wrw1818

Hi everyone,

I'm the 2nd owner of a 2000 GS 300 platinum edition. It's got 80k miles. I need to resolve this rumbling, vibrating, fast buh-buh-buh-buh noise when braking.

1) the seller and Lexus said it's the Pirelli tires.
- front tires are cupped but have good tread (just don't provide "Lexus quality ride")
- Brake pads, steering, alignment are a-okay

2) another mechanic suspected rotors. So we turned the rotors and rotated tires.
- the noise got MORE pronounced
- is rumbling noise louder because cupped tires are on the rear ?

3) then mechanic then said wheel bearings
- bad wheel bearings at 80k miles?

Anybody heard of this vibration when braking?

GSoup

which pirelli's, what size..i have pirelli P6 on my ride and i don't have those problems..hmmm

AZDesertGS

iTrader: (4)

The cupping is responsible for the road noice....burrrrrring. Now the vibration??? Don't know. Maybe if they are cupped bad enough, they aren't as pure round anymore. Just a guess since the obvious answer for vibration while braking would be the rotors.

wrw1818

the pirelli's are P6... correct size for car (i'm don't have manual here at work but they matched okay)...

(you may get some idea from the pic - only one that's small enough to quickly attach)

wrw1818

ok, so maybe it's not a vibration... but it surrrrre is annoyin'....

question: is it best to have "bad" tires on back or front?

rheiy

To be honest, the answer is neither. You should get new tires

wrw1818

oh, buying tires is no problem! if that's really the problem. what i DONT want to do is:

1) pay lexus $90/hr in diagnostics to tell me AGAIN it's the pirelli's

2) spend $600 on michelins

then still have the noise...

3) then pay another mechanic $500 for front wheel bearings (lexus will charge $950 for front wheel bearings)...

then possibly still have the noise.... (sigh)

i'm already a few hundred dollars (and too many hours) into troubleshooting this...

AZDesertGS

iTrader: (4)

Most of the time cupping happens is because of bad shocks/struts or they are going bad. What happens is the tire is not consistantly on the ground and is bouncing.....Your not going to be able to see it bouncing obviously but that is what causes those high and low points on the tires. Sometimes its caused just by crappy tires but most of the tire its the struts/shocks.

I would suggest buying some new struts/shocks and tires and it should drive like a dream after that....and should eliminate the cupping.

Oh yeah....inconsistant tire rotations don't help the cupping as well.

wrw1818

i DO remember asking lexus in the pre-purchase inspection specifically about brakes, rotors, and shocks -- they said all were fine. they harped on pirelli's being bad for the car (2 other auto people have commented on the "cupping")...

so from tires - to wheel bearings (??) - to now hearing about shocks/struts - i kinda hope the resolution is a simple as "bad tires" (even though the pirelli P6's are sweeet lookin tires)

thanks!

AZDesertGS

iTrader: (4)

Well when they did an inspection on the struts....all they probably did is look for any leakage. Struts can be going bad even with out any leakage.

GSoup

i was thinking the same thing AZ... do the old shock test... push your car down in the front or back and see how much of a bounce you get... go to each side and you shouldn't get more than 2 bounces on it...

also cupped tire wear is an indicator of shock problems (wear/dent/damaged)...

http://www.tpub.com/content/construc.../14273_307.htm

AZDesertGS

iTrader: (4)

Have you ever seen some older car that goes over a bump and it looks like it will never stop bouncing....hahaha...... Now that is some bad shocks

wrw1818

will do "the old shock test" again...

observation: nobody picked up on the WHEEL BEARINGS theory from the original post... what do bad wheel bearings sound like?

(seems like both bearings and struts should last well over 100k miles)

AZDesertGS

iTrader: (4)

Can't determine if the wheel bearing are bad.....I wouldn't think that they would be bad...but you never know. Now the facts are that you have cupping and what cause cupping is bad struts/shocks. If money is tight...buy new/better tires now....then next month buy new struts. Process of elimination

GSquicksilver

i had cupping before and it ruined my michelin pilot sport s/p's.

it WAS caused by bad shocks. no leaks, nothing. took the shocks out, i can press them down with my thumb. installed new shocks, no more cupping, and i have PIRELLI tires too, pzero nero M+S models and they are great. they are even quieter than the michelin's.