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Old 03-07-2008, 01:02 PM   #1
BlahBlahYouToo
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Default shift shock - is there no way to avoid it when driving hard/fast?

happens to me, my friends, watching professional driver videos on youtube, etc.
is that just a necessary evil of trying to shift as fast as possible during high rpm?
is it bad for the clutch/engine/drivetrain?
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Old 03-07-2008, 01:10 PM   #2
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Default shift shock - is there no way to avoid it when driving hard/fast?

Any hard shift is going to have a greater impact on the drivetrain than normal, but I'm going to assume that you don't drive on a track/do it every day so don't worry about it.
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Old 03-07-2008, 01:43 PM   #3
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Default shift shock - is there no way to avoid it when driving hard/fast?

It's actually easier on the clutch's friction material than a smooth shift is because there's not nearly as much slip during take-up. However, it stresses the springs in the clutch center more and is harder on the entire drivetrain. In most cases though you have to be almost abusively hard with the shift to cause issues. (Note that some specific cars are more or less durable than others, the original WRX supposedly is not as durable, the Honda S2000 has reports of issues with the CV joints in the rear halfshafts, and the Porsche 944 non-turbo has a weak differential; these are just examples to illustrate the importance of knowing your particular vehicle's strong and weak points and even these cars require very abrupt shifting to cause damage.)

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Old 03-07-2008, 02:19 PM   #4
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Default shift shock - is there no way to avoid it when driving hard/fast?

I used to constantly snap axles on my 5g prelude I usually got about 20k miles out of a set. They just weren't designed for boost + high-rpm launches.
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Old 03-07-2008, 03:45 PM   #5
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Default shift shock - is there no way to avoid it when driving hard/fast?

Quote:
Originally posted by: Arkaign
I used to constantly snap axles on my 5g prelude I usually got about 20k miles out of a set. They just weren't designed for boost + high-rpm launches.
Wheel hop kills Axles on the SRT-4 as well
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Old 03-07-2008, 03:53 PM   #6
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Default shift shock - is there no way to avoid it when driving hard/fast?

wheel hop kills any axles or driveshafts.
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Old 03-07-2008, 04:17 PM   #7
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Default shift shock - is there no way to avoid it when driving hard/fast?

On hard driving, I mesh the clutch out like 0.001th of a second before going back WOT. The idea is to damp the revs down from the prior gear just enough to match with the next gear yet while upshifting as quickly as possible. It's difficult to explain and takes considerable practice, but done right there is little to no shift shock, just Go, shift, Go, shift, Go...
This is IMO faster than the hard-shifting barking gears technique, and 110% nicer to the equipment.
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Old 03-07-2008, 06:44 PM   #8
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Default shift shock - is there no way to avoid it when driving hard/fast?

Quote:
Originally posted by: Vic
On hard driving, I mesh the clutch out like 0.001th of a second before going back WOT. The idea is to damp the revs down from the prior gear just enough to match with the next gear yet while upshifting as quickly as possible. It's difficult to explain and takes considerable practice, but done right there is little to no shift shock, just Go, shift, Go, shift, Go...
This is IMO faster than the hard-shifting barking gears technique, and 110% nicer to the equipment.
Can you please elaborate? It seems like what you are describing is the "normal" way to do a hard shift. How is what you do different?

Here is what I think you are saying:

1) WOT
2) foot off gas
3) clutch in
4) move shift lever
5) clutch out
6) WOT (0.001 seconds later)

The result of this in my car is a thud noise of what I assume is the engine rocking a little, a slight forward jolt and an instant pitch change.

Is this what you are saying?
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Old 03-07-2008, 06:59 PM   #9
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Default shift shock - is there no way to avoid it when driving hard/fast?

Reverse steps 2 and 3. Clutch should always go in slightly before you come off the gas.

If you're getting shift shock like the OP described, the only way that could happen is if go back WOT with the clutch out and the revs still up above what is necessary (matched) for the next gear in the upshift.

A corollary is the way race bikes use an automatic switch to briefly kill the ignition between shifts so the rider doesn't have to come off the throttle.
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Old 03-07-2008, 07:31 PM   #10
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Default shift shock - is there no way to avoid it when driving hard/fast?

Quote:
Originally posted by: Vic
Reverse steps 2 and 3. Clutch should always go in slightly before you come off the gas.

If you're getting shift shock like the OP described, the only way that could happen is if go back WOT with the clutch out and the revs still up above what is necessary (matched) for the next gear in the upshift.

A corollary is the way race bikes use an automatic switch to briefly kill the ignition between shifts so the rider doesn't have to come off the throttle.
Yup, Vic's got it right. There's usually still a little "surge" as you are landing back in the meaty part of the powerband if the gear ratios are right, but there shouldn't be a "slamming" sensation.

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Old 03-07-2008, 07:36 PM   #11
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Default shift shock - is there no way to avoid it when driving hard/fast?

The only time I would expect a real jolt would be if you were keeping the throttle open during the shift. This normally only happens in rental cars....
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Old 03-07-2008, 07:40 PM   #12
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Default shift shock - is there no way to avoid it when driving hard/fast?

Quote:
Originally posted by: DivideBYZero
The only time I would expect a real jolt would be if you were keeping the throttle open during the shift. This normally only happens in rental cars....
It was fun to do in the Mustang when I had it... But the Tremec transmission in the Mustang GT is incredibly overbuilt for that application so it's not apt to break.

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Old 03-08-2008, 05:35 AM   #13
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Default shift shock - is there no way to avoid it when driving hard/fast?

Yeah, I'm not a great fan of power shifting, I don't think you get much more out of it vs. applying WOT as soon as you've engaged the clutch. For me, as I have been driving manuals almost exclusively for almost 18 years, it's actually hard to keep the gas pedal down during a shift. It's just second nature to lift a little at least.

Oh, BTW, going for a track session in an Exige soon around Thruxton race circuit with 1 to 1 tuition. Should be a hoot!
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