C2 Clutch/Flywheel Question
07-10-2018, 05:23 PM
#1
Heel & Toe
Thread Starter
C2 Clutch/Flywheel Question
Does anyone know the average service life of an OEM cast flywheel? I know this probably varies greatly depending on how aggressively the car is driven, but I'm just curious as to what the normal life span might be. I have a '64 with a 300 hp 4 speed. I bought it from my dad years ago and it's been driven fairly aggressively in the past but mostly pampered and never abused. It's got 106k miles on the clock.
The reason I ask is that I just had it in the shop for a new clutch. I ordered a clutch kit from a reputable online corvette parts retailer and had my local shop put it in. After a few days, the shop called and said the new throw out bearing and clutch were bad. It made a terrible noise when the clutch was disengaged and you could barely get the car in gear. The pedal needs to practically hit the firewall in order to get it in gear and there's no more room for adjustment. My mechanic now wants to replace the new clutch and throw out bearing, as well as put in a new fork, pivot ball AND flywheel.
They had just sent the original flywheel off to have it resurfaced, which only removed 1/1000 of material. I don't really see the need to replace the flywheel, since it would add to the cost of the repair and I'm already being charged 2 times the labor to have to fix the defective part. The mechanic is argueing that the flywheel may be too thin, but removing 1/1000 of material shouldn't have any impact. Seems like they just want to replace everything, even if it's not really necessary. By the way, the car shifted fine before I took it to the shop (no slipping and no chattering).
I researched clutch problems on this forum and read an excellent article by Lars about inadequate clutch travel https://www.corvetteforum.com/forums...vel-range.html
but I couldn't find much info on cast flywheels. Any thoughts?
The reason I ask is that I just had it in the shop for a new clutch. I ordered a clutch kit from a reputable online corvette parts retailer and had my local shop put it in. After a few days, the shop called and said the new throw out bearing and clutch were bad. It made a terrible noise when the clutch was disengaged and you could barely get the car in gear. The pedal needs to practically hit the firewall in order to get it in gear and there's no more room for adjustment. My mechanic now wants to replace the new clutch and throw out bearing, as well as put in a new fork, pivot ball AND flywheel.
They had just sent the original flywheel off to have it resurfaced, which only removed 1/1000 of material. I don't really see the need to replace the flywheel, since it would add to the cost of the repair and I'm already being charged 2 times the labor to have to fix the defective part. The mechanic is argueing that the flywheel may be too thin, but removing 1/1000 of material shouldn't have any impact. Seems like they just want to replace everything, even if it's not really necessary. By the way, the car shifted fine before I took it to the shop (no slipping and no chattering).
I researched clutch problems on this forum and read an excellent article by Lars about inadequate clutch travel https://www.corvetteforum.com/forums...vel-range.html
but I couldn't find much info on cast flywheels. Any thoughts?
07-10-2018, 05:44 PM
#2
Safety Car
Member Since: May 2007
Location: Indiana
Posts: 3,590
Received 596 Likes
on
361 Posts
2023 C1 of the Year Finalist - Modified
2023 C3 of the Year Finalist - Unmodified
2022 C1 of the Year Finalist - Modified
2020 C1 of the Year Finalist - Modified
2019 C1 of Year Finalist (performance mods)
2018 C1 of Year Finalist
I think I would get another mechanic instead of a new clutch. I find it hard to believe that the new clutch and bearing are bad.
07-10-2018, 05:52 PM
#3
Heel & Toe
Thread Starter
Yeah, that thought crossed my mind, believe me. But after reading the thread I mentioned above I had second thoughts. Seems like several people on this forum have had issues with new clutches and throw out bearings lately...
07-10-2018, 06:27 PM
#4
Race Director
Member Since: Jan 2002
Location: Close to DC
Posts: 14,546
Received 2,127 Likes
on
1,466 Posts
C2 of the Year Finalist - Modified 2020
Find a shop that does Vettes and or muscle/performace cars. My '67 has 233K mile and the original flywheel has been resurfaced twice with no problems. 
Dennis
Dennis
The following users liked this post:
MrTwister (07-10-2018)
07-10-2018, 06:38 PM
#5
Heel & Toe
Thread Starter
Thanks, Dennis. That's what I was hoping to hear. I find it hard to believe that a cast flywheel would be worn out after 106k miles.
Surprisingly, this shop works on a lot of old muscle cars and vettes. They had a C1, 3 C2s and a C3 in there last week... And they have good reviews.
Surprisingly, this shop works on a lot of old muscle cars and vettes. They had a C1, 3 C2s and a C3 in there last week... And they have good reviews.
07-10-2018, 06:45 PM
#6
Race Director
What is brand and part number of clutch that was installed??
If TO bearing is a plastic material, many here prefer an all metal bearing instead. They are still available. Also TO bearing length and correct installation is critical for our Corvettes. What length is your new bearing??
Larry
If TO bearing is a plastic material, many here prefer an all metal bearing instead. They are still available. Also TO bearing length and correct installation is critical for our Corvettes. What length is your new bearing??
Larry
07-10-2018, 06:50 PM
#7
Team Owner
Member Since: Mar 2003
Location: Greenville, Indiana
Posts: 26,118
Received 1,843 Likes
on
1,398 Posts
What is brand and part number of clutch that was installed??
If TO bearing is a plastic material, many here prefer an all metal bearing instead. They are still available. Also TO bearing length and correct installation is critical for our Corvettes. What length is your new bearing??
Larry
If TO bearing is a plastic material, many here prefer an all metal bearing instead. They are still available. Also TO bearing length and correct installation is critical for our Corvettes. What length is your new bearing??
Larry
Forget the flywheel. This is the place to start, right here.
07-10-2018, 07:07 PM
#8
Team Owner
Member Since: Apr 2008
Location: Coloring within the lines
Posts: 27,340
Received 1,919 Likes
on
1,332 Posts
I would ask this top-rated shop to explain what about the flywheel dictates its replacement. This is a good litmus test question for a quality mechanic to answer. Obviously, "just because" is not a good reply, nor is "we should replace everything just to be sure." Flywheels can be resurfaced as long as you don't cut it to thin (there is a spec), and can be rebalanced if out of balance.
Last edited by Easy Rhino; 07-10-2018 at 07:08 PM.
07-10-2018, 07:21 PM
#9
Race Director
If you have read LARS thread on clutch release issues then you will understand that it could be a bad clutch plate. Some of them just don't release properly and require more pedal throw than a Corvette will accommodate. Throw that in with a few worn clutch linkage parts and maybe a worn clutch pedal and a clutch that won't disengage is what happens.
What clutch did you purchase? I've also found that an adjustable fork ball is a good investment to ensure that with the clutch engaged (pedal up) the fork is positioned well forward in the bell housing opening and doesn't bottom against the back of the opening when depressed. If your flywheel has been surfaced a couple of times this can make a difference as all other things being equal - that moves the fork to the rear in the opening.
I think most GM flywheels were around 1 inch thick new. As long as it hasn't been machined well below that I doubt it's your problem.
What clutch did you purchase? I've also found that an adjustable fork ball is a good investment to ensure that with the clutch engaged (pedal up) the fork is positioned well forward in the bell housing opening and doesn't bottom against the back of the opening when depressed. If your flywheel has been surfaced a couple of times this can make a difference as all other things being equal - that moves the fork to the rear in the opening.
I think most GM flywheels were around 1 inch thick new. As long as it hasn't been machined well below that I doubt it's your problem.
07-10-2018, 08:02 PM
#10
Heel & Toe
Thread Starter
I would ask this top-rated shop to explain what about the flywheel dictates its replacement. This is a good litmus test question for a quality mechanic to answer. Obviously, "just because" is not a good reply, nor is "we should replace everything just to be sure." Flywheels can be resurfaced as long as you don't cut it to thin (there is a spec), and can be rebalanced if out of balance.
Last edited by MrTwister; 07-10-2018 at 09:04 PM.
07-10-2018, 08:16 PM
#11
Heel & Toe
Thread Starter
If you have read LARS thread on clutch release issues then you will understand that it could be a bad clutch plate. Some of them just don't release properly and require more pedal throw than a Corvette will accommodate. Throw that in with a few worn clutch linkage parts and maybe a worn clutch pedal and a clutch that won't disengage is what happens.
What clutch did you purchase? I've also found that an adjustable fork ball is a good investment to ensure that with the clutch engaged (pedal up) the fork is positioned well forward in the bell housing opening and doesn't bottom against the back of the opening when depressed. If your flywheel has been surfaced a couple of times this can make a difference as all other things being equal - that moves the fork to the rear in the opening.
I think most GM flywheels were around 1 inch thick new. As long as it hasn't been machined well below that I doubt it's your problem.
What clutch did you purchase? I've also found that an adjustable fork ball is a good investment to ensure that with the clutch engaged (pedal up) the fork is positioned well forward in the bell housing opening and doesn't bottom against the back of the opening when depressed. If your flywheel has been surfaced a couple of times this can make a difference as all other things being equal - that moves the fork to the rear in the opening.
I think most GM flywheels were around 1 inch thick new. As long as it hasn't been machined well below that I doubt it's your problem.
I've found another shop as well. It's a bit of a drive but they only work on old vettes. I spent at least 20 minutes talking to the mechanic about clutch geometry and he really seems to know what he's talking about. He recommends using a Centerforce II pressure plate. It's supposedly a little beefier than stock but feels the same as an OEM clutch. Does anyone have experience with a Centerforce II pressure plate?
By the way, he also said they do not use plastic throw out bearings, which was good to hear.
07-10-2018, 08:38 PM
#12
Team Owner
Member Since: Mar 2003
Location: Greenville, Indiana
Posts: 26,118
Received 1,843 Likes
on
1,398 Posts
I have seen countless posts of people mean mouthing the plastic throw out bearings. I just did a search for specific problems owners may have encountered. Couldn't find anything other than the plastic bearings are no good. So, what's up here?
07-10-2018, 08:51 PM
#13
Heel & Toe
Thread Starter
All I can tell you is the knowledgeable mechanic I spoke to said he didn't trust them and doesn't use them. Maybe it's just a baseless rumor but I'd rather play it safe and install a metal one.
Last edited by MrTwister; 07-10-2018 at 08:52 PM.
07-10-2018, 08:57 PM
#14
Heel & Toe
Thread Starter
I'm still curious though, does anyone have experience with a Centerforce II pressure plate? It's what this new (and pretty knowledgeable) mechanic recommends using...
07-10-2018, 09:31 PM
#15
Race Director
MANY folks here like the Centerforce. A few have had issues. A fair amount of folks here also like McLeod clutches, including Lars. I have not heard of any issues with this clutch for our street driven cars. The Paragon product was probably LUK or Sachs, both have very good reputations as far as their overall product lines. I believe LUK provides current Corvette factory clutches. A LOT of folks have had good luck with these two brands, but every now and then there are also issues. I know their prices are low compared to the aftermarket types.....so that may be an issue as less costly parts are used in the construction. I just recommended to my very good friend to go with either LUK Rep Set or McLeod Street Pro for his 1969 350/350 HP car. And I will probably be doing the install...........but the car is also undergoing a complete body off restoration so a lot of things are easier to do at this time.
To address Mike's comments about TO bearings: At my age, and no lift in my garage, I have maybe one old fashioned Corvette clutch replacement left in me.
If and when I do it, laying on my back on the concrete floor, I want a made in the USA metal throwout bearing to go back with. Just call me "old school" In the last 50 years, I have never installed one that was not made in USA metal type, and I also have never had a TO bearing problem with these replacements. That is my concern and point of reference. If you are young, have a lift, have time and have the tools, be adventurous. A poor replacement doesn't hurt as bad. Larry
EDIT: To the OP, I see that you are relatively new to our forum. A LOT of good information on Centerforce Clutches are in the archives if you search. Go to SEARCH, then ADVANCED SEARCH, and then search for Centerforce clutch in the C2 and C3 Corvette General Sections. You will get MANY threads. If you cannot do, let me know and I will do it for you and provide you a link. But try it first yourself and learn.
EDIT2: Here is the C2 link: https://www.corvetteforum.com/forums/search.php?searchid=71120372&pp=25 And the C3 link: https://www.corvetteforum.com/forums...rchid=71120420
Last edited by Powershift; 07-10-2018 at 10:01 PM.
The following users liked this post:
MrTwister (07-11-2018)
07-10-2018, 10:04 PM
#16
Read my thread
https://www.corvetteforum.com/forums...h-problem.html
sorry for your troubles.
Last edited by ghostrider20; 07-10-2018 at 10:06 PM.
The following users liked this post:
GreasyFingernails (04-01-2019)
07-11-2018, 04:59 AM
#18
When I researched clutches it seemed everyone agreed that for stock power levels, Luk was the right way to go and very reasonably priced.
For an "uprated" clutch, the centerforce experience seemed roughly 50/50 with some people loving them and others talking about weights flying off and other issues. McLeod seemed to get a good wrap, thats what I bought and it is great.
For an "uprated" clutch, the centerforce experience seemed roughly 50/50 with some people loving them and others talking about weights flying off and other issues. McLeod seemed to get a good wrap, thats what I bought and it is great.
The following users liked this post:
MrTwister (07-11-2018)
07-11-2018, 11:53 AM
#19
Team Owner
Member Since: Oct 2000
Location: Washington Michigan
Posts: 38,899
Received 1,857 Likes
on
1,100 Posts
I'll just add that LuK is the largest manufacturer of OEM and replacement clutches in the world, and has been for about 40 years. Among other applications, they are the OEM supplier to Chrysler of the 12" Viper clutch, which is considered by Viper owners to be superior to the special "tuner" clutches made for the Viper. 
07-11-2018, 08:26 PM
#20
Safety Car
Had good luck recently installing a Perfection Clutch kit. Used a few Luks. The "record" grove surface of the pressure plate is different.
Did have two plastic throw out bearings that were junk. Inside bore on one was super sloppy. Another's contact surface to the pressure plate fingers was out of round.
I'd hold on to your old flywheel. Finding a new stock weight 153 tooth lately has become tough. Seems like most replacement small flywheels are scalloped/lightened ones. 16 pounds, getting close to half of stock.
Did have two plastic throw out bearings that were junk. Inside bore on one was super sloppy. Another's contact surface to the pressure plate fingers was out of round.
I'd hold on to your old flywheel. Finding a new stock weight 153 tooth lately has become tough. Seems like most replacement small flywheels are scalloped/lightened ones. 16 pounds, getting close to half of stock.
Last edited by 426 Hemi; 07-11-2018 at 08:31 PM. Reason: Because I Like Writing Stuff Down Here----You Know, REALLY Like It