Dashboard Air Ducts

When I revisited my car after it's long slumber, one of the things that most disappointed and troubled me was, on the surface of it, a small thing. The rusted chrome levers of the air duct controls. Being part of the dashboard they're right there - in your face when you sit in the car, and so fixing these felt like an important part of my restoration.

I wasn't sure what I would need to do, but over the several years, and many varied jobs of the restoration, when I thought about putting the dashboard back in, the thought of how to 'make good' on the air duct levers was never far from my mind.

Rusty levers......

Eventually I pulled the dashboard from the car back in November 2018.

Dashboard removed. Note all the dust and dirt

With the dashboard removed, the air ducts were exposed.. 

An air duct in situ. (Photo credit unknown)

 They can be unbolted from underneath and pulled forward into the cabin. They need to be twisted a little to manoeuvre them out, and untangled from hoses, cables and the wiring loom. It helps to first remove the foam seals on the engine bay side.

Removing an air duct with a twist...

The ducts on pre-1968 cars seem to have been made of metal. Mine are plastic. I think they were fitted for two years before the later three dial dash was introduced for the 1970 model year and a new duct design was needed.

 

The two levers control the input of air into the cabin via flaps inside the units.

The levers and grille....

Through a series of articulating joints and elbows, the levers pull on cables that operate the flaps to channel the air. 

The two flaps inside each duct

One flap divides air between the cabin and dashboard. And for the air coming to the dashboard, and the other flap controls the volume. A pivoting grille can be used to angle the direction of the dashboard air.

 

The earlier ducts are made of pressed and folded metal. 

The plastic duct housings are riveted together and I wanted to avoid taking them apart - for fear of breaking the plastic on disassembly or assembly

 

The operating levers were actually outside of the housings and a closer examination showed that the shafts that the levers were on were only held in place by circlips. In other words the levers could be removed. 

The levers are held on by circlips and spring washers

It was right back in November 2018 that I gingerly went about this job. It involved carefully unhooking the control lines and connectors that operated the flaps inside the units......

......removing the ciclips and winkling the shaft out.

 

Lever mechanisms removed

Each lever has a spring-loaded ratched to help the lever hold it's set position and these simply slid off the shafts. But what to do next?

I did think about getting them re-chromed just as they were. After all, the chrome would not take to the plastic. However I had heard that removing and re-chroming was quite a physical process and might involve grinding and/ or polishing. That might damage the plastic parts.  Looking more closely, I deeemed the plastic to be some kind of nylon or polythene rather than a hard plastic.

 

The chromed lever shafts have a flat spot where the knobs are fitted at a particular orientation and so clearly the levers need to be prevented from rotating in their plastic bases. But how were they fitted?

 

I tried to unscrew them - no dice - so i set about carefully trying to pull one off. Reasoning that the metal shaft would need to be cleaned and de-burred anyway, I carefully gripping the end of the shaft in a vice, close up to where the shaft disappears into the plastic piece. I used the cleft in a small jemmy to lever the plastic piece off againt the head of the vice jaw. Slowly but surely it starterd to move. It was a very satisfying feeling: like pulling the cork from a bottle. 'Slow' was also good as it reduced the risk of the jemmy marking the plastic piece. As the shaft eased out, a bulge appeared. The shaft had been squashed flat(ter) so that it held firm in the plastic piece. 

Ignore the ruler. Notice the bulge

Once removed it was clear that, before chroming,each shaft had simply been squashed in a press in two places so that it bulged at particular points. The hole in the plastic piece was probably just a straight hole - nothing fancy. After chroming the shaft had been pressed into the polythene piece (which yeilded slightly to accomodate it) and the bulge in the shaft stopped it rotating.

 

With more confidence I carefully went about removing the other three shafts.This is what I was left with.

 At this point it's worth pointing outo that two lever shafts are longer than the other two.

Notice that one pair of shafts is longer than the other

The shorter pair are for the vent on the 'flat' driver side of the dash.The longer levers go on the passenger side and accomodate the curve in the dash and the metal vent outlet cover. 

The ventilators are at each end of the dshboard

Together with a few other pieces, I sent the levers away to Derby in summer 2019  to be chromed. That wasn't cheap, but they came back looking great. However it wasn't until February of this year, and with the engine bay all painted up, that I thought about re-assembly. 

 

The first thing I needed to do was to clean the plastic duct housings. These had accumulated a load of oily dirt over the years and this was visible from within the cabin. Particulary so the 'grille' pieces.

Dirty grille......

 I didn't want to unrivet the halves and so worked with twith them as they were.

As the operating cables were set up to operate the flaps correctly I left these alone. But because of this, I didn't want  to immerse the units in water. Instead, I worked around the cables. I used a damp tooth brush to clean out the hinged grille pieces. Reaching inside, I used a damp cloth  to clean the flaps and innards. I used compressed air to both dry them and blast out any dirt remaining. Finally I offered up a tiny bit of grease to the moving parts.

They cleaned up well and the ducts looked almost like new. Almost......The bodies looked as though, in addition to rivets, an attempt had been made to glue the halves together - well certainly along the top edges. 

Signs of glue?

It was quite messy but I resisted the urge to try and tidy this up. There were no indications that the duct hosuings were broken or that, without the glue, they might leak. Plastic can be hard to work with, and these kind of jobs have a risk of going wrong. Instead, I decided to love my ducts units - glue and all.

On to reassembly of the lever mechanisms. A key point here was to make sure I matched the right shafts, to the right plastic pieces.....  

Ready for reassembly

......and to make sure the shafts are orintated correctly for the two black knobs on the ends.

Orientation of the shafts on the levers. Note the 'flat spots'

 The knobs need to face out from each other - so that they don't get in each others way.

 

Lever knobs face out

So, carefully orientating the lever to the plastic bush, I used my bench vice to slowly squeeze the two together. The risk here is that the bulges in the shaft cause the bush to crack and split but by working slowly, I hoped to reduce any 'shock'.

Using a vice to refit the lever to it's plastic bush

 

Slowly pressing the shaft onto the plastic bush

It was hard to remember how everything went back to gether after so long and I relied on photos I had taken back then. It was a case of lining all the levers and arms up and then slipping the 'axle' in, before fitting the circlips. When all was done they looked much smarter than they had done when I'd removed them.

Before....

Come early March and I was ready to refit them on the car. I offered each one up from the engine bay side. Before I screwed them in place, I cleaned and refitted the foam rubber seals that close the gaps around them. I had even tagged them back in 2018 so I could put them back on the same sides they'd been removed from! These fit in from the engine bay side and are shaped to fit the lip of the holes in the bulkhead.

 They take a bit of fiddlig to get them looking nice.

With those in place, the ventilators were screwed in place from underneath. 

I couldn't remember which way up the ratchet pieces were meant to go. They affect how high (or alternatively - low) the lever will go. It won't be until I fit the dashboard that I work that one out. However as they are 'springloaded', I've discovereded that they can be carefully pushed along the shaft and flipped over - so I can alter them later if I need to.

'Ratchets' on the lever shafts

When the dashboard is back in I can fit the decorative knobs on the ends of the levers. They are a push/ pull fit and you see cars with them missing. For that reason I took the opportunity to buy some spares that I came across. However I was surprised to find they didn't include the teeny tiny spring clips that actually hold them on the levers.

Spring clips and spare knobs

They are a very particular shape, but aren't listed as a seperate part. So if I do lose a knob, I guess 'll have to try and glue any replacement on.