My dad has a 98 gs400 and its having this weird issue with the brake rotor. the rotos itself is slipping between the hub and wheel when braking. It makes a knocking sound when it slams up against the lug studs. Its only happening on one side. the other is very solid. I can move the loose rotor with my hand while the other one i hit with a 2x4 and it didnt budge. I took everything off and torqued it all down. Anyone have any idea what would be causing this??

 

anyone??

 

Are the wheels original? Or aftermarket.

Toyota/Lexus cars use a free-float rotor which relies on the wheels holding the rotor on tight. Aftermarket wheels, when installed incorrectly, will allow it to wobble. The other problem could be in the caliper itself. If a bolt is missing or the caliper bracket is broken, it will allow the rotor to wobble.

The only other problem I can see, is that the hub bearing itself has failed which allows the whole thing to move around. Without being there to do it for you, its really tough to "show" you whats wrong. Start by taking off the wheel, and caliper, and trying to figure it out from there.

 

everything is stock, nothing is broken from what i can tell. everything is set properly and the wheels are torqued to 85. calipers dont move. ill go take it a part again when i get chance. it drives and stops just fine. gotta love coming home from college, you get to fix all the family cars. im in the middle of doing axle seals and rear brakes on my sisters 96 4runner. put a sound system and cb in mine so that cool but oh well.

 

Well obviously something is wrong. Everything can't be ok, otherwise you wouldn't be getting the wobbling problem

 

Deathcougar's on the right track. something is not properly seating to hold the rotor in place. Some european cars and i think some honda's the rotors are screwed to the hub by two screws. If those are gone and your dad has been driving like this for a while, I have to wonder what the wheel studs look like if the rotor has been slamming up againts them. When you were moving the rotor by hand, was the wheel still on? Maybe the other rotor is rusted in place around the hub and wouldn't move because of that. If you still think everything is okay, I'd say pull the calliper off and check the places where the brake pads ride on the caliper braket. Maybe theres a worn out spot the allows the pads to move when braking. Take some pictures of the hub the caliper the wheel throw them up on here so we can get a better look at whats goin on. Good luck.

 

its really wierd cuz the stud do not show any damage. The way i know its moving, i grab the studs and rotate the hub. The rotors are held back by the brakes until the studs catch it, then it move. I made sure all the places the wheels and rotors meet were all clean.

 

Could have sworn I said the rotors were free floating....

Just like on my Corolla, the rotors won't move (for a small amount, say 1/8") until the studs grab them because of the friction of the brake pads. If that is the only problem....your car is fine. Check the rotor to make sure the rotor holes are not hogged out as well.

 

x2 on deathcougar. The problem isnt the rotor. The clunking is coming from something else, a worn bushing on the suspension, the caliper braket, or wheel bearing. Not the rotor.

 

ok well i have narrowed it down to the steering system. It drives like it has partial power steering. If i make a turn the car does no center itself, it doesnt have a complete loss of power steering but its hard and its heard on both sides of the car. the alignment wasjust recently done and there is no abnormal wear on the tires from what i can see. To me i think its the steering rack but i also dont know what its like to have the ps steering pump go out. Another thing i noticed it the PS fluid in the resivior was clear when it says put atf in there. could that cause a poping/grinding noise?

 

You need to narrow down when the Noise happens, Braking, accelerating, at 20mph, on turns. Try to isolate the noise as much as possible.

 

Now its not in the brakes, its in the steering?

These cars are well known for having bad upper and lower control arm bushings, and ball joints. Since you claim its now not the brakes, make those the next parts you are going to check.

 

the noise happens while turning at any speed, sharper the turn the more noise. The car can be sitting stopped and i will turn the wheels and it will make the noise. i replaced the LCA within the last year. I looked at all the ball joins and bushing prying at them with a pry bar. i didnt notice any play as far as i know. i keep telling him to take it in and have professionals look at it but its been the weekend hopefully he does it soon. but it is most definately the steering system. brakes are no longer the issue.

 

sounds more like the pump is failing. If you crank it all the way to one side and its yelling at ya then there maybe air in the system or the pump is failing. Try flushing the pump with the proper fluid for the system. Other than that i'm not sure.

 

Busted CV joint?

ehhh nevermind its RWD

 

i was thinking that too. it doest struggle all the way through the range of motion. imo it doesnt have the wine of a failing ps pump. its more of a grind/ pop. hes gonna take it in here in a couple of days.

 

maybe the rack is toast?

 

ended up being shot ball joints...all fixed.