate the ZF style pull clutch.