My speedometer is clicking so I'd like to remove and sent it somewhere to get it fixed. How do I get the assembly out of the dash? Where can I send it?

Thanks

 

This is one of those times it would be nice to say what year you’re working on. I see you have a ‘78 based on your other threads though. See the video below.

 

GM's C3 interior engineers after sign-off on the designs:


I do not envy your project - it's a bear! Every step of the way is a struggle, but go easy – the plastic parts are 50 years old and brittle.

 

I've had my 75 dash apart a couple of times and now both tac and spedo housings are like 50% epoxy on backsides. I don't want to take apart again to resolve issue with the gauge lights fearing they will fall apart more. Didn't want to buy new ones. Good luck!

 

Now THAT is funny, sad and true! Got a chuckle - thanks for making my day.

Of course at this point I must point out that words like 'C3' 'Interior' and especially 'Engineer' probably don't belong in a sentence together. But I can think of a few that do! Thx again

 

In simple terms, drop the steering column, disconnect what you can from below, and pull the drivers dash forward and ultimately out to gain access to the 2 guages. If you don't have one you really need to get an AIM.

If you have a mechanical tach as well - it's essentially identical to the speedo and probably should be serviced as well I suppose. I don't have any specific place to recommend. There are a # of them I've seen advertised in places like the back of Corvette Mag, perhaps here, etc. I'm sure someone will recommend a place or other they've used. In fact I think there's been a thread or two recently about speedo repairs and shops here.

Having said all that have you checked out your speedometer cable? It's probably more likely to fail than a speedo itself and could also account for the clicking in your case. And that can potentially be serviced w/ the dash in (albeit w/ some chicanery).

 

If you have cruise control, I would disconnect the speedometer cable from the cruise control transducer. This will make it much easier to pull the dash bezel forward and gain access to the back of the speedometer to disconnect the cable. If you don’t have cruise, I would disconnect the cable at the transmission to enable pulling the bezel forward.

I would also put some painters masking tape on the top of the steering column, so when you pull the dash bezel forward, you don’t scratch the paint.

 

Honestly, you need to do a good amount of research first, using Google. There have been some posts that have very detailed step by step instructions. I removed the mechanical tach and speedo on my 73 and it was by far the most challenging repair I have done. Removing the drivers seat, plus many people say to remove the steering wheel. I would have the tach and the speedo restored while you have the dash pulled. This is a job you only want to do once. Start looking for a quality restoration shop that specializes in mechanical speedometers. The family shop I used, quit doing mechanical restoration work, when the Dad retired, the son only does electronic stuff.

 

Actually, the video posted by Piersonpie is pretty good, if you fast forward to the '82 section. The '78 is very similar.

As per the video, there is no need to try and drop the steering column on a '78 (how many hours did I waste when someone told me to do that years ago?!!) The dash cluster does just come out. In my case, I needed to renew a bulb or two and pulled the whole unit out complete and changed the bulbs from the back. (I believe from memory that you can remove it with the glass attached, although you'll need to remove that to get the speedo out.)

The speedo caable just pops out when the little clip is released and clips back in when pushed back after the job is done. I certainly would not remove it from the cruise control end.

Of course, this should all be prefaced by the question "Is it actually the speedo, or is it maybe the cable that needs replacing?" If you haven't changed the cable, I'd be doing that first.

 

As it happens I removed the speedo unit in my 78 yesterday, to change some bulbs. I did have to remove the glass and lower the column (I needed to loosen, but not completely remove, the 2 bolts supporting the top of the column). As Stephen says though I'd make sure it is actually the speedo before paying someone to rebuild it.

 

Yes, I see. I thought all the C3 Vettes had the same dash. Not so, it would seem. The video helped a lot. Thanks. By the way the allen wrench needed is a 9/64 or 3.5mm. Not very common.

While I was in there I noticed that a couple of my dash lights seemed to be burned out, but when I touched them, they came came on. So I thought that I had better pull the whole assembly as that looked pretty straight forward...um... not so. I had to remove the two bolts that secured the steering column under the dash and push it down really hard to get clearance to get the assembly out. I reseated the bulbs and twisted the receptacles out and back in so that now they seem to be pretty connected.

After all of that, I tested the speedo with a slow speed drill and found that it worked very smooth and did not make any noise. So I guess I need a new cable. How to do??? It doesn't look easy, but I don't have a choice.

 

I wasn't too bad until I had to pull the plastic mounting assembly. That wasn't any fun.

 

My Tach is electric, fortunately. And it seems you're right, I think it is the cable. The speedo seems to work well when I tested it with a slow drill.

 

Good idea. I did need to protect it. The assemble did not come out easy.

 

Interesting - that's two of you who had to lower the column to get the cluster out (hi John!&#128516. I know I didn't, because i couldn't get the bolts loose! I wonder if having a tilt/tele column makes a difference.

Anyway as for changing the speedo cable, I've done that as well. I removed the cable from the speedo (you'll have done that!) and tied a pice of string to the ned. I then pulled the cable and the string out through the firewall into the engine bay, ensuring of course that the other end of the string stayed in the car! I then tied the string to the end of the new cable and pulled it back through the firewall into the car.

In my case I have cruise, so it was just the cable from the transducer to the dash, but the principle would be the same with a non-cruise car. Personally, I'd connect it to the trans first, then deal with the dash end. In reality, the trans end can be the more awkward - I have next to no room to get at the cable on the trans due to the custom exhaust I have, which means a full day's job to turn out a thumbscrew and replace! But you may have better clearance!