I am in the process of replacing the tach circuit board on my 1975. I have taken all the screws out of the speedometer/tachometer cluster and have moved it a little but not enough to get in behind the guages and get the speedometer cable loosened. Does anyone have any advice on how to get it the rest of the way out? It seems to be hitting the steering column and I guess I need to loosen the 2 support bolts so it will drop a bit. Is there anything else that is holding it or is the steering column my only problem? Thanks for your time and help.

Tim

 

Even loosening the two support bolts won't get you much of a drop. To drop the column you have to take the two bolts out of the rag joint, remove any springs or links from the column for the shifting, and then the bolts at the firewall. Then you'll be able to pull it in to the cabin and lay it down.

Or...you can remove the upper dash pad. That's not easy either.

Oh, you can see and disconnect the speedo cable from under the dash, on your back on the floor.

 

DB is correct on this one. The steering column needs to be loosend up and pulled into the car. It's not really that hard to do, once you've done it once. BE sure and disconnedt the batt before you start working on anything. You'll also need to undo the electrical 'harmonica' connector at the bottom inside of the steering column. not that hard if you can do a pretty good limbo......

 

Are you saying you can get to the speedometer cable without doing anything to the dash or steering column? It's my next project. Replace the speedometer cable with a new one.

 

In the process of doing this on the 76. I went through the same exercise you described. Originally wanted to grease the speedo cable.

You could unhook speedo without taking out the left instr panel, but no clearance to pull out and grease. Also easy to crack a 30+ plastic instr panel

So dropped and pulled out the steering column. Used Chev original service manual and Haynes. As said above, disconnect battery, back drive cable and plate (for a 4sp manual) & rag joint, unhook numerous vac tubes, and wire connectors (label, label, label). While apart, also decided to fix the non working tach. And painted the steering column trim in the backyard.

Couple of things you might consider:
*new tach board from MidAmerica has 3 fiberwashers with no directions. After a couple of false starts with new board not working at all, I finally figured out the board (may?) have been touching back of needle metal base. So, used some electrical tape to make sure board was isolated. Also trimmed back of plastic board cover to make sure it was not hitting new board parts. Plus some extra gasket washers to level up. After a number of trials, finally got the needle positioned right.
Also installed new $40 filter as wanted to hopefully protect $60 board.
*Only unhooked steering column side of rag joint so far. All say to follow directions installing steering column. Jim Shea has a post on this if you do a search. I am not sure why I need to unbolt the steering gear rag joint side yet, but plan to follow the directions anyway.

Good luck, it is fun the see the wife's face when you crank up the engine to check the tach with the dash and column w/ no steering wheel in your lap!

 

Yeah, just get on your back, reach up, press the release of the clip, and pull it back from the speedo housing.

Now, if you are replacing the cable, tie a heavy string or wire to it before you push/pull it through the firewall. The string will be your guide and your 'extra' hand while pulling the new cable back through.

Once you have the new cable routed, make sure it's not bound or touching anything moving or hot, and slip it back into the speedo.

That's it.