'69 Turbo 400 code?

[SS427]

Stan, I too found the information last night (had it all the time and didn't know it!) My information also listed the "Y" code for 335 hp. I am clueless as well and have owned numerous 335 hp motors, none of which had the "Y" code. If true, I suspect it was so that the car could get out of it's own way. The transmission likely comensated for the low horsepower of the engine.

I hope to get all the numbers off this transmission in the near future. I am also curious to see if it has 6 torque convertor bolts. Incedently, this is in an Impala.

[Rowdy Rat]

Rick,

I figured it was a "big" Chevy from your previous posts... I gather that this is a 1969 L-72 car? Very cool if it is! I've been hunting for a 1969 L-72 Biscayne, Bel Air, or Impala for a while now... Not many out there as I'm sure you're aware. I'd love to hear more about your car when you get the opportunity.

I don't disagree with what you and others have located in print about the "CY" transmission usage with the 427/335. I would guess that it might be a mistake (unless the "CY" transmission used in this application is VERY different than the other applications listed). You mentioned that that this is a low horsepower engine; it is also a low rpm engine. I'm sure that someone will post the redline, but I'd be willing to bet that it is 5,500 rpm or less. With a redline (and powerband) that low, why do you need a transmission that shifts at 6200+ rpm? Logically it doesn't make much sense. I'd like to hear some feedback on this point as well...

Regards,

Stan Falenski

[Mr70]

My information shows the 1969 427/335HP Chevrolet as getting the CQ Suffix.Not the CY.
It states this code for only that L-36 engine.
1968 list shows CE as the trans.for Chevelle-Camaro with an L-78 engine.CL for the 427 Corvette.No CY or CX in 1968.
The CY trans. was avaiable before the CX was in 1969.
The CX was the trans.in the letter dated 7/12/68 in Colvins book.It was used,as the letter states,in 1969 Special Hi-perf Engine Novas,Chevelles,Camaros,Chevrolet,and Corvette.It looks COPO specific and L-72 Impala or Corvette L-71 and up also got it.
I have seen the CX in a 69 COPO chevelle with a 4:10 Posi.I believe it was specific to these rear ratio cars in 1969.

In 1970 the CY was the trans.of choice for the Hi-perf LS-6 engine.All the LS-6 M40 buildsheets have the CY code available with ANY rear ratio.Not just 4:10.Although I think the 1970 Corvette could get the CX still.Any Corvette documentation out there to prove this?


[Edited by mr70 (08-16-2001 at 01:58 PM).]

[SS427]

mr70,
The car was built in December '69 which might correlate with your statement about CY preceding CX in '69. The rear is an 3:55 large ring posi and I am positive it is the original rearend.

I need to get more numbers off the car, see if it had a tach (I don't think I would have missed that ugly thing) and check the speedo for the max speed. Many of the L-72's I have seen had 140 speedos in them. I still need to find a build sheet somewhere!

[Rowdy Rat]

<BLOCKQUOTE><font size="1" face="">quote:</font><HR>My information shows the 1969 427/335HP Chevrolet as getting the CQ Suffix.Not the CY.It states this code for only that L-36 engine.<HR></BLOCKQUOTE>

That certainly makes a lot more sense...

<BLOCKQUOTE><font size="1" face="">quote:</font><HR>The CX was the trans.in the letter dated 7/12/68 in Colvins book.It was used,as the letter states,in 1969 Special Hi-perf Engine Novas,Chevelles,Camaros,Chevrolet,and Corvette.It looks COPO specific and L-72 Impala or Corvette L-71 and up also got it.
I have seen the CX in a 69 COPO chevelle with a 4:10 Posi.I believe it was specific to these rear ratio cars in 1969.
In 1970 the CY was the trans.of choice for the Hi-perf LS-6 engine.All the LS-6 M40 buildsheets have the CY code available with ANY rear ratio.Not just 4:10.Although I think the 1970 Corvette could get the CX still.Any Corvette documentation out there to prove this?<HR></BLOCKQUOTE>

I've had the opportunity to look at quite a few 1969 Corvettes equipped with the high performance engines (L71, L89, and L88) and automatic transmission. Without exception, they have all had a "CY" code. If "CX" was somehow linked to a 4.10 rear axle ratio, that would certainly explain why the Corvettes didn't receive it. As I mentioned previously, the highest numerical ratio that could be ordered with the big block and automatic transmission was 3.36; the high performance 427s received a "special" differential with its own code of "AX" (or "CAX" depending upon how late in 1969 the car was built). As far as 1970, my understanding is that had the LS7 Corvette gone into production, it would have used the "CY" transmission along with the same "CAX" rear axle (at least the power team chart for 1970 Corvettes show a 3.36 ratio as the "performance" axle with the the LS7/M40 combination).

You and Joe both touched on a possible transmission - rear axle relationship... Could this have determined which was used for a given application?

Regards,

Stan

[William]

Stan, the CX & CY use converter 8626358. They also use the same valve body 8624854, but different control valve assemblies.

CX uses case 8623457, valve assy 8626613.

CY uses case 8626058, valve assy 8626367.

CX & CY have other internal parts not used on other versions. The cases aren't unique.

[Ray Morrison]

William,

The casting number on my CY coded 400 is 8623462, the short tail housing is 8624486.

Stan, I still believe the Transmission Identification sheet of 7-12-68 is for the CY code transmission as they came before the CX. Could the X on this document be the reason you think it is for the CX? The Gibb cars were built with a redesigned Turbo 400 for racing purposes. These first redesigned 400's were called experimental automatics (X). These transmissions are believed to be the first automatics built for Chevrolet with a high horsepower, solid lifter engine. According to documents I have, 39 pages of Hydramatic Production Parts list, the CX code was added on 10-25-68, meaning they were built for 69 cars. Would Turbohydramtic have issued this letter this far in advance on building the CX? If any of you have the November 1968 issue of Popular Hot Rodding and the article about the Harrell Novas, notice in this article they refer to the experimental transmission as 69's, however, we now know the Gibb cars were built on the tail end of 68 with these transmissions as a COPO Nova, which was never mentioned in the article. Both the Cy and CX coded transmissions shared likness in that they were built for high performance applications in 68 & 69, L-78's, L-72's, etc. Could some of the extra experimental transmissions have been built for Gibb, or someone else? Since Mark Fuss has a Harrell Nova that is an automatic, Which is not one of the 50 Gibb COPO's, but could Harrell have built his car with one of these? His Nova supports an L-88 engine. How many other Experimental Automatics could have been built for warranty? There are all kinds of questions that are still unanswered?

Ray