i notice that when my car attempts to shift, its very jerky, especially when i have my music very loud, when the bass hits really hard, i get really jerky shifting, i remember reading a post about this but cannot seem to find it, does anyone know whats causing this and how can i fix this?

Do you have a coupe or a sedan?

And I am guessing it is an automatic, right?


2004 G35 Coupe 6MT
Volk GT-7's/ TEIN Basics
Falken 245/35/ZR19 & 285/35ZR19
Kinetix Racing Camber Rods/ K&N Typhoon CAI

your amps are drawing too much power. The stock alternator simply can't keep up. The best way to fix it would be to get a HO alternator or just get your stock one re-wound. I don't know of an available aftermarket alt though. A capacitor will most likely not help.

i have a coupe, and yes it automatic, i have 2 amps, jl 300/4 and a jl 500/1, i was planning on selling my 500/1 to get a 1000/a but since you say its drawing too much power, i think having a 1000/1 would be worse... damn

what do you mean by gettin the alternator rewound? you mean rebuilt? how much for a stronger alternator? and do you know where i may be able to order one? i thought the bigger the alt, the more HP it will take away from your car, is that true?

Dude. Use the clutch.

Mt brother-in-law has the same issues with his 03 Sedan 5AT.

In my coupe, running a 1000/1 and a 450/4, my instirments go crasy. VDC turning on and off. The speedo looks like it is waving at you going from your speed to zero, back and forth. Lights blink, etc.

I haven't installed my cap yet so I am not sure if that helps or not.

Alternator rebuilding is a good idea. Need to find someone who will. They might be able to rebuild it up by 80 or so amps.

My brother-in-law said the problem got alot better after they put everything to 4 ohm instead of to 2 ohm. This makes sense, right? I=E/R, blah, blah, yes I think that is right.

But I am not sure with the JL amps...they are a "true rated" amp. Same power output from 1.5 ohm to 4ohm. Anybody have a DC ampmeter?


2004 G35 Coupe 6MT
Volk GT-7's/ TEIN Basics
Falken 245/35/ZR19 & 285/35ZR19
Kinetix Racing Camber Rods/ K&N Typhoon CAI

Our stock alts are rated at 110 amps. They draw with a 300/4 and a 500/1 is probably around 80-90 amps. When you are cranking it, there's not much left over for the car itself.

Rewinding/rebuilding the alt might bump that up to 160-200 amps. However, when you rebuild, you lose power at lower rpms and gain at higher rpms. I don't know if anyone's ever rebuilt a G alt but I'm sure it's possible.

In terms of going with a 4 ohm load, it shouldn't make a difference. JL claims the same output from from 1.5 to 4 ohms but the amps will put out more power on the lower end of that spectrum, just not to the same degree as other company's amps.

Hey guys I was the original member have that problem with my system. I had posted about this topic a while ago. I was pushing th 8w7 w/ a 500/1 amp. The power made the car shifting terrible,jerky and uncomfortable. It was pulling way too much power and I was told that a cap would not help the situation. My car is a lease so I didnt want to swap alternators or have mine re-wound. THerefore i just pulled the entire system out. It sucks cuz it was sounding reall good but I prefer to lose the sound than to mess up the tranny or anything else.