winders

That's what it would take to be as fast a Leh was in that video in the Cup Car.

No, your dog box would not be legal for my race class. What I need is for you to modify my gearbox to use G50-style synchros!

mark kibort

Yep, and as shown clearly by the two videos examined.
new stuff fast, old stuff, not fast, but effective.
I think that just about covers it.

Dr911

Hee hee hee!!
You guys are too fun!

danielyonker

I'm noticing personality differences in those from the left coast vs. those from the right. Passive observation

333pg333

It's the timezones.

https://vimeo.com/108850552

Not sure what syncro's are in a 968 6 speed but assume something G50-ish. Even so, we lose tons of time compared to a PDK or similar. This lap is right on 997 Cup pace. Excuse the year old R comps but the shift times look capable of being faster than the 915 series.

winders

I think you mean "passive aggressive observation".

333pg333

Isn't that when you're meant to edit someone's post and then say 'fify'?

Coochas

This is 1986 F1. I'm guessing it is a dog box tranny but requires quick downshifts with rev matching nonetheless. Watch at about 1:45 Dumfries goes down 5 gears sequentially so smoothly and rapidly.
On a side note, these were turbo era F1 cars that DID sound good!
Other side note: Look at the size of the TV camera mounted on his car!!!!!

JustinL

Another data point for the OP. I go in sequence 90% of the time (my local track only needs 2 gears, so that helps!). There was one corner at the old autocross track where I'd go from the top of 4th to the middle of 2nd. It was a long straight into a 90°. There I'd brake hard and keep it in 4th until just before turn in and then flick it into 2nd. I tried 4-3-2, but then the braking zone had to stretch out a little bit because I had to divert my attention from threshold braking and it was a measurable time cost.

The right answer is obvious though: PDK is PDQ

JCP911S

First, the correct answer is 352 Angels can dance on the head of a pin, so anybody with credible proof to the contrary is welcome to post.

Seriously, the "speed" of a shift has to do with the total time of power loss to the wheels. This includes disengagement of the clutch, re-engagement of the clutch, and application of throttle, and as noted, the inertia in the entire reciprocating mass of the power-train... not simply how fast the change in gear occurs.

"synchro lag" if you will, is only a small proportion of this total time.

I would argue that foot speed, mechanical leverage and play in both clutch and throttle linkage add delay into the total process that exceed synchro action by several times.

The driver can "squeeze" much of this delay out of the system by coordinating left foot, right foot and arm movements "anticipating" that each of the other two movements will be executed perfectly so as to avoid a "money shift".

It is perfection of this co-ordination, as well as the confidence of the driver that they will be executed 100 out 100 times correctly that determines shift speed.

PDK works because the computer controls engine power and clutch engagement functions in milliseconds with 100.0 percent reliability.

GTgears

Until it goes into limp mode.

JCP911S

Better than engine rebuild mode.

mark kibort

I have to respectfully disagree with you here. the reason is the coordination part, most get. its really waiting for the engine and drive trail components to be matched up. in the aston Martin for example, 1st to 2nd is a big jump and the rest are close ratio gears. you have to wait to even upshift, because the revs fall so slowly and have a long way to do. downshifts, are easier, as you are forcing the transmission to speed up to match engine RPM. (either by synchro or drive train (clutch partially disengaged).

so yes, there are some relatively quick shifts in the 911, due to the type of gear box that it is, and engine characteristics. you don't get that with other types of cars , older and newer than the 915 box.

again, nothing is faster, easier or more accurate than the new stuff. and the newest stuff, well , lets just say its cheating.

ProCoach

+1. Excellent post!

<from an old Alfa racer>

winders

With a 915, that may be true for a downshift, but for an upshift, waiting for the synchro to do its job is what slows everything down....by several times. Unless, of course, you don't care about synchro life.