Early C3 (70) Wiper Door/Cowl Grill Question

[Chuck S.]

Has anyone judging or restoring original early C3 cars seen the factory use of shims under the cowl grille to adjust it's height?

Specifically, the shims used would be the ones intended to shim the wiper door linkage forward/aft (70 AIM, UPC1, page D3, Item 5, PN 3926484). Since the hole spacing on wiper door linkage mounting studs is less than the cowl grill mounting screws, the shims can only be engaged in one hole and simply clamped in position by the cowl grill mount surfaces.

On my car, this appears it could be original (repaint overspray shows the shims were in position at that time), but the AIM shows no shims used under the cowl grill. The re-painter probably would not have removed the wiper door mechanism, and the shims are clearly PN 3926484 from the factory. Any help would be appreciated.

[Phil P.]

Re: Early C3 (70) Wiper Door/Cowl Grill Question

72 cowl i adjusted the height via the assy mounting brackets that run through the plenum area of the fire wall---(horizontal)the previous ???? had shims under neath the cowl for elevation adjustment---i removed them all---when i was happy with the final adjust i noticed that the wiper door was higher than the cowl??? started the motor and low and behold the vac. actuator pulled the door down to a near perfect fit well inside the production specs.

[Jack H.]

Re: Early C3 (70) Wiper Door/Cowl Grill Question

Yes, shims were used to adjust the wiper door assy fore/aft in relation to the rear hood lip/windshield. They're clearly called out in the AIM. The assy pictorial from my '71 AIM is: UPC 1, Sheet D3, Item 5 and I suspect the '70 AIM is similarly placed.

Shims were used, as required, on all four of the wiper door mounting platforms in the engine compartment and typically hidden by the subsequent sealing (dum dum) and black out process. Many cars that've had wiper components removed, had their factory original shims discarded by 'Bubba'....

[Chuck S.]

Re: Early C3 (70) Wiper Door/Cowl Grill Question

Hi Jack. Good answer...but actually, that's not the question I'm asking.

I'm interested if anyone has seen those shims (Item 5) being used improperly under the cowl grill by the factory to adjust the grill height. Their use to adjust the fore/aft position of the wiper linkage (aka "control asm.") is pretty straight forward per the AIM.

Phil correctly points out that the grill height can be adjusted by moving the wiper door linkage mounts up/down on the firewall as necessary. The engineers clearly didn't intend shims to be used under the cowl grill. But, I wonder how much adjustment can be done with the linkage mounting without beginning to build resistance into the control mechanism. I'm wondering if this improper shimming could have been done, say at final inspection, to minimize the work and delay if fit problems were found.

As for the proper use of the shims, the factory must have had a jig or something to determine the wiper linkage assembly shim count at each location...I can't see them doing the shimming trial and error. There are actually only three locations...the second spot from the left is a sheet metal bracket used solely for supporting the cowl grill. The desired dimension to be set by shimming would probably have been the 3.10" check dimension between the rear corner of the hood and front corner of the wiper door (UPC11, page A11).

[Dennis D.]

Re: Early C3 (70) Wiper Door/Cowl Grill Question

My .02. I found that adding firewall/linkage shims, made it neccesary to move the entire linkage up as it moved rearward to avoid hitting the lower windshield/cowl area. Sort of accomplished the lifting of the grille at the same time.Although, I wouldn't be apposed to shimming the grille.

I know, doesn't answer your question either, but its lousy out in the NE, and I have a lot of time on my hands.

[Terry M.]

Re: Early C3 (70) Wiper Door/Cowl Grill Question

Chuck -- I'm working from memory here, and that is notorious, but seems to me there are washers under my cowl grille in some spots. It has been years since I had it off, but I seem to recall some which I put back.

[Chuck S.]

Re: Early C3 (70) Wiper Door/Cowl Grill Question

You are the original owner, so it would appear the factory could have "shimmed" the cowl grill when necessary. I suppose if they had to shim, they might have used anything they could find for a "shim" that would work. Actually, I had been thinking that a washer or two under the RH front screw might help to level it up...and if your memory is true, it wouldn't be over-restoration.

[Chuck S.]

Re: Early C3 (70) Wiper Door/Cowl Grill Question

Thanks for the help guys. I hate it when I find these little discrepancies from the AIM, and I don't know if it's original or not. This information probably won't affect my restoration, but it's nice to know the answer.