s4rocket

Why is the 1st to 2nd shift easy at 2500 - 3500rpm and harder at 6500rpm when you wants to go fast?

George @ BostonAudi

I rarely if ever can hit a smooth shift unless its at WOT above 5k.

S4_Cinci (I S'edTFA)

On my test drives, I found the 1st to 2nd shift less than smooth unless I depressed the clutch a fraction of a second before releasing the accelerator pedal (or in effect blipping the gas)prior to shifting into 2nd. This seemed to smooth the shift greatly. It seems that the throttle snaps shut too quickly between 1st and 2nd gear. This makes it hard to match the revs and you beat the synchros trying to shift quickly otherwise. Also I noticed that the spring in the gearshift lever is a bit too aggressive in trying to direct to lever towards neutral, which also hinders a smooth shift from 1st to 2nd. I'm guessing that this will diminish with some miles on the car vs. new. Hope this helps...

S4NoRice

Do not totally release the gas padel!!! Instead, keep the RPMs.

Dan ex S4 owner

Well, the rpm difference between 1st and 2nd for a given ground speed is going to be greater the faster you're going. Suppose the ratio between 1st and second is 2:1 (it's not, but it makes the math easier), then a 1-2 shift at 3000 rpm requires that the revs drop 1500 rpm to match, but the same shift at 6500 rpm is going to require that the revs drop 3250 rpm. That means more work for the synchromesh.

That being said, S4Ricer is correct, not letting the throttle all the way out seems to help, even though that seemingly runs counter to what I just said, 'cause it certainly doesn't help the revs drop faster. I don't know why it works that way, but it does.

It will also help keep the turbos spooled up.

RN S4

If I understand the question correctly, its "why is the 1-2 shift difficult to do quickly" not "why is it so difficult to do smoothly" after running the car out in 1st.

The synchros in the gearbox keep the shifter from moving into 2nd until the revs are (nearly) matched (not sure how close, but pretty close). This is to eliminate gnashing and preclude double clutching (they ensure that the input shaft speed matches the output shaft speed prescribed by the chosen ratio).

Essentially, once you rev to, say 6500 rpm in 1st, and disengage the clutch, the input shaft is spinning at 6500 rpm, and this perfectly matches the road speed in 1st.

Once you move out of 1st, the input shaft will continue to spin. As you force the lever into 2nd, the synchro slows the input shaft to match the now-lower needed speed (say, 5200 rpm).

(This is, incidentally, the function of a double-clutch in a non-synchro box. One moves the lever out of 1st, matches road speed to the now-lower speed, engages the clutch to spin down the shaft to the near-correct speed, disengages clutch, shifts to 2nd, engages.)

Since the S4 shaft is (according to my theory) massive, it takes some time for it to wind down. In small, 4-cylinder engines (my Integra or motorcycle) this is really quick - the synchro has an easier job. (Are transverse engines better here, due to the proximity of engine and gearbox?)

(Also - how massive can this thing really be? Maybe its the flywheel which is givng the problem? Any ideas?)

What can you do? Here's some ideas, and I'm not sure which will work:

- Double clutch - a lost art, and deservedly so.
- Slip the shifter out of gear before the clutch is fully depressed (disengaged) - this may allow the engine to spin down the input shaft freely as the revs fall.
- Conversely, push the clutch in faster - this may reduce the engines tendency to keep the input shaft spinning and allow the synchro to do its job unencumbered by the flywheel's mass
- Buy an Integra or a motorcycle

All of this is purely speculative - I'm sure anyone who knows how cars work can prove my theories wrong (and I encourage them to do so)

To be honest, I have the exact same problem with the S4. Thanks for asking the question and making me give it some thought.

Good luck.

Jeff Vader - boscoj

Solution for a warranty tranny . . .

Jeff Vader - boscoj

you just have to wait longer for the r's to come down . . . shift sooner 5800