First, I still have factory guages on my '84 Z28.

First problem: My speedo needle shakes and when the guage reads 55mph I am really going 45mph. (speedo is one of those dual pointer needles that reads mph on one half of the gauge and kph on the other half)

Second problem: My temp guage is pegged out. It is reading infinity. When I turn the car off and thump the needle back to zero it stays down until I turn on the ignition. I replaced the temp sensor in the head, and the problem still exist. Temps in west TX are 100+ every day ... help???
Thanks.

 

first -with speedo it is the cable binding up causing that/second if temp gauge pins hot when you turn on power it should be an open in circuit check the wire on temp sensor on side of engine(in head between exhaust ports)

 

As for the speedo cable, it's two parts, out cover and inner drive cable. I don't remember which end, but the drive cable can be pulled from one of them. Just pull the drive cable, clean and regrease it. This will often cure the problem.

 

Thanks for the replies. I tried to pull the speedo out of the guage cluster, but I couldn't get two of the screws out of the white guage holder to pull the speedo from the dash, and I couldn't reach behind it through the speaker hole to unplug the speedo cable. I figured the cable is probably not going to let me move the instrument cluster forward too much anyway.

As for the temp sensor ($10 at parts store), I replaced it, and the same problem exist. The guage pegs past 220 and gets stuck in the up position as soon as the ignition is turned to start/run.

I took the car to the chevy dealer here in TX and after two hours of diagnosis they said that both guages needed to be replaced, but GM discontinued the guages.

I'm not rich, and I am mechanically inclined, but lately I have been breaking parts while replacing other parts and spending as much money as the dealer would have charged. A mechanic told me I may have overtightened the sensor when I installed it with a boxed end wrench.

At least you guys are telling me what one of my buds said, he kept going on about the gear in the transmission making the speedo off, which royaly pee'd me off because I am trying to keep all the numbers matching (because I just had it overhauled a few years ago and it was off before the rebuild, which means someone else rebuilt it, but now I dismiss his idea - thanks). Not that my car is a low mileage beauty queen, I just want to keep all parts original and/or GM (except body panels).

Temps lately have been over 100 every day so the temp guage needs to work soon. I pass cops with severe nervousness. I am desperate for help. Thanks.

 

check ebay for a new gauge cluster. You can use any camaro gauge setup except from a 91-92 car b/c they swapped to an electronic sending unit for the speedo.

the speed being off by 10 mph may mean that they put the wrong gear in when they rebuilt it.

 

"The guage pegs past 220 and gets stuck in the up position as soon as the ignition is turned to start/run."

Check the wire going to the sensor, if it's worn through and touching something it might be grounding out and reading infinity. it might have a crack in it or be laying on the manifold.

 

to get speedo off you need to stuff your hand under dash and push metal clip on cluster and pull cable at same time seems like a b*tch but as long as you get right angle it is ok

 

jayman----don't know what you want or hor much you want to spend but buddy of mine had third gen for sale on north street in salem has done alot to it don't know how much it needs(shouldn't be much if anything)i guess starting price is 2500.

 

Ditto, it's a pain but can be done, with your finger tip.

Chevy makes different drive gears, that are identifide by color; pink, green, cream, etc. for different differential ratio's.

 

Okay, I have a silly question or two ... So the gear colors and gears are swappable without removing the trans? Is it a gear in the speedo housing or where the cable connects to the tranny?

 

So the the replacement gauge you bought fit into the same spot as the factory one? The 82-84 gauges were different from the later models, but I'm not sure how much different. For example, my speedo is one of those double pointed mph/kph deals (85mph limit), and my temp guage isn't a perfect circle when you remove it from the dash.

Also, could the problem be with the printed circuit board for either problem? Someone suggested it to me.

 

yes....has a little retainer plate with one bolt.....the gear will slide out.

On the temp gauge.....sounds like the wire to the sending unit is grounded out somewhere

 

I haven't had my third-gen for a few years, but....

If I remember right, a temp. gauge pegged at the high end means there's a short, and low end = ...something else.

My 91 had a similar speedo problem; it was that little plastic gear in the transmission. When I replaced the 140k tranny, problem solved. But again, it was a 91 so my cluster was different. Tire size, rear gear ratio, and that plastic gear can cause a lack of precision in the readout. Those gears don't last forever. Find out what your rear gear ratio is, then you'll know what plastic gear you need. I'm pretty sure its only one bolt to swap it out.

 

the problem with the temp gauge could be the needle getting stuck on the backing plate. happened to me. the fix is to bend the tip of the needle slightly down with a pair of needle nose..
also i have tghe 84 style temp and volt gauges in my 89 iroc. the difference between them is that the 82-84 gauges had a gradiated red zone. 3 red lines leading to 260 on the temp. and 3 red lines on the high and low ends for the volt.

 

THE EXACT SAME THING IS HAPPENING TO ME! on my 86 IROC...the prev owner said when he got the headers put in the speedo cable got kinked...and the temp gauge now reads infinity too.

the speedo also reads 10mph over