1994-2002 [Subscribe to Daily Digest] |
I agree with Rich about checking the idle. I don't have an auto Saab so I don't know what speed they usually creep at. I have driven some auto loaners and don't remember them creeping nearly as fast as you describe. It sounds like a problem to me, but I don't know for sure.
If the idle speed checks out OK, and you are still creeping very quickly it is fine to put the car into neutral when coasting down and stopped. The problem comes when you put the car back into drive. The car should be stopped, or moving slower than the speed it would be moving without pressing the gas. (at idle) When you put it in drive the RPM should not increase. If you follow these guidelines it should be ok.
In fact it should be better than OK. It is good. When you are braking the car below the idle creep speed the torque converter will be slipping. When it slips it generates heat. Heat is a transmission's enemy. By putting the car in neutral, you will no longer be stalling the converter, and generating less heat.
I was once talking to Karl Schnieder (not sure of spelling, I am in training today, not at the office), former vice president of advanced automatic transmissions at Borg Warner and asked him a similar question. I used think that the engageing of the bands would do more damage than braking the tranny. (We were talking about sitting at red lights, and very heavy traffic) He told me that heat was the real problem and slipping (stalling) the torque converter generated serious heat. He said it was better by far to shift into neutral. He said to make sure the engine is not turning faster than idle when shifting back into drive. Also you do not want to be moving too fast.
Another point is that there will be a small increase in fuel economy. By not putting load on the engine while stopped, a smaller amount of fuel will be consumed for a given RPM. The savings is small but there. The ECU should maintain idle speed the same regardless of if you are in gear or not. GM actually has a mule vehicle running around that does exactly that puts the tranny in neutral whenever the vehicle is stopped. It re-engages when you let off the brake so you still get creep.
-Joe
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
