66 427 Fly Wheel

[Anthony P.]

Re: 66 427 Fly Wheel

Tony------


The GM #3991469 is also applicable to 1969 L-78.

I wouldn't be too concerned about the source of the 3991469 you receive. If it's a genuine GM part (which it will be), it will be OEM quality no matter where it comes from. I'd prefer it over a re-surfaced original. By the way, GM has a nodular iron foundry in Mexico as well as several engine plants.

Good to know! thanks Joe.
I have owned the Vette since 1972 and never really used it much(maybe 2,000 miles in all these years) so I just want to make sure it is right going forward.

The 69 Camaro I have had since 1971 and have replace the clutch, machined flywheel at least 8 times when it was a daily driver. It will absolutely be getting a new GM fly wheel VERY soon ! Thanks for the Information.

[Gary B.]

Re: 66 427 Fly Wheel

Gary-----


Unfortunately, I don't know what material that the LUK flywheels are cast from. All that I've ever found that LUK says about the subject is that the flywheels are made from "premium grade cast iron". That really does not tell me much.

I emailed Summit Racing to ask them what the LFW131 is made from and they claim that LUK doesn't tell them. I have no reason to doubt that, but it's a bogus answer/attitude for a reputable company. Also for Summit's price of less then $60 I suspect it's not made from nodular iron.

Gary

[Gary B.]

Re: 66 427 Fly Wheel

Jim------

LUK is a supplier to GM for clutches and related parts. However, I don't know if they supply GM with the 3991469 flywheel. The last one of these that I examined had a GM casting number on it and I believe it was cast and machined by a GM manufacturing operation. That's been awhile, though, and the manufacturing source for this flywheel could have changed by now.

The GM #3991469 flywheel is a 14", 168 tooth ring gear flywheel and designed for use with an 11" clutch. The 3991469 flywheel is cast of nodular iron. Many aftermarket flywheels are cast of gray iron.

Joe,

I emailed LUK in Germany a few days ago to ask about the material used to cast LFW131 and today I got a reply from another German company (Schaeffler) who said the LFW131 is made of gray iron. I don't know the connection between LUK and Schaeffler, but I have to think that LUK asked Schaeffler to reply to me.

Gary

[Joe L.]

Re: 66 427 Fly Wheel

Joe,

I emailed LUK in Germany a few days ago to ask about the material used to cast LFW131 and today I got a reply from another German company (Schaeffler) who said the LFW131 is made of gray iron. I don't know the connection between LUK and Schaeffler, but I have to think that LUK asked Schaeffler to reply to me.

Gary

Gary------


Schaeffler is a German automotive conglomerate. Primarily, Schaeffler is a Tier 1 OEM supplier. However, they do have an aftermarket division and LUK is part of that. Some folks, including me, have stated that LUK is a supplier of clutches to GM. That's not completely accurate, though, as Schaeffler is the company that supplies the OEM clutches and many other parts to GM and other automotive manufacturers. Aren't LUK and Schaeffler clutches the same for any particular application? Actually, I doubt it. When automotive parts suppliers have both OEM and aftermarket divisions, the parts that each manufacture, even for the same application, are usually NOT the same. Nevertheless, I still recommend LUK clutches as the closest thing one is going to get to a GM OEM clutch for 63-81 Corvettes.

[Gary B.]

Re: 66 427 Fly Wheel

Joe,

Well as least we now know the nodular vs grey iron answer.

Gary

[Joe L.]

Re: 66 427 Fly Wheel

Joe,

Well as least we now know the nodular vs grey iron answer.

Gary

Gary------


Yes, thanks for determining that.

[Joe L.]

Re: 66 427 Fly Wheel

Gary------

One more thing: notwithstanding material, I feel very confident that the LUK flywheel dimensionally matches the OEM flywheel. That's VERY important in a Corvette application. Other than NOS GM, there may not be a nodular iron flywheel available that has this attribute. Sure, there are other flywheels available, perhaps even some billet steel flywheels, that claim to SERVICE Corvette applications. But, are they in every way dimensionally identical to the original Corvette flywheels? That's the real question. If they're not, problems may ensue-----the kind of problems that one finds out after installation.

For me, if it was a choice between a resurfaced original flywheel or a LUK gray cast iron new flywheel, I'd go with the LUK flywheel. I admit, though, that's a choice I'll never need to make.

[Gary B.]

Re: 66 427 Fly Wheel

Gary------

One more thing: notwithstanding material, I feel very confident that the LUK flywheel dimensionally matches the OEM flywheel. That's VERY important in a Corvette application. Other than NOS GM, there may not be a nodular iron flywheel available that has this attribute. Sure, there are other flywheels available, perhaps even some billet steel flywheels, that claim to SERVICE Corvette applications. But, are they in every way dimensionally identical to the original Corvette flywheels? That's the real question. If they're not, problems may ensue-----the kind of problems that one finds out after installation.

For me, if it was a choice between a resurfaced original flywheel or a LUK gray cast iron new flywheel, I'd go with the LUK flywheel. I admit, though, that's a choice I'll never need to make.

Joe,

The LUK is what I plan to get for my '66 L79. Thanks for the encouragement.

Gary

[Joe L.]

Re: 66 427 Fly Wheel

Joe,

The LUK is what I plan to get for my '66 L79. Thanks for the encouragement.

Gary

Gary------


Just to be accurate, the LUK flywheel is configured a bit different than the original flywheels for your application. The configuration is similar to the GM #3866735 (used for L-78 and L-88) However, I have no doubt that the important dimensions are the same as the original flywheel.

Also, the original flywheel for your application was a GM #3791022 (casting 3791021). I do not have any information which confirms that this is a nodular iron flywheel. In fact, I've never seen one that has the "N" casting number suffix indicating that it's nodular iron. The once-available SERVICE replacement flywheel, GM #366860 (casting 366861), was a nodular iron flywheel. Every example I've seen of this flywheel has had the "N" suffix.

[Gary B.]

Re: 66 427 Fly Wheel

Gary------


Just to be accurate, the LUK flywheel is configured a bit different than the original flywheels for your application. The configuration is similar to the GM #3866735 (used for L-78 and L-88) However, I have no doubt that the important dimensions are the same as the original flywheel.

Also, the original flywheel for your application was a GM #3791022 (casting 3791021). I do not have any information which confirms that this is a nodular iron flywheel. In fact, I've never seen one that has the "N" casting number suffix indicating that it's nodular iron. The once-available SERVICE replacement flywheel, GM #366860 (casting 366861), was a nodular iron flywheel. Every example I've seen of this flywheel has had the "N" suffix.

I understand. I still think the LUK is the best game in town for my L79.

Gary

[Gary J.]

Re: 66 427 Fly Wheel

Thought I would share this information. Just replace the flywheel, clutch, pressure plate, throw out bearing any pilot bearing in a '63 Corvette this week. Did it with motor still in the car, glutton for punishment. The old set up was chattering but not not bad. I purchased everything from my local NAPA store which was LUK brand. I did upgrade the throw out bearing, just didn't like the one supplied with the kit, which may have been fine, but just didn't want to take that chance. Happy to report it is as smooth as getting out of bed in Trump Tower with silk sheets!

[Jim D.]

Re: 66 427 Fly Wheel

Thought I would share this information. Just replace the flywheel, clutch, pressure plate, throw out bearing any pilot bearing in a '63 Corvette this week. Did it with motor still in the car, glutton for punishment. The old set up was chattering but not not bad. I purchased everything from my local NAPA store which was LUK brand. I did upgrade the throw out bearing, just didn't like the one supplied with the kit, which may have been fine, but just didn't want to take that chance. Happy to report it is as smooth as getting out of bed in Trump Tower with silk sheets!

The one included in the LUK kit is most likely superior to what you thought was an "upgrade". I've installed several of their composite T/O bearings, some in service for 10+ years, and have never had a problem with any of them.

[Anthony P.]

Re: 66 427 Fly Wheel

Recieved my GM flywheel in a GM box, compared to the original and it appears to be Identical, when I miced the thickness the new one was .022 thicker then the one original that was machined 1 time that I now of. Installed it and asmbled the bell housing, inspection plate, put the tranny on and dropped it in the car Sunday. I'm adjusting shift linkage tonight and the clutch shaft and rods will be installed tonight as well. I will report back on the clutch "feel" and geometry of the rods this week.