My 1985 Camaro (V8) failed the safety inspection because the interior dash turn signal indicators did not work! Since I had to tear the dash apart to repair I decided to update the 85 MPH speedo/Idiot lights. I got a 115 MPH cluster with tach and gauges and after reading all the posts I figured this would be a simple fix. Replaced the water/oil switches with sending units and the swap went off without a hitch. That is until I drove it and found the Speedo reading way too high. Driving through the neighborhood at an estimated 35 had the Speedo reading 50+..Haven' had it out on the highway yet but I'm sure it will just get worse. Any thoughts?

 

Did it ever seem to read correctly with the old speedo? Your user account has no history, and you allow it to seem as if the new speedo reads in error without stating the condition of the old.

A same-trans., same-size tire 87 Camaro with a 145mph speedo will have the exact same speedo gears as another 87 with 85mph speedo.

You can count speedometer gear teeth, ring and pinion teeth when you change the rear gear fluid, and tire size, and you'll have a better idea of whether the rest of the car has mis-matched parts.

 

The old speedometer always read correctly. The car is otherwise stock with the original differential etc. nothing changed but the instrument cluster.

 

Wouldn't a v6 speedo read 1.5 times as high?

 

Why is this posted in the classifieds?

 

My page says Tech Boards / Interior.

 

Looks like the mods moved it.

 

If the exterior signal lights are working OK and they are not showing on the dash cluster - and this started after changing the cluster - I would suspect the cluster has issues. Factory original Cluster Printed Circuits are getting pretty old and crusty these days and it's very possible that your replacement clusters' printed circuit has caused this problem. Could be something as simple as a bent terminal on a cluster plug - or something worse like a rotten Printed Circuit.

If the exterior signal lights do NOT work....... There's going to be a lot more to check before figuring it out !

I've never found a speedo inaccuracy that traced back to the speed head. While It's not impossible that the Speedometer itself is causing the inaccuracy,..... It's not a common/usual problem. ( could be a bad / bent needle spring for example ) The V8-vs-V6 cluster conflict has to do with the Tachometer compatibility problem ( and technically the oil pressure gauge readings too.)

I'd focus on the blinker issue. If the printed circuit is bad you will (probably)need to replace it anyway,.... meaning you might be lookin' for another gauge cluster.

 

The blinker issue effected the dash lights only and was related to the original cluster. It was resolved by replacing the cluster but this introduced the Speedometer issue.