Acceleration question
09-24-2003, 07:07 PM
#1
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Thread Starter
Acceleration question
I have a quick (pardon the pun) question
How long before my neck muscles get
strong enough to hold my head steady
under acceleration? I find myself looking
at the sunroof alot, when passing.
How long before my neck muscles get
strong enough to hold my head steady
under acceleration? I find myself looking
at the sunroof alot, when passing.
09-24-2003, 09:01 PM
#3
Former Vendor
Join Date: May 2002
Location: Tampa
Posts: 6,849
Likes: 0
Received 0 Likes
on
0 Posts
The problem is that the nose of the car is being pulled up and the rear of the car is squatting. This is indicative of the need for a set of PSS9s..... The fun is just beginning. Steve has already told you to stay away from me right???
09-24-2003, 10:58 PM
#4
I defer to Bob on things mechanical, but a good 911 squats. Nothing too manly about it.
As for neck muscles, there's no neck on the planet -- short of a Rhino -- capable of holding its head steady under the "influence" of 400 horses under acceleration and over 1700 horses under deceleration. Still and all the same, I counsel against attempting to control the vehicle whilst gazing skyward through the roof ...
(I take this moment to cruise Rennlist as Cruz Bustamante bores me silly during the Guber debate here in CA ... man, is that guy slow! ... no wonder it too the CA govt nearly eleven months to realise they'd burned 30 billion dollars they didn't have ...)
As for neck muscles, there's no neck on the planet -- short of a Rhino -- capable of holding its head steady under the "influence" of 400 horses under acceleration and over 1700 horses under deceleration. Still and all the same, I counsel against attempting to control the vehicle whilst gazing skyward through the roof ...
(I take this moment to cruise Rennlist as Cruz Bustamante bores me silly during the Guber debate here in CA ... man, is that guy slow! ... no wonder it too the CA govt nearly eleven months to realise they'd burned 30 billion dollars they didn't have ...)
09-24-2003, 11:31 PM
#5
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Thread Starter
Bob, steve did tell me but as an engineer its like
looking at Pandoras box, You just want to
open it up, and you cant help yourself!!
looking at Pandoras box, You just want to
open it up, and you cant help yourself!!
09-25-2003, 12:14 PM
#7
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Thread Starter
another more technical question
when I pass in 3rd gear as I get out
and start going (still accelerating) I feel
a tiny slide. I am breaking lose all 4 as
everything kicks in?? Of course I waited till proper operating
temp before doing this.
when I pass in 3rd gear as I get out
and start going (still accelerating) I feel
a tiny slide. I am breaking lose all 4 as
everything kicks in?? Of course I waited till proper operating
temp before doing this.
Trending Topics
09-25-2003, 02:24 PM
#9
Drifting
OldGuy,
Sounds like your clutch is slipping. It will happen in the higher gears at the torque peak first and then as it progressively gets worse, it will do it at lower torque settings in the lower gears. It is VERY common for new owners of 911 Turbos to find out their clutches are worn and in need of replacement. It seems that previous owners know about the clutch issue, but want to sell the car rather than foot the bill to repair.
My C2 Turbo was the same, the PO said the clutch operated fine, but it was really heavy and the PPI showed that it would need replacement soon. It ended up lasting about 10k miles and then I replaced it.
I don't know what the cost is on the 993 Turbo, but the C2 Turbo was very expensive, especially since I changed over to a single mass flywheel.
Sounds like your clutch is slipping. It will happen in the higher gears at the torque peak first and then as it progressively gets worse, it will do it at lower torque settings in the lower gears. It is VERY common for new owners of 911 Turbos to find out their clutches are worn and in need of replacement. It seems that previous owners know about the clutch issue, but want to sell the car rather than foot the bill to repair.
My C2 Turbo was the same, the PO said the clutch operated fine, but it was really heavy and the PPI showed that it would need replacement soon. It ended up lasting about 10k miles and then I replaced it.
I don't know what the cost is on the 993 Turbo, but the C2 Turbo was very expensive, especially since I changed over to a single mass flywheel.
09-25-2003, 03:10 PM
#11
Nordschleife Master
OG,
That would be a VERY GOOD thing, as oppossed to a slipping clutch which be a VERY BAD THING. My car, which seems to be plenty healthy, does not ever spin the tires. Of course I shift it like an old lady. But it would never break a tire loose when accelerating in 3rd gear. Maybe you got yourself a monster!
That would be a VERY GOOD thing, as oppossed to a slipping clutch which be a VERY BAD THING. My car, which seems to be plenty healthy, does not ever spin the tires. Of course I shift it like an old lady. But it would never break a tire loose when accelerating in 3rd gear. Maybe you got yourself a monster!
09-25-2003, 03:22 PM
#12
The car, much as I love it, even upped to 500hp, has nowhere near the power and torque required to "over rotate" the rubber. For that reason, at stock 400hp, the reviews back in the day complained that the car lacked the spirit of a rear-wheel drive 911. Some people are never satisfied ...
I'm sure you know the difference between losing traction and a slipping clutch. It sounds like you're feeling this through the seat and the steering wheel. A dying clutch is obvious as the engine "flares" with extra revs while the car slows or doesn't accelerate as hard.
It could be the tyres are dead (hard) from too many heat cycles. It could be one tyre is dead, accentuating the torque steer.
Does it have stock wheels and tyres?
I’ve heard of trouble when using different tyres resulting in a different rolling radius front and rear. Maybe the centre diff is doing something odd.
Have you driven enough other Turbos to have a sort of baseline reference and this car feels different?
I know if I have it wide-open in 3rd there’s no loss of traction unless you’re cornering and when the boost comes on (I have GT2 turbos, so it’s a bit more lag and a bit harder onset) the car loses just the rears and then the torque goes full (18%?) to the fronts and the whole car starts using up the track-out.
If you’re over-taking on a two-lane road (one lane each way) you’re moving over the convexity of the road, so the weight distribution would move from passenger side to driver side and you could be hitting some of the painted line or just getting sufficient unweighting to require the transmission to compensate.
Hard to say.
Still, it’s the new toy, so this is a fun thing to experiment with and figure it out. I’d take it on a nice new freeway somewhere and experiment with 2nd and 3rd gear acceleration (and practice watching my mirrors for unmarked police cars...)
Welcome to the real world.
I'm sure you know the difference between losing traction and a slipping clutch. It sounds like you're feeling this through the seat and the steering wheel. A dying clutch is obvious as the engine "flares" with extra revs while the car slows or doesn't accelerate as hard.
It could be the tyres are dead (hard) from too many heat cycles. It could be one tyre is dead, accentuating the torque steer.
Does it have stock wheels and tyres?
I’ve heard of trouble when using different tyres resulting in a different rolling radius front and rear. Maybe the centre diff is doing something odd.
Have you driven enough other Turbos to have a sort of baseline reference and this car feels different?
I know if I have it wide-open in 3rd there’s no loss of traction unless you’re cornering and when the boost comes on (I have GT2 turbos, so it’s a bit more lag and a bit harder onset) the car loses just the rears and then the torque goes full (18%?) to the fronts and the whole car starts using up the track-out.
If you’re over-taking on a two-lane road (one lane each way) you’re moving over the convexity of the road, so the weight distribution would move from passenger side to driver side and you could be hitting some of the painted line or just getting sufficient unweighting to require the transmission to compensate.
Hard to say.
Still, it’s the new toy, so this is a fun thing to experiment with and figure it out. I’d take it on a nice new freeway somewhere and experiment with 2nd and 3rd gear acceleration (and practice watching my mirrors for unmarked police cars...)
Welcome to the real world.
09-25-2003, 03:48 PM
#13
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Thread Starter
Carrera Thanks for the input. I know its not a clutch
slippage My old porsche had a bad clutch and I know
what that feels like. the car goes a bit sideways
when it does it very much like my truck in dirt.
and both times its been over a painted line.
And according to the records the clutch is 2K
miles old. I dont think a clutch would make the
car squirt sideways as in a loose dirt situation.
Steve i am thinking this is a good thing.
slippage My old porsche had a bad clutch and I know
what that feels like. the car goes a bit sideways
when it does it very much like my truck in dirt.
and both times its been over a painted line.
And according to the records the clutch is 2K
miles old. I dont think a clutch would make the
car squirt sideways as in a loose dirt situation.
Steve i am thinking this is a good thing.
09-25-2003, 05:15 PM
#14
You might take it to a shop with a synchronized all wheel dyno and get some power and torque curves.
If the clutch is 2K's ago, I guess it's around 30K miles on the odo?
It should still be very close to 400hp at the flywheel.
If you get to a race track or race shop, they'll have a device capable of measuring the hardness of the tyre over the contact surface (a "durometer") which, if the previous owner happened to run the car with a rear tyre under-inflated, the extreme heat could kill a tyre pretty quickly with sustained freeway speeds in a daily commute.
My wife literally drives the tyres off cars. She took out a set of S02's on my old Boxster in six months -- the rears weren't worn out, but they were hard as a rock and the oversteer was, well, thought-provoking.
For the street, the pressures on the sticker on the door, 36 and 44lbs cold, front and rear running Asymmetricos. For country driving, I up this to 38, 46 hot. This seems to keep the tyre nicely shaped, plus I have 295's. For the track, I ended up with higher hot temps (adjusted down, then needing two laps to come up to temp) around 40, 48 at Willow Springs, which has some tyre-shredding turns. I have a half a memory of getting better results with 47 in the rear, but I'm not kidding myself that I can feel one pound in the rears. I lost the paper with my notes (don't you love it when someone "helps" you by "cleaning" ... grumble ...) from the last two days at Thunderhill and Willow Springs, so I'll be starting the process over again, hopefully with some new rubber.
If the clutch is 2K's ago, I guess it's around 30K miles on the odo?
It should still be very close to 400hp at the flywheel.
If you get to a race track or race shop, they'll have a device capable of measuring the hardness of the tyre over the contact surface (a "durometer") which, if the previous owner happened to run the car with a rear tyre under-inflated, the extreme heat could kill a tyre pretty quickly with sustained freeway speeds in a daily commute.
My wife literally drives the tyres off cars. She took out a set of S02's on my old Boxster in six months -- the rears weren't worn out, but they were hard as a rock and the oversteer was, well, thought-provoking.
For the street, the pressures on the sticker on the door, 36 and 44lbs cold, front and rear running Asymmetricos. For country driving, I up this to 38, 46 hot. This seems to keep the tyre nicely shaped, plus I have 295's. For the track, I ended up with higher hot temps (adjusted down, then needing two laps to come up to temp) around 40, 48 at Willow Springs, which has some tyre-shredding turns. I have a half a memory of getting better results with 47 in the rear, but I'm not kidding myself that I can feel one pound in the rears. I lost the paper with my notes (don't you love it when someone "helps" you by "cleaning" ... grumble ...) from the last two days at Thunderhill and Willow Springs, so I'll be starting the process over again, hopefully with some new rubber.
