MoonGxs

Hey guys,
I have an 09 G37xs 7AT and yesterday when driving on the hwy at around 80 traffic came to a quick stop. When braking hard the trans downshifted what felt like two gears and sent the revs way up like 5-6 grand. It definately did not feel right, anyone else have this issue?

15951

Yes - unsettling, isn't it? I had to slam on my brakes a week after I got my car, and the RPMs jumped up between (presumably) 4 and 3. I looked into it to find out if I had a major problem, and found that it was a normal characteristic of the transmission.

The input I got was that the engine braking is supposed to help you stop fast, but I think that's crap. As long as the brakes are capable of locking, the TIRES stop the car, not the brakes or the transmission.

Maybe the transmission was designed this way in anticipation of people racing the car and hammering the brakes before entering a corner. Otherwise it just doesn't make sense.

beerme986

iTrader: (2)

supposed to do that and mine does it too. car thinks you are driving aggressively so it will downshift quick for you. just enjoy the sounds of rev match

TinsleyC

It would be nice if we could turn off rev matching. I don't like it...

MoonGxs

Thanks guys. I figured as much. I am comming up to my first oil change and service at the dealer so I will make sure there is no update or reflash that it may need just in case.

SkyMG37x

Normal and designed as part of this performance driveline. It's rev matching downshift design not only helps on deceleration but also to put you in the optimal area of the torque curve should you need to quickly accelerate again.

mal_TX

Do you think that extra resistance created by engine braking helps the brakes stop the car with less heat build-up and thus less risk of brake fade if you need to stop hard again? I bet it does. I'd guesstimate at max engine brake effect we need maybe 15% less brake power to get the same stopping power.

I think its a good idea with absolutely no negative side effect, so why not do it? And, like someone else pointed out -- what if I need to accelerate quickly again in whatever crisis I am in? It is nice to be in the right gear for it just in case.

Note -- the car does this much more consistently when in Drive-Sport mode. In Drive, it only does it on very hard braking, again, I think as an assist to the brakes (just in case several hard repeated stops are necessary or something).

ged1067

I'm a guy who doesn't like to use his brakes. I don't usually drive agressively. My daughter says I don't make opportunities; I take opportunities!

I like to lope along until and unless I need, or feel I should be agressive.

Therefore I like engine braking. When I'm loping along and come to a stop light, I like to take my foot of the gas and let the engine do most of the braking until I have to step on the brake. My previous ride, Passat 4 motion, immediately slowed down when I stepped off the gas; this car doesn't and I miss it!

YMMV...GED

EnviedG35

iTrader: (2)

The transmission is designed to do this. Its called engine braking. It assists the brakes in slowing the car down faster. It wont hurt anything as the ecu will not let the rpms rev into redline.

stardust

you would rather replace the transmission? you do know how much stress rev matching takes off the trans right?

ridoor

rev-matching is preventing the jerk-like feeling of the car right? Does it eliminate engine braking coz rev matching is doing exactly the opp of engine braking.........

rehtea

This gotta be one of the funniest (misinformed) comments I have ever seen!

TinsleyC

I do wish I could turn it off. I don't like it. Get over it.

stardust

For what reason?


this should be good

csnpsu

That is def the way it is supposed to work. The tranny assist in hard brakeing.