Marc3.4V6

iTrader: (1)

My pinion bearings are going out on my diff and I decided to just upgrade to 3.73 gears for a few hundred bucks more while they have everything out. However I do have to take care of the speedometer being off. Thing is, my car was dyno tuned at a shop many miles away (over 8 hour drive) by one of the previous owners. Hopefully I'm wrong, but this seems to complicate things a bit.

I'm looking for the most economical way of doing this - handheld tuner, efi live/hp tuners (never used them before), mail order tune; and can this be done easily without effecting the dyno tune? Is it possible that the prevous tuner "locked" it? I don't know if this is a common practice of tuners but I read it a few times while searching for information. If it is locked, what are my options? Also, does anyone know how far off my speedo will be?

LSX Power Tuning

iTrader: (4)

Your PCM could be locked, no way to know if your tuner locked it or not. If the pcm is locked you have to go back to the tuner who locked it or buy another pcm and start over with a new tuner. The cheapest way to get the speedometer corrected would probably be through mail order. Correcting the gear ratio wont make you lose your dyno tune.

Marc3.4V6

iTrader: (1)

Thanks for the reply, should my shift points be changed as well?

LSX Power Tuning

iTrader: (4)

It depends alot on if you have a stall or not and what kind of hp you have. If you have a stock stall and bolt ons changing the just the gear ratio would be ok. If you have a big stall all the shift points would need to be adjusted to keep it from going to the rev limiter.

Marc3.4V6

iTrader: (1)

Thanks again. I was actually able to find out who dyno tuned it and called them, they say they never lock their tunes, so I should be good to go.