Behemoth7

Hey guys, I am having an issue with my gs430(120k), whenever I shift into drive or reverse the car shakes a good couple times from the rear end of the car, so it's not the tranny. If I put the brake pedal into the floor though, it doesn't happen or is very mild.

I was told by my mechanic that my rear Driveline bushing is cracked, does that have anything to do with this? And does anyone know what part he is referring to? I have a hunch that this has something to do with the rear differential or drive shaft, but I can't say for sure.

Behemoth7

I've also heard this could possibly be a problem with the brakes, since the problem practically disappears when the brakes are fully engaged.

So what do you guys think? Is this a problem with the drive shaft, differential, or brakes? I look forward to your replies

marshun

tranny mount probably

Behemoth7

Sorry I forgot to mention I replaced the motor and tranny mounts already. My first thought was tranny mount too, but like I said before I now notice that the sound comes from the rear of the car.

ThomasGS4

iTrader: (19)

Rear upper control arm bushings are toast, like mine.

Behemoth7

Thanks for the reply! How exactly do the brakes effect these? Because the car doesn't shake at all when the brake is fully depressed, but I can still feel a slight clunk from the rear.

Alphaman19

If the rim of the wheel is hot to touch after driving the car it would mean that something is lodged/dragging in that area. I had the same problem with a rear clunk recently. After taking of the rear rotor, I discovered that park brake assembly had self destructed and was the source of the clunking sound.

mk2tmr2

iTrader: (1)

When the brakes are on, the force of the car shifting into gear and applying sudden torque (albeit a small amount) to the wheels is isolated. When the brakes are not applied, this shock causes the whole car to jerk slightly - which could be why you hear a clunk coming from bushings that would otherwise prevent metal-on-metal contact.

Behemoth7

I'll have my shop check out the rear brakes and rear suspension and i'll get back to you guys, thanks for the help!

BertDeclan

Hey Behemoth-Just got my car back after similar complaint plus clicking, every time I go forward or reverse. The clicking was the Brake pad shim clips and the Loud Clunk was, believe it or not, my Frt/Lft brake rotor bolt holes had become elongated only about 1/16-1/8th". Can't believe that was causing that god awful 'Clunk/Clang' EVERY time I went forward or back. Using the brake did change the sound, but didn't eliminate it. I'd have your guy check for out of round rotor bolt holes. We didn't SEE the problem because the holes weren't elongated enough to show behind the Bolt heads, so you have to hold the hub and turn the rotor. Sounds like your issue may be something drivetrain oriented, but it's worth a look. Hope you find your 'Clunk'. Getting rid of mine was worth the cost of a pair of new rotors, definitely. GL

GSGenesis

Honestly, the clunking when shifting into drive or reverse from Park, is def. Not brake issues my man. You started off smart by replacing tranny mounts, which! Now, may even cause you to feel the real issue even more due to direct distribution through the mounts. I am experiencing this right now, best way I can make people aware is, you know that shift you have when parked on a hill, and you didn't push the E-Brake down BEFORE putting her into park? That shift that you just hear the whole cars load being taken off the tranny when shifting that makes you just hurt hearing it? Well yea that on flat it that just not as bad obviously, but on flat ground. I doubt it's got anything to do with the differential, so I'm not going to even start there, I've got a Trans from another newer GS that's got less than half of the miles that this GS that's experiencing the issue has, so I'm going to start by first: doing a complete flush of my Trans fluid, by that I mean running it with the return line off blah blah... So all the Trans fluid is new, cleaning filter and what not, and once I'm down in there I'll take a look at my mounts and what not and report back my results, if that doesn't do anything, I think my Trans will slowly start slipping some time soon here, I live up hill that I must climb EVERY day.... Multiple times a day, and it's not just a hill, it's a long, very steep, curvy road that takes you all the way to my home... Like a canyon ride type deal... My Trans hates it I guarantee it. But I'm good to them always, I never hammer the gas causing down shifts and all that unnecessary abuse, no no, I just cruise up...and if that doesn't yield the desired results, well then I'll swap the Trans and see how things feel from there to give you an idea.

tmf2004

iTrader: (15)

start with the rear fit kit on both calipers. with 120k miles maybe they haven't been replaced and are worn and stretched... Sewell or Lexuspartsnow will have the kit... start with the inexpensive things first... unfortunately sometimes its trial and error... GL

Behemoth7

Funny thing is that my tranny mount wasn't even bad when I had it replaced... It was still intact. And like I said before, the problem is in the rear, not the tranny.

My car feels like right after I shift into gear that it wants to take off in that direction, and the brakes are having a hard time holding it in place. Besides, my brakes have been very squeaky lately, so i'm going to do the brakes first and see if that fixes my issues.

Sorry to hear about your issue, but my issue is different from yours. I know that feeling your talking about, and my doesn't shake that hard. If I were you, I would have someone take a look at your e-brake assembly like Alphaman19 said.

Behemoth7

My brakes have also been very squeaky too, not just when I first start driving, but the whole time i'm driving. It's hard to tell which side the squeaking is coming from. It sounds farther away though, so i'm thinking it's the rears.

Would it still be beneficial to buy the kit first? When I took my car in, they said my brakes were fine and had plenty of pad left... Could these brakes just need some brake quiet? I haven't worked with brakes yet, so I have no idea what bad brake pads look like. The car grabs pretty well still.

ThomasGS4

iTrader: (19)

^ Bingo. That 'clunk' you hear when you put it in drive is the rear upper control arm shifting due to worn bushings.