Shortly after reaching the 2500 mile mark, my 2007 G35x started down shifting from 2nd to 1st rather abruptly and causing some major jerking. I noticed it most when slowing down and my speed is at or near 7-5 miles per hr. Has anyone else noticed this?

 

Very odd .... why would the tranny downshift to first at 15 mph ??
Its too fast !!!

If it all downshifts to 1, it should be at something like 5 mph or lower

If you can reproduce it easily, just take it to the dealer ..... its probably harming the drivetrain with that abrupt downshifts.

 

is your shifter in sports mode?

 

I just checked again and it happens between7-5 miles hr.

I'm running D mode.

 

that's pretty slow. my car downshifts early too. it might be more pronounced on the AWD version since the front tires will "dig in" and cause the body to pitch forward.

 

Don't think so - thought I read that the X will only send power to the front wheels if it finds wheel slip in the rear? You'd think that means no direct connection, and thus bite, on the front wheels at this speed?

I have not noticed this as a concern on my S, although when the car downshifts to 1st it is noticeable (partly because the brakes are already on, and this adds braking force).

 

Yes I have also experienced this. However, it does not happen on all second to first downshifts. I have also noticed that the rev matching does not work as well when going into second from third or into first from second (it is not a smooth as the other downshifts). From fifth to fourth or fourth to third it works like a charm.

 

good point. not sure how the front drive wheels work under braking forces vs acceleration forces. There could be a difference.

 

I have an X, and mine drops to first only coming to a complete stop, or very close to it, like 1-2 mph.
No jerking

 

Mine will downshift early on aggressive braking, but on light braking, the downshift is hardly noticable.
At first I didn't like how newer cars downshift when braking, but now that I am used to it, I kindof like it.

 

I was thinking it had something to do with the type of gas I'm using (BP Ultimate - 90+ octane). I've seen other threads related to the type of fuel to use, but none reference this possible side effect.