DarrellC

I have follow-up question to Jeff's regarding the Cup and RSR sequential gearboxes. My question is - why is the gearbox designed so that the throttle must be blipped on downshifts? On upshifts, you keep the throttle on full and just pull back on the shifter. There is a sensor on the shifter that "cuts" the throttle for a split second on the upshift. Why can't that same sensor recognize a downshift and blip the throttle for you?

MJSpeed

You're braking and off the throttle when downshifting...this would mean that there needs to be a program that actually blips/hits the throttle for you.

Having said that I don't know why it's such an issue since other manufacuturers have them...

DarrellC

It would seem like the technology is in place with the Cup & RSR cars because they "cut" the throttle on the upshift. Maybe Porsche is saving this for the next release?

krC2S

i think this requires syncronizing the clutch release/engage with blipping and also
knowing the rpm and throttle input vs just cutting power to prevent damage on upshifts

difference with street car systems like f1 smg pdk that blip for you is that those have full control of clutch enegament since there is no pedal for you to use

ssarchi

From this discussion, is it safe to conclude that for street use, one would not want Sabine's type of manual, clutched, sequential gearbox because its life expectancy is so short?

Sure looked like a street car to me.......

SS

Greg Fishman

This is true. I have seen them apart.

MJSpeed

Actually I'm not 100% positive about Sabine's car, but it seems to me that the only difference with her car and a standard "HH" pattern car is the motion of your hand. Since there is a clutch pedal and you're still in control/responsible for blipping/lifting/breathing the throttle then it would seem to me that it would be just as reliable as the standard box. What might not be as reliable is the mechanism/device that allows the shifter to move in a sequential-type motion and whatever software that may bring.

Carrera GT

Somebody's got to find a Web site explaining the various sequential shifter systems (and distinguish them from paddle shifters on automatics with torque converters) ... this is getting a bit painful ... : )

Jean

Any of these Porsche sequential gearboxes can be fitted with a paddle shifter, I tried one on the Radical and they work flawlessly. They cost around 5k USD from a UK specialized shop.

I don't know many race drivers who would want a program to blip the throttle on their behalf when downshifting, the BMW system is very nice on the street but can be quite confusing and slow if one is racing as you don't have any control on the blip. Sabine can lap the 'Ring in a Yugo in less than 9 minutes, her BMW "tiptronic" system is maybe not a reference of perfection because of that.

There is also the cartronic "sequential shifter" and the RUF EKS "sequential shifter" and..etc... "sequential shifter", that are in fact exactly that, shifters, and not gearboxes!

ssarchi

Any of these Porsche sequential gearboxes can be fitted with a paddle shifter.....????????

... this is getting a bit painful ... : )

AMEN....... HELP!!!!!!!!!!!


Does anyone have Sabine's e-mail address????????

Dodo

I think krCS2 explained it very clearly in a nutshell.

I had SMG in BMW M3 CSL which uses a hydrolic system around the std six speed manual transmission. Main points that comes to my mind are:

- Two hands on the streering wheel (makes life easier and safer on the track) though you can also shift with the gear lever if you want to.
- At fastest mode, can upshift at 0.08 sec (yes 80 milisec). That's as fast as any racer and it does it every time, all the time.
- Throtlle blips for downshifts (i.e. rev matching by heel and toeing for you). Thus you can't over run the engine at downshifts. If it calculates red range, it just doesn't down shift. Good for you, good for the next owner.
- You can upshift without lifting the accelarator.
- Has launch control that takes you from stand still to Vmax without lifting the accelerator (could be fun for the traffic light racers)
- Has hill ascent control (i.e. prevents slipping down when starting up hill from stan still. Never used it myself).
- Has an auto mode, that you can let it shift up and down when you're occupied with something or in stop and go traffic.
- Has several shift programmes (5 auto and six manual) for your and your passengers' mood. It might be a bit jerky at fast programmes but you like that for enthusiastic driving. Otherwise, just pick a slower programme or lift slightly then it's smooth.

Overall, I liked it very much on the road and on the track and never had any problems with it. I understand BMW is considering DSG like double clutch systems that are even smoother and faster for their next generation. Look forward to GT3 having it at least as an option.

Jean

ssarchi, I have her residence phone number if it helps you?

ssarchi

I would like to speak with her- but my German is not too good..... besides I might be too confused to ask a meaningful question......
Let's get one of our German speaking friends (Jean) to call her on the phone and get some of these difficult questions answered.....

Carrera GT

Sabine speaks very good English. Her interviews are great. And she's usually at full tilt in an interesting car.

The topic is great, the pain is just the round and round grinding of gears, so to speak.

I do agree the SMG description is about right. But I've never liked the SMG or F1 variants. Although I accept that driven hard, they work well, while tootling around, they tend to buck. Launch control is very cool in a Maranello ... : ) ... but having had both SMG in a new (recently outdated) M3 stall repeatedly and fail to engage reverse until the car was rolling, well, not impressive. And F1 in a 360 is just annoying ... and mindbogglingly expensive for regular maintenance even by Ferrari standards.

As for paddle shifter, no, there's no easy way to fit a paddle shifter to a conventional gearbox, but a sequential shifter (single mechanical lever to go +1 or -1) and still have a foot clutch, that's not too expensive or difficult. Adding in a solenoid for the clutch is tricky and I imagine wildly expensive.

Going to a fully robotic shifter than can make revs on a downshift and accept multiple downshifts to be performed as road speed falls in rpm ranges, that would be more expensive again.

As soon as PDK is light, durable and strong enough for the big engines, it will change the planet. Much as I enjoy my cog-swapping, I'd much rather be banging around with PDK even if only for the novelty and I could well end up back in a floor shift double-H pattern.

Keep in mind PDK will allow multiple gear ratios (different 2nd gear ratio on a downshift) and more forward gears (six, seven, eight?) with all kinds of possibilities as far as cornering effort, differential gearing (connecting the diff gearing to the steering angle, road speed, yaw sensors, etc.) so we're on the slippery slope of electronic driver aids like it or not: PDK is the nose of a very big camel in the tent. : )