Changing flywheel
Thread Starter
7th Gear
Joined: Aug 2012
Posts: 7
Likes: 1
From: Sydney NSW
Changing flywheel
I have had my Corvette for 15 years and there has always been a rattle in the gear box at idle; both with the original Muncie and also with the aftermarket Tremec TKO. The engine is a mild 350 (which replaced the original 327). I believe the problem is the light-weight alloy flywheel which was installed by the previous owner.
I intend to replace the light flywheel with a standard weight one and I wanted to know if the current flywheel can simply be replaced with a heaver one or are there any balancing issues that need to be addressed.
I intend to replace the light flywheel with a standard weight one and I wanted to know if the current flywheel can simply be replaced with a heaver one or are there any balancing issues that need to be addressed.
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
The weight of the flywheel alone should not cause a balance issue.
A stock replacement flywheel will weigh 30-35#. I like the low 20# billet-steel flywheels which aren't particularly light like an aluminum (10-15#).
327s and 350s are both internally balanced so you SHOULDN'T have an issue unless someone did something strange. When you pull the flywheel off it wouldn't hurt to have it checked for balance, b/c you may just be barking up the wrong tree.
A stock replacement flywheel will weigh 30-35#. I like the low 20# billet-steel flywheels which aren't particularly light like an aluminum (10-15#).
327s and 350s are both internally balanced so you SHOULDN'T have an issue unless someone did something strange. When you pull the flywheel off it wouldn't hurt to have it checked for balance, b/c you may just be barking up the wrong tree.
Thread Starter
7th Gear
Joined: Aug 2012
Posts: 7
Likes: 1
From: Sydney NSW
Thanks Shark Racer. I acknowledge that I could be barking up the wrong tree, but the other problem that I did not mention was that the engine is easy to stall; and I am pretty sure that a heavier flywheel will fix that problem.
Frank
Frank
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
Yes, launching can be a lot more difficult with a light flywheel. I'd want to make sure that my carb was dialed in first.
If you're running an aluminum flywheel, I'd highly recommend splitting the difference and going with billet steel. I like the flywheel in my 78 a lot more than the one in my Z.
If you're running an aluminum flywheel, I'd highly recommend splitting the difference and going with billet steel. I like the flywheel in my 78 a lot more than the one in my Z.
Thread Starter
7th Gear
Joined: Aug 2012
Posts: 7
Likes: 1
From: Sydney NSW
I have read in other forums that a light flywheel can cause an erratic idle. If the idle is increased to 900/1000 rpm the rattle stops. It's a mild cam and I like the idle at 750rpm. Yes, I know I am very finicky.
Racer
Joined: Sep 2009
Posts: 437
Likes: 3
From: Alvin Texas
Your noise is probably the main drive gear rattling against the counter gear. At idle with the clutch out there is no load on the gears producing that noise, changing the flywheel won't cure it. Muncies had a spring loaded interference gear riveted to the 1'st gear on the counter gear to address the noise. They worked well until the rivets back out then there was another issue,usually a real loud noise.
The rattle doesn't seem to do any damage.
The rattle doesn't seem to do any damage.
Thread Starter
7th Gear
Joined: Aug 2012
Posts: 7
Likes: 1
From: Sydney NSW
Your noise is probably the main drive gear rattling against the counter gear. At idle with the clutch out there is no load on the gears producing that noise, changing the flywheel won't cure it. Muncies had a spring loaded interference gear riveted to the 1'st gear on the counter gear to address the noise. They worked well until the rivets back out then there was another issue,usually a real loud noise.
The rattle doesn't seem to do any damage.
The rattle doesn't seem to do any damage.
I think you are right; it probably is the input shaft rattling on the cluster gear. The interesting thing is that of all my fellow corvette owners, mine is the only one with a light flywheel and mine is the only one with a rattle. The Muncie rattled and the TKO now rattles.
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
Pro
Joined: Nov 2009
Posts: 667
Likes: 7
From: Milpitas Calyfornua
Recently removed L88 clutch and its 15??? pound 10.5 inch flywheel from my 71 and replaced with 30 pound Centerforce billet 10.5 inch flywheel. Idles smoother, not as skittish off the line from stop and is far easier to manage. Quite happy with the change.
However wished I had installed a hydraulic clutch while everything was apart. My 59 with a hydraulic clutch seems far smoother to release and engage as 1/2 dozen pivot points on stock 71 mechanical linkage all add up and take a toll. Using Sachs clutch, it seems to be ok. Car is just a cruiser now so hard to say.,
However wished I had installed a hydraulic clutch while everything was apart. My 59 with a hydraulic clutch seems far smoother to release and engage as 1/2 dozen pivot points on stock 71 mechanical linkage all add up and take a toll. Using Sachs clutch, it seems to be ok. Car is just a cruiser now so hard to say.,