maat
01-09-2005, 07:37 PM
So this summer I did a lot of highway driving and I noticed this weird thing that the transmission does at highway speed. I was wondering if anyone could explain what's happening.
So say I'm doing around 65 mph, around 2000 rpm's or so (I can't remember exactly), and I want to accelerate to get around someone. If I push the gas down a little farther, the car accelerates slowly because it's in 4th gear/overdrive. If I push it down farther than that, my tach jumps about 1 grand and the car starts accelerating a little faster, but I don't get any of the hesitation that a downshift would cause. And if I push it down even farther, I get a real 4-3 downshift (you can feel the slight hesitation during tranny transition) and my tach jumps up to 4 grand or so. And if I floor it, I get the 3-2 downshift and the very top of 2nd gear (>5000 rpm's).
What I don't understand is what's happening when the tach jumps that first grand. There's no palpable downshift, just an increase in rpm's that leads to an increase in power. The tranny's been doing this since 55,000 miles when I bought the car, so I doubt it's a problem. It really just seems that the torque converter has completely decoupled the engine from the transmission, and they're now spinning at completely unrelated speeds--but wouldn't that cause a lot of friction/heat/wear in the torque converter? It's like it's pretending to be a 5-speed.
Sorry for the novel. Thoughts?
So say I'm doing around 65 mph, around 2000 rpm's or so (I can't remember exactly), and I want to accelerate to get around someone. If I push the gas down a little farther, the car accelerates slowly because it's in 4th gear/overdrive. If I push it down farther than that, my tach jumps about 1 grand and the car starts accelerating a little faster, but I don't get any of the hesitation that a downshift would cause. And if I push it down even farther, I get a real 4-3 downshift (you can feel the slight hesitation during tranny transition) and my tach jumps up to 4 grand or so. And if I floor it, I get the 3-2 downshift and the very top of 2nd gear (>5000 rpm's).
What I don't understand is what's happening when the tach jumps that first grand. There's no palpable downshift, just an increase in rpm's that leads to an increase in power. The tranny's been doing this since 55,000 miles when I bought the car, so I doubt it's a problem. It really just seems that the torque converter has completely decoupled the engine from the transmission, and they're now spinning at completely unrelated speeds--but wouldn't that cause a lot of friction/heat/wear in the torque converter? It's like it's pretending to be a 5-speed.
Sorry for the novel. Thoughts?