L46-M20 replacement flywheel

[Bill L.]

This is a follow up to a thread from last year.

Now that I have the transmission and clutch out, I found the flywheel has some pretty deep grooves. Rather than resurface I would like to replace the flywheel. Does anyone make a high quality Made in USA flywheel that is either the same as OEM or an upgrade? Maybe a flywheel that is a little lighter?

I read previous threads that indicated the LUK was the same as OEM or the closest out there. However, it looks like their flywheels are made in China now.

Any suggestions are appreciated.

Bill

[Joe L.]

Re: L46-M20 replacement flywheel

This is a follow up to a thread from last year.

Now that I have the transmission and clutch out, I found the flywheel has some pretty deep grooves. Rather than resurface I would like to replace the flywheel. Does anyone make a high quality Made in USA flywheel that is either the same as OEM or an upgrade? Maybe a flywheel that is a little lighter?

I read previous threads that indicated the LUK was the same as OEM or the closest out there. However, it looks like their flywheels are made in China now.

Any suggestions are appreciated.

Bill

Bill-----

You can still obtain one from GM under GM #3991469. Where it's currently manufactured I do not know.

[Bill L.]

Re: L46-M20 replacement flywheel

Thank you Joe. For some reason I thought they were discontinued.

Once procured do I need to do anything as far as balancing or should it be good to go out of the box?

Bill

[Duke W.]

Re: L46-M20 replacement flywheel

You could also go with the 18-pound current L-88 replacement flywheel that is listed in the GMPP catalog, but that would also require a 10.4" rather than 11.0" clutch assembly. The decision should be based on your driving conditions and environment. If you live in a hilly area or your total first gear multiplication is less than about 8:1, I'd recommend the original type 30-pound flywheel.

OE flywheels and clutch covers had an "X" stamped on each and they should be lined up as close as possible, but I don't know about the new replacements. If they're not stamped it would be a good idea to have them balanced. The flywheel should be neutral balanced, then the clutch assembly should be bolted on and any balance weight added or subtracted from the clutch cover as necessary to balance the assembly. Then both the cover and flywheel should be stamped with an X to indicate proper indexing.

Duke

[Joe L.]

Re: L46-M20 replacement flywheel

You could also go with the 18-pound current L-88 replacement flywheel that is listed in the GMPP catalog, but that would also require a 10.4" rather than 11.0" clutch assembly. The decision should be based on your driving conditions and environment. If you live in a hilly area or your total first gear multiplication is less than about 8:1, I'd recommend the original type 30-pound flywheel.

OE flywheels and clutch covers had an "X" stamped on each and they should be lined up as close as possible, but I don't know about the new replacements. If they're not stamped it would be a good idea to have them balanced. The flywheel should be neutral balanced, then the clutch assembly should be bolted on and any balance weight added or subtracted from the clutch cover as necessary to balance the assembly. Then both the cover and flywheel should be stamped with an X to indicate proper indexing.

Duke

Duke-----


Changing to the 12-3/4" flywheel also requires changing the bellhousing and starter. Also, SERVICE flywheels and clutch assemblies do not have the "X" marks. That is found only on PRODUCTION pieces. If either the original clutch or flywheel is replaced, the "X" mark on the non-replaced, original piece is meaningless.

[Joe L.]

Re: L46-M20 replacement flywheel

Thank you Joe. For some reason I thought they were discontinued.

Once procured do I need to do anything as far as balancing or should it be good to go out of the box?

Bill

Bill-----

The flywheel should be neutral-balanced out-of-the-box. However, I would highly recommend having the flywheel and clutch assembly custom-balanced by a competent balancing shop.

[Bill L.]

Re: L46-M20 replacement flywheel

I will heed the advice. Thanks Joe and Duke.

[Duke W.]

Re: L46-M20 replacement flywheel

Sorry, guys. I forgot about the bell housing/starter issue when changing flywheel/clutch size. Duuuuuuh...

...probably best to stick with the original size flywheel/clutch, especially if the starter and bell housing are OE correct for the engine. The L-46 is a nice engine configuration.

Duke

[Bill L.]

Re: L46-M20 replacement flywheel

HI Duke,

It is a very original example of a 70 L46 Convertible so I am planning to keep it stock when ever possible. Interestingly I felt that something was a bit amiss with the clutch when I was driving. Once apart, found the disc is worn to the rivets, the throw out bearing is pretty dry, the flywheel has some fairly deep grooves, the clutch fork ball stud spring retainer was broken, and the ball stud has quite a bit of wear. Other than that it looked good. I am really looking forward to getting it right.

Thanks for all your help.

Bill

[Tom P.]

Re: L46-M20 replacement flywheel

Just as an added comment.
FUNCTIONALLY, any 14in diameter, 168 teeth NEUTRAL BALANCE (key words there!!!!) flywheel, with a bolt pattern for an 11in clutch, from ANY Chevy engine up through 1985 (86-later changed for 1-piece rear main seal crankshaft), will work just fine. In the past several years, I have picked up many Chevy flywheels (BOTH neutral and EXternal balance) at swap meets for $25-50. Two weeks ago, I picked up two for $35!!!! Both were in GREAT shape, no grooves or gouges.

Casting number???????????????? Heck, not even the most scrutnizing judge will be able to see the casting number.