[War eagle]

With the lower windshield grille removed, the wiper transmission linkage attaches with 2 screws at 2 locations. There is a third support drilled/threaded for another linkage but not used. Always speculated this was for another GM "A" body. I looked for the supports but they don`t show separately. The part called panel, shroud vent upper grp 12.804, 4411782 without a/c. probably included the supports. I looked in a chevelle MPC and the part does not cross to anything. You guys with a cutlass or skylark MPC might have the answer.The wiper transmission would also be different than the Tempest 4913654 RH and 4913655 LH. grp. 10.159. So what does the "empty" support fit?

[John V.]

If you notice, you will see that there is a stamped area to accommodate a 4th support to the passenger side, but no support installed.

Seeing that, it occurred to me that perhaps with a RH drive vehicle, the wiper linkage would be reversed and the unused support along with an added support in the 4th position would be used, along with a specific louvered panel.

I can't explain why Fisher would have provided the one unused support for all builds, that seems like a waste for the few RH drive builds especially if the 4th support was not also always provided.

But that is my best guess.

I figured the louvered panel was different for each Div. A body, but from what I see in early Chevy & Olds Parts Catalogs, the '64 Chevelle was different, but the '64 F85 used the same 4489189 (Gr. 10.307) as the '64 Tempest and the '64 Chevelle and the '64 F85 used the same wiper trans p/ns you listed. Couldn't find anything pertaining to the Skylark but pix of it show the wipers in the same position from what I see.

So I don't see any Left Hand Drive application that required that unused support.

Do you know if that extra support is also found on the '65 Tempest? Just wondering if they realized it was unneeded and ever deleted it.

[War eagle]

My 01A 65 body date, has the 3 supports. The 64's two in the center are stamped Z20 and the driver side support Z21. I probably would rather say that the center pair are structurally important with the outboard support more in line with John`s right hand drive thought. The panel/shroud may or may not be different in a right drive configuration. A/C would make me assume they would have a specific right hand drive shroud. The firewall of course and the dash panel would also be reversed along with steering components, most of the a/c components to dash and emergency brake parts. (many more I`m sure) The only added support at the shroud would be addition of the right support. (Perhaps omitting the left drive support). So again, the center supports are probably a structural component, and created identical. Wish we had a Aussie MPC.

The only other idea for the unused support could be some sort of "special option wiper" devoted to an ambulance, station wagon heavy duty or Police." However nothing in the regular MPC show any special option.

[John V.]

The Z20 and Z21 stampings are date codes. 20th and 21st week of 1964. Many parts on my Nov '63 build show the 45th or 46th week of 1963. My centermost supports show Z45, the driver side support shows Z43. The date coding of sheet metal components has been discussed here in the past. As I recall, the "Z" is not well understood, I recall that the thinking is that the letter prefix may have identified the location of one of the sheetmetal fab plants around the country (I seem to recall some of my components show a "W" prefix instead of "Z"). The no. seems certain to correspond to the week of the calendar year when the component part was produced and will certainly be in advance of the final assembly.

Take a look at how the narrow sheetmetal strip that is between the windshield and the louvered vent panel is attached.

I believe this strip, which is painted body color, is part of the upper dash & duct assembly. Not a separately serviced body part that I can tell.

Looks to me that the strip is secured to the centermost supports with mastic (in the same way the hood inner structure is attached to the outer hood skin).

I suspect the "extra" support ensured alignment of this piece once made part of the upper dash & duct assembly.

That would go a long way to explaining why Fisher always provided this "extra" piece.

The attachment of the supports was by spot welds, so they wouldn't have any substantial structural purpose, but "structural" in the sense that they wanted that body color sheetmetal strip to align nicely, the supports to either side of center gave them two "solid" places to secure it with mastic.

May still have been a RH drive wiper set-up that reversed the wiper action and would have required the additional support location (as you say, they may or may not have deleted the driver side support for this set-up).

I believe the mystery of the "extra" center support for standard LH drive applications is solved.

[3 Deuce 64]

John I had pictures of a right had drive 64 convertible I was trying to put the money together to buy it but it never happened . If my memory is correct the wipers were the same as left hand drive . , any way not an A body but a 64 B body right hand drive
http://www.carandclassic.co.uk/car/C493398#


found a 65 right hand drive notice wiper motor is in the normal left hand drive location but of course the master cylinder is reversed.

[War eagle]

Actually I believe I am correct and the center supports are identical and add to the structure strength. You must look at the center supports again John and note they are not mastic attached(whatever that is) but rather resistance welded to the "wall" of the shroud panel as well as the leading edge of the firewall.

The resistance or "spot" welds have been used in auto construction as well as other products needing a great deal of strength beginning in the early 20th century. In 55, Chevy announced that 92 % of the assemblys were joined by spot welds. That number peaked in the 1990`s and currently is going DOWN with the use of super adhesives.

For clarification, the dash rods at steering column dash mount, attach to the left of the left "center" wiper link support and also thru the left outboard support. One could assume that a right hand drive Tempest would use a right outboard support to also attach the rod to the the lower dash.

[John V.]

Yes, the supports are spot welded in place. I made mention of that in my post.

I described the strip of sheetmetal that fits between the windshield and the louvered vent panel as being attached to the supports by mastic (which is a generic term for sealers/adhesives). Mastic was specified for attaching the hood skin to the underlying structure as I mentioned.

This piece of sheetmetal gets painted body color, it is external sheetmetal. I do not think it was separately serviced unless you can determine otherwise.

Without deconstructing the upper dash & duct assembly, I do not know what that strip looks like as an individual part before it was made part of the upper dash and duct assembly.

All I can see is that there is mastic between it and the center supports where it crosses them. I suspect there may be mastic all along this body piece and a formed lip beneath it. The mastic appears to be all that holds this strip in place. Note, it is not attached to the driver side support, I can't make out how it is fastened at the ends.

I disagree with your notion that spot welds provide a great deal of structural strength. But that is a quibble based on mechanical properties of various welding methods and other joining systems which provide greater structural load carrying capability.

They have been very well suited to automobile body construction as you point out. Largely because of other attributes, among them economy.

I am not sure what you mean by dash support "rods"? Only thing I see attached to the supports is the wiper linkage. Adjacent to the unused center support is something from the interior which bolts thru to a thick square backing plate on my car, haven't tried to determine what that is, but the connection is independent of the supports.

I guess I'm just cringing at the idea of structural strength being attributed to these supports.

I don't think I am disagreeing with you at all, just think the idea of structural strength is misleading, I don't get the sense that the support is intended for load bearing, not to any significant degree at least.

The supports used for the wiper linkage definitely provide a rigid mounting for the loads induced by the wipers.

The extra center support may have been to add some "rigidity" to the dash assembly, perhaps to control "flutter" in that area.

Maybe once I understand what you mean by the "rods" you mention, perhaps these rods are inducing a load. Just not seeing that at the moment.

I think we both agree, the "extra" support is not extra at all, Fisher put it there for a specific reason and I'm now pretty convinced it was unrelated to Right Hand Drive, something I was skeptical of even as I suggested it because that is a pretty "expensive" piece of metal to add to the build if it had no purpose except for a rare Right Hand Drive equipped build.

It is likely a structural reason, so I guess I should just accept "structural strength" as the descriptor.

[War eagle]

I found in Grp.12.803 Cowl and Dash Asm. (L.H.D) but nothing leads to the Right Hand Drive in the 64 MPC.
The "rods" I made reference to are found in group 6.750 support assy stg column.

[John V.]

Ok, got it. The LH rod threaded into a nut and attached at the driver side support. Didn't notice the penetration in that support yesterday.

The RH rod is the piece I did see yesterday and noted, doesn't hit a support (least not on mine), connects to a thick square plate adjacent to the unused support. I think (didn't look close) the square plate is spot welded to the Dash Assembly, same as the supports are. But since it is independent of the support, doesn't seem the unused support has anything to do with it.