C2 speedometer cable repair

[Mark F.]

Hi friends:

The speedometer in my '65 small block/Powerglide Corvette just died. Before it went, it began making a ticking sound for a few miles, and then went to zero.

I'm hoping that the fix is the cable (unknown age). It is possible to remove the cable without removing the instrument cluster? As I recall it's a tight squeeze behind the cluster.

If the cable is broken within its housing, what's the fix then?

Thanks for your help.

Mark Fleishman

[Stephen L.]

Re: C2 speedometer cable repair

The cable pulls out of the housing from the top end....It has a small collar on that end..... therefore you need to disconnect it at the speedometer. If only part comes out then you can retrieve the other half from the transmission end.
If the cable was frozen in the housing, rusty or whatever, then you'll probably need to replace the housing also.
In either case, remember to disconnect the battery when working under the dash so you don't cause some other problems.
The cable can be removed without taking the instrument cluster out...its a bear but can be done. You might want to remove the seat to get better access and possibly drop the steering column. I hope you have slender fingers....and a small stature......
If you remove the housing from the car you may need a new firewall grommet

[Joe R.]

Re: C2 speedometer cable repair

It's pretty easy to determine whether the problem is the cable or the speedometer. You can easily disconnect the cable from the back of the speedometer without removing the cluster. If the protruding end of the inner core of the cable does not turn when when the rear wheels turn, the core is broken somewhere inside the cable housing.

You can pull the core out from the speedometer end, and if it is broken you will clearly see the broken end. The fun part will be getting the remaining piece of the core out of the cable housing.

I recently performed this operation on my 67 Powerglide, and found that I had to remove the rear transmission mount to gain access to the area where the speedometer cable attaches to the transmission.

By the way, in my case the core was broken about two inches from the transmission end. I could see why it had happened, because there was a sharp bend in the cable housing where it had to turn to avoid the shift rod. I was not able to completely eliminate the sharp turn. It lookes like either a design flaw from GM or possibly a bent shift rod. I have not yet installed the new core I bought, but it wouldn't surprise me if it eventally breaks in the same place.