Originally Posted by cadillackid
that sounds about write.. I did a punkin swap on my Superior from 6 something to a 4.78 and got a fully reman punkin for about $1300 or so from weller.. I did the swap myself so I saved the labor but your pricing sounds about inline..
remember with your computer you need to change the pulses per mile for it to show up on the dashboard speedometer.. the axle ratio and trans ratios are just for the fuel curve aggressiveness.. I think you have an AT545? that unit places 16 pulses per driveshaft rev.. by correctly calculating the number of tire revs per mile.. then muiltiply by your new axle ratio then multiply by 16 should give you your total pulses per mile you need to put into the ECM.
this new gear ratio while much faster will also make MUCH more heat into your AT545 as well.. it will get hot unless you put in a big cooler.. the converter ratio from engine speed to output shaft speed will be generally higher as you are working the trans harder esp at speedsin the 55-65 range or doing any hill climbs..
As Bama quoted me, mine's a 5-speed manual. So, no transmission worries at this time.
I did change the gear ratio in the computer (and left the tire revs per mile unchanged), but mistakenly didn't realize the pulses per mile didn't recalculate automatically. I'll change this later, but it's helpful to know why the parameters are separate in the computer.
Pulses per mile - old, roughly 44,000; new, roughly 32,000 (I'll program the correctly calculated values when I do it, this is just going off memory for now).
My dash *STILL* works intermittently, I've already re-flowed the solder joints on the circuit board once before. I see RockAuto has new boards for under $300 (no gauges, just the circuit board). I may just go the BlueFire route and set up an old phone with the Bluetooth for gauges.