66 L36 Harmonic Balancer, Steering coupler

[John M.]

The L72 balancer is about 8" in diameter and according to Paragon the L36 is about 6.75". Is this correct? I think the judging manual says both are 8"? This car has the 6.75".
The judging manual says the telecolumn steering coupler is smaller than the standard. Is this correct. The one on this car is a bit longer.
Thanks
JB McRae 30025

[John H.]

Re: 66 L36 Harmonic Balancer, Steering coupler

The L72 balancer is about 8" in diameter and according to Paragon the L36 is about 6.75". Is this correct? I think the judging manual says both are 8"? This car has the 6.75".

Yes, that's correct - the solid-lifter BB took an 8" balancer, and the hydraulic-lifter BB took a 7" balancer.

[John M.]

Re: 66 L36 Harmonic Balancer, Steering coupler

Thank you John. Here's another unrelated question. I've just finished rebuilding and installing a 67 327-300. The rebuild includes a special cam designed by Duke Williams, pocket porting, port matching, CR control, etc. The car runs very strong but I've run into a problem with the original Holley. I can't get the idle down to 500 RPM. The idle screw is completely backed off at about 650. When I rebuilt this carb I noticed a screw under the throttle body that controls the closed position of the secondaries. I didn't touch the as found position but was wondering if this might be the problem? Any other thoughts?

[John H.]

Re: 66 L36 Harmonic Balancer, Steering coupler

John -

The factory setting of that secondary throttle plate stop screw is to back it out until the blades are fully closed against the bores, then turn it in exactly 1/2-turn.

[John M.]

Re: 66 L36 Harmonic Balancer, Steering coupler

Thanks again John. I'll check it out.
John

[Wayne M.]

Re: 66 L36 Harmonic Balancer, Steering coupler

The L72 balancer is about 8" in diameter and according to Paragon the L36 is about 6.75". Is this correct? I think the judging manual says both are 8"? This car has the 6.75".

John -- I have the harmonic balancer off a 325hp version of the 1965 BB (which I'm fairly certain is the same as the '66 L36), and it is EXACTLY 7.0" in diameter. No way it could be mistaken for 6.75".

[Joe L.]

Re: 66 L36 Harmonic Balancer, Steering coupler

John -- I have the harmonic balancer off a 325hp version of the 1965 BB (which I'm fairly certain is the same as the '66 L36), and it is EXACTLY 7.0" in diameter. No way it could be mistaken for 6.75".

Wayne and John-----


The 396 and 427 hydraulic lifter balancers were, indeed, 7" OD. I don't know of any, Corvette or otherwise, that were 6-3/4".

[John M.]

Re: 66 L36 Harmonic Balancer, Steering coupler

Thanks Guys,
The 6.75" was an "about" dimension. I was just wanting to make sure it wasn't the 8" like for the L72.
Does anyone know the difference in the steering couplers for standard and tele columns?
Thanks,
John

[Jim S.]

Re: 66 L36 Harmonic Balancer, Steering coupler

I have been in New Jersey with my daughter's family for the last week. I should be back in Michigan tonight. I have recently obtained drawings of the 1965-66 telescoping column and the standard (non-adjustable column) flexible couplings. I will look them up tonight and try to describe and/or scan them for the differences.

Jim

[John M.]

Re: 66 L36 Harmonic Balancer, Steering coupler

Thank you Jim, that's good news. We're putting this 66 coupe together without the luxury of having taken it apart so we'll probably have lots of questions for the NCRS crew as we move along.
John

[Page C.]

Re: 66 L36 Harmonic Balancer, Steering coupler

The steering coupler for the standard column is the same length on both sides of the rag joint. The tele column use a much shorter piece on the side closest to the steering box with the upper side the same as the standard coupler. Also note that all replacement rag joints that I have seen are 4 ply rather than the originals that were 8 ply.
Regards.
Page Campbell

[Joe L.]

Re: 66 L36 Harmonic Balancer, Steering coupler

The steering coupler for the standard column is the same length on both sides of the rag joint. The tele column use a much shorter piece on the side closest to the steering box with the upper side the same as the standard coupler. Also note that all replacement rag joints that I have seen are 4 ply rather than the originals that were 8 ply.
Regards.
Page Campbell

Page-----


Yes, that's my recollection, too. The 65-66 tele column coupling is configured somewhat similar to the 67-69 coupling rather than the 63-66 non-tele coupling. I have NOS examples of both these couplings but I REALLY don't want to dig them out for comparison ( I have a LOT of group 6 parts filled tote-bins and every one of them is HEAVY).

Jim's information will be definitive and better than anything I could come up with anyway (and, help preserve my back to "fight another day").

[Jim S.]

Re: 66 L36 Harmonic Balancer, Steering coupler

I am back in Saginaw and have taken a look at the drawings.

Interesting stuff. The two assembly drawings were made in the early 1960s with very little change or revisions through the years.

The flange assembly (5690809) used on the 1965-66 Corvette with a standard (non-adjustable) steering column was originally released for production at Saginaw in late 1961. It always had a rubber coupling consisting of seven laminations of cotton cloth and neoprene. Production parts always had a brass ground strip. Service parts manufactured after February 1971 should have seven ply couplings (basically the same construction) with a screen ground.

Now some real interesting things with respect to the flange assembly (5692974) used on 1965-66 Corvettes with telescoping columns. The drawing was released for production at Saginaw in 1963. It has the same seven lamination neoprene/cotton coupling as above. There is only one revision to the assembly drawing and that was made in 1975. The revision was some minor changes to the flange that attached to the steering gear. The flange assembly was never revised to the screen ground coupling. There is note on the assembly drawing that this flange assembly is to be painted black! There is no such note on the flange assembly drawing for the standard column. From this assembly drawing you would expect all service parts for the telescoping column flange assembly to be painted black and also have a brass ground strip.

Jim

[Michael H.]

Re: 66 L36 Harmonic Balancer, Steering coupler

There is note on the assembly drawing that this flange assembly is to be painted black!

Very interesting Jim. Thanks.

I found an NOS telly coupler in the box (tube, actually) years ago and it was natural, not painted black. I wonder if later service parts deleted the paint operation.

[Jim S.]

Re: 66 L36 Harmonic Balancer, Steering coupler

It would be interesting if any people with survivor vehicles could comment on the paint. I have to think that when in production, vehicles with telescoping columns would have had the flange assembly painted. The note goes on to say, "Paint in serrations and tapped holes must not be detrimental to function or assembly of part."

The telescoping steering column drawing does not indicate any paint at final assembly.

We like to think that service parts were manufactured exactly the same as production parts but even the OEM source (such as Saginaw) would update components to use the latest designs on their service orders (as long as it didn't affect fit, form, or function.) I know that we updated a lot of service flange assemblies to use the screen ground couplings and virtually got rid of the ground strips and ground wire assemblies because they were a pain to assemble.

One other comment: We like to think that a "released for production" date should give a pretty good benchmark as to when something went into production. However, at Saginaw it indicated that tool engineering was now authorized to go out and use the released engineering drawing(s) to spend money and tool up a part. This could mean that one year (or maybe just months) would lapse between the release date at Saginaw and the actual production date. At the same time the GM Car Division was expected to release those Saginaw drawings into their system so that the AIM and other Car Division engineering documents could be updated to document the change and alert the GM car assembly plants. Many times the Car Division documents lagged the Saginaw drawings by considerable amounts of time.

Many times it seemed that the General Motors system put the Car Divisions and the suppliers in a "chicken and egg" situation. The Car Divisions were the final authority on whether a change or a new component could be put into production. So Saginaw (or other suppliers) were not supposed to spend tooling money until authorized by the Car Division (who typically was footing the tooling bill.) However, the Car Division couldn't release the change until they had Saginaw drawings to release into their system. Saginaw technically couldn't make or change their drawings until authorized by the customer (the Car Divisions.)

In a lot of cases a common part (flange assemblies, steering gears, power steering pumps, etc) would need to be released by multiple Car Divisions (i.e. Chevrolet, Buick, Oldsmobile, etc). Saginaw technically had to wait until every affected Car Division had released the change. Needless to say this rarely happened exactly according to "the book."

Eventually General Motors went to a "Lead Division" concept. Oldsmobile was the lead division for steering. Then for common part changes Saginaw went to Oldsmobile who coordinated the change with the other GM car divisions. The lead division concept was in use when I took over the flexible coupling (flange assembly) engineering group in 1971. From my perspective, Chevrolet never completely bought into the lead division philosophy and with their volume of production vehicles they had a pretty hefty club.

Jim