I recently picked up this 84 Z28. The Speedo is not working. If I driver down the road with the cluster removed I can watch the cable spin. If I manually spin the back of the Speedo the needle moves. But when I mate the two and drive down the road the Speedo does not move at all. I am fairly certain the cable has the correct square end on it. Has anyone had this issue before?

 

The speedo in that car is not electrical at all, let alone electronic; only magnetic.

Does this car have cruise control?

 

I am aware that the speedo is mechanical. I posted on the electrical thread because I didn't see another thread that matched the concern better. I am pretty sure it does have cruise control, I can verify later after I get home from work.

 

There's a set of gears in the cruise regulator, connecting the "lower" cable to the "upper", that can strip. Try turning the cable end in the dash with needlenose or something; they might work well enough to spin the cable with no load on it, but not be able to drive anything; if you can get it to turn, that's probably the problem.

 

Mine stripped out in that gearbox in the past.

 

Where is that gearbox located?

 

'84s have electronic cruise control working off the VSS -no gearbox like on 83-earlier cruise control .

 

that's what I thought. My cable looks like it goes right from the trans to the dash and there's a vacuum servo for the cruise....so back to the drawing board. Anyone else have any ideas?

 

It's odd because the GM service manual for an 84 Camaro shows the gear drive cruise control but this car definitely does not have that. The cluster end of the cable looks correct and seems to be fully engaging into the speedo. When I drove the car with the cluster removed I pinched the cable between my fingers and could feel it spinning. If I spin the back of the speedo with my fingers the needle bounces, if I spin it with a drill it moves like it would when driving. The previous owner changed the gauge cluster and when I got it the gauges were all screwed up (circuit board) and the speedo did not work at all. Luckily they kept the original so I replaced the circuit board on it and installed it. All gauges now operate perfectly with the exception of the speedo (doesn't work at all). I pulled the cluster back out to make sure I got the cable into the hole and I definitely did. It looks like they changed the cable too but I'm assuming they did that properly because it spins in the dash. I guess I'll have to remove the trans side of the cable to see if there's any problems there but I don't expect any because like I said, it's spinning at the cluster side.

 

84 should have had the old-style cruise with the external regulator module. At least, my little step-bro's 84, which he bought in maybe 86 or so, had it like that.

The presence of the cruise servo is an almost certain guarantee that the car came with it. No sense in installing one otherwise.

The cruise regulator is a sort of carburetor-colored box bolted to the driver's side strut tower. The original servo was mounted close to that and used a cable about 3' long to connect to the carb.

Of course, 40 years after the car was built, who knows what sodomy might have been inflicted upon it.

It's not impossible that they bought a "universal" cable, and when they cut it all to length and put the end piece on the transmission end of the inner, they didn't get it crimped on right. It's also not impossible that the regulator had gone bad in the other way that they always fail, wherein the spinning copper disk rubs against the somewhat stationary one that works the vacuum valve and thereby makes the whole thing bind up, and it destroyed the gears inside the transmission. Which might have been the first-cause reason they dinked with the whole system to begin with. Forgive me though for being unable to back-interpret (guess) the motive for why some stupid person did any given random inexplicable stuuuupid things.

"2 things are infinite: the universe and human stupidity, and I'm not sure about the universe." – Albert Einstein

 

Are you locking the cable onto the back of the speedo? There's a clip on the back that holds the cable against the speedo. You should here a click if you did, if not that could be one reason why its not working.

 

Ok, I finally got back into this and I found one spot on the speedo gear that is worn down. New gear on order.