Warning! Potential Failure Point on 911s with Cruise Control
03-21-2008, 05:14 PM
#31
Rennlist Member
So does that mean we solved the mystery
Well, it's just about quitin time here on the East Coast, FedEx just delivered my new master cylinder from Pelican, and the GF will be here in a couple hours, so hopefully I get to do my three favorite things this weekend....Fix the car, drive the car, and, well you know....
Well, it's just about quitin time here on the East Coast, FedEx just delivered my new master cylinder from Pelican, and the GF will be here in a couple hours, so hopefully I get to do my three favorite things this weekend....Fix the car, drive the car, and, well you know....
03-21-2008, 05:16 PM
#32
OK,
This is a very good theory. For that matter what if someone just bumps the cable while working on the car and cracks the anchor?
But I tend to agree, once the anchor is cracked all bets are off because the cable's outer shell can pull away from the anchor and then not return back in place. Did I get it?
This is a very good theory. For that matter what if someone just bumps the cable while working on the car and cracks the anchor?
But I tend to agree, once the anchor is cracked all bets are off because the cable's outer shell can pull away from the anchor and then not return back in place. Did I get it?
My theory, at least for the Carrera setup....
The Bowden tube is pretty stiff. When the anchor breaks as shown on the first post & #14, the CC cable assembly is free to move. When you depress the throttle the cable would normally stay put. But, since there is nothing holding it now (broken fitting) the stiffness of the Bowden tube can pull it back as much as an inch (post #14). when you release the throttle the CC cable in now 1 inch "shorter" and the end of the tube can catch on the broken anchor and hold the throttle open. It hasn't happened to me but I could see it happening based on the pictures posted.
That's my story and I'm sticking to it! Now I got to get back to work.
The Bowden tube is pretty stiff. When the anchor breaks as shown on the first post & #14, the CC cable assembly is free to move. When you depress the throttle the cable would normally stay put. But, since there is nothing holding it now (broken fitting) the stiffness of the Bowden tube can pull it back as much as an inch (post #14). when you release the throttle the CC cable in now 1 inch "shorter" and the end of the tube can catch on the broken anchor and hold the throttle open. It hasn't happened to me but I could see it happening based on the pictures posted.
That's my story and I'm sticking to it! Now I got to get back to work.
03-21-2008, 05:22 PM
#33
Peter,
Yes you are correct about picture #1 in post #1, I missed the bracket with the slot , it's out of focus in the background. Thanks for pointing this out.
So all CC cables seem to have the slotted design.
The trouble begins if the anchor point gets cracked (How or why it gets cracked I'm not sure) once it's cracked it can pull away from the anchor bracket and not return back to place. I agree with AJ88CAB about this theroy.
Last, we all agree that by design the CC cable only moves when CC is activated? This is my understanding.
Yes you are correct about picture #1 in post #1, I missed the bracket with the slot , it's out of focus in the background. Thanks for pointing this out.
So all CC cables seem to have the slotted design.
The trouble begins if the anchor point gets cracked (How or why it gets cracked I'm not sure) once it's cracked it can pull away from the anchor bracket and not return back to place. I agree with AJ88CAB about this theroy.
Last, we all agree that by design the CC cable only moves when CC is activated? This is my understanding.
In post #1 the pictures do show the slotted bracket, which allows the CC cable to float with no outside influence. My '82 is the same, and every other CIS car, from memory, also uses the same design. The CC cable is never supposed to move unless the CC is activated.
03-21-2008, 08:07 PM
#34
Addict
Is this the first post in history that we all agree on the cause and the solution? I was actually thinking it could be a tranny or DME issue. ;') Roll credits.
03-22-2008, 12:48 AM
#35
Drifting
I had this exact same thing happen right before the haripin ta sebring (at a DE) on a fairly new engine - when I pushed in the clutch the engine would start racing towards redline. I quickly dropped a gear and rode the breaks around until I could pit.
I needed a spatula to pop me off the seat. Definitely check if your plastic connector is broken. It's part of my DE checklist now.
I needed a spatula to pop me off the seat. Definitely check if your plastic connector is broken. It's part of my DE checklist now.
03-22-2008, 10:33 AM
#37
Burning Brakes
Thread Starter
I actually left the funniest part of the story out of my original post.
When this first happened, at an indicated 80 which is probably a real 72 according to my GPS on other days, I tried to brake and unstick it. I tried that several times, braking softly, and then a little harder. No good. Then I tried accerating, and unfortunately, every time I sped up, the car would stick at the new higher speed. Just as I got set to pull over, a state trooper pulls up along side, gives me an admonishing glance, and then speeds up and drives off! He must have seen my brakes on and off, speeding up to what must now be at least 80 real mph (in a 65). All I could think was, "This should know that he is riding next to a Porsche that can't stop!" Ahh, NJ's finest!
When this first happened, at an indicated 80 which is probably a real 72 according to my GPS on other days, I tried to brake and unstick it. I tried that several times, braking softly, and then a little harder. No good. Then I tried accerating, and unfortunately, every time I sped up, the car would stick at the new higher speed. Just as I got set to pull over, a state trooper pulls up along side, gives me an admonishing glance, and then speeds up and drives off! He must have seen my brakes on and off, speeding up to what must now be at least 80 real mph (in a 65). All I could think was, "This should know that he is riding next to a Porsche that can't stop!" Ahh, NJ's finest!
03-22-2008, 02:56 PM
#38
Rennlist Member
The CC cable does move when CC is actuated. However, the accelerator cable is also attached to it and this movement pushes the cable out causing the problem. If that cable outer sheathing is broken where the plastic threaded area joins it, that is a potential catastrophy.
