To my other GT6 pages

January 18, 2022

Behind the Dash

With a temporary reprieve in the cold weather here on the prairie, I got a chance to play in the garage for a time.  I used the opportunity to install a couple of the things that have been on the shelf.  When installing things on the interior of the car, it makes sense to start behind the dash.  It is one of the hardest places to access, and the more items we add, the worse it gets.

Before I did anything under there, I wanted to apply some sound damping material.  Much of the unwelcome noise in a car is generated by the car's panels themselves.  Driven by normal engine, road, and wind vibrations, some panels can resonate and create sounds of their own.  The larger and flatter a panel is, the louder, lower, and more sustained the resonance can be.  Smaller panels with a lot of shape aren't usually a problem.  I use the "thump test" to determine whether it is worth trying to damp a panel's vibrations.  I give the center of the panel a good thump with a knuckle.  If the sound is a dead thud, damping won't change anything.  If it sounds like a gong, damping will help.  Between these two extremes, it's a judgement call.

The vertical firewall panel isn't all that large, but it's relatively flat, and the thump test suggested that some damping would be a good thing.  I use CLD (Constrained Layer Damping) mats, which, when applied to a steel panel, makes a sandwich of two metal layers with a gooey substance in between.  The mat increases the mass of the panel, which lowers the resonant frequency. Vibrations stress the metal layers, and the goo absorbs the energy.

This is the firewall.  The big hole is the heater air intake.




That being done, the first-up install was the recently finished  windscreen wiper wheel boxes, and associated parts.




I put the wheel boxes in first, then connected them with the new guide tubes for the drive cable.




I lubed the boxes, cable and tubes pretty well, and, shoving the cable in, everything appeared to operate smoothly.  The factory manual advises that the maximum permissible force needed to move the cable without wiper arms is six pounds.  I was really happy to see that only a little over two pounds would move my cable through its whole stroke.




I made sure to add a little anti seize to those weird octagonal nuts on the wheel box noses.  Those are notorious for seizing.




One small step...




Related to the wiper gear, I turned to the washer jets.  I couldn't find my originals, so I ordered replacements.  Literally minutes after pressing the "Place Order" button, I remembered where the originals were.  They were dirty, but still clear. 




I neglected to change the order, so when the new ones showed up, I had a chance to compare them.  The new ones looked fine, but there were some differences.  The hose barbs on the new ones were significantly smaller than the originals.  I don't know if that would be a problem.  Also, rather than the 1/4-28 threads of the originals, the replacements were 5 mm metric.  It's a little irritating when a replacement isn't really a replacement. 




In the end, I decided to use my originals.  They are in good shape except for the fiber washer that goes under the hex to protect the paint.  I've got some on order.


Next up was the rebuilt heater, which had been on the shelf for almost two years.




There was a small disappointment attached to the heater install.  There are some foam rubber gaskets or seals that close off the largish holes in the firewall where the coolant tubes pass through.  This is what I paid good money for from one of our vendors.




Now, it's true, they didn't cost a lot of money, and, once installed, they will probably do the job, and no one will ever see them again, but I still had some expectations that weren't met here.  I couldn't in good conscience use these.

Here are some seals I made by slicing off short pieces of some pipe insulation.  The material looks and feels identical
 



There was also a gasket for the air intake.  Nothing at all wrong with this part.  (Other than I don't see the purpose of the two ears.  This is probably a part borrowed from some other application.)




Gathered all the parts, replated the original mounting bolts, and hauled it all to the garage.




It actually would have been a little easier to install the heater before the wheel boxes, but it finally went home fine.




The funnest part of this project is bolting stuff onto the car, but it probably won't be until Spring that I can do much more of that.

Comments to Ed at elhollin1@yahoo.com

To my other GT6 pages