69 rag joint
The lastest discussion about a 67 rag joint got me thinking that maybe my 69 should also have those black rubber/plastic "guides" on the "studs"...so should it? I always thought that the 67-69 rag joints were the same but maybe I'm wrong on this.
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Re: 69 rag joint
Greg-----
The 1967-69 steering couplings are "functionally interchangeable" but they are not the same. For one thing, the 67-68 couplings were of GM #5699250. The 1969 coupling (from start-of-production to about October, November or December, 1969) was GM #7806391. There were probably also some variations even within these part numbers which Jim Shea could probably provide more information on.
A very curious thing occurred with respect to the two part numbers mentioned above. The GM #5699250 was discontinued without supercession in January, 1970. Sometime during 1969, the 7806391 became the CATALOGED replacement for 67-68 applications. However, the 7806391 never OFFICIALLY replaced the 5699250 through supercession. Why this occurred this way I can only guess. It sort of "sniffs out" like a "legal issue" inasmuch as steering component parts probably have "special liability" issues associated with them.
The GM #7806391 remains the SERVICE coupling for 67-E69 Corvettes to this day.In Appreciation of John Hinckley -
Re: 69 rag joint
Thanks Joe that helps.
I guess the reason for the part number change might even be something as trivial as omitting those little rubber guides for the 7806391.
Did your steering coupler ever have them? I wonder if they were used on any 68s or if they were only used on C2s?Comment
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Re: 69 rag joint
I have the 7806391 drawing. It was released for production at Saginaw Steering Gear Division on March 11, 1968. That date is not the date that it started being used in Corvette production. It was the date that Saginaw engineering released it to the Saginaw manufacturing plant.
The March 1968 Saginaw release would most likely allow for a 1969 Corvette Start of Production date.
This part went into production with a coupling disc with 7 laminations of rubber and neoprene rubber. There was a brass grounding strip encircling the center of the assembly. It had two different size attaching bolts (3/8-24 UNF and 5/16-24 UNF) with extensions on the hex head that were 0.42 inch diameter and extended 0.31 inch above the hex.
In April 1968 plastic alignment spacers were added. There is no mention that rubber "boots" were ever part of this assembly.
As I recall the rubber "boot" type parts that went on the rivet stop pins were used in 1967 (and maybe 1968) to eliminate rattle between the flex coupling pins and the column flange. I think that they found that if they used the plastic alignment spacers and followed the mandatory steering column assembly instructions in the AIM the rubber boots were not needed.
In Feb 1971 the grounding strip was eliminated and wire mesh was added to the laminated rubber coupling. Now by this time the flat had been added to the wormshaft on the gear. (This was a flex coupling assembly with a full serrations and no flat broached into the flange.) So this was most likely just an update to standardize service parts at Saginaw. (You get no indication from the drawing as to when it stopped being used in production.)
I do not have the 5699250 Coupling & Flange Assembly drawing.
JimComment
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Re: 69 rag joint
Joe,
I do not have 5699250, I will try to get a drawing from Saginaw.
We pretty much know the history of 7806391.
I don't have 7808553. Although I suspect that it added the flat to the flange and most likely added the capturing strap reinforcement. It also eliminated the long headed bolts. I will try to get this drawing.
I am quite sure that 7813351 was the first Corvette Flange & Coupling Assembly with the screen ground. I will try to get this drawing.
I have the 7818568 drawing. It was engineering released at Saginaw in November 1973. You indicate that it was first used on the Corvette in 1975. This assembly now services from 1969L through 1982. The only difference that I can surmise between the 7813351 and the 7818568 is the type of washers that held the bolts in place. I am suprised that such a minor change as that would have triggered a part number change.
Once the flange & coupling assembly was bolted to the column flange the bolt retainers would be buried between the two parts. That would essentially make the 7813351 indistinguishable from 7818568 unless you unbolted them.
I don't know if I mentioned the following facts. I don't believe that Saginaw manufactures the flexible couplings any longer. Hopefully they have a dedicated source where they can follow production of the parts. Also Delphi Saginaw is in the process of being sold. It is getting harder to find current engineers that have much background with this part. Also the type of information that I require is in the archives. The engineers that I deal with have a lot more pressing work than digging through the 35+ year old archives for drawings and parts lists. I have to be careful that I don't wear out my welcome.
Jim SheaComment
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Re: 69 rag joint
Jim-----
The model years of use for the various couplers that I have mentioned is very approximate. It is hard for me to come up with exact change-over dates on these couplers. The 7808553 was discontinued from SERVICE and replaced by the 7813351 in February, 1972. The 7813351 was discontinued from SERVICE in May, 1975 and replaced by the 7818568. While SERVICE change dates often imply an approximate date for a PRODUCTION change, that's not always the case. It may be that GMSPO had a large, slow-moving inventory of the 7813351 and it took until 1975 to exhaust it. However, if the 7818568 had been used in PRODUCTION for the 1974 model year, I would have expected it to show up in SERVICE for that model year and then supercede the 7813351 for earlier models when the GMSPO inventory of that piece was exhausted. The first SERVICE availability I show for the 7818568 is late 1974 for the 1975 model year.
As you are likely aware, the 7818568 coupler was not unique to Corvettes. It was used for many 1970-75 Chevrolet models as well as 1976-79 Chevrolet Nova. It was also used for similar Buick, Oldsmobile (RIP), and Pontiac models of the 70-79 period. However, long before now, I would expect that SERVICE demand for these couplers has been seriously reduced. So, it would not surprise me, at all, that GMSPO has gone to some alternate source for these; DELPHI-Saginaw might not have been too interested in manufacturing such a low volume piece. The last examples I purchased did appear to be of very high quality, though. However, it's been quite awhile since I got these.
Regarding your comment that you were surprised that such a small change in the coupler would have triggered a part number change: one of the "eternal mysteries" for me is the seeming "incongruity" of part changes versus part number changes. At times, it seems like when a part undergoes the most minor of changes, the part number changes. At other times, a part is greatly revised and no part number change occurs. I've never been able to figure out a "method to this madness". I don't doubt that there are some underlying principles and internal policy on the matter, but I've just never been able to figure it out.
I can COMPLETELY understand what you're saying about trying to get information from your sources. I do exactly the same thing, myself. I try very hard to not "overburden" and, when I need to get outside help, reserve my inquiries for very important issues. Like you say, I don't want to wear out my welcome.In Appreciation of John HinckleyComment
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Re: 69 rag joint
We were supposed to go by the 3 F's when deciding the need to change a part number, (Fit, Form, or Function).
We used to host a GM Steering Coordination Meeting at Saginaw once per month. Representatives from all the car & truck divisions, GM Parts, some of the other component divisions, etc attended. The one big concern was that the car plants could never track the introduction of a change unless there was a part number change at the same time. The concern was "what if we have to go out and get them?"
Usually if you had a Feb or March release date at Saginaw you could expect a regular model year SOP. But the only way to find out the planned introduction date would be to locate the Saginaw Engineering Notice. The EN would indicate that information. That document initiated all of the engineering and planning to make the drawing change go into affect at Saginaw. Usually there would be a corresponding piece of paperwork at the Car Divisions as well.
With regard to the flexible couplings in the 1967-1969 timeframe, there was a lot of change activity. There was great concern about the energy absorbing steering columns causing the flex couplings to be pulled apart. That is why in 1969 there were some "long headed bolts" introduced. Later in that year, when the "capturing strap reinforcement" was introduced there was no longer a need for those special bolts.
There was a huge campaign right after the EA steering columns were introduced. It was found that steering column shafts could break right at the lower column bearing because of high bending stresses. Part of the problem was that the assembly plants were not aligning the steering column to the flexible coupling within certain limits. (The flexible coupling came into the assembly plants already installed on the steering gear.) The plastic alignment spacers were added to the 7806391 assembly the end of April, 1968 only one month after the official Engineering Release date. Now this one could have been an ASAP introduction (scrap or send old stock back for rework, etc.) because of the steering shaft concerns.
One month after the alignment spacers were added to the flex coupling drawing the following note was also added.
"These spacers are for alignment purposes only and mut be removed after final assembly with mating flange. Pins must not contact upper flange in either radial or axial direction after assembly."
This note was a Saginaw cya note because the car division plants never really ever got to see the flex coupling drawing (the flex coupling was part of the gear assembly.)
With the introduction of the screen mesh coupling disc around 1972, the ground straps and wires were eliminated.
Jim SheaComment
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Re: 69 rag joint
At the Chevrolet Pilot Line in Flint, we went to great lengths in our 1967 pre-production presentations and build sessions for the plants to emphasize the importance of following the "mandatory assembly sequence" for the new energy-absorbing steering columns outlined in detail by Engineering in UPC 9 in the Assembly Manuals; if that sequence wasn't followed exactly, the axes of the column shaft, rag joint, and gear input shaft wouldn't be properly aligned and could affect column collapse. This was a "big deal" in those days, and I remember the introduction of the throwaway plastic spacers and the torque controls on the bolts through the injected-in-place shear capsules on the column mounting bracket.Comment
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Re: 69 rag joint
Hi John,
Is the page detailing the specific "mandatory assembly sequence" for the steering column MISSING from the common 1967 Assembly Manual?
The 1966 AIM has the "Mast Jacket & Steering Shaft Asm. Sequence" on UPC 9-A4. It also has pages 9-A1 and 9-A2 which are missing from the 1967 AIM (but should be included/added for '67, according to posts in the archives).
I have two copies of the 1967 AIM, both have "(Steering) Column and Support Assembly" on page 9-A4, and the very next page is 10-A1 ("Wheels & Tires - Contents"). Neither 1967 AIM shows anything specific about the steering column assembly sequence.
The 1968 AIM does include a separate "Steering Column Mandatory Installation Sequence" page on UPC 9-A6, but there is no equivalent page 9-A6 (or 9-A5) in the 1967 AIM. Is the 1968 steering column installation sequence (9-A6) applicable to the 1967 model year, and therefore this 1968 page should also be added to the 1967 AIM?
Or are my copies of the 1967 AIM (both are older versions) missing a 1967-specific page that should be there, on the '67 steering column installation sequence?Comment
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Re: 69 rag joint
Scott -
Never could figure out why Engineering didn't release a Mandatory Assembly Sequence sheet for the '67 Corvette A.I.M. (your manuals are complete in that regard - no sequence sheet). Every other car line A.I.M. had it laid out in gory detail in 1967, with the text covering almost a whole page.Comment
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Re: 69 rag joint
Considering that the standard steering column for 1967-68 are so similar (if my understanding is correct), can/should the installation procedure from the 1968 AIM be applied to the 1967 model, or are there enough differences that it would cause more harm than help?
(attached below: 1968 AIM, page 9-6A, Mandatory Assembly Sequence)Comment
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Re: 69 rag joint
The clamp design on the lower end of the column is somewhat different 1967 to 1968. The basic procudure is the same however.
JimComment
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