Jack777

Hi I have had my car for a few months now and over the last week or two I have noticed a sound coming from the rear. It happens when the car is shifted from park to drive, as well as the car lowering an inch. Is there something wrong with the car or is this normal?

ItzFilyO

It's like a slight knock right?

Jack777

It's more like a compressor decompressing.

ItzFilyO

Oh I don't have that. Mine is more of a knock like the parking brake releasing.

FastTags

perhaps its the fuel door lock/unlock?

TonyCarson

I noted this also, I had my significant other put it in Drive while I was looking and the rear end raises up slightly once the car is put into drive. Reminds me of a bus that lowers as people get in then goes back to driving height. Thought it was just another amazing feature of the car but perhaps I should ask the dealer.

ItzFilyO

I think the rear raises up a little cause it's RWD and it's trying to push the car forward but the brakes are still holding it. U don't see it on FWD cars cause the front is pulling it, so it stays flat.

TonyCarson

My Z is RWD and it doesn't do this, and when I worked at an auto-body shop RWD cars didn't do it. I am not sure, I will research the matter and try to find an evidenced based answer! =)

GregCanada

If you power brake your car for a drag race, with your left foot on the brake and right on the gas, you will really see the back of the car lift.

Justin2JZ

Lift? Mine is the exact opposite. When I power brake in my car the rear squats and when I take off the front end lifts. This is like this in my 2GS, 4GS, and my BMW hell every automatic RWD car I have lol.

Afrosheen

I've read that the Sport+ mode does realtime dynamic ride height and ride quality adjustments based on conditions. Lots of accelerometers and other tech involved. It will proactively prevent the car from nosediving on hard braking and try to prevent that "boat hull up" effect on launch also.

What you're talking about, I've never experienced and I doubt you flip the **** to Sport+ before you put it in gear anyway.

GregCanada

Thats interesting, i found a few vid's and the bmw's do seem to squat (independent rear suspension) But the solid rear axle cars seem to lift
I guess this is why a proper IRS car launches better in a drag race, it significantly helps weight transfer to the rear wheels.

Jack777

Sorry for not not responding to the thread and I took the car to the dealer and they said it was just the automatic parking brake and that it's normal.

ItzFilyO

See I was right, it is the parking brake.