Air conditioning connecting rod

(David) #1

In putting my MK IV 1 1/2 litre car back together I have found that the connecting rod between the dash board “heat/cool” knob and the bulkhead water control valve is missing!! The drawing in the Service Manual is not clear, so does anyone have any photos of the rod and how it links into the two slotted ends, or any better drawings with sizes/lengths, etc.

It’s marked up as “REMOTE CONTROL ROD” on the drawing - fixing between the “WATER CONTROL VALVE” and the “REMOTE CONTROL KNOB”.

Here are pictures of the Water Control Valve (on the bench) and at the back of the bulkhead when fitted, and the back of the Control Knob on the dashboard. I guess at each end of the connecting rod it fits into the respective hole and fixed with split pins through the slots, but cant remember if there was a “flexi link” to help rotation and line-up?

View from behind bulkhead

View from behind dashboard of Control Knob.

Any information much appreciated.

(Peter Scott) #2

Hi David,

I’m away from home for the next week so can’t measure it but therod ends are “T” shaped to fit into the slots in the tap and control knob shaft. It is retained by slipping a short length of rubber hose over each end. The hose is a firm fit over the slotted pieces and keeps the “T” shaped rod ends centrally placed in the slotted pieces.


(Roger McWilliams) #3

Hello David, the Mark V Air Conditioning Remote Control Rod is just over 15.5" long and has “T” end on both ends, flexible element a few inches long one third of the way down. Attached is a photo of one third of a rod and the associated valve.

(- 1950 MkV, 1959 XK150,) #4

I think it was Ed Nantes in an earlier post who put forward the great idea putting a sleeve of hose over the flexible join. This will hold the rod in place whilst you juggle the fittings into place.

(Timothy M Fox) #5

The rod appears to be the same as on a MKV (and why wouldn’t it be, I guess?). It’s just over 15 1/2" in length, as Roger said. I was told never to take the tap apart unless you have done it before as the waxed string seal is really tricky. Mine doesn’t leak so I’m not touching it!:grin:


(Ed Nantes) #6

I’ve never seen the flexible bit on a MK IV rod. I doesn’t need to go anywhere ona MK IV but straight.
I’ll dig one out and measure it.

(David) #7

I guess the flexible part will help with any mis-alignment of the control valve to control knob, and the fact that their position on the bulkhead and dashboard are are slightly different angles.

(Roger McWilliams) #8

For the 1 1/2 litre car, the parts book indicates (p.67):
BD.921 Rod, Control, Assembly
BD.338 Fork-End for Tap
BD.342 Fork-End for Control Knob

For the Mark IV (parts book p.62):
BD.921 Rod, Control, Assembly [for 3 1/2]
BD.1344 Rod, Control, Assembly [for 2 1/2]
BD.338 and BD.342 as for the 1 1/2

For the Mark V:
C.2719 Rod, Control, Assembly
C.2845 Fork-End [this is the same for both ends]

So, it seems the 1 1/2 litre search may be guided best by finding someone with a 3 1/2 litre Mark IV and old parts off a 3 1/2 Mark IV…

(Ed Nantes) #9

OK at great expense and effort I took one out of my car.
They overall length is 18 1/4" and it has no flexible section . The slots in the tap and the control knob and the T pieces on each end of the rod, act like a crude universal joint.

(Biskit) #10

Ebay has 3mm, 4mm etc universal joints out of China dirt cheap.
I bought a couple to connect the reserve switch on the dash to the two way fuel cock on the fire wall.

(David) #11

Thanks Ed. 18 1/4 inch would make the correct rod length to reach both ends on my 1 1/2 litre car - so I’ll make one up without a flexi joint to see how it aligns and hopefully turns the control ok.

(David) #12

Just made up a heater rod - and it works great!! If I ever find an actual MK IV one to buy I will replace it at some time, but for now it does the job.

I only had a length of threaded rod of the right diameter in my workshop (3/8"), so used this cut at 18 1/4", rounded off the ends (to swivel inside the valve connector and dashboard control knob), drilled holes to locate the needed “T” pins, and fitted it OK under the dashboard. In order to locate the rod in place (and avoid it sliding up and down the slots in the control spindles) I was going to use some rubber tubing (which I think Ed suggested) to grip the ends in position, but I couldn’t find any of the right diameter or flexible enough. So instead I popped on some bell washes and some nuts.

Once the rod was offered up and located into the slotted ends, I locked up the nuts to pull in the bell washers but left sufficient movement to allow them to twist when the rod is rotated. This takes up the misalignment/different angle of the dashboard knob and control valve on the bulkhead and allows the rod to swivel nicely (and won’t drop out).

Job done thanks to the feedback and help given in the Posts to my initial question. Cheers.