Why does my car only have a 110 speedo and electronic cutoff? Can I buy an aftermarket guage face (like BBK) that goes up to 150? thanks

 

Your car was not ordered from the factory with the "high performance rear axle", or the Z-rated tires. As a result, you got 2.73 gears, the 110MPH speedo, and the PCM speed limiter.

You simply replace the entire instrument cluster with one from a car that had the upgraded package, and have the PCM reprogrammed with a higher speed limit.

 

I'm not positive this is the correct answer (If it's not I'd really like to know the right one). I'm not sure about the 4th gen, but in the third gen (at least some years) z28's came stantard with a 110 speedo and the 150 speedo was like a $350+ option. As I understand it the 150 speedo option not only gave you the higher speedo, but it also gave you speed rated tires which allowed GM to take the 110 limit off. It was a liability thing. If they let you go faster than 110 without speed rated tires and you drive off the lot and go 140 mph and have a blowout, you could sue them.

Like I said, I don't know if this is correct, and as for 4th gens, my 2000 Z has the 150 speedo and I've personally never seen a 4th gen Z with only a 110 speedo.

The extent of my experience is limited to 3rd and 4th gen as I was only 16 in 1987. Although my uncle has a 69 red vert that I got to drive once.

 

The 4th Gens are per my response.... the base V8 cars with A4 trannies - Z28, Formula and Trans Am - left the factory with 2.73 gears, the 110/115MPH speedo, and a speed limiter (varied from 108-118MPH depending on year), and non Z-rated tires.

 

As Injuneer said, just find yourself a 150mph speedo out of a wrecked car then buy white face overlays. It's just unplug one and plug the other one in.

 

after reading this thread... got a ? i have a 94 z with the 110 speedo and i have a M6 though... and i havent seen any of these other then myself. this mean anything different?

 

The Z-rated tires were optional on the M6's as well. Base V8 - A4 or M6 - got 235/55-16 non Z-rated tires. You have to get the RPO "QLC" (or some other option/package that contained QLC) to get the 245/50-16 Z-rated tires.

On some years, you got a "performance" package, that didn't change the 3.42 rear axle ratio, but added the Z-rated tires, an oil cooler, and maybe a few other odds and ends.

Minor point.... even the cars with Z-rated tires have a speed limiter, but its set at 255 MPH (largest number in an 8-bit binary field), so its not a factor.

 

ill say it just like everyone else says it... once again thank you injuneer

 

Performance rear axle? Do you just mean the gears or like everything? I have the 110 speedo with the 2.73's.

 

Performance rear axle refers to just the gears and the carrier I believe, which would have been 3.23's and a 3-series carrier instead of the base 2.73's and 2-series carrier.

 

I have one too, didn't notice it until I had the car home.