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I need to replace the flywheel in my 1966 327/300 with 4 speed. The flywheel removed is cast number 3791021 with 153 teeth and I believe the part number is 3791022. The clutch is 10 1/2". What is the modern replacement for this? I'm having some problems finding a new one. If it matters, by bell housing is number 3858403.
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Re: C2-66 Flywheel Replacement
I like LUK clutches.
I also like Borg clutches.
All you need is a standard duty clutch.
You do not need a "high performance" clutch, or "heavy duty" clutch.
You use a diaphragm, and not a Borg-and-Beck type.
Single disc clutch.
I don't like Centerforce clutches.
Their clucch hub "sliding weight" technology is a bunch of crapola.
If you have an "overcentering" problem on powershifts at high engine speed, the Centerforce gimmick will only exacerbate it.
I have a Borg, standard duty clutch in my car.
Bought it at a local parts jobber fer under 100 bucks.
Try this Luk unit:
Make sure that you have the flywheel surfaced before installing new disc/pressure plate, TO bearing, and pilot BUSHING.
I don't recommend a needle bearing here. Use the sintered bronze bushing.
Tally ho! -
Re: C2-66 Flywheel Replacement
I like LUK clutches.
I also like Borg clutches.
All you need is a standard duty clutch.
You do not need a "high performance" clutch, or "heavy duty" clutch.
You use a diaphragm, and not a Borg-and-Beck type.
Single disc clutch.
I don't like Centerforce clutches.
Their clucch hub "sliding weight" technology is a bunch of crapola.
If you have an "overcentering" problem on powershifts at high engine speed, the Centerforce gimmick will only exacerbate it.
I have a Borg, standard duty clutch in my car.
Bought it at a local parts jobber fer under 100 bucks.
Try this Luk unit:
Make sure that you have the flywheel surfaced before installing new disc/pressure plate, TO bearing, and pilot BUSHING.
I don't recommend a needle bearing here. Use the sintered bronze bushing.
Tally ho!Comment
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Re: C2-66 Flywheel Replacement
Ed-----
These 63-68 Corvette small block flywheels could get to be a problem for folks needing one. As you mentioned, the original PART number for the flywheel was GM #3791022. That was replaced by GM #3973452 in December, 1971 and GM #366860 in June, 1977. About 4 years ago, though, the GM #366860 was discontinued without supercession.
The above-referenced flywheels were, by no means, Corvette-only pieces. They were used on a wide range of small block applications over the 63-68 period. However, they were used on only a VERY small number of low-volume applications after 1968. The last PRODUCTION use for them that I can find is 1973, although it's possible they were used for some limited number of applications after that time.
With so many 63-68 applications, though, one would think that replacements would be fairly easy to find. The problem here is that the last large-scale use of them was so long ago. Aftermarket replacement manufacturers just don't want to get involved in making parts for what now amount to "antique" applications in what is otherwise a "mass-market" sort of business.
Barring someone coming up with a source for this flywheel, there are a few POSSIBILITIES I could suggest:
1) GM #14085720. This is a "lightweight" 12-3/4" flywheel. Its predecessor was used for 1965 with L-78, 1967-69 L-88/ZL-1, and 1970-72 ZR-1. The GM #3791022 and successor flywheels were, I believe, about 25 or 30 pound flywheels. I believe the 14085720 is about 15-20 pounds. I can't see any reason that it shouldn't work, though;
2) Hays #10-330. This is a 12-3/4" steel flywheel of 30 pound weight. I've never used one on a 63-68 small block, but I would think it would work fine. It might even be better than the original since it's steel and not cast iron. Check with a Hays tech rep first, though.In Appreciation of John HinckleyComment
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Re: C2-66 Flywheel Replacement
Ed-----
These 63-68 Corvette small block flywheels could get to be a problem for folks needing one. As you mentioned, the original PART number for the flywheel was GM #3791022. That was replaced by GM #3973452 in December, 1971 and GM #366860 in June, 1977. About 4 years ago, though, the GM #366860 was discontinued without supercession.
The above-referenced flywheels were, by no means, Corvette-only pieces. They were used on a wide range of small block applications over the 63-68 period. However, they were used on only a VERY small number of low-volume applications after 1968. The last PRODUCTION use for them that I can find is 1973, although it's possible they were used for some limited number of applications after that time.
With so many 63-68 applications, though, one would think that replacements would be fairly easy to find. The problem here is that the last large-scale use of them was so long ago. Aftermarket replacement manufacturers just don't want to get involved in making parts for what now amount to "antique" applications in what is otherwise a "mass-market" sort of business.
Barring someone coming up with a source for this flywheel, there are a few POSSIBILITIES I could suggest:
1) GM #14085720. This is a "lightweight" 12-3/4" flywheel. Its predecessor was used for 1965 with L-78, 1967-69 L-88/ZL-1, and 1970-72 ZR-1. The GM #3791022 and successor flywheels were, I believe, about 25 or 30 pound flywheels. I believe the 14085720 is about 15-20 pounds. I can't see any reason that it shouldn't work, though;
2) Hays #10-330. This is a 12-3/4" steel flywheel of 30 pound weight. I've never used one on a 63-68 small block, but I would think it would work fine. It might even be better than the original since it's steel and not cast iron. Check with a Hays tech rep first, though.In Appreciation of John HinckleyComment
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what is wrong whith your flywheel-let's start ther *NM*
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what is wrong whith your flywheel-let's start ther *NM*
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Re: what is wrong whith your flywheel-let's start
First of all, thanks all for the responses. I'm in the process of swapping engines. The machine shop told me the flywheel was heat cracked and didn't think they could resurface it. Once I found I couldn't get one right away I came here to get help.Comment
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Re: what is wrong whith your flywheel-let's start
First of all, thanks all for the responses. I'm in the process of swapping engines. The machine shop told me the flywheel was heat cracked and didn't think they could resurface it. Once I found I couldn't get one right away I came here to get help.Comment
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Re: what is wrong whith your flywheel-let's start
Ed------
Having not seen the flywheel, I cannot comment on its serviceability. However, if the machine shop says that it's too severely heat cracked for re-surfacing, I'd go with that recommendation. They have an interest in doing a re-surfacing, not in telling you it shouldn't be done. To be honest, I don't like to use a re-surfaced flywheel even if they can be so-reconditioned. A flywheel is an engine component with serious safety implications (one of the few engine components that are seriously safety related). You don't want one coming apart. Believe me, you'll never forget it if it happens AND you survive it.
If it were me, I think I'd go with the Hays steel unit (after confirming fitment with Hays).In Appreciation of John HinckleyComment
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Re: what is wrong whith your flywheel-let's start
Ed------
Having not seen the flywheel, I cannot comment on its serviceability. However, if the machine shop says that it's too severely heat cracked for re-surfacing, I'd go with that recommendation. They have an interest in doing a re-surfacing, not in telling you it shouldn't be done. To be honest, I don't like to use a re-surfaced flywheel even if they can be so-reconditioned. A flywheel is an engine component with serious safety implications (one of the few engine components that are seriously safety related). You don't want one coming apart. Believe me, you'll never forget it if it happens AND you survive it.
If it were me, I think I'd go with the Hays steel unit (after confirming fitment with Hays).In Appreciation of John HinckleyComment
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Re: what is wrong whith your flywheel-let's start
Joe
Happy to hear you and I are on the same wave length on clutches and flywheels. My partner and I drag raced too many years to not respect external rotating parts. I suggest to everyone to put that correct bellhousing on the shelf and use a scattershield until you decide to sell your ride. I saw too many explosions !!!!
Regards...FrankComment
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Re: what is wrong whith your flywheel-let's start
Joe
Happy to hear you and I are on the same wave length on clutches and flywheels. My partner and I drag raced too many years to not respect external rotating parts. I suggest to everyone to put that correct bellhousing on the shelf and use a scattershield until you decide to sell your ride. I saw too many explosions !!!!
Regards...FrankComment
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