ok i have a 94z w/ 4l60e so it came with 115 mph gauges. where can i go to get them corrected for the right speed. right now when it reads 70 im doing about 55. i got a ticket and the cop told me if i got written proof of getting them fixed he drop to charge so its pretty important thanks guys
Rob

 

Sounds like someone changed the rear axle gears, without entering the correct info into the computer. That's where corrections to the speedometer are made - in the PCM, not in the gauge cluster. But usually, people put in higher numerical rear gear ratios, causing the speedo to read higher than actual speed.

 

did i mention in the thread above that im a retard? im sorry i ment to put that i installed a 150 mph gauge overlay so thats why there off now. this is a perfect example of why you shouldnt have your girlfriend around when your talkin car stuff. my bad

 

how did you get a 94 Z with 115mph speedo?

my 90 v6 firebird even goes up to 120..haha

i thought the 115s or whichever only came with v6s

 

Some of the earlier 4th Gens came with 115mph speedo, it was an option to get the 150mph cluster.

 

hmm i didnt realize that...kind of odd that they did it like that.

 

If you bought the car from the factory with the "base" tires (235/55-16?) you got a 108mph speed limiter, and the 115mph (or maybe 120???) speedometer. If you bought the optional "performance tires" package, 245/50-16 Z-rated GS-C's, you got the 155mph cluster.

 

So, you got a ticket for going too slow?

 

 

You should have gotten [or try to get] a 150 speedo guage cluster used... it's easier to change the 'guage cluster', than it is the speedo itself...
I am not sure whether the 110 speedo can be reprogrammed that far? [I know for tire size or gear change it can be..]
Z's came with 110 or 150's and Bird's came with 115 or 155's and they don't fit each other...

Curious why you would 'overlay' it, and then ignore the obvious large error?

 

man this went three different ways. Its not that i didnt realize i was speeding or that it was off, i knew it was off bad i just havent had it fixed yet.when the gauge reads 70 mph im actually doing 55. i got a ticket for 55 in a 35. i knew i was speeding but i told the cop i didnt cause my gauges were off cause they were aftermarket. he told me to get them fixed and he'd drop the ticket. so therefore im trying to find out if its possible to correct them or not?