Hard brake triggered an extreme downshift. Normal?
10-04-2013, 09:26 AM
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Hard brake triggered an extreme downshift. Normal?
Hey all,
Sorry for the newbie question, but I'm very new to the G. I have a 2009 G37x with the 7AT I purchased last week. I had the car inspected by an Infiniti dealer and everything checked out. So far everything has been wonderful!
However, when I was driving home from work yesterday I was driving in typical Chicago rush hour traffic and was cut off bad on the highway. I had to brake HARD. I was going about 50MPH, after the brake, maybe I was going 20MPH? So after blasting my horn and waving my arms around like any other self-respecting Chicagoan would do, the transmission downshifted big time. The RPMs jumped up to about 3500 while i was going maybe 20ish MPH. My foot was still on the brake. I was caught of guard by it big time. Frankly, it scared the **** out of me. Felt like the car had a mind of its own for a second.
Does that seem normal? There's a ton of computerized components in these vehicles and I'm wondering if the transmission still has the habits of the previous owner in its memory.
Sorry for the newbie question, but I'm very new to the G. I have a 2009 G37x with the 7AT I purchased last week. I had the car inspected by an Infiniti dealer and everything checked out. So far everything has been wonderful!
However, when I was driving home from work yesterday I was driving in typical Chicago rush hour traffic and was cut off bad on the highway. I had to brake HARD. I was going about 50MPH, after the brake, maybe I was going 20MPH? So after blasting my horn and waving my arms around like any other self-respecting Chicagoan would do, the transmission downshifted big time. The RPMs jumped up to about 3500 while i was going maybe 20ish MPH. My foot was still on the brake. I was caught of guard by it big time. Frankly, it scared the **** out of me. Felt like the car had a mind of its own for a second.
Does that seem normal? There's a ton of computerized components in these vehicles and I'm wondering if the transmission still has the habits of the previous owner in its memory.
10-04-2013, 10:02 AM
#3
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That Rev Matching scares me half to death sometimes as well.
My understanding is that if it didn’t rev match then the car would lurch backwards as kinetic energy is transferred from the forward motion of the car to the engine’s crankshaft as the downshift takes place. This has the effect of upsetting the balance of the car which is what you don’t want when you’re in the middle of a high speed turn. Race car drivers, at least those who drive actual stick shifts with clutch pedals, perform a “heel and toe” downshift to accomplish this.
My understanding is that if it didn’t rev match then the car would lurch backwards as kinetic energy is transferred from the forward motion of the car to the engine’s crankshaft as the downshift takes place. This has the effect of upsetting the balance of the car which is what you don’t want when you’re in the middle of a high speed turn. Race car drivers, at least those who drive actual stick shifts with clutch pedals, perform a “heel and toe” downshift to accomplish this.
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dbeachy1 (10-12-2013)
10-04-2013, 10:26 AM
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Makes sense now. Thanks for the answer.
10-04-2013, 11:10 AM
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The first time it happened to me, I thought the transmission failed and I was like #^$^^$.
Then I asked one of my Bimmer friends (335is have had this feature since 2007) and he explained how rev matching works and it made more sense. To be honest, I wish there was a button to turn it off like there is with VDC
Then I asked one of my Bimmer friends (335is have had this feature since 2007) and he explained how rev matching works and it made more sense. To be honest, I wish there was a button to turn it off like there is with VDC
10-06-2013, 05:50 AM
#7
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LOL you guys seriously need to stop babying your cars!
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YellowJacket (10-13-2013)
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10-06-2013, 11:48 AM
#8
The first time it happened to me, I thought the transmission failed and I was like #^$^^$.
Then I asked one of my Bimmer friends (335is have had this feature since 2007) and he explained how rev matching works and it made more sense. To be honest, I wish there was a button to turn it off like there is with VDC
Then I asked one of my Bimmer friends (335is have had this feature since 2007) and he explained how rev matching works and it made more sense. To be honest, I wish there was a button to turn it off like there is with VDC
Turn it off?!? I don't know how to respond to that.
10-06-2013, 02:26 PM
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I played with it a little more. Put it in DS mode and figured out how to trigger the rev matching. Now it's no longer scaring me and I enjoy it 
vrooom!
vrooom!
10-09-2013, 08:59 PM
#10
The first time it happened to me, I thought the transmission failed and I was like #^$^^$.
Then I asked one of my Bimmer friends (335is have had this feature since 2007) and he explained how rev matching works and it made more sense. To be honest, I wish there was a button to turn it off like there is with VDC
Then I asked one of my Bimmer friends (335is have had this feature since 2007) and he explained how rev matching works and it made more sense. To be honest, I wish there was a button to turn it off like there is with VDC
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