Wiper Arm Bolts. Quandary of the Day.

[zKars]

Good morning. I'm in a mood of distracted boredom, and thought I'd start a rousing games of  "why'd they do that?", 'they' being the factory.

I have noticed on more than a half dozen odd Z's that I would say are relatively unmolested, that the six bolts that hold the wiper arm pivots to the cowl are quite surprising. Five are identical, one, the same one on every car, isn't.

Here we see on the left side, that the inner, rear fastener is a round headed machine screw, bereft of even a lock washer, while all the other five are nice hex SEMS bolts with the expected lock washer.  All are of course M5x0.8 thread.

Right side, all is happy with three matchy matchy.

As those of you who have had the pleasure of removing this lovely flock of fettid fluffy fasteners have experienced, it is not enough that 4 out of 5 of the bolts snap off, but you have to resort to vise grips to get that lone round headed bastard, rendering its head beyond repair for future use, causing all sort of consternation and wringing of hands. 

This was recently observed on 3798 (pics above) and  on a 73, VIN 127xxx. Can't say for sure what other years I've seen, but a good sampling. 

Let the speculation begin. Why in the world would they use one odd bolt in that group of six in such a systemic way? I think the assembler was a clever prankster, and revels in the joy of imagining the future angst he/she will have caused. Well congratulations. It worked. 

 

 

[motorman7]

Yes, the left side has that one pan head screw.  That is factory.  My guess is that the pan head has a lower profile than the hex head.  Also, there is no washer.  My bet is that this was originally intended to be a hex also, but the hex contacted the cowl in this location, so they had to switch to a lower profile screw head.  That's my theory for now unless otherwise corrected.

[Patcon]

3 hours ago, motorman7 said:

Yes, the left side has that one pan head screw.  That is factory.  My guess is that the pan head has a lower profile than the hex head.  Also, there is no washer.  My bet is that this was originally intended to be a hex also, but the hex contacted the cowl in this location, so they had to switch to a lower profile screw head.  That's my theory for now unless otherwise corrected.

That was always my theory too. Clearance issue or rattle issue

[Pat Carr]

Damn, who knew?. Now I have to remove the cowl and see if I put that pan head screw in the right place.?

[Phil Z]

Yes, the left side has that one pan head screw.  That is factory.  My guess is that the pan head has a lower profile than the hex head.  Also, there is no washer.  My bet is that this was originally intended to be a hex also, but the hex contacted the cowl in this location, so they had to switch to a lower profile screw head.  That's my theory for now unless otherwise corrected.

Exactly what I was thinking! Or, somewhere in Japan at the Sake bar is this little old gentleman telling all his friends about his days at Nissan building the Z car and how someday someone would notice that screw, post comments and then every Z owner would pull their cowls just out of curiosity. I’m checking mine tomorrow. Damn.


Phil Smith

[cbuczesk]

I've seen it many, many times too. I figured it was for clearance to the cowl.

Chuck