I have always wanted to swap my gay 115 speedo to the 150 is there any other mods i have to make?? the harness should be same in dash to hook up but will it read correctly???

 

i cant honestly say that i have heard of a 115 speedo on an lt1. what year is your car?

 

His car was not ordered from the factory with Z rated tires, thus it was speed governed (the computer actually starts to pull timing) at 108 mph (just under the 112 speed rating of H rated tires) and it came with. I believe if you get the 150mph speedo you'll have to get the computer reprogrammed, but don't quote me on that, I'm not 100% on it.

 

it would make sense that you'd have to get it tuned...right? or at least recalibrated which i suppose would probably be done through the computer. i'm not 100% sure either but i agree with slvr that it makes sense you'd have to get the computer programmed

 

Well its a completly different make, but my buddy switched speedometers in his 95 Dodge 2500 to one out of like a 94 or 95 1500 v8 because the speedo went to like 140 instead of 120 and he didn't have to reprogram anything and the gauge reads dead on. However those trucks came stock with the same tire sizes

 

The speedo in our cars are completely electronically controlled by the PCM. You can adjust the PCM for the size of tires, different rear end gears etc. The fact that it isn't mechanical would seem to necessitate a PCM reflash.