How do I shift without the thump? You should wait until the point where you are no longer pressed into the back of your seat to let the clutch out on your second gear shift. As to the actual application of this technique:
1. You are in first gear, taking it to your favorite shift RPM.
2. Once you reach this RPM, let off the gas pedal and depress the clutch.
3. Shift into second. (Items 2 & 3 can be done quickly)
4. "The wait". Judge it based on your body's movement. Visualize your pelvis as the axis....when the rearward pressure of acceleration leaves your body and you feel as if you can naturally lean forward at the waist.....this is the shift point.
5. Release the clutch.
another mtd works for me better:
Steps 1,2 and 3 are the same as above. Without having to wait (step 4 above), I would quickly release the clutch until just before the 'biting' point. Then I would gradually release the clutch until fully. During the process of releasing the clutch, i would gradually step on the gas. If done correctly, there will be no rear diff klunk no matter slow the car is or how low the engine revs are.
This method is very similar to moving from stationary in 1st gear and it works for all gears.
my 2 cents