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1978 Speedo Cable Replacement Advice

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Old 01-23-2014, 11:59 AM
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Stephen Irons
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Default 1978 Speedo Cable Replacement Advice

Hi Chaps!

I’m in the process of replacing the non functioning Cruise Control Transducer in my ’78. I’ve swapped the unit for a nice new replacement, but now need to put in new speedo cables, as the old unit had been “by-passed”.

So, a long, long time ago I pulled the instrument panel out to pop in a new bulb, and on that occasion I recall releasing the speedo cable from the speedo head, but not quite how I did it! A little bit of research brought up this guideline from a while back on the CCCUK forum. Given that I’ll be putting in two bales they’ll be a few differences to this, but in principle, does this sound reasonable to anyone who’s done this?

1) Remove the drivers seat (so you can get up underneath the dash).
2) Jack car up.
3) before removing old cable make a note of the route it takes through the engine bay (to make sure it doesn't rub on any moving parts or anything hot).
4) unscrew old cable from Transmission.
5) lower car back down.
5) remove the grommit where the cable goes through the firewall (keep it - you can reuse it)
6) To remove the speedo end - lie on your back in the driver footwell. If your hands are small enough you can do this without removing the dash. If my memory serves me right - to remove the cable from the back of the speedo, there is a little lever the you press in (with a screwdriver). This will release the cable and you can pull it free.
7) Lube the new cable before putting it back in the outer-casing.
8 ) to re-install, thread the speedo end back through the firewall (dont replace the grommit yet as you may have to pull it through a bit more)
9) Get back in the driver footwell and reach up and push the cable into the back of the speedo until it clicks into place (Give it a little tug to make sure).
11) Check routing of cable through engine bay.
12) Jack car back up and now connect the transmission end (it just screws in)
13) re-install grommit
14) lower car.
15) reinstall seat.

I plan on putting the lower cable in first, gearbox end first. And there is no grommet at the moment, so I have to assume that it’s a split type that I could feed round the installed cable?

Thanks for any little tips!
Old 01-23-2014, 01:15 PM
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Easy Mike
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Sounds correct. Removing the driver's seat may not be necessary provided you can reach the back of the dash with it in place. If not, removing it doesn't take much.

Most of the replacement cables come with casings. Putting a new cable in an old casing may not be needed.

Drive cable ends are square. You want to ensure the new drive cable seats securely in the rear of the speedo head.
Old 01-24-2014, 08:00 AM
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Stephen Irons
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Thanks Mike

Yes, I have new cables.

My plan is to locate the speedo head end of the cable first, so I can ensure that it's fully in place.
Old 01-24-2014, 10:16 AM
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jcloving
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If you do pull the seat it you will be much more comfortable as you do this work. It does not take much time or effort to pull it.
Old 01-24-2014, 11:06 AM
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If you slide the airduct out that supplies air to the left side of the dash you should be able to reach the back of your speedometer to release the speedometer cable. Remove the cover under the steering column and it will give you easy access to the air duct.
Old 01-25-2014, 04:27 AM
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Stephen Irons
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Originally Posted by thegazman
If you slide the airduct out that supplies air to the left side of the dash you should be able to reach the back of your speedometer to release the speedometer cable. Remove the cover under the steering column and it will give you easy access to the air duct.
I was wondering about that little panel. I seemed to recall that I'd removed it before, when I was changing the instrument cluster bulbs.

Thanks for the tip re the air tube!

So, yesterday I fitted the lower cable. The aftermarket exhaust setup on our car makes access to the speedo drive on the transmission a bit tricky, but that was nothing compared to the struggle to get the other end of the cable screwed onto the transducer! When I finally gave up and took the transducer off to see what the problem was, I found the thread was damaged (out of sight when looking down on it)! Some judicious work with a hacksaw sorted that, but it watsed a good hour and did my hands no good at all! So today it'll be the upper cable.......
Old 01-25-2014, 12:11 PM
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Originally Posted by thegazman
If you slide the airduct out that supplies air to the left side of the dash you should be able to reach the back of your speedometer to release the speedometer cable. Remove the cover under the steering column and it will give you easy access to the air duct.

All I did was remove the air duct crossmember from the center console to the driver air duct. The cable just pushes in. There is a lock lever that will need to be depressed to make it slide in easier. The same lock lever used to remove the cable. Takes me about 5 minutes to replace the upper cable once you know the path the cable routes.

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