Loud groan in brakes or suspension? halp!

[papa_g]

I bought an automatic '05 coupe in September. 87k miles. I noticed immediately there is this loud, abrupt groaning sound right before the car comes to a complete halt, and when changing from drive to reverse & vis-versa. Per PPI, the brake pads were at 85%, the control arms/bushings and rear shocks needed to be replaced. Also the brakes desperately needed a flush as there was still super blue fluid in there. I took care of all the above, thinking this would solve my issues. Nothing has changed in regards to this groaning sound.
Imagine this. You are stopped in the garage. Your foot is on the break and you put the car in reverse. There is a slight lurch backward, with a short groan as well. You back out of the garage while applying the break, and there is no squeal or whine from the brakes. Right before you stop reversing, another groan. You put the gear in drive; a small lurch forward with an associated groan. I think this is an easy diagnosis to those versed in the brakes and suspension of these cars. Sadly, I know very little.

Any help would be appreciated. I hope it is something as simple as tightening a suspension or frame component.

[SaltyNC]

Since it is easy to do, it might be worth loosening the sway bar brackets and greasing the inner rubber that contacts the sway bar.

Does it sound like this?
https://www.youtube.com/watch?v=4ODcxWm4Icg

Salty

[papa_g]

I have a feeling it is associated with the sway bars, i just can't believe the shop that did my PPI didn't pin point the noise. It does kind of sound like that vid, but it's much louder, much more pronounced and often has a high pitched squeal associated with it. I asked my brother to stand by the car while I moved and stopped, as well as shifted between park, drive and reverse. He says when I put it into reverse and drive, he noticed the back end rise and fall a little, respectively, and heard the sound coming from the rear when that happened. When just braking, he couldn't really pinpoint the sound. I wish i knew someone with a lift so i could just walk under the car and look at everything from a good vantage point.

[SaltyNC]

I know what you mean about the lift. I always get a little jealous when I read about our European friends that have rent-a-garages. Man, that would be so handy, and they seem to be common in some European countries.

Salty

[papa_g]

There's a self service garage where I live that rents for $40/hour, including lift and 450+ tools. But knowing me, I am very meticulous and take a long time doing anything with the car. I would end up paying a lot more than I feel comfortable with. If I knew I could diagnose and fix the job in an hour, I would do it. Hopefully someone on the forum knows exactly what I am talking about and can tell me how to fix it.

[papa_g]

Just started doing more research. I am not sure if the "lurch" i feel when shifting to drive or reverse is normal. Also, the back end moving up and down when shifting also seems suspect. Read some stuff about rear diff bushing or transfer case bushings going bad. Any other insights?

[Newjack]

Just started doing more research. I am not sure if the "lurch" i feel when shifting to drive or reverse is normal. Also, the back end moving up and down when shifting also seems suspect. Read some stuff about rear diff bushing or transfer case bushings going bad. Any other insights?

I don't have an automatic, but a slight lurch when switching from drive to reverse sounds pretty normal to me. Instead of a clutch, you have a torque converter which sends power to the wheels. It keeps spinning even when the brakes are pressed and it wants to keep moving, that's why the lurch is there.

I think SaltyNC called it with the sway bar bushings. It would explain your sound issue. Start with those bushings and see if the noise persists. Cars are just one of those things that you sometimes have to guess what the issue is and just start replacing things until you find the issue. Ask me about my cooling system...

Someone with an auto might chime in about the drive to reverse issue

[papa_g]

I am getting an alignment tomorrow at Firestone, I will have them inspect my brakes and suspension in detail while they have the car on the lift. Hopefully they find the issue.

[Newjack]

Post back and let us know what they find

[papa_g]

Got my alignment. I asked them to check brakes and suspension, and they told me the car was "pad slapped", which basically means new pads were put on without putting on new rotors which were needed as well. I know very little about brakes, but and Indy BMW shop in San Francisco said the brakes were fine. Also, my friends and I don't see anything wrong with the rotors. Long story short, they tried to quote me $1,600 to do all the brakes, and rear control arms and nothing was solved.