Corkscrew

Did all 1969 L89's with manual trans come with the heavy duty clutch? It was my undestanding that they did, but I just read somewhere that the ma6 option was not available until mid 1969. A car that I saw recently was built early in the model year(October) and it has a LU engine suffix which indicates aluminum head, manual trans, and heavy duty clutch. No docs to refer to, so could this engine be original?

JC68

Corkscrew

The MA6 HD clutch option was not required with the L89 option. A vast majority of L89's were built without it.

The LP and LU engine code was for an L89 with 4 speed manual transmission.

The LT engine code was used for L89's with the MA6 HD clutch option.

John

Easy Mike

I believe that information comes from Bizzoco's book. As I recall, he mentions the dual disc clutch and says they were difficult to obtain.

WESCH

Hi

That is not what the BB says

the LT code is for L71 manual transmission
LU is for L89 manual transmission with heavy duty clutch
LP is for L89 with manual transmission ( no heavy duty clutch )

is the BB for 69 wrong ?

Rgds Günther

steersdad

Does anyone have the part numbers for the L89 heavy duty clutch, pressure plate, and flywheel?
If so, please PM me?
thanks

Rowdy Rat

This is the 1971 version of the GM dual disc clutch...



The 1969 version is similar, but is coarse spline input rather than fine spline on this 1971 version. The dual disc clutches also used a specific flywheel... One for the internally balanced 427 and one for the externally balanced 454.

The clutch was being used by GM as early as 1968 (there is mention of an L-78 Nova equipped with it in a Car & Driver article), but we don't see it as an available option until later in the 1969 model year. In 1969, it was an RPO for L-71/89 Corvettes, L-78/89 Camaros and Novas, and L-72 Impalas and Biscaynes. The fine spline version was used on 1971 LS-6 Corvettes and as an option on some 1971 Olds 442s. It was never used with the L-88/ZL-1 Corvettes or COPO Chevelles/Camaros.

Regards,

Stan Falenski

JC68

Günther

Sorry for the confusion. A lot of engine codes in 69. I can't read a table correctly and type at the same time, the NCRS guiding guide has:

LR = L71 manual transmission
LT = L71 Manual transmission plus MA6 HD clutch
LP = L89 manual transmission
LU = L89 manual transmission

They don't make a distinction in engine code on L89 cars equipped with MA6 and cars that are not.

John

Corkscrew

The clutch was being used by GM as early as 1968 (there is mention of an L-78 Nova equipped with it in a Car & Driver article), but we don't see it as an available option until later in the 1969 model year.

Regarding the above paragraph: Who is "we" and what time period qualifies as "later in the model year?"In the c3 registry I see at least two L88s built before late September. These all supposedly have ma6 included as standard equipment. And I found one other BB (serial number 702675) built Sep 28, 1968, that lists ma6 as an included option. If they were available on L88's, what kept them from being available in beginning 69 model year production? At this time, I do not have any C3 books to reference other than the Black Book, so any help you can provide will be much appreciated, as I am trying to determine an engine's authenticity. Also, is there any way to visually determine if there is an actual ma6 installed? Any link to that article available? Thanks, Bob

Rowdy Rat

Bob,

"We" includes those of us who have been looking at these model years (1968-1972) in detail for many, many years. It's not the last word by any means, but it is a good indication of what was available... Continued study of these cars always tends to turn up new information, but it also provides some standards that are typical of factory production. That is what I base my comments on.

No L-88 Corvette ever used the dual disc (MA-6) clutch. It used the lightweight 10.4" clutch/flywheel assembly in an attempt to keep rotating inertia to a minimum... Lousy for starting out from a dead start, but great in a road racing application (its intended purpose).

Same clutch was used in 1970-1972 ZR-1s and while I have no proof, probably 1971 ZR-2s as well.

As far as use in the L-71/L-89 goes...

Later in the model year refers to January/February 1969. That's where I have copies of documentation of and have seen real MA-6 equipped cars. Could the dual disc clutch been available earlier? Sure... It was used in the 1968 Nova I mentioned previously so it was being field tested late in the 1968 model year. In practice though, there isn't any evidence of it showing up early in the 1969 model year.

Regards,

Stan

Rowdy Rat

Posting a good, clear photo of the stamp pad would be a big help. Photos of any documentation as well as any details on the car would be helpful too.

Not to my knowledge. Of course, pulling the inspection plate would make clutch identification easy.

Car & Driver, August 1968 I believe. Near the end of the article, there is mention made of the Nova being equipped with an experimental twin disc clutch (they liked it a lot).

Regards,

Stan

Rowdy Rat

You can thank Joe Lucia for this...


It sounds like an MA-6 unit from what you describe. MA-6 discs did have "Veelok" stamped on them. However, I expect that many other clutches did, too.

Original PART numbers for the 1969 MA-6 were as follows:

flywheel-----GM #3955151

friction disc (2 required)----GM #3959176 (10 spline)

pressure plate assembly-----GM #3959175. This assembly includes the cover, dual pressure plate assembly, and ONE of the GM #3959176 friction discs.

The 1971 dual disc clutch used with all 4 speed equipped LS-6 used the following:

flywheel-----GM #3992094

friction discs (2 required)----GM #3993815 (26 spline)

pressure plate assembly------GM #3993814. This assembly includes cover, dual pressure plates, and ONE GM #3993815 friction disc.


The 3959175 and 3993814 were discontinued in July, 1972 and replaced by GM #231254. The latter assembly included NO friction discs and they both had to be obtained separately.

The GM #3955151 flywheel was discontinued in April, 1981 and the 3992094 flywheel was discontinued in July, 1983.

The GM #3959176 friction disc was discontinued in June, 1982 and the GM #3993815 friction disc was discontinued in October, 1985.

Finally, the GM #231254 pressure plate assembly was discontinued in November, 1988.

Regards,

Stan