Inconsistents values of acceleration with acceleration sensor ADXL335 and MMA776

TomGeorge:
PLEASE post a link to data/specs of your Accelerometer Board.

I used the ADXL335 this far : SparkFun Triple Axis Accelerometer Breakout - ADXL335 - SEN-09269 - SparkFun Electronics
However, the wires and the accelerometer are not stick together anymore (it detached when I tried to fix the accelerometer on the car properly). I will have to buy equipments to weld again those two.

I have another accelerometer, the MMA7760 https://www.seeedstudio.com/Grove-3-Axis-Digital-Accelerometer(%26plusmn%3B1.5g)-p-765.html
I think I'm gonna use this one now as the other one can't be used for now.

Thank you for replying this far.
Kevin