Speedometer not working.

[Piece-it pete]

Well my speedometer stopped working completely this morning, now I'm always going OD mph.

I sure wish I could resolve one freakin' issue before another hits! Anyway it's been wonky for a while. Sometimes, particularly under harder acceleration, it would jump up to 80-85 and stay there till I stopped or at least slowed down a lot.

So, this is the cable? Seems like I've read/been told something about little plastic gears too?

Pete

[MattsLincoln]

Well my speedometer stopped working completely this morning, now I'm always going OD mph.

I sure wish I could resolve one freakin' issue before another hits! Anyway it's been wonky for a while. Sometimes, particularly under harder acceleration, it would jump up to 80-85 and stay there till I stopped or at least slowed down a lot.

So, this is the cable? Seems like I've read/been told something about little plastic gears too?

Pete

i thought the plastic gears are in 91's only.


also digi dashes for the win. there still cable powered but they dont jump numbers as easily as mechanical speedo's.

[GM_Guy]

There is also a plastic gear at the transmission end. You need to investigate if your speed cable is turning steadily, and if it is, problem lies with the speed-o-meter itself. If it is herky jerky standing still more than rotating, you have trans/cable issue. Pull the sender out of the trans, inspect gear. If good, that leaves only the cable.

Alex.

[86VickyLX]

Well my speedometer stopped working completely this morning, now I'm always going OD mph.

I sure wish I could resolve one freakin' issue before another hits! Anyway it's been wonky for a while. Sometimes, particularly under harder acceleration, it would jump up to 80-85 and stay there till I stopped or at least slowed down a lot.

So, this is the cable? Seems like I've read/been told something about little plastic gears too?

Pete

If your odometer is working, then the plastic gear in the trans is ok. Sounds like the speedo head died. Since the Odometer works off of a set of gears that run off of the speedometer head.

[Piece-it pete]

Thanks guys. Yeah I'm a little thick, heck I tightened up that gear at the 'fest and completely forgot about it Now that I think about it I had to change that gear on my old 87 too.

So as preparation I hit a couple of JYs and pulled a couple gears. My speedo was off anyway. Out of 7 lines I pulled I got 2 gears. Found a nice drivers seat though, I'm going back for it.

Sidenote - the factory manual lists the tolerances for the speedo. At 30 mph, the tolerance is 28-35 mph! Crap.

I'll pull the gear. If it's good I'll go ahead and change the cable (why not, got it already, <$13 in stock at Advanced Auto). If it's the head I'll find one with less miles. Just kidding....

Maybe. Earlier boxes are becoming harder and harder to come by herebouts. I might have a hard time finding any replacement, let alone one near correct mileage.

Pete

[Piece-it pete]

Changed the cable, it's easy. Dead battery so no test yet. I do believe it's the head anyway. Will report back.

Pete

[Kestas]

I had a similar situation on mt 91 Tracer. The problem was traced to corrosion of the speed sensor housing, mounted on the transmission. Working from memory, I believe I changed the speed sensor for the fix.

[Piece-it pete]

It works better, but still likes to jump up once you get going at highway speeds.

So the search for a head unit begins. I'll also try swapping the sender, that I'll find easily at least.

Btw, when I had the dash open I stuck a hose clamp on my broken shift indicator collar, fast, easy, and it worked!

Pete

[86VickyLX]

If you felt like seeing what your actual speed is next to what is displayed by your speedometer, use a gps. It's what helped me determine that I had the wrong gear for my 3.55s.