ZEUS+

Different car same principal.
http://www.porsche.com.cy/nqcontent....raphic&lang=l1

dr bob

CIS cars are more sensitive to throttle opening, compared with the EFI cars. That's just an observation.

Comparing the 5sp vs the S4 autos is not a great comparison. The autos have the rotating mass of the torque converter to spin up, larger diameter and probably a lot more weight at the outer reaches compared with a 5sp with flywheel and clutch. And that's just an observation based on absolutely no experience with the 5-speed cars.

The throttle linkages are way different on the S4. I'll speculate that Porsche decided that a slower pedal would help with driveability and fuel economy. It seems at first like it's really sluggish since it takes a lot of pedal movement to get WOT. Are the early cars a little more responsive because the throttle plate moves quicker?

JKelly

The cats aren't gutted are they?

When the clutch is pushed in and the car at a stand still, the only thing rotating is the 2,000lb flywheel.

You said that the header pipes are "rusted out". If they are rusted out with holes in them, the car is going to rev faster.

Mrmerlin

this fact was noticed with the 86.5 clutch relased so the driveshaft was turning as well as the mainshaft in the trans, the S4`s were checked with them in park.... The cats as far as we could tell seemed to be working judging by the smell of the exhaust however the cat pipes were pretty rusted and had a few holes in them just after the manifold connection, The car is getting an X pipe from Motorsport and it will have 300 cell cats with a new O2 sensor, this would have been done but the manifold boltsa were too rusted to remove easily....... Anyway the engine just seems to want to jump out of the engine compartment as soon as the throttle is blipped

heinrich

This has not been my experience at all.

mark kibort

right! With the clutch in, they are all the same. infact, push in the clutch and rev the engine. THEN, let out the clutch in neutral and rev the engine, see if there is any difference. there wont be, AND , you are spinning a 45lb clutch (in the case of the S4) with the entire driveline, with whatever is connected to that in the gear box.

Like i said, Scots 2 valve 5 liter with the same hp and even before when it was down 30hp, still reved in neutral faster. Its that accelerator linkage thing bob was talking about.

MK

edit: wrong information above. corrected in posts below

SMTCapeCod

Perhaps a variable intake/flappy drawback?

Imo000

Mark,

Maybe I’m wrong here but with the clutch in, the only things not spinning is/are the clutch disk/s. The disk/s are not 45lds are they? The rest (flywheel, intermediate (if it has one) and pressure plate) are still spinning just as they did when the clutch was out. With the clutch in there will be added forces from the clutch fork and release bearing too so wouldn’t this pretty much equal out the non spinning disks mass too?

JKelly

With the double-disk clutch:

If the car is at a stand still with the clutch pedal pushed in, the only thing that rotates (or should be rotating) is the flywheel (EDIT: intermediate plate and pressure plate too). Pressing the clutch pedal releases the pressure of the clutch disk(s) off of the flywheel. The function of the pilot bearing is to allow the flywheel to rotate independently from the rest of the drive line and clutch disks. If you hear chirping or grinding sounds with the clutch pedal pushed in, check your pilot bearing for binding.

If the car is at a stand still with the clutch pedal not pushed in, and the shifter is in neutral, the flywheel, clutch plates, intermediate plate, pressure plate, intermediate shaft, and driveshaft are all turning....., but the car is not going anywhere because the transmission is not in gear. If you hear chirping/grinding in this position and the sound goes away when you push in the clutch, check your throw-out bearing for binding. The throw-out bearing functions to keep your clutch release fork from rotating, which would not be good if that happened .

- With clutch pushed in, only the flywheel spins (EDIT: flywheel, intermediate plate, and pressure plate).
- With clutch not pushed in, but trans in neutral, everything from the flywheel back to the trans spins.

mark kibort

see jkelly's response.
mk

Imo000

Wait a minute! In a dual disk system when the clutch is pushed in the pressure plate is not spinning? For some reason I can’t picture how this works. I haven’t taken my dual apart yet but over the years I’ve work on dozens of single disk systems.

Tom. M

I think the pressure plate assembly as well as the intermediate plate on the dual disk continues to spin when you step on the clutch. The release arm pulls back on the release bearing..thereby pulling pressure off the pressure plate and int. plate...and disks do not have contact with the plates at all (in theory). The release bearing is now spinning at engine speed...and that is why it's bad to keep the clutch pushed in for long periods of time.

interesting setup for sure..

later,
Tom
89GT

So..with clutch out ...noise would be related to pilot bearing...and with clutch in..noise would be related to release bearing..

JKelly

Yep, my mistake. The pressure plate and intermediate ring are bolted to the flywheel and continue to spin when the clutch pedal is pushed in, but the disks inside and the intermediate shaft do not unless the car is rolling and in gear.

I've only pulled my clutch about half a dozen times......and still can't remember it right .

JKelly

Nope, it's still the other way around.

mark kibort

thats right! i forgot about that small detal! Ive only bolted the pressure plate to the flywheel, how many times now????

mk