Heavy duty clutch question

[Keith B.]

What were the components that made up a HD clutch?
153 or 168 flywheel?
10.4 or 11in clutch?
Single disc or dual disc clutch?

If a HD clutch included the larger 168 teeth flywheel, then it would have had a 621 style bell housing.
If it included the smaller (maybe light weight???) 153 teeth flywheel, then it would have had the 403 style bell housing.

Last, starter. The 153 teeth flywheel would have used a starter (hi-torque version???) with a nose that had the straight across bolt pattern.
A 168 teeth flywheel would use a starter with a cast iron nose and staggered bolt pattern.

SOOOOOOOOOOOOO, who knows for sure (maybe has an original car?) what components were included in a HD clutch?
Also, would a Chevelle, Corvette, Camaro, Nova with the HD clutch have had the same components?
Who knows for sure?

this was posted on a Chevelle forum and no one really has an answer. so can one help out

[David B.]

Re: Heavy duty clutch question

I believe I have an NOS HD clutch assembly still in the box. Can you provide a part number to verify?

[Keith B.]

Re: Heavy duty clutch question

Part numbers are what the person was looking for along with descriptions of what's different

[Ray K.]

Re: Heavy duty clutch question

Keith,

Corvette 1967 -69 H D clutch single disc
Flywheel 3866735 153 teeth
Cl Disc 3886059 10.4"
P Plate 3886066 10.4"
Cl Hsg 3858403

Corvette 1969 H. D. clutch dual disc
Flywheel 3955151 153 teeth
Cl Disc 3959176 10.4" ( 2 )
P Plate 3959175 10.4"
Cl Hsg 3858403

Chevelle's & Camaro's did not use the Corvette components. However, they did have an option to upgrade a 10" or 10.4" clutch assembly to an 11" unit which was their H. D. clutch option. This option change would change the clutch housing from the #403 to the #621 to accommodate the larger flywheel.

Ray

[Mark M.]

Re: Heavy duty clutch question

The MA6 dual disc uses a special flywheel which brings the clutch assembly closer to the engine. It's 168 tooth using the 621 housing. The 69 used a 10 spline pair of discs and the flywheel was internally balanced. It was available on the L71 and L89 engines in 69. The 71 version used on LS6 option used 26 spline discs and an externally balanced flywheel. The same 71 clutch was used in Oldsmobile W37 option for 455 HO which had it's own special flywheel.

[Joe L.]

Re: Heavy duty clutch question

I believe I have an NOS HD clutch assembly still in the box. Can you provide a part number to verify?

David------


If by "assembly" you are referring to an assembly which includes both pressure plate assembly and friction disc, I do not think that GM ever supplied such an assembly in SERVICE except, possibly, through GM performance Parts and this would not have included PRODUCTION HD components.

[Joe L.]

Re: Heavy duty clutch question

Keith,

Corvette 1967 -69 H D clutch single disc
Flywheel 3866735 153 teeth
Cl Disc 3886059 10.4"
P Plate 3886066 10.4"
Cl Hsg 3858403

Corvette 1969 H. D. clutch dual disc
Flywheel 3955151 153 teeth
Cl Disc 3959176 10.4" ( 2 )
P Plate 3959175 10.4"
Cl Hsg 3858403

Chevelle's & Camaro's did not use the Corvette components. However, they did have an option to upgrade a 10" or 10.4" clutch assembly to an 11" unit which was their H. D. clutch option. This option change would change the clutch housing from the #403 to the #621 to accommodate the larger flywheel.

Ray

Ray------

The 1967-69 L-88/ZL-1 clutch was also used on 1970-72 ZR-1 except that for 1971-72 the clutch disc changed to 26 spline. These clutches were not used on any other Corvette application or any other Chevrolet application (except possibly COPO 1969 Camaros with ZL-1).

The 1969 dual disc HD clutch (RPO MA-6) available only on L-71/L-89 was also used on 1971 LS-6 as the standard clutch. Once again, the only difference from 1969 was the 26 spline friction disc (versus 10 spline for 1969). These clutches were not used for any other Corvette or Chevrolet application.

Also, I believe the dual disc HD clutch used a 14" flywheel with '621 bellhousing.

[David B.]

Re: Heavy duty clutch question

David------


If by "assembly" you are referring to an assembly which includes both pressure plate assembly and friction disc, I do not think that GM ever supplied such an assembly in SERVICE except, possibly, through GM performance Parts and this would not have included PRODUCTION HD components.

Found HD clutch assemblies (had 2) yesterday. They were both too high on a pallet rack to inspect however I do remember they included all components including flywheel. Part number is Gr. 0.859 10054110. A quick check indicates they are listed for '90, '91 ZR1 Corvettes. Not sure of their history but I think I got these along with '89 Corvette challenge series engines. Can pull down to inspect if interested.

[Joe L.]

Re: Heavy duty clutch question

Found HD clutch assemblies (had 2) yesterday. They were both too high on a pallet rack to inspect however I do remember they included all components including flywheel. Part number is Gr. 0.859 10054110. A quick check indicates they are listed for '90, '91 ZR1 Corvettes. Not sure of their history but I think I got these along with '89 Corvette challenge series engines. Can pull down to inspect if interested.

David------


GM #10054110 is catalogued as the standard pressure plate assembly applicable to 1990-1991 Corvette with LT5 engine. It remains available from GM to this very day with a current GM list price of $466.37. As far as I can determine, it includes only the pressure plate and cover.

Flywheels for LT-5 engines as well as 1989-96 L98/LT1/LT4 with manual trans were "dual mass" and very expensive. In fact, the flywheel for the LT5, last available under GM #10174481, carried a GM list price of $1113.00 as of the year 2000 and is long-since GM-discontinued..

[Mark F.]

Re: Heavy duty clutch question

David------Flywheels for LT-5 engines as well as 1989-96 L98/LT1/LT4 with manual trans were "dual mass" and very expensive. In fact, the flywheel for the LT5, last available under GM #10174481, carried a GM list price of $1113.00 as of the year 2000 and is long-since GM-discontinued..

You gotta luv this TDB ! always learning something new every so often...

I never heard of a dual-mass flywheel, so I did a little research and it seems they work best at low RPM and in engines with a low number of cylinders.

My '67 L68 "lumbers" and "gently rocks" in neutral after warmed up @ ~750 RPM...definitely smooths out @ 1,500 RPM.

Were the Corvettes that had those DMFs particularly susceptible to "lumpiness"(?) and that's why they went w/ the DMFs ?
Do they still equip any Corvettes with DMFs ?
If not, why not ? horsepower and torque seem to keep climbing...

After looking at some cutaways, they certainly look complicated.
I wonder what their failure rates were - and man, if one of those springs broke, I wonder what that would do to the crank ?

[Joe L.]

Re: Heavy duty clutch question

You gotta luv this TDB ! always learning something new every so often...

I never heard of a dual-mass flywheel, so I did a little research and it seems they work best at low RPM and in engines with a low number of cylinders.

My '67 L68 "lumbers" and "gently rocks" in neutral after warmed up @ ~750 RPM...definitely smooths out @ 1,500 RPM.

Were the Corvettes that had those DMFs particularly susceptible to "lumpiness"(?) and that's why they went w/ the DMFs ?
Do they still equip any Corvettes with DMFs ?
If not, why not ? horsepower and torque seem to keep climbing...

After looking at some cutaways, they certainly look complicated.
I wonder what their failure rates were - and man, if one of those springs broke, I wonder what that would do to the crank ?

Mark------


No other Corvette I am aware of utilized a dual mass flywheel. I believe it was limited to the applications I previously mentioned. It was somehow related to the ZF 6 speed transmission used exclusively for those same applications. As I vaguely recall, it was used to eliminate an idle "clattering" sound. If so, it did not resolve the problem because I can tell you, for certain, that there has always existed a mild idle "clattering" sound with my original owner 1992.

As I seem to recall, the Corvette dual mass flywheel uses an elastomer "coupling" between the masses is not surfaceable. So, if the surface was damaged, it had to be replaced. As I also mentioned, these flywheels were very expensive and all have been discontinued for a long time. There is no reproduction or aftermarket direct replacement that I know of. Typically, if replacement is required, a single mass (i.e. conventional style) flywheel designed for the application is used. How well these perform in replacement I do not know.

Some foreign cars use dual mass flywheels, mostly of different design than the Corvette flywheels.

[Ray K.]

Re: Heavy duty clutch question

Joe,

Thanks for the confirmation. Yes, I was very aware that the 67-69 clutch was used for The ZR-1's and that the spline changed to the the 26 involute spline. It did not seem to me that this was the time frame that Keith was referring to so I did not provide the details.

Ray

[Duke W.]

Re: Heavy duty clutch question

So-called "dual mass" flywheels are essentially like typical front torsional dampers, and their purpose is to damp certain torsional vibrations. What Joe mentioned as "clattering" I believe is also described as "gear rattle", which is a torsional vibration in the gearbox that creates a rattling sound, usually at very low revs under load, and sometime at idle.

For example, my '88 Mercedes 190E 2.6 special order 5-speed exhibits "gear rattle" at idle when the AC compressor is engaged. The idle stabilization system maintains the normal idle of 700, but for some strange reason the transmission goes into a torsional vibration mode that causes a noticeable rattling sound. It's not a reliability issue, just cosmetic. I could eliminate it with the throttle by raising idle speed to about 800 or declutching.

I believe later year models got a dual mass flywheel to address the issue, but I'm glad mine has a plain old flywheel, because from what I've heard these dual mass flywheels lack durability and are VERY expensive to replace, but in most cases a reliable single mass flywheel from another model will work, but might cause some gear rattle under some operating conditions.

Duke

[David B.]

Re: Heavy duty clutch question

Curiosity got the best of me this morning so I took down and removed contents of box marked 10054110. Heavy as hell! Contained flywheel with an attached plate along with entire clutch assembly. Flywheel cast date FKG8 (1988) cast #1204074 00 153 teeth. Clutch assy. ink stamped 04N8 and GM 10085207. A check with Chevy dealer (located behind my shop) mentioned "Dual Mass" Can not buy the flywheel but clutch assembly still available. Part # has been superceded at least 4 times. I photographed contents but not computer smart enough to post.

[Joe L.]

Re: Heavy duty clutch question

Curiosity got the best of me this morning so I took down and removed contents of box marked 10054110. Heavy as hell! Contained flywheel with an attached plate along with entire clutch assembly. Flywheel cast date FKG8 (1988) cast #1204074 00 153 teeth. Clutch assy. ink stamped 04N8 and GM 10085207. A check with Chevy dealer (located behind my shop) mentioned "Dual Mass" Can not buy the flywheel but clutch assembly still available. Part # has been superceded at least 4 times. I photographed contents but not computer smart enough to post.

David------


I'd love to see a photo of the flywheel!

Also, and as I mentioned, my information says the 10054110 is just "plate and cover". If it does, in fact, contain a dual mass flywheel, it's a fabulous bargain as the dual mass flywheel alone for the LT5 application carried a $1113 GM list price in the year 2000.